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Factors influencing low temperature performance of EPDM compounds.



Elastomers, unlike thermoplastic materials thermoplastic materials

materials used in making casts for broken limbs. Malleable when warmed in hot water or heated with a hairdrier, very quick setting and very strong, e.g. Hexcelite.
, are normally required to perform over a relatively wide range of temperatures and significantly above their glass transition temperature The glass transition temperature is the temperature below which the physical properties of amorphous materials vary in a manner similar to those of a solid phase (glassy state), and above which amorphous materials behave like liquids (rubbery state).  ([T.sub.g]). The advantage of an elastomer elastomer (ĭlăs`təmər), substance having to some extent the elastic properties of natural rubber. The term is sometimes used technically to distinguish synthetic rubbers and rubberlike plastics from natural rubber.  over a thermoplastic A polymer material that turns to liquid when heated and becomes solid when cooled. There are more than 40 types of thermoplastics, including acrylic, polypropylene, polycarbonate and polyethylene.  material is its ability to recover almost completely from an elongated e·lon·gate  
tr. & intr.v. e·lon·gat·ed, e·lon·gat·ing, e·lon·gates
To make or grow longer.

adj. or elongated
1. Made longer; extended.

2. Having more length than width; slender.
 state (high flexibility), as well as having generally high resilience resilience (r·zilˑ·yens),
n
, low hardness and low modulus See modulo.  characteristics.

When elastomers are used at below ambient temperatures Outside temperature at any given altitude, preferably expressed in degrees centigrade. , there is a trend toward increased hardness, increased modulus, decreased flexibility (lower elongation elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the planet as measured from the earth. ) and increased compression compression, external stress applied to an object or substance, tending to cause a decrease in volume (see pressure). Gases can be compressed easily, solids and liquids to a very small degree if at all.  set (ref. 1). Depending on the elastomer in question, two types of phenomena can occur simultaneously--glassy stiffening stiff·en  
tr. & intr.v. stiff·ened, stiff·en·ing, stiff·ens
To make or become stiff or stiffer.



stiff
 and partial crystallization Crystallization

The formation of a solid from a solution, melt, vapor, or a different solid phase. Crystallization from solution is an important industrial operation because of the large number of materials marketed as crystalline particles.
. Some examples of elastomers that exhibit crystallization are natural rubber, polychloroprene and ethylene ethylene (ĕth`əlēn') or ethene (ĕth`ēn), H2C=CH2, a gaseous unsaturated hydrocarbon. It is the simplest alkene.  propylene propylene /pro·pyl·ene/ (pro´pi-len) a gaseous hydrocarbon, CH3CHdbondCH2.

propylene glycol  a colorless viscous liquid used as a humectant and solvent in pharmaceutical preparations.
 diene Dienes are hydrocarbons which contain two double bonds. Dienes are intermediate between alkenes and polyenes. Classes
Dienes can be divided into three classes:
  1. Unconjugated dienes have the double bonds separated by two or more single bonds.
 elastomers (EPDM EPDM Ethylene-Propylene-Diene-Monomer
EPDM Enterprise Product Data Management
EPDM Ethylene Propylene Dimonomer (industrial/commercial piping/plumbing components)
EPDM Engineering Product Data Management
).

In this article, we will examine the factors influencing the low temperature performance of EPDM compounds, such as ethylene content, diene level, molecular weight and influence of plasticizer plas·ti·ciz·er  
n.
Any of various substances added to plastics or other materials to make or keep them soft or pliable.


plasticizer or -ciser
Noun
 selection. We will also review briefly the various low temperature tests currently in use in the industry.

Experimental

The compound preparation for this work was carried out using a BR 82 internal mixer mixer, either of two electronic devices in which two or more signals are combined. In the type of mixer used in radio receivers, radar receivers, and similar systems, a signal is translated upward or downward in frequency. . Standard laboratory mill mixing procedures were used to incorporate the curatives in a separate mixing step. All the physical tests were carried out according to according to
prep.
1. As stated or indicated by; on the authority of: according to historians.

2. In keeping with: according to instructions.

3.
 ASTM ASTM
abbr.
American Society for Testing and Materials
 methods. A listing of these tests is shown in table 1.

The blooming A condition with older CCD devices that causes distortion at the pixel level. It occurs when the electrical charge created exceeds the storage capacity of the device and spills over into adjacent pixels. Newer CCDs incorporate anti-blooming circuitry to drain the excess charge. See CCD.  test was performed according to GM 6259 M, except that specimens from cured tensile tensile,
adj having a degree of elasticity; having the ability to be extended or stretched.
 sheets were employed. This test is performed by exposing the test specimens to alternating alternating /al·ter·nat·ing/ (-nat?ing)
1. occurring in regular succession.

2. alternately direct and reversed.
 environments of -30[degrees]C and 100[degrees]C for specified spec·i·fy  
tr.v. spec·i·fied, spec·i·fy·ing, spec·i·fies
1. To state explicitly or in detail: specified the amount needed.

2. To include in a specification.

3.
 lengths of time and reporting any change in the surface appearance (blooming, discoloration dis·col·or·a·tion  
n.
1.
a. The act of discoloring.

b. The condition of being discolored.

2. A discolored spot, smudge, or area; a stain.

Noun 1.
, etc).

In order to simplify discussions around the various EPDM polymers used, a simple nomenclature nomenclature /no·men·cla·ture/ (no´men-kla?cher) a classified system of names, as of anatomical structures, organisms, etc.

binomial nomenclature
 is employed. The first number signifies the Mooney Mooney is family name, which is probably predominantly derived from the Irish Ó Maonaigh. It can also be spelled Moony, Meaney, Mauney, Moon, Money. The word can refer to: Companies
  • Mooney Airplane Company
People
Meaney spelling
 viscosity (ML 1+4 @ 125[degrees]C). The second number provides an indication of the diene content as a percentage. The third number shows the relative ethylene content, while the fourth provides an indication of the amount of oil added to the polymers. None of the polymers used in this study was oil extended. Thus, the last number is always a zero. For example, polymer polymer (pŏl`əmər), chemical compound with high molecular weight consisting of a number of structural units linked together by covalent bonds (see chemical bond).  A (3440) has a Mooney of 28, ENB content of 4, ethylene content of 48 and no oil added. A complete listing of the polymers and other compounding ingredients is given in table 2. All formulations used are shown in table 3.

Results and discussions

Low temperature testing review

The low temperature tests used in this article are shown in table 1, along with their test identification. Brittleness Brittleness

That characteristic of a material that is manifested by sudden or abrupt failure without appreciable prior ductile or plastic deformation.
, compression set, retraction In the law of Defamation, a formal recanting of the libelous or slanderous material.

Retraction is not a defense to defamation, but under certain circumstances, it is admissible in Mitigation of Damages. Cross-references

Libel and Slander.
, stiffening and low temperature hardening hardening, in metallurgy, treatment of metals to increase their resistance to penetration. A metal is harder when it has small grains, which result when the metal is cooled rapidly.  have been used for many years to characterize the performance of polymers at low temperatures. Compressive stress Compressive stress is the stress applied to materials resulting in their compaction (decrease of volume). When a material is subjected to compressive stress, then this material is under compression. Usually, compressive stress applied to bars, columns, etc. leads to shortening.  relaxation re·lax·a·tion
n.
1. The act of relaxing or the state of being relaxed.

2. Refreshment of body or mind.

3. A loosening or slackening.

4. The lengthening of inactive muscle or muscle fibers.
 is relatively new and used mainly to determine the sealing force of materials over time under various environmental conditions. The blooming test is used to determine compatibility of various compounding ingredients when subjected to environmental temperature swings and, here in particular, to evaluate the plasticizer systems. We will briefly review how each of these tests is performed.

Brittleness point

ASTM D 2137 defines brittleness point as the lowest temperature at which a rubber vulcanizate will not exhibit cracking cracking - cracker  or fracture fracture, breaking of a bone. A simple fracture is one in which there is no contact of the broken bone with the outer air, i.e., the overlying tissues are intact. In a comminuted fracture the bone is splintered.  when subjected to specified impact conditions. Five rubber specimens are die cut to a pre-determined shape and conditioned in a chamber or liquid medium to the desired test temperature for 3 [+ or -]0.5 minutes, then subjected to an impact speed of 2.0 [+ or -]0.2 m/sec. The samples are removed and examined for cracking or fractures Fractures Definition

A fracture is a complete or incomplete break in a bone resulting from the application of excessive force.
Description
. None is permitted to fail. The test is repeated until the brittleness point--lowest temperature of non-failure is found to the nearest 1[degrees]C.

Compression set and hardening at low temperatures

Low temperature compression set is run very similarly to the standard compression set procedures, except the temperature is held at the desired temperature through the use of a cold box controlled by some source such as dry ice, liquid nitrogen Noun 1. liquid nitrogen - nitrogen in a liquid state
atomic number 7, N, nitrogen - a common nonmetallic element that is normally a colorless odorless tasteless inert diatomic gas; constitutes 78 percent of the atmosphere by volume; a constituent of all living
 or mechanical means to within [+ or -] 1[degrees]C of the desired temperature. Recovery after removal from the jig jig, dance of English origin that is performed also in Ireland and Scotland. It is usually a lively dance, performed by one or more persons, with quick and irregular steps. When the jig was introduced to the United States, it was often danced in minstrel shows.  is then performed at this desired low temperature as well. The specimens are usually molded mold 1  
n.
1. A hollow form or matrix for shaping a fluid or plastic substance.

