Ethylene propylene terpolymer degradation

The polyacrylate and ethylene-acrylic copolymers and one of the ethylene-propylene terpolymers (Nordel) were the best of the Intermediate temperature elastomers. Except for resistance to compression set, these materials were Inferior to the silicones in thermal stability as measured by their retention of tensile properties. The other EPDM compounds and butyl rubber were considerably inferior to the above-mentioned elastomers. It is not expected that the service life of the tested materials will be limited solely by their ability to resist hydrolytic degradation. The only caulking compositions which retained moderate physical integrity on thermal aging were the silicones. 

There are a number of grades of fluorocarbon rubber (copolymers, terpolymers and tetrapolymers) and they are mainly used in applications where the temperatures would degrade ethylene-propylene rubber products. They are able to withstand prolonged use at temperatures up to 200 °C. Typical conditions are high temperature (<150 °C) gaskets under flow or static conditions, in contact with aqueous or fatty foods (including oils). 

Zaharescu, T., Assessment of compatibility of ethylene-propylene-diene terpolymer and polypropylene. Polymer Degradation and Stability 2001,73,113-118. 

Yamada and co-workers [6] determined the degradation products in the region of ethylene-propylene-diene terpolymer (EPDM). These are listed in Table 2.1. 

Table 2.1 Characteristic degradation products of ethylene-propylene-diene terpolymer or the region ...

The mechanical properties of polymer nanocomposites are also influenced by the chemical treatment of nanoparticles due to the different neighborhood in the material. The free volume that characterizes the density of material is modified and, consequently, the penetration of fluids (solvents, oxygen) is rather favorable to degradation. The diffusion of xylene in ethylene-propylene diene terpolymer is unlike, if material presents different consistency (Fig. 14, [191]). The competitive radiochemical processes, crosslinking of polymer and degradation of covering layer are the most important reasons responsible for the different shapes of swelling curves. 

Formation of a strong interfacial layer is the key factor of the mechanism describing retardation of ozone degradation of a diene rubber by elastomer additives with a low degree of unsaturation [1-4]. The effect of comonomer ratio in ethylene-propylene-diene terpolymers (EPDMs) and stereoregularity of propylene units on the interfacial interaction and the amount of crosslinks in ihe interfacial layer was considered for heterophase crosslinked blends with butadiene-acrylonitrile mbbers (BNRs) of different polarities. 

The photo-oxidative degradation of poly(ethylene-co-propylene-co-l,4-hexadiene) (3.133) occurs by a combination of reactions characteristic of the degradation of polyethylene and polypropylene (section 3.1) and polydienes (section 3.12). Quantum yields of different photochemical processes which occur in this terpolymer are shown in Figure 3.68. 

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