Polymer blends with dicumyl peroxide

Chitosan (CS) is a partially acetylated glucosamine obtained by deacetylation of chitin, one of the most abundant natural polymers. As a polysaccharide of natural origin, chitosan has many useful features such as nontoxicity, biocompatibility, biodegradability, good mechanical strength and antimicrobial properties. Blends of chitosan (CS) and NR obtained by solvent casting improved the thermal resistance of chitosan. Johns and Rao have also developed chitosan and NR blends vulcanized with dicumyl peroxide (DCP) and... 

Similar blends have been made by cross-linking the E-plastomer with peroxides. This process suffers from an inherent degradation of the iPP by peroxide. In a representative formulation, a mixture of 60 parts of E-plastomer (octene commoner), 15 parts maleated (0.6%) iPP, 25 parts of EPDM, 10 parts of paraffinic plasticizer, 5 parts of dicumyl peroxide, and 1 part of stabilizer was treated at 170°C for 5 min to give a cross-linked blend with Shore A hardness 66, tensile strength 5.5 MPa, and elongation 190%. Similar blends have been made with the incorporation of a limited amount of a SEES polymer to act as a compatibilizer between the E-plastomer and the iPP. 

For ageing experiments the toluene solution of the grafted polymer was first treated with an excess of triphenyl phosphine (reduction of residual hydroperoxides into alcohols), then suitable amount of the parent polymer was added and co-precipitation was performed into methanol. The polymer blend was vulcanized by adding dicumyl peroxide (5% w)prior precipitation (pressing conditions became 190°C, 190 bar, 5 min). 

Figure 15,6 Effect of serene content iqxm dongadon at break erf peroxide and sulfur vulcanizates from serene-butadiene copolymer rubbers, together with results for similar vulcanizates from blends

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