2. A frame or model around or on which something is formed or shaped.

3. Something that is made in or shaped on a mold.
 buttons with the dimensions of 29 mm in diameter diameter - The diameter of a graph is the maximum value of the minimum distance between any two nodes.  and 12.5 mm thick. Low temperature compression set is an indirect method to relate compound performance to sealing applications. Compressive stress relaxation is a direct method and will be discussed later.

Low temperature hardening is generally also measured on cured compression set buttons (29 mm by 12.5 mm), but again tested at a low temperature controlled by the same methods as the low temperature compression set testing. Once again, the hardness is measured at the same temperatures as they were conditioned.

Hardening and low temperature compression set are influenced directly by the decrease in temperature, but also by the tendency of the polymer to crystallize crys·tal·lize also crys·tal·ize  
v. crys·tal·lized also crys·tal·ized, crys·tal·liz·ing also crys·tal·iz·ing, crys·tal·liz·es also crys·tal·iz·es

v.tr.
1.
. The rate of crystallization is temperature dependent. For example, polychloroprene compounds tend to crystallize fastest around--10[degrees]C, and crystallization slows down again at low temperatures, most likely due to the immobility immobility

standing still and disinclined to move, as in an animal suddenly blinded; responds to other stimuli unless immobility is part of a dummy syndrome when all stimuli are ignored.
 of the polymer chains (frozen before they can realign re·a·lign  
tr.v. re·a·ligned, re·a·lign·ing, re·a·ligns
1. To put back into proper order or alignment.

2. To make new groupings of or working arrangements between.
) (ref. 1).

Stiffening at low temperatures (Gehman)

ASTM D 1053 describes the test method for low temperature stiffening as: "A specimen SPECIMEN. A sample; a part of something by which the other may be known.
     2. The act of congress of July 4, 1836, section 6, requires the inventor or discoverer of an invention or discovery to accompany his petition and specification for a patent with specimens
 of flexible polymer is secured and connected in series to a wire of known torsional tor·sion  
n.
1.
a. The act of twisting or turning.

b. The condition of being twisted or turned.

2.
 constant, while the other end of the wire is attached to a torsion head 1. That part of a torsion balance from which the wire or filament is suspended.  to allow a twist to the wire. The specimen is immersed im·merse  
tr.v. im·mersed, im·mers·ing, im·mers·es
1. To cover completely in a liquid; submerge.

2. To baptize by submerging in water.

3.
 in a heat transfer medium at a specified subnormal subnormal /sub·nor·mal/ (-nor´m'l) below normal.

subnormal

below or less than normal.
 temperature. The torsion head is then twisted 180[degrees] and in turn twists the specimen by some amount (less than 180[degrees]) that is dependent on the specimen's compliance or inverse (mathematics) inverse - Given a function, f : D -> C, a function g : C -> D is called a left inverse for f if for all d in D, g (f d) = d and a right inverse if, for all c in C, f (g c) = c and an inverse if both conditions hold.  stiffness stiffness

half way to rigidity, tetany; result of insufficient use of the part.
. The amount of the specimen's twist is then measured with a protractor protractor

Instrument for constructing and measuring plane angles. The simplest protractor is a semicircular disk marked in degrees from 0° to 180°. A more complex protractor, for plotting position on navigation charts, is called a three-arm protractor, or station
. The angle of twist is related to the stiffness of the compound. The temperature is then systematically raised in increments, and the angle of twist plotted versus temperature. Temperatures to reach modulus increases of T2, T5, T10 and T100 relative to the specimen's modulus value at room temperature, are generally recorded." (ref. 2).

Retraction at low temperatures (TR test)

Where compression set and compression stress relaxation Stress relaxation describes how polymers relieve stress under constant strain. Because they are viscoelastic, polymers behave in a nonlinear, non-Hookean fashion.[1]  use compressive com·pres·sive  
adj.
Serving to or able to compress.



com·pressive·ly adv.
 forces to measure the effect of low temperature, retraction (TR test) uses measurement under tension to evaluate the specimen's capability. As mentioned earlier, many polymers such as natural rubber and polychloroprene will crystallize at low temperatures, but they can also strain crystallize as well, leading to additional factors when investigating low temperature performance. For applications performed under tension, such as exhaust Exhaust may refer to:

In mathematics:
  • Proof by exhaustion, proof by examining all individual cases
  • Exhaustion by compact sets, in analysis, a sequence of compact sets that converges on a given set
 hangers hangers

used for hanging x-ray films to dry. There is a clip type, with a clip at each corner, and a channel type in which the film sits in channels in the sides of the frame.
, low temperature retraction (TR) is a very suitable test and is used frequently.

In this test, a specimen is elongated (usually 50 or 100%) and frozen in an elongated state. The specimen is released and the temperature is increased at a fixed rate while measuring the recovery of the specimen. The length of retraction is measured and recorded as a percentage. Temperatures when the specimen retracts 10, 30, 50 and 70% are generally recorded as TR10, TR30, TR50 and TR70. It is said that TR10 correlates to brittleness point, TR70 to low temperature compression set and the difference between TR10 and TR70 provides a measure of crystallization of the specimen (the greater the difference, the greater the crystallization tendency [ref. 3]).

Compressive stress relaxation (CSR (1) (Customer Service Representative) A person who handles a customer's request regarding a bill, account changes or service or merchandise ordered. Agents in call centers are known as CSRs. See call center. ) at low temperature Compressive stress relaxation (CSR) testing may be used as a prediction "Prediction is very difficult, especially if it's about the future." - Niels Bohr

A prediction is a statement or claim that a particular event will occur in the future in more certain terms than a forecast.
 of the performance and lifetime of sealing materials Noun 1. sealing material - any substance used to seal joints or fill cracks in a porous surface
material, stuff - the tangible substance that goes into the makeup of a physical object; "coal is a hard black material"; "wheat is the stuff they use to make bread"
 (ref. 4). An elastomeric compound develops a resultant force (Mech.) a force which is the result of two or more forces acting conjointly, or a motion which is the result of two or more motions combined. See Composition of forces, under Composition.

See also: Resultant
 when subjected to a constant deformation deformation /de·for·ma·tion/ (de?for-ma´shun)
1. in dysmorphology, a type of structural defect characterized by the abnormal form or position of a body part, caused by a nondisruptive mechanical force.

2.
. The ability of the material to maintain this force over a range of environmental conditions is a measure of its sealing ability. Physical and chemical mechanisms are responsible for stress relaxation and, depending on time and temperature, one will dominate the other. Physical relaxation is observed ob·serve  
v. ob·served, ob·serv·ing, ob·serves

v.tr.
1. To be or become aware of, especially through careful and directed attention; notice.

2.
 at low temperatures and immediately after a strain is applied. This results in a rearrangement re·ar·range  
tr.v. re·ar·ranged, re·ar·rang·ing, re·ar·rang·es
To change the arrangement of.



re
 of chain entanglements and changes in the rubber-filler and filler-filler interactions. The relaxation is reversible reversible,
adj capable of going through a series of changes in either direction, forward or backward (e.g., reversible chemical reaction).

reversible hydrocolloid,
n See hydrocolloid, reversible.
 upon removal of the strain to the system. Chemical components dictate TO DICTATE. To pronounce word for word what is destined to be at the same time written by another. Merlin Rep. mot Suggestion, p. 5 00; Toull. Dr. Civ. Fr. liv. 3, t. 2, c. 5, n. 410.  the rate of relaxation at higher temperatures and when the physical processes have diminished di·min·ish  
v. di·min·ished, di·min·ish·ing, di·min·ish·es

v.tr.
1.
a. To make smaller or less or to cause to appear so.

b.
. Chemical relaxation is irreversible irreversible (ir´ēvur´sebl),
adj incapable of being reversed or returned to the original state.
, leading to chain scission scis·sion
n.
1. A separation, division, or splitting, as in fission.

2. See cleavage.
 and crosslinking reactions (ref. 5).

Temperature cycling or a sudden increase in temperature can have an effect on the stress relaxation of an elastomer. The relaxation process is accelerated when a test piece is subjected to an increase in temperature during a CSR test. The amount of additional relaxation increases when it occurs earlier in the testing, and it is at its greatest in the first cycle (ref. 6).

Washer washer Orthopedics A flattened disk of metal with a central hole used to distribute stress under a screw head to prevent thin cortical bone from splitting; serrated washers are used to affix avulsed ligaments, small avulsion fractures or comminuted fractures to the  samples (19 mm OD, 15 mm ID) were punched out from a tensile macro sheet. The samples were compressed in an Elastocon jig by 25% of their room temperature thickness thickness (thik´nes) a measurement across the smallest dimension of an object.

triceps skinfold (TSF) thickness
 and placed in an environmental test chamber at 25[degrees]C. The temperature was maintained at 25[degrees]C for a period of 24 hours. The temperature was then dropped to -20[degrees]C and held for 24 hours Adv. 1. for 24 hours - without stopping; "she worked around the clock"
around the clock, round the clock
. The temperature was subsequently cycled from -20[degrees]C to 110[degrees]C in 24 hour periods. Counterforce coun·ter·force  
n.
A contrary or opposing force, especially a military force capable of destroying the nuclear armaments of an enemy.


 measurements were made continuously throughout the testing period at the test temperature.

