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Paper No. 52 Cure Systems and Antidegradant Packages for Hose and Belt Polymers by Robert F. Ohm * R. T Vanderbilt Company, Inc 30 Winfield Street Norwalk, CT 06855 Peter A. Callais, PhD and Leonard H Palys Arkema, Inc. 900 First Avenue King of Prussia, PA 19406-0936 Presented to the 155th Meeting of the Rubber Division, American Chemical Society Chicago, Illinois * = Speaker April, 1999 Cure Systems and Antidegradant Packages for Hose and Belt Polymers by Robert F. Ohm, Peter A Callais, and Leonard H Palys ABSTRACT Higher engine compartment temperatures in motor vehicles are placing more severe demands on hose and belt polymers. This presentation reviews the polymers used in hose and belt applications and discusses cure systems and antidegradant packages for each polymer that can increase heat resistance, improve flex fatigue and provide ozone resistance. Historically, there has been a trade-off in performance characteristics between heat resistance and flex fatigue. By

considering the cure system and antidegradant package together, it may be possible to simultaneously improve both heat resistance and flex fatigue. INTRODUCTION Traditionally, sulfur cure systems have been used to vulcanize many hose and belt compounds. The heat resistance of sulfur cure systems can be improved by reducing or eliminating elemental sulfur, which minimizes or eliminates polysulfide crosslinks and provides mainly mono- and di-sulfide crosslinks. For maximum heat resistance and thermal stability, peroxides must be used because they provide carbon-carbon crosslinks. Peroxides require special attention to the additives used in compounding. For example, antidegradant selection is more restricted because many antioxidants interfere with peroxide crosslinking. Furthermore, when using peroxides it is important to minimize acidic fillers to prevent cationic decomposition of the peroxide. The addition of basic ingredients such as zinc oxide or magnesium oxide, when possible,

will generally increase peroxide crosslinking efficiency. Finally, paraffinic oils are preferred, and the use of aromatic oils and solvents should be avoided (1). This presentation will discuss cure systems and antidegradant packages for belt polymers: polychloroprene (CR), alkylated chlorosulfonated polyethylene (ACSM), hydrogenated nitrile2 butadiene copolymer (HNBR) and ethylene-alkyene-(diene) polymers (EPDM, EOM). Cure systems and antidegradant packages for hose applications will then be discussed. BELT POLYMERS Polychloroprene (CR) For many years, the standard V-belt polymer has been chloroprene copolymerized with sulfur. These polymers can be cured with metal oxides alone, but the addition of an organic accelerator such as a thiourea can speed up the rate of cure. Nevertheless, the polysulfide linkages in the chloroprene-sulfur copolymer limit the high temperature resistance of the vulcanizate. With more aerodynamic automotive styling, which restricts the size of the

engine compartment, and increased engine operating temperature for better fuel efficiency, the service limit of the chloroprene-sulfur copolymer is exceeded. Increased heat resistance can be obtained with chloroprene polymerized with a thiuram modifier. The thiuram-modified polychloroprene requires an organic accelerator for cure and generally does not achieve the excellent flex fatigue of the sulfur copolymer. A typical example as reported by Dowd (2) is shown in Figure 1 with complete test data given in Table II. By judicious selection of the antidegradant and curative, R. T Vanderbilt Company’s commercial literature (3) demonstrates that it is possible to improve both the heat resistance and flex fatigue of thiuram-modified polychloroprene, as shown in Figure 2, with all test data given in Table III. While not generally recognized, it is also possible to crosslink polychloroprene with peroxides to generate the most thermally stable carbon-carbon crosslinks, as shown by one of

the authors (4). Peroxide crosslinking requires some modification in the antioxidant system to obtain a high state of cure. A polymerized quinoline (TMQ) is typically used with peroxides because it interferes least with a peroxide cure. However, TMQ can not be used in polychloroprene because it causes scorch and results in poor bin storage stability of the mixed compound. The contour curves in Figures 3 to 5 demonstrate the state of cure, aging and flex fatigue obtainable by various levels of two antioxidants in a thiuram-modified polychloroprene 3 cured with dicumyl peroxide. Selected data from the experimental design are shown in Table IV. An octylated diphenylamine (ODPA) is used in most polychloroprene compounds This aromatic amine antioxidant provides good oxidative stability. However, when curing with peroxide, the amount of this antioxidant must be limited because it severely lowers the state of cure, as shown in Figure 3. In contrast, the zinc 2-mercaptotoluimidazole

(ZMTI) antioxidant synergist does not reduce – but rather increases – the state of cure. Both antioxidants contribute to improved high temperature aging, as indicated by the retention of elongation contours in Figure 4. While ODPA exhibits better DeMattia flex fatigue, as shown in Figure 5, this result could be due to the lower hardness and modulus it conveys. In contrast, the ZMTI increases both modulus and DeMattia cut growth resistance. Properly compounded, polychloroprene is serviceable to 120 ºC (5). Alkylated Chlorosulfonated Polyethylene (ACSM) With increasingly higher under-the-hood temperatures, polymers with fully saturated backbones must be employed. One such candidate is ACSM, which can be crosslinked either through the chlorosulfonyl group with sulfur cure systems or at the hydrocarbon backbone with peroxides. With sulfur cures, 1 phr nickel di-n-butyldithiocarbamate (NBC) is commonly used For performance at higher temperatures, 1 phr meta-phenylene bismaleimide

(MBM) is substituted for the elemental sulfur and the amount of NBC is increased to 3 phr (6). Peroxides crosslink ACSM through the hydrocarbon backbone but, as shown in Figures 6 and 7, heat resistance is similar to crosslinking through the chlorosulfonyl groups with a high temperature cure system. The formula and test data are given in Table V Nevertheless, peroxides provide the flexibility to increase the cure state beyond that allowed when crosslinking through the chlorosulfonyl group. For synchronous timing belts, see Figure 8, Pillow (5) finds the normal failure mode is tooth root failure, which can be a consequence of low tooth modulus or excessive tooth loading. Delgarno and Pillow (7) report a high modulus at the tooth root can minimize failures due to loss of teeth. A high tenacity 4 reinforcing polyamide can give a significant improvement in belt life (5). Also, higher crosslink density via higher peroxide levels is another way stiffness and modulus can be

improved. Delgarno and Pillow (7) report that ACSM is suitable in timing belts for service to 135 ºC. Hydrogenated Nitrile-Butadiene (HNBR) HNBR polymers possess excellent heat and oil resistance and can be compounded for good flex fatigue. It is the dominant polymer for synchronous belts in Japan and is gaining use in Europe, according to Hashimoto and coworkers (8). As previously observed with polychloroprene, the selection of the cure system involves a trade-off between heat aging and flex fatigue. Peroxides provide the best heat resistance, but low sulfur or sulfurless cures generally have better flex fatigue. The work of Upadhyay (9) in this area is shown in Figure 9 and Table VI. With peroxide crosslinking that also polymerizes zinc diacrylate to form an in-situ filler, Brown (10) reports that HNBR can provide excellent toughness and high dynamic modulus at elevated temperature. Recchio and Bradford (11) have shown that meta-phenylene bismaleimide (MBM) coagent will

