Non-polar synthetic rubber blends

Natural Rubber Based Non-Polar Synthetic Rubber Blends... 

The miscibility of natural rubber (NR) blends is one of the most important factors when designing NR products. For instance, when the NR is miscible with a dissimilar polymer on a molecular level, we may improve the properties of NR as a function of the composition of the polymer. This is significantly different from the design for immiscible NR blends, whose properties are greatly dependent upon the morphology of the blend but less so on the composition. In most cases, NR is immiscible with non-polar synthetic rubbers, i.e. NR/butadiene rubber (BR) with high c -1,4-butadiene units, NR/styrene-butadiene rubber (SBR), NR/butyl rubber (IIR), NR/silicone rubber (q)13,i4 NR/ethylene-propylene-diene rubber (EPDM). This means it is important to find miscible NR blends and to control the morphology of the immiscible NR blends in a rational way. In this chapter, properties of NR blends are described from the viewpoint of miscibility, i.e. the miscible blend of NR/BR and the immiscible blend of NR/SBR. 

The natural rubber does not generally exhibit all the desired properties for use in the rubber industry. Thus, it is possible to obtain better mechanical and physical properties at a lower cost by blending natural rubber with synthetic rubbers. Normally, natural rubber is deteriorated by ozone and thermal attacks due to its highly unsaturated backbone, and it also shows low oil and chemical resistances due to its non-polarity. However, these properties can be achieved by blending it with low unsaturated ethylene propylene diene monomer rubber, styrene butadiene rubber, carboxylate styrene butadiene rubber, nitrile butadiene rubber, chloroprene rubber, chlorosulfonated polyethylene rubber, and acrylonitrile butadiene rubber. 

Natural rubber/chlorosulfonated polyethylene rubber blends also exhibited immiscibility. Chlorosulfonated polyethylene rubber is the synthetic rubber used for applications in electric cables, hoses for liquid chemicals, waterproof cloths, floor tiles, and oil-resistant seals. It is chosen to blend with natural rubber to improve the resistance of natural rubber to ozone, oil, heat, flame and non-polar chemicals. This is due to the effect of the polarity of the chlorine groups in the chlorosulfonated polyethylene rubber. The tensile strength, elongation at break, and tear strength of these blends decreased with the increasing chlorosulfonated polyethylene rubber contents. In addition, the compatible natural rubber/chlorosulfonated polyethylene rubber blends were improved by adding the epoxidized natural rubber (Epoxyprene 25) as a... 

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