Bloom/bleed testing--GM 6259 M

This test is performed by placing specimens (for our testing modified mod·i·fy  
v. mod·i·fied, mod·i·fy·ing, mod·i·fies

v.tr.
1. To change in form or character; alter.

2.
 to half tensile panels versus tubing) in alternating environments of low temperature of -30[degrees]C in a cold chamber and 100[degrees]C in a forced hot air oven It has been suggested that , , , , and be merged into this article or section.  for specified periods of time, and observing observing,
v 1. to look or notice through visual inspection.
2. to quietly look at the client's inhalation and exhalation patterns to discern the breath wave and perceive areas that need therapeutic intervention.
 the specimens for any signs of blooming or bleeding bleeding /bleed·ing/ (-ing)
1. the escape of blood, as from an injured vessel.

2. phlebotomy.


dysfunctional uterine bleeding
 that would suggest incompatibility The inability of a Husband and Wife to cohabit in a marital relationship.


incompatibility n. the state of a marriage in which the spouses no longer have the mutual desire to live together and/or stay married, and is thus a ground for divorce
. In our case, we were specifically looking at the impact of plasticizers plasticizers

mostly triaryl phosphates, such as tricresyl, triphenyl phosphates, which are poisonous. See also triorthocresyl phosphate.
 on bleeding (paraffinic oils versus ester plasticizers).

EPDM elastomers

EPDM elastomers are terpolymers of ethylene, propylene and a diene material--the most common being ENB (ethylidene ethylidene /eth·yl·i·dene/ (eth´il-i-den) the bivalent radical CH3CHdbond; its chloride derivative is used as a solvent and fumigant and is toxic and irritant.

eth·yl·i·dene
n.
 norbornene Norbornene or norbornylene or norcamphene is a bridged cyclic hydrocarbon. It is a white solid with a pungent sour odor. The molecule consists of a cyclohexene ring bridged with a methylene group in the para position. ). An example of the structure for EPDM is shown in figure 1.

[FIGURE 1 OMITTED]

Influence of ethylene content

Of the EPDM polymer properties, ethylene content has the largest impact on low temperature behavior. Polymers with ethylene contents varying from 48% to 72% were evaluated in a high quality seal seal, in zoology
seal, carnivorous aquatic mammal with front and hind feet modified as flippers, or fin-feet. The name seal is sometimes applied broadly to any of the fin-footed mammals, or pinnipeds, including the walrus, the eared seals (sea lion and fur
 formulation formulation /for·mu·la·tion/ (for?mu-la´shun) the act or product of formulating.

American Law Institute Formulation
 (table 3, formulation 1). All attempts to minimize In a graphical environment, to hide an application that is currently displayed on screen. For example, in Windows and Mac, the application's window is removed from the screen and represented by an icon on the Windows Taskbar. In the Mac, the icon is placed in the Dock. See Win Minimize windows.  changes to Mooney and ENB were taken between these different polymers.

If the ethylene/propylene ratio is about equal and the distribution of both monomers in the polymer chain is random, then the EPDM rubber EPDM rubber (ethylene propylene diene monomer rubber) is an elastomer which is characterized by wide range of applications. EPDM rubber is used in vibrators and seals; glass-run channel; radiator, garden and appliance hose; tubing; washers; belts; and electrical insulation.  is amorphous Unorganized or vague. A lack of structure. For example, the amorphous state of a spot on a rewritable optical disc means that the laser beam will not be reflected from it, which is in contrast to a crystalline state which will reflect light. See crystalline. . This effect can be seen from the DSC (1) (Digital Signal Controller) A microcontroller and DSP combined on the same chip. It adds the interrupt-driven capabilities normally associated with a microcontroller to a DSP, which typically functions as a continuous process. See microcontroller and DSP.  curves of EPDM polymers with different ethylene content, as shown in figure 2. Both the 48 and 54% ethylene polymers have no crystallization occurring at or above room temperature. When an ethylene content of about 65% is reached, ethylene sequences begin forming in increasing numbers and length, and are capable of forming crystallites. These crystallites are observed in the DSC curves as crystalline Like a crystal. It implies a uniform structure of molecules in all dimensions. For example, phase change technology, widely used for rewritable optical discs, uses crystalline spots (bits) to reflect the laser beam. Amorphous, non-crystalline bits do not reflect light.  peaks at approximately ap·prox·i·mate  
adj.
1. Almost exact or correct: the approximate time of the accident.

2.
 40[degrees]C. The larger the DSC crystalline peaks, the larger the crystals formed.

[FIGURE 2 OMITTED]

In addition to the effects of ethylene content on low temperature properties, which will be discussed momentarily mo·men·tar·i·ly  
adv.
1. For a moment or an instant.

2. Usage Problem In a moment; very soon.

3. Moment by moment; progressively.
, the size of the crystallites influences the ease at which compounds containing them can be mixed and pro-cessed. The larger the size of the crystallites, the more work in the form of heat and shear shear: see strength of materials.
Shear

A straining action wherein applied forces produce a sliding or skewing type of deformation.
 that is required in the mixing stage to get adequate dispersion dispersion, in chemistry
dispersion, in chemistry, mixture in which fine particles of one substance are scattered throughout another substance. A dispersion is classed as a suspension, colloid, or solution.
 of the polymer and other ingredients. The green strength of the EPDM compound increases as the level of ethylene increases, as shown in figure 3. In the seal formulation used to test the influence of ethylene, the green strength increased at least four-told from 50% ethylene to 68% ethylene. Hardness at room temperature also increases as the ethylene content increases (table 4). The compounds with am-orphous polymers had a hardness of about 63 durometer Du`rom´e`ter

n. 1. An instrument for measuring the degree of hardness; especially, an instrument for testing the relative hardness of steel rails and the like.
 A, while the highest ethylene polymer gave a hardness of 79 durometer A. This is due to the increase in ethylene sequencing, the development of crystallites and consequently a more thermoplastic polymer in the compound.

[FIGURE 3 OMITTED]

When testing hardness at low temperatures, the amorphous polymers show less hardness change as opposed op·pose  
v. op·posed, op·pos·ing, op·pos·es

v.tr.
1. To be in contention or conflict with: oppose the enemy force.

2.
 to the higher ethylene polymers (table 4). While the change in hardness does not appear to be linear with higher ethylene, one needs to keep in mind the higher hardness at room temperature. Thus, the higher ethylene containing polymers still have the highest hardness values at low temperatures.

Compression set is highly dependent on test temperature (figure 4). If one tests at 175[degrees]C, there is no difference in compression set between any of the polymers tested (the set is a function of the compound design and cure system used). The ethylene crystallites have melted melt  
v. melt·ed, melt·ing, melts

v.intr.
1. To be changed from a solid to a liquid state especially by the application of heat.

2.
, and the polymer behaves as if it is amorphous. Testing at 23[degrees]C already begins to show the influence of ethylene content, with the higher ethylene polymer having noticeably no·tice·a·ble  
adj.
1. Evident; observable: noticeable changes in temperature; a noticeable lack of friendliness.

2. Worthy of notice; significant.
 higher set (more than doubled). When testing at -20[degrees]C and -40[degrees]C, the effects of ethylene are even stronger. Polymers with ethylene content above 60% showed high set (greater than 80%); while only the completely amorphous polymer (3440) provided low set values at -40[degrees]C (17% set).

[FIGURE 4 OMITTED]

Figure 5 shows the impact of ethylene content on stiffening at low temperatures as measured by the Gehman test. At a given temperature, the higher the twist angle, the lower the stiffness increase (or modulus increase). The graph graph, figure that shows relationships between quantities. The graph of a function y=f (x) is the set of points with coordinates [x, f (x)] in the xy-plane, when x and y are numbers.  clearly shows that as the ethylene content increases, the stiffening modulus increases drastically dras·tic  
adj.
1. Severe or radical in nature; extreme: the drastic measure of amputating the entire leg; drastic social change brought about by the French Revolution.

2.
 at low temperature. T2 and T100 values are shown in table 4 and for the amorphous polymer (3440), the T2 is -47[degrees]C while the highest ethylene polymer (2370) it is only -16[degrees]C.

[FIGURE 5 OMITTED]

Temperature retraction (TR) measures retraction recovery after a specimen has been frozen under extension. Again, ethylene content has a large impact on this test method, similar to the Gehman test. Figure 6 shows retraction % versus temperature for the various polymers tested. The amorphous polymer (3440) has the highest retraction recovery at low temperature; while, as expected, recovery at a given temperature is poorer as the ethylene content increases. TR10 values are shown in table 4 and vary from -53[degrees]C for the amorphous polymer to -28[degrees]C for the high ethylene grade.

[FIGURE 6 OMITTED]

Compressive stress relaxation (CSR) cycling is shown in figure 7 for compounds containing the polymers 3440 (A, amorphous) and 2370 (E, crystalline) only. The compounds were compressed and allowed to relax re·lax
v.
1. To make or become lax or loose.