increase low-strain modulus (MDR-MH) at elevated temperature, as shown in Figure 10 and Table VII. As previously mentioned, increased lowstrain modulus may be beneficial in preventing tooth loss in synchronous timing belts As is typical of peroxide cures in many polymers, the selection of the antioxidant system in HNBR is important for optimum high temperature performance. Generally, a combination of a primary, alkoxy radical trap and an antioxidant synergist such as zinc 2-mercaptotoluimidazole (ZMTI) is used. Ferradino (12), in previously unpublished Vanderbilt work, measured the elongation retention of HNBR containing one of three different radical traps both with and without ZMTI synergist, as shown in Figure 11, with full data presented in Table VIII. The addition of ZMTI significantly improves the aging of an otherwise unprotected HNBR compound. However, the best results are obtained with a combination of ZMTI and a radical trap antioxidant. In the presence of ZMTI, the aging

differences among the primary, radical trap antioxidants tested are relatively minor. 5 Cure speed and high temperature dynamic properties can be affected by the choice of peroxide and coagent. Figure 12 and Table IX excerpt the work of Recchio and Bradford (11) The high performance peroxide, Bis-40HP, can increase scorch time with minimal sacrifice in cure time. The optional use of meta-phenylene bismaleimide (MBM) coagent can provide shorter cure times with lower loss factor (tangent delta) at elevated temperature. Peroxide cured HNBR is suitable for service at 150 ºC (7). Ethylene-Alkylene-(Diene) Polymer (EPDM and EOM) It has been determined that, in several belt applications, casual oil and grease contact does not cause belt failure. This allows the use of hydrocarbon polymers such as EPDM as a material of construction for belts. In addition to being relatively economical, EPDM can be compounded to provide excellent heat resistance and flex fatigue. For maximum heat

resistance, a peroxide cure is required, and flex fatigue can be increased by the addition of the antioxidant synergist ZMTI. Ethylene-octene copolymer (EOM) has even better high temperature resistance than EPDM, according to Kotz and Grant (13). The aged elongation data are given in Figure 13, and full test results in Table X. This polymer contains no unsaturation and so must be cured with peroxides. Palys and coworkers (14) have shown dramatic improvements in crosslinking efficiency with certain high performance peroxides. Figure 14 and Table XI give one example The “HP” or high performance peroxide formulation gives improved scorch times without sacrifice in cure times. In EOM, the dose of the HP peroxide can be cut by one-third and still provide the same state of cure as the regular dicumyl peroxide. If the scorch time or mold flow time of regular DCP is satisfactory, the molding temperature of the HP grade can be increased to shorten cure time and improve productivity

by giving more cured parts per hour. HOSE POLYMERS Fuel Hose 6 In the past, the standard construction for fuel hose in air-aspirated engines with carburetors has been a nitrile rubber (NBR) tube with a polychloroprene (CR) cover. Today, fuel injection systems dominate in Japan and Europe and are increasingly gaining use in the U.S For these systems, the fuel hose is usually made with a fluoroelastomer (FKM) tube or liner to resist gasoline/alcohol mixtures and survive the peroxidized gasoline formed by fuel recirculation in injection systems. FKM also has lower fuel permeability than predecessor polymers, according to Foster and Capriotti (15), which assists compliance with stricter emission regulations such as the 1995 California SHED test (8). Adhering the FKM liner in large diameter hose has been a challenge. Peroxide crosslinking systems with zinc methacrylate coagents are helpful Figure 15 and Table XII compare DBPH peroxide to its high performance DBPH-HP version in a FKM

GF-205NP base compound. The high performance peroxide gives longer time before crosslinking begins, which allows higher cure temperatures for higher productivity. The cover stock nowadays can be either chlorinated polyethylene (CPE) or an alloy of polyvinyl chloride (PVC) and NBR. CPE can be cured with either peroxides or thiadiazoles Two thiadiazoles are compared in Table XIII (16). The original thiadiazole, A-ECO, has a very fast rate of cure, but the mixed compound has poor bin storage stability, sometimes requiring shipment in refrigerated trailers. A newer thiadiazole, A-829, is slower curing but the mixed compounds have much improved storage stability, and the physical properties of the vulcanizate are very good. Vanderbilt and DuPont Dow Elastomers are jointly researching new thiadiazoles that provide faster cure times and without bin storage problems. A standard sulfur cure of NBR is shown in Table XIV (17). In an actual hose compound, 45 to 50 phr of PVC would be fluxed

in during mixing, along with an appropriate stabilizer for the PVC. A newer, low nitrosamine offset to the traditional thiuram monosulfide (TMTM) is shown in the second recipe. The sterically-hindered tetra-iso-butyl thiuram disulfide (TiBTD) that emits less nitrosamines also gives comparable cure properties to TMTM. This replacement of TMTM 7 with TiBTD gives higher rheometer maximum torque and modulus along with lower compression set, properties that are beneficial to the retention of hose couplings in service. Power Steering Hose For many years, an NBR tube and CR cover were used in the power steering pressure hose and return lines. Increasing under-the-hood service temperatures require a change to fully saturated polymers. Today, chlorosulfonated polyethylene (CSM) is used as the tube stock for power steering hose, with a CSM or CPE cover. CPE curatives were presented in the preceding section and in Table XIII. The cure systems and antioxidants for CSM can be essentially the

same as those previously discussed for ACSM in the belt section, see Table V. On a practical basis, peroxides are generally used for high modulus and coupling retention. Nichols and Pett (18) report that CSM power steering hose can be deteriorated by zinc dithiophosphates that are present in older power steering fluids. This result might be expected, given the CSM manufacturer’s warning that zinc will deteriorate compounds based on CSM (19). The power steering fluid becomes less aggressive towards CSM as the fluid ages, presumably due to oxidation of the zinc dithiophosphate. Zinc dithiophosphate is also an accelerator of sulfur vulcanization. Because CSM can be crosslinked either through the chlorosulfonyl group with sulfur cures or at the hydrocarbon backbone with peroxides, it is possible that peroxides make CSM less susceptible to attack by brake fluids that contain zinc dithiophosphates. Air Conditioner Hose Air conditioner hose can be made with any of several polymers. The

most basic hose construction is CSM or peroxide cured CPE. With the change from dichlorodifluoromethane (CFC-12) to the less ozone-depleting tetrafluoroethane (HFC-134a), a broader variety of polymers are suitable for use. Concurrent with this change in refrigerant, the compressor lubricant has changed from mineral oil to polyalkylene glycol, and the operating temperature of the system has increased. 8 Harmsworth (19) has recently suggested that halobutyl rubber is a suitable candidate for air conditioner hose. Halobutyl rubbers possess outstanding resistance to permeation, thus minimizing the loss of the ozone-depleting refrigerant. One general requirement of hose is a high modulus in order to provide good retention of the metal couplings. Work in the Vanderbilt Rubber Laboratory (21,22) shows a significant increase in hardness and modulus through the use of a 2,5-bis (alkylether alkylthio)-1,3,4-thiadiazole crosslinker (A-189), see Table XV. As shown in Figure 16, this

