Ethylene-propylene-diene-monomer characteristics

The model describes the characteristic stress softening via the prestrain-dependent amplification factor X in Equation 22.22. It also considers the hysteresis behavior of reinforced mbbers, since the sum in Equation 22.23 has taken over the stretching directions with ds/dt > 0, only, implying that up and down cycles are described differently. An example showing a fit of various hysteresis cycles of silica-filled ethylene-propylene-diene monomer (EPDM) mbber in the medium-strain regime up to 50% is depicted in Figure 22.12. It must be noted that the topological constraint modulus Gg has... 

The elastomer determines most of the physical and chemical characteristics of a rubber compound. Typical elastomers are natural elastomers such as natural rubber (NR), sometimes called crepe, and synthetic elastomers such as butyl (including chlorobutyl and bromobutyl), ethylene propylene diene monomer (EPDM), and styrene butadiene rubber (SBR). A list of commonly used elastomers is shown in Table 2. 

The elastomeric sealing components of the metering valve are particularly critical. In those valves used with CFC propellants, the elastomeric seals have typically been formed from an acrylonitrile/butadiene rubber, which has been cured with sulfur. These rubber seals may not be fully compatible with HFA propellants hence, alternative elastomeric materials have been used. These materials include peroxide-cured acrylonitrile/ butadiene, ethylene-propylene diene monomer (EPDM), and chloroprene and thermoplastic elastomers (TPE). The elastomeric materials used to form the dynamic seals around the stem and the static gasket seal between the can and valve may differ based on the required properties of the rubber for the specific function of the seal. The most important characteristics of the elastomeric seals... 

Gatos KG, Thomann R, Karger-kocsis J (2004) Characteristics of ethylene propylene diene monomer rubber/organoclay nanocomposites resulting from different processing conditions and formulations. Polym Int 53 1191... 

An ethylene propylene diene monomer/poly (ethylene-co-vinyl acetate) (EPDM/ EVAc) blend has also been proven to exhibit the above observations in systems with benzene, toluene and xylene as probe molecules [64]. The reduction in solvent uptake was prominent when the EVAc content was increased, and the compositions became less rubbery or more plastic-like due to the semicrystalline nature of EVAc. The liquid sorption characteristics of sulfur- and peroxide-cross-linked 40/60 EPDM/EVAc blends can be explained by the nature of the S—S and C—C chemical bonds. 

Beside the compounds in which the characteristic constituents are polyolefins, other products also may be employed for insulation and jackets. These include crosslinked compounds and constituted from chloro-sulfonated polyethylene (CP insulation and jackets for wires and cables used for deep wall submersible pumps subjected to 60, 90, and 105°C) chlorinated polyethylene (CPE Insulation and jackets for wires subjected to 90°C) ethylene-propylene-diene monomer (EDPM)... 

It was proved that the expanded ethylene-propylene-diene monomer is a good component for the manufacture of high quality roofing spare parts [95]. It minimizes the harsh characteristics under the conditions of permanenfly subjected plates to the activities of natural factors. The thermal conductivity of EPDM/NR/wood... 

Blending methyl methacrylate-butadiene-styrene copolymer with poly(vinyl chloride) for instance was shown to decelerate the dehydrochlorination (leading to discoloration). The gel content, surface energy, and the spectroscopic characteristics of the blend was altered by the presence of the seccHid polymer [158]. In ethylene-propylene-diene rubber EPDM where the third monomer is ethylene-2-norbomene (NB), the photo-oxidation rate as measured by the accumulation of typical products such as hydroperoxides, varied linearly with the NB content [159]. The same held true for peroxide-crosslinked compounds of the same EPDM except that the linear relationship was found between the relative carbonyl absorbance on photoxidation and the amoiuit of peroxide used to crosslink the material... 

Another of the monomers used in addition to ENB is dicyclopentadiene (DCPD), which is shown in Figure 8.9. As can be seen from the structure, there are two double bonds in DCPD. Each of the two dienes will have different tendencies for long chain branching, which will influence processing rates and cross-linking by sulfur or peroxide cures [3], Table 8.5 shows some of the characteristics of the two dienes [5], In addition, Table 8.6 shows general features of ethylene-propylene elastomers as related to the ter-... 

An EPDM rubber is produced by the terpolymerisation of ethylene and propylene with a small amount (typically of the order of 5%) of an unconjugated di-olefin. The di-olefins used, include dicyclopentadiene, 1,4-hexadiene, 5-methylene-2-norbornene, 5-ethylidene-2-norbornene and methyl tetrahydroindene, 1,5 cyclo octadiene. A number of other dienes [74,75] have been tried. Infrared spectroscopy [35] is used to find out the ter monomer content. The characteristic peaks for the ter monomer are shown in Table 3.4. In view of the relatively low concentrations, it is probable that ter monomer base units are present largely as isolated units in EPDM but the distribution of propylene and methylene sequences is of considerable interest. 

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