2. To relieve or become relieved from tension or strain.
 at 25[degrees]C for 24 hours, then subjected to temperature cycling from -20[degrees]C to 110[degrees]C in 24 hour intervals. When first compressed, the crystalline polymer (E) shows a much higher force loss after the equilibrium equilibrium, state of balance. When a body or a system is in equilibrium, there is no net tendency to change. In mechanics, equilibrium has to do with the forces acting on a body.  period than the amorphous polymer. When lowered to -20[degrees]C, both polymers show a drop in sealing force, with the amorphous polymer (A) showing the higher force retention (higher F/[F.sub.0]). Heating the compound back to 110[degrees]C shows a recovery in sealing force. When re-cooling to -20[degrees]C, the crystalline polymer retains less than 20% of its sealing force, which is generally considered too low for most applications. The amorphous polymer retains over 50%. Again, the amorphous polymer shows higher recovery than the crystalline polymer. Subsequent cycling showed similar results. Clearly, amorphous polymers are superior for sealing applications requiring both low and high temperature performance.

[FIGURE 7 OMITTED]

Influence of diene content

Non-conjugated diene monomers such as ethylidene norbornene (ENB), hexadiene (HX) and dicyclopentadiene Dicyclopentadiene, abbreviated DCPD, is the chemical compound with the formula C10H12. At room temperature, it is a white crystalline solid with a camphor-like odor.  (DCPD DCPD Dicyclopentadiene
DCPD Direct Current Potential Drop
DCPD Direct Compensation Property Damage (automobile insurance coverage)
DCPD Daly City Police Department (California)
DCPD Directional Canister Passage Detector
) are added to ethylene propylene polymers to provide unsaturation un·sat·u·rat·ed  
adj.
1. Of or relating to an organic compound, especially a fatty acid, containing one or more double or triple bonds between the carbon atoms.

2. Capable of dissolving more of a solute at a given temperature.
 sites for curing purposes. One double bond reacts in the polymer matrix, while the second is pendant pendant
 or pendent

In architecture, a sculpted ornament suspended from a vault or ceiling, especially an elongated boss (carved keystone) at the junction of the intersecting ribs of the fan vaulting associated with the English Perpendicular style.
 to the polymer chain and provides a site for sulfur sulfur or sulphur (sŭl`fər), nonmetallic chemical element; symbol S; at. no. 16; at. wt. 32.06; m.p. 112.8°C; (rhombic), 119.0°C; (monoclinic), about 120°C; (amorphous); b.p. 444.674°C;; sp. gr. at 20°C;, 2.  curing. Figure 1 provides an illustration of EPDM using ENB, which is the most common diene used and is discussed further in this article.

The influence of ENB was evaluated in a weather strip profile. The formulation is shown in table 3, formulation 2. Polymers with 2%, 6% and 8% ENB were compared.

The addition of ENB has a considerable impact on curing properties and crosslink density, as illustrated in table 5. The modulus increases while the elongation decreases significantly. Hardness increases and compression set at elevated temperatures is improved. The scorch times are shorter as the level of ENB increases.

ENB is an amorphous material. When it is added to the polymer backbone backbone: see spinal column.


The part of a network that handles the major traffic. It employs the highest-speed transmission paths in the network and may also run the longest distances.
, it is capable of disrupting the crystallinity Crystallinity refers to the degree of structural order in a solid. In a crystal, the atoms or molecules are arranged in a regular, periodic manner. In a gas, the relative positions of the atoms or molecules are completely random.  of the ethylene segments that are formed. Hence, one would expect polymers with the same ethylene level but higher ENB levels to have improved low temperature properties.

At room temperature, higher ENB provides slightly better compression set due to the improved crosslink density, as shown in table 5. But in the low temperature tests, the higher ENB polymers are clearly better than the polymer with only 2% ENB (polymer I 6250), especially at -40[degrees]C.

Figure 8 shows the impact of ENB on brittleness point, low temperature retraction and Gehman testing. Generally, there is no significant difference between the polymers in brittleness point. For Gehman and TR testing, in each case the low temperature performance is improved by the increase in ENB content.

[FIGURE 8 OMITTED]

Influence of Mooney viscosity on low temperature performance

It is well known that Mooney viscosity (molecular weight) has a significant impact on processing behavior of elastomeric compositions. Mooney selection is critical for having the proper compound viscosity for extrusion and injection molding injection molding
n.
A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold.
 applications. The influence of Mooney viscosity on low temperature was evaluated in the same formulation as was ENB (weatherstrip formulation; table 3). Polymers with Mooney viscosities of 30, 60 and 80 Mooney units were compared. The compound Mooney viscosity increases relative to the viscosity of the polymer that was used, as shown in table 6.

Figure 9 demonstrates the impact of Mooney viscosity on the strength properties of the compound tested. As Mooney increases, tensile strength tensile strength

Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its
, modulus and green strength all in crease crease (kres) a line or slight linear depression.

flexion crease , palmar crease
.

[FIGURE 9 OMITTED]

Low temperature properties are not significantly impacted by Mooney viscosity, as indicated in table 6. Likewise, there is no trend in improved compression set at room temperature, -20[degrees]C and -40[degrees]C with increased molecular weight. Compression set at elevated temperature (175[degrees]C) was improved somewhat with higher Mooney viscosity.

Plasticizer variations

We have reviewed the key parameters of EPDM polymers with regard to low temperature performance. In addition to the polymer, the plasticizer used has a considerable impact on low temperature performance. In our study, we looked at six plasticizers used in EPDM. These plasticizers are outlined in table 7.

Paraffinic oil is the most common oil used in EPDM compounding. It provides good compatibility, good plasticizing behavior and relatively good performance at low temperature. But like ethylene, it too can exhibit blocking at low temperature and can be extracted out of the compound via various fluids. Here, ASTM Type 104 oil is used as a standard.

Naphthenic oil is used where lower cost is more of a consideration and heat requirements are not too severe. Due to the higher level of aromatic aromatic /ar·o·mat·ic/ (ar?o-mat´ik)
1. having a spicy odor.

2. in chemistry, denoting a compound containing a ring system stabilized by a closed circle of conjugated double bonds or nonbonding electron pairs, e.g.
 and polar materials in the oil, discoloration will also be greater than a paraffinic oil, and naphthenic oil is generally used in black loaded formulations.

Polybutene Noun 1. polybutene - a polymer of butylene; used in lubricants and synthetic rubber
polybutylene

butene, butylene - any of three isomeric hydrocarbons C4H8; all used in making synthetic rubbers
 and polyisobutylene are generally used where extraction extraction /ex·trac·tion/ (eks-trak´shun)
1. the process or act of pulling or drawing out.

2. the preparation of an extract.
 resistance is required, such as in brake fluid brake fluid nlíquido de frenos

brake fluid nBremsflüssigkeit f 
 applications. It is believed that polybutene is capable of forming a network in sulfur cured compounds. Polyisobutylene is a relatively inert inert /in·ert/ (in-ert´) inactive.

in·ert
adj.
1. Sluggish in action or motion; lethargic.

2.
 material that cannot crosslink with either peroxide peroxide (pərŏk`sīd), chemical compound containing two oxygen atoms, each of which is bonded to the other and to a radical or some element other than oxygen; e.g.  or sulfur cure systems.

The last two are both ester plasticizers. DIOA DIOA Defense Industry Offset Association
DIOA ((Dihydronindenyl)oxy) Alkanoic Acid (specific inhibitor of the potassium/chloride cotransporter
 is a monomeric monomeric /mono·mer·ic/ (mon?o-mer´ik)
1. pertaining to, composed of, or affecting a single segment.

2. in genetics, determined by a gene or genes at a single locus.
 type that provides good low temperature performance in various elastomers, but due to its polar composition has limited compatibility with EPDM elastomers. The last experimental ester plasticizer was designed to be more compatible with EPDM by attaching an oily component to the molecule molecule (mŏl`əkyl) [New Lat.,=little mass], smallest particle of a compound that has all the chemical properties of that compound.  matrix. Hence, improved compatibility is expected. Esters esters (esˑ·terz),
n.pl organic compounds synthesized from acids and alcohols, typically possessing fruity aromas.
 are usually added along with paraffinics at low levels to improve low temperature performance. The esters are believed to interfere with the blocking of the paraffinic oil and crystallization of the ethylene segments in the EPDM polymer.

Plasticizer studies

Two studies were made on plasticizer performance. The first study was a simple screening study (table 8) comparing the six plasticizers listed in table 7 in the weatherstrip compound (table 3, formulation 2). Total plasticizer phr was held at 95 phr, except for the combinations using the ester plasticizers where the total was varied from 70 phr to 85 phr.

The data in table 8 illustrate the effect of plasticizer combinations on the compound Mooney viscosity. The standard paraffinic and naphthenic oils, polybutene and ester (85 phr) combinations gave similar viscosities, while the polyisobutylene and ester combinations (at 70 phr) with paraffinic oil were higher in Mooney viscosity. The same trend was also seen in higher hardness (table 8). This would suggest that the ester plasticizer/paraffinic oil combinations should have been evaluated at the same loading levels as the other plasticizers (and this was done in plasticizer study 2). Hot air aging suggested that the paraffinic and paraffinic/polybutene combinations provided the best performance. Elevated and room temperature compression sets were similar, except for the use of polyisobutylene, which showed significantly higher compression set at room temperature.