thiadiazole curative also improves high temperature aging. The higher state of cure and better aging presumably result from the minimization of the dehydrohalogenation side reaction that occurs with conventional accelerators for the zinc oxide cure system. Baldwin and coworkers (23) provide information on this undesirable side reaction. The low compression set of this new cure system should also contribute to good coupling retention of the hose. Brake Hose Brake hose can be based on either CR or peroxide crosslinked EPDM. The CR should be crystallization resistant for the best low temperature properties, and also contain gel for low nerve and good extrusion characteristics. EPDM will survive longer in higher temperature operating environments. For maximum retention of coupling force, the selection of antioxidant for the peroxide cure is important. Conventional radical trap antioxidants can lower the hardness and modulus of peroxide cured EPDM. In contrast, the inclusion of ZMTI

antioxidant synergist actually increases hardness and modulus, as shown in Figure 17 and Table XVI (24). Radiator Hose Coolant or radiator hose compounds are based almost exclusively on EPDM. Both sulfur and peroxide cure systems are used. The latter can be useful in preventing the treeing phenomenon that results in premature failure of hoses coupled to electrically insulated, plastic fittings. Keller (25) shows that a peroxide cure gives lower electrical conductivity and coolant absorption as compared to a sulfur cure, as reproduced in Figure 18 with compound data in Table XVII. The absorption of coolant is associated with the development of dendritic 9 structures, the formation of cracks, the filling of cracks by coolant and the premature failure of the hose. Keller finds that other factors, eg the type of reinforcing fabric, lower carbon black levels, and the optional use of hydrophobic clay fillers, can minimize coolant absorption and prevent the formation of dendritic

structures under a small (6 or 12 volt) applied electrical potential. Nevertheless, a major determinant of this type of failure is the cure system Table XVIII from Keller’s work shows the effect of four different sulfur cure systems as compared to a peroxide cure on electrical conductivity and coolant absorption. The peroxide cure is significantly better than any of the sulfur cures, despite widely varying crosslink network structures and crosslink densities. The expected advantage of peroxide crosslinking in the retention of elongation after one week at 150 °C and in compression set after 70 hours at 150 °C is shown in Figure 19, as derived from Keller’s data. The ZDBC, ZDMC, TMTD and DTDM cure system in this study is one of the best sulfur cure systems for compression set and aging. The exceptionally low compression set of the peroxide cure should contribute to good coupling retention. Recently, Vroomen and coworkers (26) discussed some of the factors that must be

considered when selecting peroxide or sulfur cures for EPDM hose compounds. They confirm the work of Keller and others on the superiority of peroxide cures over sulfur cures to prevent electrochemical corrosion. And they verify the typical benefit of peroxide cures for superior heat stability, see Figure 20 as reproduced from their work. Some of the weak points they report for peroxide cures are: a) restriction on the ingredients as we have previously discussed, b) poor hot tear strength during assembly or disassembly on the mandrel, c) bloom with peroxides that generate high molecular weight decomposition products and d) sticky surfaces upon exposure to oxygen in the air during vulcanization. These are some of the areas of current research work by Elf Atochem. 10 SUMMARY In most polymers, heat resistance is improved by going from a sulfur cure to a sulfur donor cure. For maximum heat resistance, a peroxide cure is required Newer peroxide formulations are being introduced which

offer improved processing and enhanced physical properties. The antidegradant system requires careful consideration when using peroxide cures. The use of a minimal level of primary antioxidant with an antioxidant synergist often gives the best results. Several examples of cure systems and antidegradant packages in hose and belt polymers have been presented. In belt applications, the data indicate that the traditional falloff in flex fatigue with peroxides can be overcome by antioxidant optimization. In hose applications, peroxides provide the expected benefits of improved high temperature aging and better compression set. REFERENCES 1. L. H Palys, P A Callais and M F Novits, Selection and Use of Organic Peroxides for Crosslinking, Paper No. 2 presented at a meeting of the Rubber Division ACS, (May 5-8 1998) 2. J. P Dowd, II, Neoprene GW - Properties, Processing and Performance, DuPont Technical Sales Literature, (Nov. 1983) 3. Anon., VANAX CPA versus NA-22F in Neoprene W,

Technical Data Sheet No 1132, Vanderbilt Technical Sales Literature, (May 1983) 4. R. F Ohm, Peroxide Cures of Neoprene W, Technical Newsletter 0J, Vanderbilt Technical Sales Literature, (Sept. 1990) 5. J. G Pillow, Review of Materials for Power Transmission Belts, European Seminar on Belt Drives, Inst. of Mech Engineers, (Feb 22, 1994) 6. Anon., ACSIUMTM HPR-6367 Product Information, DuPont Technical Sales Literature, (Aug. 1991) 7. K. W Delgarno and J G Pillow, Performance Predictions in a High Temperature Dynamic Application, Presented at Rubbercon ’95, (May 9-12, 1995) 8. K. Hashimoto, A Maeda, K Hosoya and Y Todani, Specialty Elastomers for Automotive Applications, Rubber Chem. and Technol, Vol 71, No 3, pages 449-519 (July-Aug 1998) 9. N. B Upadhyay, Sulfur versus Peroxide Crosslinking of HNBR Elastomers, Paper No 13, presented at a meeting of the Rubber Division ACS, (May 5-8, 1998) 10. T. A Brown, Compounding for maximum heat resistance and load bearing capacity

in HNBR belts, Rubber World, pages 53-59, (Oct. 1993) 11 11. M. J Recchio and W G Bradford, Innovative peroxide and coagent cure systems for use with HNBR elastomers, Rubber World, pages 29-36 & 45, (Nov. 1995), based on Paper No. 17 presented at a meeting of the Rubber Division ACS, (Oct 11-14 1994) 12. A. Ferradino, Antioxidant Study in Peroxide Cured HNBR, Vanderbilt Rubber Lab Report V-8027, (Nov. 1993) 13. D. A Kotz and C S Grant, Engage® excels at high temperatures, DuPont Dow Lab Notes, Vol. VI, No 2 page 4, (Fall 1998) 14. L. H Palys, P A Callais, M F Novits and M G Moskal, New Peroxide Formulations for Crosslinking Chlorinated Polyethylene, Silicone, Fluoroelastomer, and Polyethylene Coand Ter-polymer type Elastomers, Paper No. 92 presented at a meeting of the Rubber Division ACS, (May 6-9 1997) 15. S. R Foster and D R Capriotti, A Survey of Performance Elastomers – Meeting the Automotive Requirements of the ‘80s, SAE Technical Paper Series 840408 (Feb

1984) 16. R. F Ohm, New Developments in Curing Halogen-Containing Polymers, Rubber World, Vol. 218, No 1, pages 26-32 (Oct 1998) 17. Anon., Low Nitrosamine Ultra Accelerators in NBR, Technical Data Sheet No 1169, Vanderbilt Technical Sales Literature, (July 1995) 18. M. E Nichols and R A Pett, Predicting the life of automotive power steering hose materials, Rubber World, Vol. 211, No 6, pages 28-31 & 58 (1995) 19. Anon., Basic Compounding of HYPALON® Selecting A Curing System, DuPont Dow Technical Literature HP-320.1 Rev 2, (Aug 1997) 20. N. Harmsworth, Elastomers in Hoses for Air Conditioning Systems, Paper No 45, presented at a meeting of the Rubber Division ACS, (Sept. 29-Oct 2, 1998) 21. Anon., VANAX 189 as a Curative for Chlorobutyl Elastomers, Technical Data Sheet No 1190, Vanderbilt Technical Sales Literature, (Oct. 1997) 22. Anon., VANAX 189 as a Curative for Bromobutyl Elastomers, Technical Data Sheet No 1191, Vanderbilt Technical Sales Literature, (Oct.

