Chloroprene mbbers

Ozonc-rcsjstant elastomers which have no unsaturation are an exceUent choice when their physical properties suit the appHcation, for example, polyacrylates, polysulfides, siHcones, polyesters, and chlorosulfonated polyethylene (38). Such polymers are also used where high ozone concentrations are encountered. Elastomers with pendant, but not backbone, unsaturation are likewise ozone-resistant. Elastomers of this type are the ethylene—propylene—diene (EPDM) mbbers, which possess a weathering resistance that is not dependent on environmentally sensitive stabilizers. Other elastomers, such as butyl mbber (HR) with low double-bond content, are fairly resistant to ozone. As unsaturation increases, ozone resistance decreases. Chloroprene mbber (CR) is also quite ozone-resistant. 

Fig. 3. Heat and oil resistance of CSM compared to other elastomers by ASTM D2000. A—K iadicate grades of CSM. The other ASTM designations are as follows AM, acryhc elastomers CR, chloroprene mbber EPDM, ethylene—propjiene—diene mbber FKM, fluorocarbon elastomers FQ, fluorosiUcones ...

Chloroprene mbber is usually manufactured by either batch or continuous emulsion polymerization and isolated either by freeze coagulation or dmm drying of a polymer film. Figure 1 is a schematic flow sheet of this process. 

Fig. 2. Effect of polymerization temperature on the crystalline melting point of chloroprene mbbers produced by emulsion polymerization ...

Other uses of HCI are legion and range from the purification of fine silica for the ceramics industry, and the refining of oils, fats and waxes, to the manufacture of chloroprene mbbers, PVC plastics, industrial solvents and organic intermediates, the production of viscose rayon yam and staple fibre, and the wet processing of textiles (where hydrochloric acid is used as a sour to neutralize residual alkali and remove metallic and other impurities). 

Accelerated sulfur vulcanization is the most widely used method. This method is useful to vulcanize NR, SBR, BR, HR, NBR, chloroprene mbber (CR), XIIR, and EPDM mbber. The reactive moiety present in aU these mbbers is... 

Chlorinated natural rubber (CNR) is applied as an additive in glue compositions based on chloroprene mbber that, in its turn, is widely used in industry for gluing of different mbbers together with metals or each other [2]. As an individual brand glues based on CNR are rarely produced. 

Rubbers are polymers with large engineering application areas. The weathering oxidation progresses in the elastomers according with the namre of substrate. A comparison between styrene-butadiene mbber (SBR), ethylene-propylene-diene monomer (EPDM), chloroprene mbber (CR) and natural rabber (NR) [109] allowed stating some relevant outlines ... 

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