The low temperature behavior of the plasticizers is shown in figures 10 and 11. Here, the ester combinations had the best brittleness point values and Gehman T2 values.

[FIGURES 10-11 OMITTED]

Since the ester plasticizer combinations showed promising low temperature properties at lower loading levels in study 1, a second study using total phr loadings of 95 was conducted. The influence of polymer ethylene content was also included (51 versus 68% ethylene--6850 vs. 6470, respectively). In study 2, paraffinic oil was once again used as the reference control at 95 phr and compared to combinations of ester plasticizer and paraffinic oil. When doing this, compound Mooney viscosities and hardness were comparable. The ester blends did show higher elongation values and slightly lower modulus values (table 9).

A noticeable improvement is seen in brittleness points with the addition of ester plasticizer, particularly the DIOA combination in both high and low ethylene polymers (table 9). Figures 12 and 13 illustrate the impact of these plasticizers on temperature retraction and Gehman stiffness. In the low ethylene polymer (6850), the combination of DIOA/ paraffinic oil performed best, with the experimental ester plasticizer similar to the neat paraffinic oil. In the high ethylene polymer (6470), the combination of DIOA/paraffinic oil performed best, but no clear advantage was seen with the experimental ester plasticizer over the neat paraffinic oil. One possible explanation would be the compatibility of the ester material with the high ethylene polymer.

[FIGURES 12-13 OMITTED]

In order to determine if there were any compatibility issues, we conducted a bleed Printing at the very edge of the paper. Many laser printers, including all LaserJets up to the 11x17" 4V, cannot print to the very edge, leaving a border of approximately 1/4". In commercial printing, bleeding is generally more expensive, because wider paper is often used, which is later  test according to GM 6259 M. Results are shown in table 10. Ratings given the individual specimens would suggest that, at these loadings, the ester plasticizers bleed slightly more than the paraffinic oil. If one considers also the impact in hardening during this cycling test, one would conclude that the experimental ester is considerably better than the DIOA and very similar in hardening to the paraffinic oil. Hot air aging shown in table 9 confirms these findings.

Finally, the impact of ethylene content on the low temperature performance of the compound is clearly demonstrated in figure 14. The low temperature compression sets for the given plasticizer blends are fairly comparable, but there is an obvious advantage in low ethylene (6850) over high ethylene (6470) in set. The same trends are seen in temperature retraction and Gehman low temperature testing.

[FIGURE 14 OMITTED]

Conclusions

It has been demonstrated that ethylene content followed by diene content have the most impact on the performance of EPDM elastomers in low temperature applications. Low ethylene polymers are optimal in performance, with higher diene content showing some improvements by disrupting the crystallization of the ethylene segments. Low ethylene polymers should be employed when there are stringent low temperature requirements.

The choice of plasticizer also has an impact on low temperature performance and, depending on the needs of the compound, can be used to modify the polymer performance. However, care must be taken to ensure the compatibility of the system. Here, low ethylene again has a distinct advantage over high ethylene EPDM grades.
Table 1--test methods

Test method                                 ASTM procedure

Mooney viscosity and scorch                 ASTM D 1646
MDR rheometer                               ASTM D 5289
Stress strain properties/green strength     ASTM D 412
Hardness durometer A                        ASTM D 2240
Gehman low temperature stiffening           ASTM D 1053
Low temperature retraction                  ASTM D 1329
Brittleness point                           ASTM D 2137 Method A
Compression set                             ASTM D 395 Method B
Low temperature compression set             ASTM D 1229
Air oven aging                              ASTM D 573
Fluid immersions                            ASTM D 471
Bloom/bleed testing                         GM 6259 M Sec. 3.1.4.1
Compressive stress relaxation               Modified ASTM D 6147

Table 2--material ingredient listing

Common name               Chemical name (tradename)

Polymers
Polymer A (3340)          EPDM (Buna EP grades)
Polymer B (2450)          EPDM
Polymer C (2460)          EPDM
Polymer D (2470)          EPDM (VP KA 8956)
Polymer E (2370)          EPDM
Polymer F (6850)          EPDM
Polymer G (8850)          EPDM (VP KA 8806)
Polymer H (6470)          EPDM
Polymer I (6250)          EPDM
Polymer J (6650)          EPDM
Polymer K (3850)          EPDM

Fillers
Carbon black N550         Furnace carbon black
Carbon black N650         Furnace carbon black
Carbon black N990         Thermal carbon black
Calcium carbonate         Calcium carbonate (Omyacarb 3)

Plasticizers
Plasticizer 1 (Par.)      Paraffinic oil (Type 104)
Plasticizer 2 (Naph.)     Naphthenic oil (Type 103)
Plasticizer 3 (But.)      Polybutene (Indopol H1500)
Plasticizer 4 (Iso.)      Polyisobutylene (Vistanex MML-100)
Plasticizer 5 (DIOA)      Diisooctyl adipate (Plasthall DIOA)
Plasticizer 6 (Ester)     Ester plasticizer (FIX 13804, C.P. Hall)

Vulcanizers
Sulfur                    Spider sulfur
DBPH (~45% active)        2,5-dimethyl-2, 5-di(t-butylperoxy)hexane
DPTT                      Dipentamethylene thiuram tetrasulfide
                          (Tetrone A)

Antioxidants
Amine antioxidant         4-4'-bis(a,-dimethyl benzyl)
                          diphenylamine (Naugard 445)
ZMMBI                     Zn salt of 4 and 5-methyl-2-mercapto-
                          benzimidazole (Vulkanox ZMB-2/C5)

Accelerators
TMTD                      Tetramethylthiuram disulfide
ZDBC                      Zinc dibutyldithiocarbamate
MBTS                      Dibenzothiazyl disulfide

Additives
ZnO                       Zinc oxide
MgO                       Magnesium oxide (Elastomag 170)
CaO (80%)                 Calcium oxide (Desical P)
Stearic acid              Stearic acid
PEG                       Polyethylene glycol (Carbowax 3350)
Acrylic coagent           Trifunctional methacrylate (Saret 517)

Table 3--compound formulations

Brake seal formulation (Formulation 1)

Polymers A - E (varied)                   100
Carbon black N 650                         35
Carbon black N 990                         40
Plasticizer 3 (polybutene)                 15
MgO                                         5
Amine antioxidant                           2
ZMMBI                                       2
ZnO                                         5
Acrylic coagent                             2
DBPH--50 (peroixide)                        8
Total phr                                 214

Weatherstrip profile

Formulation                                 2          3
Polymers (varied)                         100          -
Polymer F (6850) or H (6470)                -        100
Carbon black N 550                        140        140
Calcium carbonate                          40         40
Plasticizer 1 (paraffinic type 104)        95          -
Plasticizer--varied                         -      70-95
PEG                                         2          2
CaO (80%)                                   8          8
Stearic acid                                1          1
ZnO                                         5          5
Sulfur                                    1.7        1.7
DPTT                                      0.5        0.5
M BTS                                     1.4        1.4
ZDBC                                      0.5        0.5
TMTD                                      0.5        0.5
Total phr                               395.6     Varied

Table 4--comparison of EPDMs with different ethylene contents

Polymer codes                             A(3440)   B(2450)   C(2460)
Ethylene content                               50        60        63

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                  57.6      47.7      46.2

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                           9.27     11.39     11.13

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dNm range
MH (dN.m)                                   45.75     48.04     49.37
ML (dN.m)                                    1.68      1.18      1.30
ts 1 (min.)                                  0.54      0.60      0.57
t' 90 (min.)                                11.12     10.76     11.01

Green strength @ 23[degrees]C
Peak stress (MPa)                            0.45      0.43      0.61
Ultimate elongation (%)                       464       281     1,495

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cured 13 min.
  @ 177[degrees]C
Hardness durometer A2 (pts.)                   63        64        65
Ultimate tensile (MPa)                      14.20     15.92     15.44
Ultimate elongation (%)                       239       265       257
Stress @ 100% (MPa)                          4.07      3.99      3.97
Stress @ 200% (MPa)                         10.94     11.22     11.01
Brittle point method B ([degrees]C)          >-70      >-70      >-70

Temperature retraction--initial elongation--50%, cured 13 min.
  @ 177[degrees]C
TR 10 ([degrees]C)                          -53.7     -39.3     -31.7
TR 70 ([degrees]C)                          -39.7     -13.9      -0.3
Temp. retraction TR10-TR70 ([degrees]C)        14     25.40     31.40

Gehman low temp. stiffness--cured 13 min. @ 177[degrees]C
Temperature @ T2 ([degrees]C)               -46.7       -30     -11.5
Temperature @ T100 ([degrees]C)             -58.7     -57.1     -53.3

Hardness (duro A2)--buttons, cured 26 mins. @ 177[degrees]C, reading
@ 5 sec. @ 23[degrees]C

Hardness pt. change from 23[degrees]C          63        63        65
  after 22 hrs.
@ -20[degrees]C                                 1         2        10
@ -40[degrees]C                                 3         6        12