1997) 23. F. P Baldwin, D J Buckley, I Kuntz and S B Robinson, Rubber and Plastics Age, Vol 42 page 500 (1961) 24. Anon., VANOX ZMTI in High Heat Resistant Peroxide Cured EPDM, Vanderbilt News, Vol 41 No. 1, page 13 (Oct 1988) 25. R. C Keller, Performance Studies of Ethylene-Propylene Rubber Automotive Coolant Hoses, SAE Technical Paper Series 900576 (Feb. 1990) 26. G. Vroomen, J Noordermeer and M Wilms, Automotive Coolant Hose Technology Keltan® EPDM, peroxide curing, Paper No. 42, presented at a meeting of the Rubber Division ACS, (Sept. 29-Oct 2, 1998) 12 FIGURE CAPTIONS Fig. 1 - Heat Aging and DeMattia Flex of Polychloroprenes Fig. 2 - Heat Aging and DeMattia Flex of Thiuram Modified Polychloroprene Fig. 3 - Effect of Antioxidants on State of Cure of Peroxide Cured CR Fig. 4 - Effect of Antioxidants on Peroxide Cured CR Aged 168 hours at 121 ºC Fig. 5 - Effect of Antioxidants on Flex Fatigue of Peroxide Cured CR Fig. 6 - Effect of Cure System on Elongation of ACSM

Aged at 140 ºC Fig. 7 - Effect of Cure System on 50% Modulus of ACSM Aged at 140 ºC Fig. 8 - Schematic of Synchronous Timing Belt Construction Fig. 9 - Heat Aging and DeMattia Flex of Hydrogenated Nitrile Rubber Fig. 10 - Effect of Coagent on Low Strain Modulus of Bis-40 Peroxide Cured HNBR Fig. 11 - Effect of Antioxidants on Aging of Peroxide Cured HNBR at 175 ºC Fig. 12 - Effect of Peroxide on Cure Properties of HNBR at 170 ºC Fig. 13 - Effect of Antioxidants on Aging of Peroxide Cured EPDM & EOM at 175 ºC Fig. 14 - Rheometer Curves of DCP-40 and DCP-40HP in EOM Fig. 15 – Rheometer Curves of DBPH and DBPH-HP in FKM Fig. 16 - Modulus and Heat Aging of Bromobutyl Rubber Fig. 17 - Modulus and Heat Aging of DCP-40 Peroxide Cured EPDM Fig. 18 - Effect of EPDM Cure Systems on Conductivity and Coolant Absorption Fig. 19 - Effect of EPDM Cure Systems on Aging and Compression Set Fig. 20 - Time to 50% Decay in Elongation for Black Filled EPDM Compounds 13 Elongation Retention

DeMattia Flex 85 300 250 80 200 75 150 70 100 65 60 DeMattia Flex cut growth, kilocycles to 1.3 cm 90 o Elongation after 140 hrs at 100 C, percent retained Fig. 1 - Heat Aging and DeMattia Flex of Polychloroprenes 50 Sulfur Copolymer Sulfur Copolymer, Thiuram Modified, Thiuram Modified Cured/ETU Elongation Retention DeMattia Flex 300 95 250 90 200 85 150 80 100 75 50 70 0 ETU/ODPA&ZMTI DeMattia Flex cut growth, kilocycles to 1.9 cm 100 o Elongation after 168 hrs at 121 C, percent retained Fig. 2 - Heat Aging and DeMattia Flex of Thiuram-Modified Polychloroprene CPA/ODPA&ZMTI 14 Fig. 3 - Effect of Antioxidants on State of Cure of Peroxide Cured CR 200% Modulus: 7 MPa 6 MPa 5 MPa 2 2 R = 96% ZMTI, phr 1.5 1 0.5 0 0 0.5 1 1.5 2 ODPA, phr Fig. 4 - Effect of Antioxidants on Peroxide Cured CR Aged 168 hours at 121 ºC 25% Elongation Retained: 50% 75% 2 ZMTI, phr 1.5 2 R = 84% 1 0.5 0 0 0.5 1 ODPA, phr 1.5 2 15

Fig. 5 - Effect of Antioxidants on Flex Fatigue of Peroxide Cured CR Cut Growth to 1.9 cm: 250 kc 500 kc 750 kc 2 ZMTI, phr 1.5 1 2 R = 87% 0.5 0 0 0.5 1 1.5 2 ODPA, phr Fig. 6 - Effect of Cure System on Elongation of ACSM Aged at 140 ºC 300 Standard High Temp. 250 Elongation, % Peroxide 200 150 100 50 0 0 200 400 600 800 1000 Time at 140 ºC, hours 16 Fig. 7 - Effect of Cure System on 50% Modulus of ACSM Aged at 140 ºC 15 Standard 50 % Modulus, MPa High Temp. Peroxide 10 5 0 0 200 400 600 800 1000 Time at 140 ºC, hours Fig. 8 - Schematic of Synchronous Timing Belt Construction 17 Fig. 9 - Heat Aging and DeMattia Flex of Hydrogenated Nitrile Rubber Elongation after 336 hrs at 150 oC, percent retained Elongation Retention DeMattia Flex 3,500 70 3,000 60 2,500 50 2,000 40 1,500 30 1,000 TMTD/CBS Cure DeMattia Flex cut growth, kilocycles to 1.3 cm 80 Bis-40 Peroxide Cure Fig. 10 - Effect of Coagent on Low Strain

Modulus of Bis-40 Peroxide Cured HNBR Scorch Time Cure Time MDR-MH 30 10 8 25 6 4 20 2 0 MDR Maximum Torque at 170 oC, dN-m Scorch (ts2) & Cure (tc90) times at 170 oC, minutes 12 15 No MBM 4 phr MBM 8 phr MBM 18 Fig. 11 - Effect of Antioxidants on Aging of Peroxide Cured HNBR at 175 ºC o Elongation after 70 hrs at 175 C, percent retained 70 60 50 40 1.5 phr ZMTI No ZMTI 30 20 No Antioxidant AO-445 AO-29 AO-961 12 Scorch Time Cure Time Loss Factor 0.08 0.07 8 0.06 6 0.05 4 0.04 2 0.03 0 0.02 Bis-40 Bis-40HP o 10 Loss Factor at 170 C, tangent delta o Scorch (ts2) & Cure (tc90) times at 170 C, minutes Fig. 12 - Effect of Peroxide on Cure Properties of HNBR at 170 ºC Bis-40 & MBM 19 Fig. 13 - Effect of Antioxidants on Aging of Peroxide Cured EPDM & EOM at 175 ºC o Elongation after 70 hrs at 175 C, percent retained 110 1 ADPA & 2 ZMTI 100 No Antioxidant 90 80 70 60 50 40 30 20 10 0 EPDM EOM Fig. 14 -

