Next generation EPDMs for auto, wire and cable.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 , a terpolymer ter·pol·y·mer n. A polymer that consists of three distinct monomers. [Latin ter, thrice; see trei- in Indo-European roots + polymer.] of 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. and a non-conjugated diene Dienes are hydrocarbons which contain two double bonds. Dienes are intermediate between alkenes and polyenes. Classes Dienes can be divided into three classes:
mostly triaryl phosphates, such as tricresyl, triphenyl phosphates, which are poisonous. See also triorthocresyl phosphate. to be added while still maintaining good physical properties. Its low specific gravity specific gravity, ratio of the weight of a given volume of a substance to the weight of an equal volume of some reference substance, or, equivalently, the ratio of the masses of equal volumes of the two substances. combined with its high extendibility allow for inexpensive functional parts to be produced. There is a wide variety of types of EPDM available, varying in Mooney viscosity, molecular weight, ethylene/propylene ratio and cure rate. The different types are designed for optimum performance in specific applications, allowing compounding latitude in choosing the best polymer for particular processing and product requirements. EPDM has found wide use in applications that take advantage of its excellent aging characteristics, as well as low temperature flexibility and chemical resistance. Articles made from EPDM include automotive weatherseal, hose, tire sidewalls, single-ply roof membranes and wire and cable insulation. EPDM is used in electrical insulation Electrical insulation A nonconducting material that provides electric isolation of two parts at different voltages. To accomplish this, an insulator must meet two primary requirements: it must have an electrical resistivity and a dielectric strength due to its excellent dielectric dielectric (dī'ĭlĕk`trĭk), material that does not conduct electricity readily, i.e., an insulator (see insulation). A good dielectric should also have other properties: It must resist breakdown under high voltages; it should not properties, superior resistance to weather, ozone, corona, water and heat, and its resistance to flow at elevated temperature. This article will discuss this polymer's characteristics, and physical properties of a new EPDM polymer that was developed in response to customer needs for a high performance automotive weatherseal and for medium voltage insulation applications. What is RE-EPDM? RE-EPDM employs new polymerization polymerization Any process in which monomers combine chemically to produce a polymer. The monomer molecules—which in the polymer usually number from at least 100 to many thousands—may or may not all be the same. technology resulting in a controlled composition distribution. Controlled composition distribution provides a unique microstructure mi·cro·struc·ture n. The structure of an organism or object as revealed through microscopic examination. microstructure Noun a structure on a microscopic scale, such as that of a metal or a cell within and between polymer chains, combining a concept of multiple grades of EPDM in one polymer. This results in a single polymer with the capability of meeting opposing properties (table 1). Automotive weatherseal applications RE-EPDM was first introduced to the automotive weatherseal market in North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. in 1997. It combines the properties and performance characteristics of two (or more) grades of EPDM having different properties. Extruded automotive profiles are often made with blends to obtain shape retention, wrinkle Wrinkle A feature of a new product or security intended to entice a buyer. resistance and smooth surfaces. RE-EPDM 4316 was developed to obtain extremely smooth extruded and cured skin surfaces on automotive sponge weatherseal while retaining the required physical properties. Compared to conventional EPDM, RE-EPDM 4316 also provides ultra smooth extrusion, wrinkle resistance, low expanded density in sponge and low compression set, while at the same time providing excellent mixing and milling performance. Polymer properties The polymer Mooney viscosity of RE-EPDM 4316 is 85. compared to 65 for a conventional EPDM (table 2). It is interesting to note that when RE-EPDM 4316 is directly substituted for the conventional EPDM in the same sponge extrusion compound (table 3), a comparable compound Mooney viscosity is obtained (table 4). This is the direct result of the unique microstructure provided by this technology. The REEPDM 4316 polymer developed a longer scorch time, lower expanded density and load deflection deflection /de·flec·tion/ (de-flek´shun) deviation or movement from a straight line or given course, such as from the baseline in electrocardiography. de·flec·tion n. 1. with identical compression set and water absorption. Also, a wrinkle resistant, very smooth skin surface was observed. Performance advantages There are numerous advantages with RE-EPDM in mixing and milling performance which include faster mix rates (up to 10-15% improvement), excellent filler dispersion, reduced compound viscosity and more cohesive batches for faster and easier milling. Advantages in molding and extrusion processing include reduced head pressure, improved strip feed into process equipment (good green strength), excellent shape retention, extremely smooth cured skin surface and improved mold flow. The advantages in physical properties are improved expansion properties (density reduction), development of excellent physical properties and RE-EPDM is comparable or better than blends of EPDM grades. Wire and cable applications It is known that insulation compounds based on 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. vary widely in physical and electrical properties, due to their base polymer and the type and levels of compounding ingredients employed. The following discussion will illustrate polymer characteristics, heat and electrical stability of RE-EPDM 4191P. Polymer properties EPDM for medium voltage insulation requires a high ethylene content for 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 . Low Mooney viscosity and a branched structure imparts the correct shear thinning A pseudoplastic material is one in which viscosity decreases with increasing rate of shear (also termed shear thinning). This property is found in certain complex solutions, such as ketchup, whipped cream, blood, paint, and nail polish. properties for ease of processing. The broad molecular weight distribution (mwd) indicates that RE-EPDM 4191P is particularly suited for processing at low filler loading in the absence 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 . The low level of 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. (1.5% 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 ) provides excellent heat characteristics, typically comparable to EP copolymer copolymer: see polymer. . Peroxide cure systems are used in EPDM for a broad range of applications in low to medium voltage constructions and in automotive ignition wire where high heat resistance is required. Table 5 shows RE-EPDM 4191P polymer properties. Complex dynamic viscosity dynamic viscosity n. Symbol  A measure of the molecular frictional resistance of a fluid as calculated using Newton's law. and tangent tangent, in mathematics.1 In geometry, the tangent to a circle or sphere is a straight line that intersects the circle or sphere in one and only one point. delta The complex dynamic viscosity for RE-EPDM 4191P as related to shear rate Shear rate is a measure of the rate of shear deformation:  For the simple shear case, it is just a gradient of velocity in a flowing material. is shown in figure 1. Properties were measured between 0.25 and 200 radians per second at 150[degrees]C. Note that the shear thinning properties of RE-EPDM 4191P are very low, with viscosity ranging from 80,000 Pascal-second (pa-s) at 0.25 r/s to approximately 1,100 pa-s at 200 r/s. [FIGURE 1 OMITTED] Figure 2 shows the tangent delta profile of RE-EPDM 4191P. Tangent delta is the ratio of viscous/elastic modulus. Thus, a lower tangent delta equates to a more elastic behavior. The low tangent delta at low frequency and relatively flat slope are indicative of broad mwd and branched structure. [FIGURE 2 OMITTED] The relatively low viscosity and significant shear thinning characteristics of RE-EPDM 4191P are requisite for the demanding processing requirements of the end use application in medium voltage insulations. RE-EPDM evaluation compound RE-EPDM 4191P was evaluated in a typical medium voltage formulation (table 6). This discussion focuses on the heat stability of the insulation compound up to 150[degrees]C and the electrical stability in 90[degrees]C water. RE-EPDM 4191P developed excellent cure characteristics and heat resistance up through 150[degrees]C, as shown in tables 7 and 8. Electrical properties The key electrical properties for high performance insulation compounds are low dielectric constant dielectric constant n. See permittivity. and dissipation factor In physics, the dissipation factor (DF) is a measure of loss-rate of power of a mechanical mode, such as an oscillation, in a dissipative system. For example, electric power is lost in all dielectric materials, usually in the form of heat. , as well as high insulation resistance. The dielectric constant or specific inductive inductive 1. eliciting a reaction within an organism. 2. inductive heating a form of radiofrequency hyperthermia that selectively heats muscle, blood and proteinaceous tissue, sparing fat and air-containing tissues. capacitance capacitance, in electricity, capability of a body, system, circuit, or device for storing electric charge. Capacitance is expressed as the ratio of stored charge in coulombs to the impressed potential difference in volts. (sic) measures the amount of energy stored in the material or the tendency of the material to act as a capacitor. The dielectric constant is related to the energy required to charge the insulated wire wire covered with some nonconducting material, such as plastic or silk, for use in conducting electricity. See also: Insulated on positive and negative cycles of alternating current. Lower values relate to lower losses and reduced energy cost. The dielectric constant is primarily a function of the crystallinity of the polymer. The dissipation factor or power factor is a measure of hysteresis hysteresis (hĭs'tərē`sĭs), phenomenon in which the response of a physical system to an external influence depends not only on the present magnitude of that influence but also on the previous history of the system. in charging and discharging the insulation. A lower dissipation factor value relates to a more efficient insulation, which will run cooler. This is part of the losses in a cable system and affects the energy cost to run the system. The dissipation factor is a function of polar additives in the insulation, such as stabilizers and catalyst residues. The electrical properties of RE-EPDM 4191P are excellent. Both dielectric constant and power factor remain stable on long term immersion. The data in tables 9-11 show the electrical values obtained with compound applied to #14 AWG (American Wiring Gauge) A U.S. measurement standard of the diameter of non-ferrous wire, which includes copper and aluminum. In general, the thicker the wire, the greater the current-carrying capacity and the longer the distance it can span. solid copper and tested continuously in 90[degrees]C water with an applied 600 volt AC source at 60 Hz frequency. Electrical properties were measured over 12 months. Summary This new generation of RE-EPDM polymers was recently introduced in response to growing customer needs for a high performance EPDM for both automotive weatherseal and medium voltage insulation for the wire and cable market. RE-EPDM 4316, designated for the automotive weatherseal market, provides an ultra smooth extruded and cured skin surface on automotive sponge weatherseal while retaining the required physical properties with low compression set and wrinkle resistance. RE-EPDM 4191P achieved market success, demonstrating excellent wet electrical stability and heat resistance required for the demanding wire and cable industry. Other potential applications for RE-EPDM include hoses, single-ply roof membranes and mechanical goods.