Compression set--method B--buttons, cured 26 min. @ 177[degrees]C,
  25% deflection
22 hrs. @ 175[degrees]C (%)                    10        11        11
22 hrs. @ 23[degrees]C (%)                      4         5         6
22 hrs. @ -20[degrees]C (%)                    14        36        82
22 hrs. @ -40[degrees]C (%)                    17        50        89

Polymer codes                             D(2470)   E(2370)
Ethylene content                               73        69

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                  50.2      39.5

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                          11.04      9.98

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dNm range
MH (dN.m)                                   52.93     45.69
ML (dN.m)                                    1.55      1.34
ts 1 (min.)                                  0.51      0.60
t' 90 (min.)                                10.65     11.02

Green strength @ 23[degrees]C
Peak stress (MPa)                            3.67      3.61
Ultimate elongation (%)                     1,966     1,375

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cured 13 min.
  @ 177[degrees]C
Hardness durometer A2 (pts.)                   71        78
Ultimate tensile (MPa)                      17.69     15.16
Ultimate elongation (%)                       274       309
Stress @ 100% (MPa)                          4.78      4.75
Stress @ 200% (MPa)                         12.57     10.14
Brittle point method B ([degrees]C)          >-70      >-70

Temperature retraction--initial elongation--50%, cured 13 min.
  @ 177[degrees]C
TR 10 ([degrees]C)                          -29.2     -28.1
TR 70 ([degrees]C)                            5.7      12.1
Temp. retraction TR10-TR70 ([degrees]C)      34.9      40.2

Gehman low temp. stiffness--cured 13 min. @ 177[degrees]C
Temperature @ T2 ([degrees]C)                -9.9     -16.3
Temperature @ T100 ([degrees]C)             -53.3     -57.2

Hardness (duro A2)--buttons, cured 26 mins. @ 177[degrees]C, reading
  @ 5 sec. @ 23[degrees]C
Hardness pt. change from 23[degrees]C          71        79
  after 22 hrs.
@ -20[degrees]C                                 8         7
@ -40[degrees]C                                12         9

Compression set--method B--buttons, cured 26 min. @ 177[degrees]C,
  25% deflection
22 hrs. @ 175[degrees]C (%)                    11        11
22 hrs. @ 23[degrees]C (%)                     25        44
22 hrs. @ -20[degrees]C (%)                    82        80
22 hrs. @ -40[degrees]C (%)                    87        89

Table 5--comparison of EPDMs with different diene levels

Polymer codes                             I(6250)   J(6650)   F(6850)
ENB target (wt. %)                              2         6         8

Raw Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                  55.1      63.2      62.7

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                 49.97     51.23     45.88

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                           9.72      5.53      4.93

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dNm range
MH (dN.m)                                   16.17     20.35     22.54
ML (dN.m)                                    1.86         2      2.02
ts 1 (min.)                                  1.11      0.69      0.63
t' 90 (min.)                                 4.32      5.81      7.44

Green strength @ 23[degrees]C
Peak stress (MPa)                           0.411     0.336     0.321
Ultimate elongation (%)                       212       169       212

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cured T90 +
  2 min. @ 177[degrees]C
Hardness durometer A2 (pts.)                   57        64        65
Ultimate tensile (MPa)                      10.14     12.53     12.65
Ultimate elongation (%)                       517       285       255
Stress @ 100% (M Pa)                         2.22      4.58      5.02
Stress @ 200% (MPa)                          5.11      9.57     10.54
Brittle point method B ([degrees]C)           -52       -51       -51

Temperature retraction--initial elongation--50%, cured T90 + 2 min.
  @ 177[degrees]C
TR 10 ([degrees]C)                          -23.8     -43.5     -44.6
TR 70 ([degrees]C)                            4.1     -22.6     -24.9
Temp. retraction TR10-TR70 ([degrees]C)      27.9      20.9      19.7

Gehman low temp. stiffness--cured T90 + 2 min. @ 177[degrees]C
Temperature @ T2 ([degrees]C)               -17.4     -35.1     -35.5
Temperature @ T100 ([degrees]C)             -56.5     -58.5     -57.8

Compression set--method B--buttons, cured 790 + 15 min. @
  177[degrees]C, 25% deflection
22 hrs. @ 175[degrees]C (%)                 86.99     65.77     72.39
22 hrs. @ 23[degrees]C (%)                  13.46      8.37      7.63
22 hrs. @ -20[degrees]C (%)                 70.68     16.16     18.76
22 hrs. @ -40[degrees]C (%)                 91.36     50.79     54.93

Table 6--comparison of EPDMs with increasing Mooney viscosities

Polymer codes:                            K(3850)   F(6850)   G(8850)

Raw polymer viscosity
ML 1+4 @ 100[degrees]C (MU)                    30        62        88

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                  29.7      45.6      54.8

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                           5.27      4.18      4.29

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. are 30 motor,
  100 dN.m range
MH (dN.m)                                   21.96     22.11     23.13
ML (dN.m)                                    1.12      1.78      2.53
ts 1 (min.)                                  0.72      0.63       0.6
t'90 (min.)                                 11.06     10.15     10.65

Green strength @ 23[degrees]C
Peak stress (MPa)                           0.274     0.361     0.396
Ultimate elongation (%)                       290       291       261

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cured 13 min.
  @ 177[degrees]C
Hardness durometer A2 (pts.)                   66        65        66
Ultimate tensile (MPa)                      10.82     12.02        13
Ultimate elongation (%)                       254       247       248
Stress @ 100% (MPa)                          4.47      4.71      5.32
Stress @ 200% (MPa)                          8.84      9.93      11.1
Brittle point method B ([degrees]C)           -50       -51       -51

Temperature retraction--initial elongation--50%, cured 13 min.
  @ 177[degrees]C
TR 10 ([degrees]C)                          -47.3     -45.2     -44.9
TR 70 ([degrees]C)                           -212       -24     -24.4
Temp. retraction TR10-TR70 ([degrees]C)      26.1      21.2      20.5

Gehman low temp. stiffness--cured 13 min. @ 177[degrees]C
Temperature @ T2 ([degrees]C)               -34.4     -35.9     -36.4
Temperature @ T100 ([degrees]C)             -57.7     -57.7     -57.2

Compression set--method B--buttons, cured 26 min. @ 177[degrees]C,
  25% deflection
22 hrs. @ 175[degrees]C (%)                 78.57     68.31     68.62
22 hrs. @ 23[degrees]C (%)                   8.74      6.22      6.25
22 hrs. @ -20[degrees]C (%)                 15.27     14.19      17.2
22 hrs. @ -40[degrees]C (%)                 40.93     37.13     54.21

Table 7

Plasticizer type                   Plasticizer code

Paraffinic oil                     Par.
Naphthenic oil                     Naph.
Polybutene                         But.
Polyisobutylene                    ISO.
Diisooctyl adipate                 DIOA
Experimental ester plasticizer     Ester

Table 8--comparison of different plasticizers

Polymer codes:                                  (Par.)        (Naph.)
PHR levels                                          95             95

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                       48.1           50.7

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                                5.88           4.88

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dN.m range
MH (dN.m)                                         2.41            226
ML (dN.m)                                        18.92          18.25
ts 1 (min.)                                       0.75           0.69
t' 90 (min.)                                     11.79           2.99

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cured T90 +
  2 mins.
Hardness durometer A2 (pts.)                        66             66
Ultimate tensile (MPa)                           13.27          12.95
Ultimate elongation (%)                            224            282
Stress @ 100% (MPa)                               6.15            526

Stress strain (hot air oven)--tested @ 23[degrees]C, aged 70 hrs. @
  125[degrees]C
Chg. hard. A2 (pts.)                                 7             14
Chg. ulti. tens. (%)                                10              6
Chg. ulti. elong. (%)                              -24            -55
Brittle point method B ([degrees]C)                -48            -45

Temperature retraction--initial elongation--50%, cured T90 + 2 mins.
  @ 177[degrees]C
TR 10 ([degrees]C)                               -43.3          -42.7
TR 70 ([degrees]C)                               -23.2          -25.8
Temp. retraction TR10-TR70 ([degrees]C)           20.1           16.9

Gehman low temp. stiffness--cured T90 + 2 mins. @ 177[degrees]C
Temperature @ T2 ([degrees]C)                    -33.3          -33.9
Temperature @ T100 ([degrees]C)                  -55.6          -51.4

Compression set--method B--buttons, 25% deflection, cured T90 +
  15 mins.
22 hrs. @ 125[degrees]C (%)                      45.63          49.87
22 hrs. @ 23[degrees]C (%)                        5.39           5.54
22 hrs. @ -20[degrees]C (%)                      12.08          13.67

Polymer codes:                                  (But.)     (Par/But.)
PHR levels                                          95          50/45

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                       54.8           51.6

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                                5.45           4.97

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dN.m range
MH (dN.m)                                         2.43           1.97
ML (dN.m)                                         9.62          14.78
ts 1 (min.)                                       0.78           0.72
t' 90 (min.)                                      6.23          15.76

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cured T90 +
  2 mins.
Hardness durometer A2 (pts.)                        65             66
Ultimate tensile (MPa)                           12.91          13.69
Ultimate elongation (%)                            242            236
Stress @ 100% (MPa)                               4.91           5.72