Rheometer Curves of DCP-40 and DCP-40HP in EOM 17 15 Torque, dN-m 13 tc90 tc90 11 9 7 6 phr DCP-40 @ 170 °C 5 4 phr DCP-40HP @ 170 °C 3 4 phr DCP-40HP @ 180 °C 1 0 1 2 3 4 5 6 7 8 9 10 Time, minutes 20 Fig. 15 - Rheometer Curves of DBPH and DBPH-HP in FKM 50 45 Torque, dN-m 40 35 30 3 phr DBPH 25 3 phr DBPH-HP 20 15 10 5 0 0 1 2 3 4 5 6 Time at 177 °C, minutes Fig. 16 - Modulus and Heat Aging of Bromobutyl Rubber Initial Modulus Elongation Retention 100 7 95 6 90 5 85 4 80 3 75 2 70 MBTS/TMTD Cure Elongation after 168 hrs at 121 oC, percent retained 200% Modulus, MPa 8 A-189 Thiadiazole Cure 21 Fig. 17 - Modulus and Heat Aging of DCP-40 Peroxide Cured EPDM Initial Modulus 100% Modulus, MPa 5.9 Elongation Retention 85 80 75 5.7 70 5.5 65 5.3 60 5.1 55 4.9 50 4.7 45 4.5 40 No Antioxidant TMQ & ZMTI 3 phr ZMTI Elongation after 168 hrs at 177 oC, percent retained 6.1 6 phr ZMTI Fig. 18 - Effect

of EPDM Cure Systems on Conductivity and Coolant Absorption Conductivity Coolant Absorption 35 1.0 30 0.8 25 20 0.6 15 0.4 10 0.2 5 0.0 0 ZDBC/ZDMC/TMTD/DTDM Cure Coolant Absorption, Mass Percent Cell Equilibrium Conductivity, Milliamperes 1.2 Bis-40 Peroxide Cure 22 Fig. 19 - Effect of EPDM Cure Systems on Aging and Compression Set Compression Set 90 50 40 80 30 70 20 60 10 50 40 ZDBC/ZDMC/TMTD/DTDM Cure Bis-40 Peroxide Cure after 70 hrs at 150 oC, percent Elongation Retention Compression Set Elongation after 168 hrs at 150 oC, percent retained 100 0 Fig. 20 - Time to 50% Decay in Elongation for Black Filled EPDM Compounds 100 90 Peroxide EV Cure SEV Cure 80 Time, days 70 60 50 40 30 20 10 0 100 125 150 Temperature, °C 23 Abbr. A-189 A-829 A-ECO ACSM ADPA AO-29 AO-445 AO-961 Bis-40 Bis-40HP CBS CPA CPE CR-G CR-GW CR-W CSM DBPH DBPH-HP DCP-40 DCP-40HP DTDM EOM EPDM EPM ETU-75 HNBR MBM MBTS NBC NBR ODPA TAIC TMQ TiBTD XIIR ZDBC ZDMC

ZMTI Table I Abbreviations, Materials and Sources Composition Alkylether Thiadiazole Derivative Thiadiazole Derivative Monobenzoyl Derivative of 2,5-Dimercapto Thiadiazole Alkylated Chlorosulfonated Polyethylene Acetone-Diphenylamine reaction product Styrenated Diphenylamine Alpha-methyl Styrenated Diphenylamine Alkylated Styrenated Diphenylamine Bis(t-butylperoxyisopropyl)benzene Bis(t-butylperoxyisopropyl)benzene – high performance N-cyclohexyl-2-benzothiazole Sulfenamide Dimethylammonium Hydrogen Isophthalate Chlorinated Polyethylene Chloroprene Copolymerized with Sulfur Sulfur Copolymerized, Thiuram-Modified Polychloroprene Thiuram-Modified Polychloroprene Chlorosulfonated Polyethylene 2,5-Dimethyl-2,5-dibutylperoxy hexane, 50% active DBPH, 50% active – high performance Dicumyl Peroxide, 40% on calcium carbonate Dicumyl Peroxide, 40% – high performance Dithio Dimorpholine Ethylene-Octene Copolymer Ethylene-Propylene-Diene Terpolymer Ethylene-Propylene Copolymer Ethylene

Thiourea Hydrogenated Nitrile-Butadiene Copolymer Meta-phenylene Bismaleimide Mercaptobenzothiazole Disulfide Nickel Di-n-butyl Dithiocarbamate Nitrile-Butadiene Copolymer Octylated Diphenylamine Triallyl Isocyanurate Polymerized 1,2-dihydro-2,2,4-trimethyl Quinoline Tetra-iso-butyl Thiuram Disulfide Bromobutyl Rubber Zinc Dibutyl Dithiocarbamate Zinc Dimethyl Dithiocarbamate Zinc 2-Mercaptotoluimidazole Trade Name VANAX 1 189 VANAX 1 829 Echo 2 A ACSIUM 3 HPR-6367 VANOX 1 AM WINGSTAY 4 29 NAUGARD 5 445 VANOX 961 VAROX 1 802-40KE VAROX 802-40KE-HP DURAX 1 VANAX CPA TYRIN 3 CM-0136 Neoprene GNA 6 Neoprene GW 6 Neoprene W 6 HYPALON 3 40 VAROX DBPH-50 VAROX DBPH-50-HP VAROX DCP-40C VAROX DCP-40KE-HP VANAX A ENGAGE 3 8180 NORDEL 3 1040 VISTALON 7 457 END-75 8 ZETPOL 10 2010 VANAX MBM ALTAX 1 VANOX NBC CHEMIGUM 4 N685B AGERITE 9 STALITE 9 S DIAK 3 No. 7 AGERITE RESIN D 9 ISOBUTYL TUADS 1 EXXON 7 2244 BUTYL ZIMATE 1 METHYL ZIMATE VANOX ZMTI = Registered Trademark of R. T Vanderbilt

