Rubber formulation Heat build

Before World War II (1939-1945) natural rubber was used for practically all rubber applications. Natural rubber is preferred in many products because of its superior building tack, green stock strength, better processability, high strength in non-black formulations, hot tear resistance, retention of strength at elevated temperatures, better resilience, low heat build-up, fatigue resistance, and better dynamic properties. Rubber products are broadly classified as dry rubber products and latex based products [60]. 

Tread. Tread is the wear resistance component of the tyre and is in direct contact with the road. It must provide traction, wet skid and good cornering characteristics with minimum noise generation and also low heat build-up. Tread components can consist of blends of NR, polybutadiene (BR) and SBR, compounded with carbon black, silica, oils and vulcanizing chemicals." Among recently reported formulations for tyre tread with economic and environmental merits is the work of Rattanasom, in which a blend of NR and tyre tread reclaimed rubber (RR) was prepared and mechanically characterized. Their results showed that the blends prepared with different curing systems, i.e. conventional vulcanization (CV) and efficient vulcanization (EV), exhibit an increase in their hardness and modulus with increasing RR content, while other mechanical properties were adversely affected. ... 

Retrospective View of Vinyl-BR Properties In the 1950s, the Phillips Petroleum Company and the Firestone Tire and Rubber Company started commercial production of polybutadienes by organolithium polymerization for use in tyres. These solution BRs, having low vinyl contents (8-10%), were used in blends with emulsion SBR in tyre treads for balancing traction and wear performance properties. In the early 1970s when styrene monomer was in short supply, developments from Phillips Petroleum Company and EniChem (formerly the International Synthetic Rubber Company) showed that vinyl-BRs with 50-55% vinyl content behaved like emulsion polymerized SBR in tyre tread formulations and exhibited very similar tread wear and wet skid resistance. Tread compounds containing 45%-vinyl polybutadiene showed lower heat build-up and better blow-out resistance than E-SBR and blends of E-SBR with cw-BR. EniChem introduced trial quantities of a medium-vinyl butadiene rubber (MVBR) under the name Intolene 50 in 1973. 

Introducing halobutyl into natural rubber formulations for motor vehicle engine mounts, suspension bushings, steering couplings, and exhaust system mounts, all of which must withstand operating temperatures of 120°C or more, is one practical example. The halobutyl improves heat resistance, shock absorbency, and resistance to cut growth, ozone and the weather, at some cost in terms of heat build-up, permanent set and resilience (Table 26),... 

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