Stress strain (hot air oven)--tested @ 23[degrees]C, aged 70 hrs. @
  125[degrees]C
Chg. hard. A2 (pts.)                                 8              7
Chg. ulti. tens. (%)                                 3              3
Chg. ulti. elong. (%)                              -42            -22
Brittle point method B ([degrees]C)                -47            -48

Temperature retraction--initial elongation--50%, cured T90 + 2 mins.
  @ 177[degrees]C
TR 10 ([degrees]C)                               -43.5          -43.5
TR 70 ([degrees]C)                               -20.1          -23.2
Temp. retraction TR10-TR70 ([degrees]C)           23.4           20.3

Gehman low temp. stiffness--cured T90 + 2 mins. @ 177[degrees]C
Temperature @ T2 ([degrees]C)                    -26.2          -30.8
Temperature @ T100 ([degrees]C)                  -61.0          -59.1

Compression set--method B--buttons, 25% deflection, cured T90 +
  15 mins.
22 hrs. @ 125[degrees]C (%)                      50.87          46.38
22 hrs. @ 23[degrees]C (%)                        6.16           6.27
22 hrs. @ -20[degrees]C (%)                      21.25          14.67

Polymer codes:                             (Par./Iso.)    (Par./DIOA)
PHR levels                                       50/45          40/30

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                       90.9           68.2

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                                4.46           4.27

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dN.m range
MH (dN.m)                                         4.20           4.23
ML (dN.m)                                        21.91          22.93
ts 1 (min.)                                       0.63            0.6
t' 90 (min.)                                     11.07           8.06

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cured T90 +
  2 mins.
Hardness durometer A2 (pts.)                        72             73
Ultimate tensile (MPa)                           12.05          13.73
Ultimate elongation (%)                            191            161
Stress @ 100% (MPa)                               7.15           8.89

Stress strain (hot air oven)--tested @ 23[degrees]C, aged 70 hrs. @
  125[degrees]C
Chg. hard. A2 (pts.)                                 4             13
Chg. ulti. tens. (%)                                 6             10
Chg. ulti. elong. (%)                              -29            -41
Brittle point method B ([degrees]C)                -48            -60

Temperature retraction--initial elongation--50%, cured T90 + 2 mins.
  @ 177[degrees]C
TR 10 ([degrees]C)                                 -45          -49.4
TR 70 ([degrees]C)                               -25.4          -29.4
Temp. retraction TR10-TR70 ([degrees]C)           19.6             20

Gehman low temp. stiffness--cured T90 + 2 mins. @ 177[degrees]C
Temperature @ T2 ([degrees]C)                    -33.9          -41.4
Temperature @ T100 ([degrees]C)                  -57.5          -65.9

Compression set--method B--buttons, 25% deflection, cured T90 +
  15 mins.
22 hrs. @ 125[degrees]C (%)                      50.69          46.16
22 hrs. @ 23[degrees]C (%)                       12.48           5.14
22 hrs. @ -20[degrees]C (%)                      42.18          13.44

Polymer codes:                            (Par./Ester)   (Par./Ester)
PHR levels                                       40/30          70/15

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                       70.7           53.8

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                                4.32            4.8

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dN.m range
MH (dN.m)                                         4.03           2.57
ML (dN.m)                                        18.35          17.96
ts 1 (min.)                                        0.6           0.66
t' 90 (min.)                                      6.66            8.6

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cured T90 +
  2 mins.
Hardness durometer A2 (pts.)                        70             68
Ultimate tensile (MPa)                           14.18          12.58
Ultimate elongation (%)                            246            224
Stress @ 100% (MPa)                               6.35           5.81

Stress strain (hot air oven)--tested @ 23[degrees]C, aged 70 hrs. @
  125[degrees]C
Chg. hard. A2 (pts.)                                 6              7
Chg. ulti. tens. (%)                                -1             10
Chg. ulti. elong. (%)                              -41            -26
Brittle point method B ([degrees]C)                -51            -50

Temperature retraction--initial elongation--50%, cured T90 + 2 mins.
  @ 177[degrees]C
TR 10 ([degrees]C)                               -44.6          -43.4
TR 70 ([degrees]C)                               -25.2          -24.5
Temp. retraction TR10-TR70 ([degrees]C)           19.4           18.9

Gehman low temp. stiffness--cured T90 + 2 mins. @ 177[degrees]C
Temperature @ T2 ([degrees]C)                    -36.2          -34.1
Temperature @ T100 ([degrees]C)                  -60.3          -57.7

Compression set--method B--buttons, 25% deflection, cured T90 +
  15 mins.
22 hrs. @ 125[degrees]C (%)                      46.67          50.73
22 hrs. @ 23[degrees]C (%)                        6.18           6.39
22 hrs. @ -20[degrees]C (%)                      21.65          21.71

Table 9--evaluations of plasticizers in high and low ethylene EPDM
polymers

Polymer codes:                               F(6850)      F(6850)
Plasticizer ratio                               Par.    Par./DIOA
Plasticizer phr                                   95        50/45

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                     41.2           38

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                              5.11         4.84

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dNm range
MH (dN.m)                                      20.58        17.22
ML (dN.m)                                       1.52         1.51
ts 1 (min.)                                     0.69         0.66
t' 90 (min.)                                    9.16         3.34

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cure T90 +
  2 mins. @ 177[degrees]C
Hardness durometer A2 (pts.)                      64           64
Ultimate tensile (MPa)                         12.18        10.68
Ultimate elongation (%)                          258          305
Stress @ 100% (MPa)                             5.03         4.22

Stress strain (hot air oven)--tested @ 23[degrees]C, aged 70 hrs. @
  125[degrees]C, cured t90 +2 min. @ 177[degrees]
Chg. hard. A2 (pts.)                               9           17
Chg. ulti. tens. (%)                               1           15
Chg. ulti. elong. (%)                            -35          -65
Brittle point method B ([degrees]C)              -50          -64

Temperature retraction--initial elongation--50%, cured 190 + 2 min. @
  177[degrees]C
TR 10 ([degrees]C)                             -45.4        -53.7
TR 70 ([degrees]C)                               -25        -31.5
Temp. retraction TR10-TR70 ([degrees]C)         20.4         22.2

Gehman low temp. stiffness--cured T90 + 2 mins. @ 177[degrees]C
Temperature @ T2 ([degrees]C)                  -33.8        -45.9
Temperature @ T100 ([degrees]C)                -56.4          -69

Compression set--method B--buttons cured 190 + 15 min. @ 177[degrees]C,
  25% deflection
22 hrs. @ 125[degrees]C (%)                    52.61        57.88
22 hrs. @ 23[degrees]C (%)                       8.3         8.15
22 hrs. @ -20[degrees]C (%)                    15.24        15.21

Polymer codes:                               F(6850)      F(6850)
Plasticizer ratio                         Par./Ester   Par./Ester
Plasticizer phr                                50/45        65/30

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                     42.6         42.9

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                              5.25         5.42

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dNm range
MH (dN.m)                                      14.57        15.05
ML (dN.m)                                       1.77         1.72
ts 1 (min.)                                     0.66         0.69
t' 90 (min.)                                    4.38         3.06

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cure T90 +
  2 mins. @ 177[degrees]C
Hardness durometer A2 (pts.)                      59           60
Ultimate tensile (MPa)                         10.67        10.99
Ultimate elongation (%)                          403          353
Stress @ 100% (MPa)                             3.08         3.51

Stress strain (hot air oven)--tested @ 23[degrees]C, aged 70 hrs. @
  125[degrees]C, cured t90 +2 min. @ 177[degrees]
Chg. hard. A2 (pts.)                              11           12
Chg. ulti. tens. (%)                              11            8
Chg. ulti. elong. (%)                            -45          -51
Brittle point method B ([degrees]C)              -55          -57

Temperature retraction--initial elongation--50%, cured 190 + 2 min. @
  177[degrees]C
TR 10 ([degrees]C)                             -47.5        -45.7
TR 70 ([degrees]C)                             -25.1        -24.3
Temp. retraction TR10-TR70 ([degrees]C)         22.4         21.4

Gehman low temp. stiffness--cured T90 + 2 mins. @ 177[degrees]C
Temperature @ T2 ([degrees]C)                  -37.8        -37.1
Temperature @ T100 ([degrees]C)                -63.4        -61.2

Compression set--method B--buttons cured 190 + 15 min. @ 177[degrees]C,
  25% deflection
22 hrs. @ 125[degrees]C (%)                    52.49        54.69
22 hrs. @ 23[degrees]C (%)                      9.48         9.87
22 hrs. @ -20[degrees]C (%)                    22.84        22.05

Polymer codes:                               H(6470)     (H(6470)
Plasticizer ratio                               Par.    Par./DIOA
Plasticizer phr                                   95        50/45

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                     50.1         43.9

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                               6.9         6.18

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dNm range
MH (dN.m)                                       18.4        15.57
ML (dN.m)                                       1.87         1.76
ts 1 (min.)                                     0.84         0.81
t' 90 (min.)                                    6.14         4.06