Company, Inc, Norwalk, CT = Registered Trademark of Hercules, Inc., Wilmington, DE 3 = Registered Trademark of DuPont Dow Elastomers, Wilmington, DE 4 = Registered Trademark of Goodyear Tire & Rubber Company, Akron, OH 5 = Registered Trademark of Uniroyal Chemical Company, Naugatuck, CT 6 = Available from DuPont Dow Elastomers, Wilmington, DE 7 = Registered Trademark of Exxon Corporation, Houston, TX 8 = Registered Trademark of Rhein Chemie Corporation, Trenton, NJ 9 = Registered Trademark of The B.F Goodrich Company, Akron, OH 10 = Registered Trademark of Zeon Chemicals, Inc., Louisville, KY 1 2 24 Table II (Data taken from reference 2) Comparison of Polychloroprene Compolymerized with Sulfur and/or Modified with Thiuram Polychloroprene Type CR-G CR-GW CR-W Polychloroprene 100 100 100 Magnesium Oxide 4 4 4 Stearic Acid 1 1 1 N-774 Carbon Black 58 58 58 Aromatic Oil 10 10 10 5 5 5 Zinc Oxide ETU-75 -- -- 0.66 TMTD -- -- 0.75 Mooney Viscosity

at 100 °C, ML1+4 54 62 58 Mooney Scorch at 121 °C, MS t2, minutes 33 22 12 Rheometer at 160 °C ML, N-m 1.1 1.7 1.5 MH, N-m 11.3 11.8 9.7 4.0 3.5 2.5 Ts2, minutes Tc90, minutes 26 8.5 21 Press Cured 20 minutes at 160 °C 100% Modulus, MPa Tensile Strength, MPa Elongation, % Hardness, Durometer A DeMattia Flex, kilocycles to 1.3 cm cut growth 3.4 4.0 4.2 19.2 21.0 21.0 410 410 340 70 70 68 250 180 110 Aged 140 hours at 100 °C 100% Modulus, MPa Tensile Strength, MPa Elongation, % Hardness, Durometer A 6.4 6.0 5.6 19.2 20.0 21.5 270 310 290 78 79 72 64 39 21 Compression Set after 22 hours at 100 °C Set, % 25 Table III (Data taken from reference 3) Comparison of Curatives in Thiuram-Modified Polychloroprene Curative ETU CPA CR-W 100 100 Magnesium Oxide 4 4 Stearic Acid 0.5 0.5 N-770 Carbon Black 60 60 Naphthenic Oil 10 10 Zinc Oxide 5 5 ODPA Antioxidant 2 2 ZMTI Antioxidant 1 1 ETU-75 0.7 CPA

Mooney Scorch at 121 °C, MS t2, minutes Viscosity, ML -- -1.5 7 7 40 40 Aged 2 weeks at 38 °C MS t2, minutes Viscosity, ML 6 7.5 52.5 43 200% Modulus, MPa 11.6 11.4 Tensile Strength, MPa 20.9 21.1 Press Cured 20 minutes at 160 °C Elongation, % 340 350 Hardness, Durometer A 68 66 DeMattia Flex, kilocycles to 1.9 cm cut growth 57 250 Aged 168 hours at 121 °C Tensile Strength, MPa Elongation, % Hardness, Durometer A 17.0 15.9 310 330 74 74 26 19 Compression Set after 70 hours at 100 °C Set, % 26 Table IV (Data taken from reference 4) Comparison of Antioxidants in Peroxide-Cured, Thiuram-Modified Polychloroprene ODPA 0 2 0 2 ZMTI 0 0 2 2 100 100 100 100 4 4 4 4 N-990 Carbon Black 75 75 75 75 Naphthenic Oil 10 10 10 10 5 5 5 5 CR- W Magnesium Oxide Zinc Oxide ODPA Antioxidant -- ZMTI Antioxidant -- DCP-40 Peroxide 2 -- -- 2 2 2 1 1 1 1 Scorch, ML t5, minutes 16 30 5 5 Viscosity, ML 30 27 30

32 MS t2, minutes 16 31 4 3 Viscosity, ML 35 31 38 42 Mooney at 121 °C Aged 2 weeks at 38 °C Press Cured 30 minutes at 160 °C 200% Modulus, MPa Tensile Strength, MPa Elongation, % Hardness, Durometer A 7.7 4.2 8.3 5.9 14.5 14.1 15.2 12.6 300 480 340 530 62 55 68 65 241 15 >1,000 DeMattia Flex kilocycles to 1.9 cm cut growth 0.5 Aged 168 hours at 121 °C Tensile Strength, MPa 12.5 13.1 12.7 11.7 Elongation, % 50 300 100 450 Hardness, Durometer A 82 73 84 68 13 20 20 29 Compression Set after 70 hours at 100 °C Set, % 27 Table V Comparison of Cure Systems in Alkylated Chlorosulfonated Polyethylene Cure System Type ACSM 6367 Low MW Polyethylene/ Paraffin Wax N-762 Carbon Black Standard 100 3/2 High Temp. 100 3/2 Peroxide 100 3/2 35 35 35 Magnesium Oxide 4 4 10 Pentaerythritol 3 3 -- Sulfur 0.5 MBM -- MBTS 1 TMTD 1 DPTH NBC -1 -- -- 1 -- 1 -- -- -- 1 -- 3 -- DBPH-50 -- -- 6 TAIC --

-- 4 Initial Properties 100% Modulus, MPa Tensile Strength, MPa 4.7 4.5 4.5 25.5 25.5 20.2 Elongation, % 297 279 284 Hardness, DIN 76 74 75 Aged 250 hours at 140 °C 100% Modulus, MPa 10.1 5.3 6.0 Tensile Strength, MPa 19.0 20.3 19.7 Elongation, % 164 260 257 Hardness, DIN 82 77 78 100% Modulus, MPa -- 10.7 11.3 Tensile Strength, MPa 14.2 17.4 14.3 Elongation, % 48 150 128 Hardness, DIN 91 82 85 83 65 41 Aged 750 hours at 140 °C Compression Set after 72 hours at 100 °C Set, % 28 Table VI (Data taken from reference 9) Comparison of Curatives in Hydrogenated Nitrile Rubber Cure System Peroxide Sulfur HNBR 100 100 Magnesium Oxide 2 2 Stearic Acid 0 1 ODPA Antioxidant 1 1.5 ZMTI Antioxidant 0.4 2 N-550 Carbon Black 45 45 TAIC Coagent 1.5 -- Bis-40 Peroxide 7 -- Sulfur -- 0.5 TMTD -- 2 CBS -- 0.5 Mooney Scorch at: MS t5, minutes 140 °C 14 130 °C 8 Rheometer at: 180 °C 170 °C Tc50,

minutes 4.2 2.9 180 °C 170 °C 200% Modulus, MPa 18.6 8.1 Tensile Strength, MPa 24 32 255 590 74 72 1,500 3,000 750 1,600 180 180 Press Cured 15 minutes at: Elongation, % Hardness, Durometer A DeMattia Flex, kilocycles to 1.3 cm cut growth Aged 168 hrs at 150 °C, kc to 1.3 cm cut growth Aged 336 hours at 150 °C Elongation, % 29 Table VII (Data taken from reference 11) Effect of Coagent on Peroxide-Cured HNBR MBM Dose, phr -- 4 8 100 100 100 50 50 50 Zinc Oxide 5 5 5 AO-445 Antioxidant 1.5 1.5 1.5 ZMTI Antioxidant 1 1 1 Bis-40 Peroxide 8 8 8 4 8 HNBR N-774 Carbon Black MBM Coagent -- Mooney at 125 °C Scorch, ML t5, minutes 28.6 11.2 12.3 Viscosity, ML 59 61 61.8 MDR at 170 °C ts2, minutes 1.1 0.5 0.5 tc90, minutes 10.2 8.1 7.6 ML, N-m 0.1 0.1 0.1 MH, N-m 2.0 2.5 2.9 Loss Factor, tangent delta 0.0525 0.039 0.036 Press Cured at 170 °C 100% Modulus, MPa Tensile Strength, MPa Elongation, % Hardness,

