Printer Friendly
The Free Library
23,396,934 articles and books


Factors influencing low temperature performance of EPDM compounds.

Elastomers, unlike thermoplastic materials, are normally required to perform over a relatively wide range of temperatures and significantly above their glass transition temperature ([T.sub.g]). The advantage of an elastomer over a thermoplastic material is its ability to recover almost completely from an elongated state (high flexibility), as well as having generally high resilience, low hardness and low modulus characteristics.

When elastomers are used at below ambient temperatures, there is a trend toward increased hardness, increased modulus, decreased flexibility (lower elongation) and increased compression set (ref. 1). Depending on the elastomer in question, two types of phenomena can occur simultaneously--glassy stiffening and partial crystallization. Some examples of elastomers that exhibit crystallization are natural rubber, polychloroprene and ethylene propylene diene elastomers (EPDM).

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 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. 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 ASTM methods. A listing of these tests is shown in table 1.

The blooming test was performed according to GM 6259 M, except that specimens from cured tensile sheets were employed. This test is performed by exposing the test specimens to alternating environments of -30[degrees]C and 100[degrees]C for specified lengths of time and reporting any change in the surface appearance (blooming, discoloration, etc).

In order to simplify discussions around the various EPDM polymers used, a simple nomenclature is employed. The first number signifies the Mooney 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 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, compression set, retraction, stiffening and low temperature hardening have been used for many years to characterize the performance of polymers at low temperatures. Compressive stress relaxation 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 or fracture 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. 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 or mechanical means to within [+ or -] 1[degrees]C of the desired temperature. Recovery after removal from the jig is then performed at this desired low temperature as well. The specimens are usually molded buttons with the dimensions of 29 mm in diameter 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. 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 of the polymer chains (frozen before they can realign) (ref. 1).

Stiffening at low temperatures (Gehman)

ASTM D 1053 describes the test method for low temperature stiffening as: "A specimen of flexible polymer is secured and connected in series to a wire of known torsional constant, while the other end of the wire is attached to a torsion head to allow a twist to the wire. The specimen is immersed in a heat transfer medium at a specified subnormal 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 stiffness. The amount of the specimen's twist is then measured with a protractor. 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 use compressive 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 hangers, 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) at low temperature Compressive stress relaxation (CSR) testing may be used as a prediction of the performance and lifetime of sealing materials (ref. 4). An elastomeric compound develops a resultant force when subjected to a constant deformation. 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 at low temperatures and immediately after a strain is applied. This results in a rearrangement of chain entanglements and changes in the rubber-filler and filler-filler interactions. The relaxation is reversible upon removal of the strain to the system. Chemical components dictate the rate of relaxation at higher temperatures and when the physical processes have diminished. Chemical relaxation is irreversible, leading to chain scission 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 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 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. The temperature was subsequently cycled from -20[degrees]C to 110[degrees]C in 24 hour periods. Counterforce 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 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 for specified periods of time, and observing the specimens for any signs of blooming or bleeding that would suggest incompatibility. In our case, we were specifically looking at the impact of plasticizers 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 norbornene). 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 formulation (table 3, formulation 1). All attempts to minimize 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 is amorphous. This effect can be seen from the DSC 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 peaks at approximately 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, 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 that is required in the mixing stage to get adequate dispersion 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 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 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, 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 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 clearly shows that as the ethylene content increases, the stiffening modulus increases drastically 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 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 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 (DCPD) are added to ethylene propylene polymers to provide unsaturation sites for curing purposes. One double bond reacts in the polymer matrix, while the second is pendant to the polymer chain and provides a site for sulfur 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, it is capable of disrupting the crystallinity 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 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, modulus and green strength all in 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 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 and polyisobutylene are generally used where extraction resistance is required, such as in brake fluid applications. It is believed that polybutene is capable of forming a network in sulfur cured compounds. Polyisobutylene is a relatively inert material that cannot crosslink with either peroxide or sulfur cure systems.

The last two are both ester plasticizers. DIOA is a monomeric 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 matrix. Hence, improved compatibility is expected. Esters 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 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, H. Bechen and M. Mezger, "Polychloroprene grades and compounding for long term flexibility at low temperatures," Bayer AG, Germany.

(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 (Stress Relaxation) in Compression Section 3 Terminology.

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

(6.) Derham, C.J., "Creep and stress relaxation of rubbers--the effects of stress history and temperature changes," Journal of Materials Science 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.
Copyright 2005, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

 Reader Opinion

Title:

Comment:



 

Article Details
Printer friendly Cite/link Email Feedback
Author:Lanxess, Don Tsou
Publication:Rubber World
Date:May 1, 2005
Words:8445
Previous Article:Fully automatic x-ray inspection for tire manufacturers--part 1.
Next Article:A new generation of cost saving curatives.



Related Articles
Computer control of internal mixer for more consistent EPDM compounds.
Understanding the influence of polymer and compounding variations on EPDM extrusions.
Optimization of the production of EPDM sponge rubber seals for automotive use.
Mold fouling during rubber vulcanization.
EPDM-metallocene plastomer blends for W&C.
Compounding EPDM for heat resistance.
Techniques for achieving high hardness EPDM formulations.
EPDMs for automotive sponge products.
Next generation EPDMs for auto, wire and cable.
A new nitrosamine-free curing agent.

Terms of use | Copyright © 2014 Farlex, Inc. | Feedback | For webmasters