Table 1
Opposing properties Typical applications
Low temperature flexibility--with Weatherseal and
good green strength hose
Wrinkle and abrasion resistance-- Sponge weatherseal
with Class A show surface
Good processing properties - with Wire and cable
excellent electricals
Good mold flow--with superior General mechanical
hot tear strength goods
Excellent physical properties-- TRP, TPV, plastics
improved melt flow modification
Table 2--polymer properties
EPDM RE-EPDM 4316
ML 1 + 4 @ 100[degrees]C 65 85
E/P ratio 60/40 64/36
% ENB 8.1 8.5
Molecular weight Medium Broad
distribution
Table 3--RE-EPDM evaluation compound
Ingredients PHR
Polymer 100.00
N-660 black 80.00
N-550 20.00
Whiting 40.00
Zinc oxide 5.00
Stearic acid 1.00
TE-28 G 9 2.00
Sunpar 2280 80.00
MBT 1.20
Tellurac 0.50
Butazate 1.20
Sulfads 1.00
Sulfur 1.70
Celogen 754A 4.00
Celogen OT 2.00
Total 339.60
Table 4--physical properties
EPDM
ML 1 + 4 @ 100[degrees]C 61
Mooney scorch @ 125[degrees]C 2.2
Expanded density lb./[ft..sup.3](kg/[m.sup.3]) 25.1 (402)
% water absorption 0.15
25% load deflection, lb.(kg) 2.8 (1.27)
% compression set 17.0
50% deflection
22 hr. @ 70[degrees]C
Skin surface Very slight grain
Wrinkle resistance Very good
Green strength Good
RE-EPDM
4316
ML 1 + 4 @ 100[degrees]C 63
Mooney scorch @ 125[degrees]C 2.5
Expanded density lb./[ft..sup.3](kg/[m.sup.3]) 23.6 (378)
% water absorption 0.15
25% load deflection, lb.(kg) 2.5 (l.13)
% compression set 17.0
50% deflection
22 hr. @ 70[degrees]C
Skin surface Very smooth
Wrinkle resistance Very good
Green strength Excellent
Curing conditions:
Continuous microwave--hot air curing line
1.5 minutes @ 200[degrees]C--automotive bulbular cross section
Table 5
Polymer E/P ML 1 + 4 % MWD
ratio @ 125[degrees]C diene
RE-EPDM 75/25 24 1.5 DCPD Broad
4191P
Table 6--RE-EPDM 4191P in medium
voltage insulation
Ingredients PHR
RE-EPDM 4191P 100.00
Low density PE 5.00
Surface treated calcined clay 60.00
Polymerized trimethylquinoline 1.5
Paraffin wax 5.00
Vinyl silane, 50% on wax 2.00
Zinc oxide 5.00
Red lead, 90% in EPR 5.00
Dicumyl peroxide, 40% on clay 6.25
Total 189.75
Table 7
ODR 2000 @ 177[degrees]C RE-EPDM 4191P
ML, N x m (in.-lb.) 0.53 (4.6)
MH, N x m (in.-lb.) 2.30 (21.8)
MH-ML, N x m (in.-lb.) 1.97 (17.2)
Ts2, min. 1.7
Tc90, min. 7.9
Table 8--physical properties
RE-EPDM 4191P
100% modulus, MPa (psi) 7.1 (1,050)
Tensile, MPa (psi) 13.2 (1,950)
Elongation, % 330
After 7 days @ 121[degrees]C
Tensile, % retention 100
Elongation, % retention 109
After 7days @ 136[degrees]C
Tensile, % retention 102
Elongation, % retention 105
After 7 days @ 158[degrees]C
Tensile, % retention 99
Elongation, % retention 103
Table 9--electrical stability in 90[degrees]C water,
600 VAC applied continuously
Dielectric constant 40 volts/mil 80 volts/mil
1 day 2.53 2.54
7 days 2.53 2.54
14 days 2.53 2.54
28 days 2.57 2.57
3 months 2.56 2.56
6 months 2.63 2.63
8 months 2.64 2.64
12 months 2.63 2.63
Table 10--electrical stability in 90[degrees]C water,
600 VAC applied continuously
Power factor, % 40 volts/mil 80 volts/mil
1 day 0.16 0.15
7 days 0.16 0.15
14 days 0.16 0.15
28 days 0.17 0.17
3 months 0.13 0.13
6 months 0.19 0.18
8 months 0.19 0.18
12 months 0.43 0.43
Table 11--insulation resistance
megohms/1,000 ft.
1 day 7,500
7 days 7,500
14 days 6,600
28 days 6,900
3 months 9,600
6 months 12,000
8 months 13,500
12 months 12,000
Ralph A. Annicelli Crompton Uniroyal Chemical |
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