Durometer A 4.8 11.2 15.2 28.9 28.3 26.3 317 206 164 68 74 80 28.9 30.1 28.8 Aged 70 hours at 150 °C Tensile Strength, MPa Elongation, % Hardness, Durometer A 276 195 140 73 81 80 20 16 14 Compression Set after 70 hours at 150 °C Set, % 30 Table VIII (Data taken from reference 12) Comparison of Antioxidants in Peroxide-Cured HNBR Antioxidant None AO-445 AO-29 HNBR 100 100 100 AO-961 100 Stearic Acid 0.5 0.5 0.5 0.5 Zinc Oxide 5 5 5 5 N-990 Carbon Black 45 45 45 45 N-330 Carbon Black 20 20 20 20 Naphthenic Oil 10 10 10 10 AO-445 -- -- -- AO-29 -- -- AO-961 -- -- Bis-40 Peroxide Mooney Scorch at 121 °C, ML t5, min. 1.5 1.5 -- -1.5 8 8 8 8 44 56 55 46 Rheometer at 171 °C ts2, minutes 0.7 1.1 0.9 0.9 tc90, minutes 11.3 12.7 12.6 11.7 200% Modulus, MPa 23.2 18.6 18.4 19.1 Tensile Strength, MPa 25.8 24.9 23.8 24.1 Press Cured 30 minutes at 171 °C Elongation, % 235 275 265 260

76 74 74 74 Tensile Strength, MPa 13.2 24.7 23.1 21.2 Elongation, % 65 163 150 130 Hardness, Durometer A 84 81 81 81 22.2 26.7 25.7 24.8 Hardness, Durometer A Aged 70 hours at 175 °C – No ZMTI Aged 70 hours at 175 °C + 1.5 phr ZMTI Tensile Strength, MPa Elongation, % Hardness, Durometer A 145 195 205 180 82 82 82 82 23.5 27.5 27.5 26.0 Compression Set after 168 hours at 150 °C Set, % 31 Table IX (Data taken from reference 11) Comparison of Peroxide and Coagent in HNBR Bis-40 Bis-40HP Bis 40 & MBM 100 100 100 50 50 50 Zinc Oxide 5 5 5 AO-445 Antioxidant 1.5 1.5 1.5 ZMTI Antioxidant 1 1 1 Bis-40 Peroxide 8 HNBR N-774 Carbon Black Bis-40HP Peroxide -- MBM Coagent -- -8.42 8 -- -- 4 >30 11.2 Mooney at 125 °C Scorch, ML t5, minutes 28.6 Viscosity, ML 59 56 61 MDR at 170 °C ts2, minutes 1.1 1.5 0.5 tc90, minutes 10.2 11.5 9.5 ML, N-m 0.1 0.1 0.1 MH, N-m 2.0 1.6 2.8 Loss Factor,

tangent delta 0.0525 0.070 0.039 Press Cured at 170 °C 200% Modulus, MPa 17.7 14.3 27.8 Tensile Strength, MPa 28.9 28.2 28.4 Elongation, % Hardness, Durometer A 317 398 206 68 66 74 28.9 27.9 30.1 Aged 70 hours at 150 °C Tensile Strength, MPa Elongation, % Hardness, Durometer A 276 314 195 73 75 81 20 25 16 Compression Set after 70 hours at 150 °C Set, % 32 Table X (Data taken from reference 13) Effect of Antioxidants in Peroxide-Cured EPDM and EOM Antioxidant None EPDM 100 100 -- -- EOM -- -- 100 100 N-650 Carbon Black 50 50 50 50 Paraffinic Oil 30 30 30 30 ADPA Antioxidant -- 1 -- 1 ZMTI Antioxidant -- 2 -- 2 TAIC DLC Coagent Bis-40 Peroxide ADPA & ZMTI None ADPA & ZMTI 2 2 2 2 10 10 10 10 24 24 36 37 Mooney at 121 °C ML 1 + 4, Mooney units Rheometer at 180 °C ts2, minutes 0.6 0.8 0.6 0.7 tc90, minutes 5.6 6.5 4.1 4.8 tc95, minutes 7.7 8.4 5.8 6.6 5.0 4.0 3.4 3.7 16.0

17.1 13.8 14.0 Press Cured to tc95 + 3 minutes at 180 °C 100% Modulus, MPa Tensile Strength, MPa Elongation, % 330 265 330 360 69 71 65 71 2 16 3 14 Elongation, % 15 220 70 390 Hardness, Durometer A 80 75 72 74 Tensile Strength, MPa 5 3 4 9 Elongation, % 2 30 2 215 91 83 88 79 11 17 11 16 Hardness, Durometer A Aged 70 hours at 175 °C Tensile Strength, MPa Aged 168 hours at 175 °C Hardness, Durometer A Compression Set after 70 hours at 175 °C Set, % 33 Table XI (Data taken from reference 14) Comparison of Peroxides in Ethylene-Octene Copolymer Peroxide DCP-40 DCP-40HP EOM 100 100 N-774 Carbon Black 75 75 Paraffinic Oil 10 10 Zinc Oxide 5 5 TMQ Antioxidant 2 2 DCP-40 Peroxide 8.3 DCP-40HP Peroxide -- -5.4 MDR at 185 °C ML, dN-m 1.9 1.7 MH, dN-m 20.0 19.1 ts0.4, minutes 0.3 0.4 tc90, minutes 2.1 1.8 7.0 6.4 Press Cured at185 °C 100% Modulus, MPa Tensile Strength, MPa Elongation, % Hardness,

Durometer A 400 480 94 92 35 34 Compression Set after 70 hours at 150 °C Set, % 34 Table XII (Data taken from reference 14) Comparison of Peroxides in Fluoroelastomer Peroxide DBPH DBPH-HP FKM GF-205NP 100 100 30 30 TAIC Coagent 3 3 DBPH Peroxide 3 N-330 Carbon Black DBPH-HP Peroxide -- -3 MDR at 176.7 °C ML, dN-m 0.1 0.1 MH, dN-m 4.2 4.6 ts2, minutes 0.4 0.9 tc90, minutes 1.1 3.1 ML, dN-m --- 0.1 MH, dN-m --- 4.3 ts2, minutes --- 0.4 tc90, minutes --- 0.8 6.7 6.3 14.9 13.9 MDR at 195 °C Press Cured at 176.7 °C 100% Modulus, MPa Tensile Strength, MPa Elongation, % Hardness, Durometer A 310 275 69 70 26.5 27.6 Compression Set after 70 hours at 200 °C Set, % 35 Table XIII (Data taken from reference 16) Comparison of Thiadiazoles in Chlorinated Polyethylene (CPE) Curative CPE A-ECO A-829 100 100 Magnesium Oxide 10 10 N-774 Carbon Black 50 50 Aromatic Oil 30 30 Butryaldehyde-Aniline Reaction Product