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cure T90 +
  2 mins. @ 177[degrees]C
Hardness durometer A2 (pts.)                      65           66
Ultimate tensile (MPa)                         12.50        11.41
Ultimate elongation (%)                          331          343
Stress @ 100% (MPa)                             4.26         3.91

Stress strain (hot air oven)--tested @ 23[        C
  125[degrees]C, cured t90 +2 min. @ 177[degrees]
Chg. hard. A2 (pts.)                               5           11
Chg. ulti. tens. (%)                               8           21
Chg. ulti. elong. (%)                            -42          -62
Brittle point method B ([degrees]C)              -47          -67

Temperature retraction--initial elongation--50%, cured 190 + 2 min. @
  177[degrees]C
TR 10 ([degrees]C)                             -29.7        -34.8
TR 70 ([degrees]C)                                 2          1.8
Temp. retraction TR10-TR70 ([degrees]C)         31.7         36.6

Gehman low temp. stiffness--cured T90 + 2 mins. @ 177[degrees]C
Temperature @ T2 ([degrees]C)                    -16        -18.9
Temperature @ T100 ([degrees]C)                -54.3          -66

Compression set--method B--buttons cured 190 + 15 min. @ 177[degrees]C,
  25% deflection
22 hrs. @ 125[degrees]C (%)                    62.01        58.15
22 hrs. @ 23[degrees]C (%)                     24.91        24.57
22 hrs. @ -20[degrees]C (%)                    94.91        93.27

Polymer codes:                               H(6470)      H(6470)
Plasticizer ratio                         Par./Ester   Par./Ester
Plasticizer phr                                50/45        65/30

Compound Mooney viscosity
ML 1+4 @ 100[degrees]C (MU)                     48.1         48.2

Compound Mooney scorch--small rotor, 135[degrees]C
t value t03 (min.)                              6.23         6.30

MDR cure characteristics--1.7 Hz, 177[degrees]C, 1 deg. arc, 30 motor,
  100 dNm range
MH (dN.m)                                      12.43        13.84
ML (dN.m)                                       1.81         1.79
ts 1 (min.)                                     0.78         0.81
t' 90 (min.)                                    3.13         3.65

Stress strain (dumbbells)--die C, tested @ 23[degrees]C, cure T90 +
  2 mins. @ 177[degrees]C
Hardness durometer A2 (pts.)                      62           63
Ultimate tensile (MPa)                          9.55        10.69
Ultimate elongation (%)                          501          468
Stress @ 100% (MPa)                             2.97         3.14

Stress strain (hot air oven)--tested @ 23[degrees]C, aged 70 hrs. @
  125[degrees]C, cured t90 +2 min. @ 177[degrees]
Chg. hard. A2 (pts.)                               8            7
Chg. ulti. tens. (%)                              23           12
Chg. ulti. elong. (%)                            -45          -45
Brittle point method B ([degrees]C)              -60          -55

Temperature retraction--initial elongation--50%, cured 190 + 2 min. @
  177[degrees]C
TR 10 ([degrees]C)                             -23.5        -22.7
TR 70 ([degrees]C)                               9.6            9
Temp. retraction TR10-TR70 ([degrees]C)         33.1         31.7

Gehman low temp. stiffness--cured T90 + 2 mins. @ 177[degrees]C
Temperature @ T2 ([degrees]C)                  -19.1        -16.6
Temperature @ T100 ([degrees]C)                -61.1        -59.1

Compression set--method B--buttons cured 190 + 15 min. @ 177[degrees]C,
  25% deflection
22 hrs. @ 125[degrees]C (%)                    66.63        59.76
22 hrs. @ 23[degrees]C (%)                     33.79        28.64
22 hrs. @ -20[degrees]C (%)                    95.97        94.60

Table 10--bloom test via GM 6259M

Polymer                              F(6850)        F(6850)
Plasticizer                             Par.      Par./DIOA
Phr                                       95          50/45
Sequence        Temp. [degrees]C
(Hrs.)
24 hrs.         -30                        0              0
48 hrs.         -30                        0              0
24 hrs.         100                        1              3
48 hrs.         100                        1              3
48 hrs.         -30                        1              3
72 hrs.         -30                        2              3
24 hrs.         100                        2              4
48 hrs.         100                        2              4
72 hrs.         100                        3              4
168 hrs.        100                        3              4
Hardness        Unaged                    70             68
Hardness        After cycling             76             86
Hardness        Pt.                       +6            +18
Chg.

Polymer                              F(6850)        F(6850)
Plasticizer                       Par./Ester     Par./Ester
Phr                                    50/45          65/30
Sequence        Temp. [degrees]C
(Hrs.)
24 hrs.         -30                        0              0
48 hrs.         -30                        0              0
24 hrs.         100                        2              1
48 hrs.         100                        2              2
48 hrs.         -30                        2              2
72 hrs.         -30                        3              2
24 hrs.         100                        3              3
48 hrs.         100                        4              4
72 hrs.         100                        4              4
168 hrs.        100                        4              4
Hardness        Unaged                    67             68
Hardness        After cycling             75             75
Hardness        Pt.                       +8             +7
Chg.

Polymer                              H(6470)        H(6470)
Plasticizer                             Par.      Par./DIOA
Phr                                       95          50/45
Sequence        Temp. [degrees]C
(Hrs.)
24 hrs.         -30                        0              0
48 hrs.         -30                        0              0
24 hrs.         100                        2              3
48 hrs.         100                        2              3
48 hrs.         -30                        2              3
72 hrs.         -30                        2              3
24 hrs.         100                        3              4
48 hrs.         100                        3              4
72 hrs.         100                        3              4
168 hrs.        100                        3              4
Hardness        Unaged                    71             70
Hardness        After cycling             76             84
Hardness        Pt.                       +5            +14
Chg.

Polymer                              H(6470)        H(6470)
Plasticizer                       Par./Ester     Par./Ester
Phr                                    50/45          65/30
Sequence        Temp. [degrees]C
(Hrs.)
24 hrs.         -30                        0              0
48 hrs.         -30                        0              0
24 hrs.         100                        2              2
48 hrs.         100                        3              3
48 hrs.         -30                        3              3
72 hrs.         -30                        3              3
24 hrs.         100                        4              4
48 hrs.         100                        4              4
72 hrs.         100                        4              4
168 hrs.        100                        5              5
Hardness        Unaged                    68             70
Hardness        After cycling             74             75
Hardness        Pt.                       +6             +5
Chg.

Rating:

0 = No blooming; 2 = slight bloom; 5 = moderate blooming (slightly
greasy or iridescence); 10 = heavy oil bloom

Figure 10-plasticizer study 1-brittle point

95      Par.
95      Naph.
95      But.
50/45   Par./But.
50/45   par./Iso.
40/30   Par./DIOA
40/30   Par./Ester
70/15   Par./Ester

Note: table made from bar graph.


References

(1.) E. Rohde Rohde is a surname, and may refer to:
  • Brigitte Rohde (born 1954), East-German athlete
  • David S. Rohde (born 1967), American journalist
  • Eleanour Sinclair Rohde (1880-1948), British gardner
  • Erwin Rohde (1845-1898), German classical scholar
, H. Bechen and M. Mezger, "Polychloroprene grades and compounding for long term flexibility at low temperatures," Bayer AG Bayer AG

German chemical and pharmaceutical company. Founded in 1863 by Friedrich Bayer (1825–1880), it now operates plants in more than 30 countries. Bayer has originated scores of pharmaceuticals, chemicals, and synthetic materials; it was the first developer and
, Germany Germany (jûr`mənē), Ger. Deutschland, officially Federal Republic of Germany, republic (2005 est. pop. 82,431,000), 137,699 sq mi (356,733 sq km). .

(2.) ASTM Standards Volume 09.01 ASTM D 1053--Rubber Property--Stiffening at Low Temperatures: Sec. 3 Summary of Test Methods.

(3.) ASTM Standards Volume 09.01 ASTM D 1329--Rubber Property--Retraction at Low Temperatures (TR Test): Sec. 4 Significance and Use.

(4.) ASTM Standards Volume 09.01 ASTM D 6147-Determination of Force Decay The reduction of strength of a signal or charge.

decay - [Nuclear physics] An automatic conversion which is applied to most array-valued expressions in C; they "decay into" pointer-valued expressions pointing to the array's first element.
 (Stress Relaxation) in Compression Section 3 Terminology The terminology used in the computer and telecommunications field adds tremendous confusion not only for the lay person, but for the technicians themselves. What many do not realize is that terms are made up by anybody and everybody in a nonchalant, casual manner without any regard or .

(5.) Bielby J., Wall D.W., (Test method) TM #2,000-042, "Continuous Measurement of Stress Relaxation."

(6.) Derham Derham is a surname, and may refer to:
  • Enid Derham
  • Katie Derham
  • Michael Derham
  • William Derham
Derham is may also refer to:
  • Derham(coachbuilder), an American coachbuilder
See also
  • Durham
, C.J., "Creep and stress relaxation of rubbers--the effects of stress history and temperature changes," Journal of Materials Science materials science

Study of the properties of solid materials and how those properties are determined by the material's composition and structure, both macroscopic and microscopic.
 8, 1,023-1,029, 1973.
COPYRIGHT 2005 Lippincott & Peto, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
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Date:May 1, 2005
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