0.8 A-ECO 2.5 A-829 -- 0.8 -2.5 Mooney at 121 °C - Original ML t5, minutes 22 39 Viscosity, ML 48 49.5 Mooney at 121 °C -After 2 weeks at 38 ºC Viscosity, ML 150+ 69 Rheometer at 171 °C ML, N-m 0.8 0.9 MH, N-m 3.9 6.2 ts2, minutes 1.2 2.5 tc90, minutes 3.0 13.6 8.2 9.1 14.4 15.1 Press Cured at 171 °C 200% Modulus, MPa Tensile Strength, MPa Elongation, % Hardness, Durometer A 450 390 78 82 14.4 14.5 Aged 336 hours at 121 °C Tensile Strength, MPa Elongation, % Hardness, Durometer A 375 310 83 87 32 22 Compression Set after 70 hours at 100 °C Set, % 36 Table XIV (Data taken from reference 17) Comparison of Sulfur Curatives in Nitrile-Butadiene Rubber (NBR) Curative Standard Low Nitrosamine NBR 100 100 N-550/N-990 Carbon Blacks 35/65 35/65 Processing Aid 2.5 2.5 Dioctyl Phthalate 10 10 Zinc Oxide/Stearic Acid 5/1 5/1 ODPA/ZMTI Antioxidants 1/1 1/1 Sulfur 0.25 0.25 CBS 2 2 TMTM 3 TiBTD -- -3 Mooney at

121 °C ML t5, minutes 31 26 Viscosity, ML 52.5 53.5 ML, N-m 1.1 1.2 MH, N-m 5.3 7.6 ts2, minutes 3.0 2.5 tc90, minutes 7.2 7.0 200% Modulus, MPa 4.9 7.4 Tensile Strength, MPa 9.8 12.5 Rheometer at 166 °C Press Cured to tc90 + 2 minutes at 166 °C Elongation, % Hardness, Durometer A 480 410 72 70 14.4 15.0 Aged 70 hours at 125 °C Tensile Strength, MPa Elongation, % Hardness, Durometer A 290 220 80 78 58 40 Compression Set after 70 hours at 125 °C Set, % 37 Table XV (Data taken from reference 22) Comparison of Curatives in Bromobutyl Rubber Curative XIIR MBTS/TMTD A-189 100 100 N-550 Carbon Black 55 55 Parafinnic Oil 10 10 Zinc Oxide 3 3 Stearic Acid 1 -- MBTS 1.5 -- TMTD 0.25 -- Sulfur 0.5 -- A-189 -- 2.5 ML t5, minutes 15.5 8.3 Viscosity, ML 46 52 Mooney at 121 °C Rheometer at 160 °C ML, N-m 1.3 1.5 MH, N-m 3.8 8.1 ts2, minutes 2.3 2.1 tc90, minutes 11.5 3.8 2.6 7.4 11.5 10.6 Press

Cured to tc90 at 160 °C 200% Modulus, MPa Tensile Strength, MPa Elongation, % Hardness, Durometer A 760 340 52 60 10.4 11.5 Aged 168 hours at 121 °C Tensile Strength, MPa Elongation, % Hardness, Durometer A 570 320 62 64 62 14 Compression Set after 70 hours at 100 °C Set, % 38 Table XVI (Data taken from reference 24) Effect of Antioxidants on State of Cure and Heat Aging of Peroxide-Cured EPDM Antioxidant None EPDM 100 CR-W Magnesium Oxide 3 ZMTI 6 ZMTI 100 100 100 8 8 8 8 5 5 5 5 Zinc Oxide 15 15 15 15 N-990 Carbon Black 35 35 35 35 N-550 Carbon Black 65 65 65 65 Paraffinic Oil 20 20 20 20 TMQ Antioxidant -- 2 -- -- ZMTI Antioxidant -- 3 3 6 2 2 2 2 10 10 10 10 MBM Coagent DCP-40 Peroxide TMQ & ZMTI Rheometer at 171 °C ts2, minutes 0.4 0.6 0.5 0.8 tc90, minutes 8.0 7.3 7.8 8.3 MH, N-m 9.8 8.5 9.7 9.9 5.5 5.0 5.3 5.9 10.1 10.1 9.7 9.8 Press Cured 10 minutes at 171 °C 100%

Modulus, MPa Tensile Strength, MPa Elongation, % Hardness, Durometer A 180 210 180 170 75 77 76 77 Aged 168 hours at 177 °C Tensile Strength, MPa 5.2 7.6 6.6 8.2 Elongation, % 80 150 120 140 Hardness, Durometer A 87 91 90 90 Brittle Brittle Brittle Elongation, % ↓ ↓ ↓ 70 Hardness, Durometer A ↓ ↓ ↓ 91 20 28 24 25 Aged 336 hours at 177 °C Tensile Strength, MPa 6.5 Compression Set after 70 hours at 150 °C Press Cured 20 minutes at 171 °C Set, % 39 Table XVII (Data taken from reference 25) Comparison of Curatives in EP(D)M Hose Compounds Curative Sulfur Peroxide EPDM 100 75 EPM -- 25 N-650 Carbon Black 45 40 N-762 Carbon Black 55 50 Parafinnic Oil 50 45 Zinc Oxide 5 3 Stearic Acid 1 -- ZDBC 3 -- ZDMC 3 -- DTDM 3 -- TMTD 3 -- Sulfur 0.5 -- TMQ Antioxidant -- 0.5 MBM Coagent -- 1.0 Bis-40 Peroxide -- 7.4 Physical Properties 200% Modulus, MPa Tensile Strength, MPa Elongation, %

Hardness, Durometer A 8.4 7.3 14.9 12.6 390 310 70 65 13.4 12.5 Aged 168 hours at 150 °C Tensile Strength, MPa Elongation, % Hardness, Durometer A 180 305 79 67 46 12 Compression Set after 70 hours at 150 °C Set, % 40 Table XVIII (Data taken from reference 25) Relationship of Cure System on Crosslink Network and Coolant Absorption of EPDM Cure System A B 0.2 C 2 MBTS 1 TMTD 0.8 1.5 3 2.5 -- ZDBC 0.8 1.5 -- 2.5 -- -- 0.75 E Sulfur -- 1.5 D -- --- TMTM -- 1.5 -- -- -- DTDM -- 2 -- 1.7 -- Copper salt of MBT -- -- 0.5 -- -- ZDMC -- -- -- 2.5 -- MBM -- -- -- -- 1 DCP-40 Peroxide -- -- -- -- 10 83.6 64.0 78.2 73.5 31.1 5.7 4.3 5.4 5.2 4.7 0.6 0.5 0.5 0.6 0.1 10.7 17.1 12.0 14.5 2.3 Rheometer Data MH - ML, dN-m Press Cured Properties 100% Modulus, MPa Coolant Immersion Test Conditions: 14 days at 80 °C and 6 volt applied potential Current, mA Weight Increase, % 41