Hardness build vulcanization

Thermoplastic rubber is a relatively new class of polymer. It has the solubility and thermoplasticity of polystyrene, while at ambient temperatures it has the toughness and resilience of vulcanized natural rubber or polybutadiene. These rubbers are actually block copolymers. The simplest form consists of a rubbery mid-block with two plastic end blocks (A-B-A), as shown in Figure 5.7. Examples of commercial products are Kraton and Solprene . These materials are often compounded with plasticizers to decrease hardness and modulus, eliminate drawing, enhance pressure-sensitive tack, improve low-temperature flexibility, reduce melt and solution viscosity, decrease cohesive strength or increase plasticity if desired, and substantially lower material costs. Low levels of thermoplastic rubbers are sometimes added to other rubber adhesives. These materials are used as components in the following applications PSAs, hot-melt adhesives, heat-activated-assembly adhesives, contact adhesives, reactive contact adhesives, building construction adhesives, sealants, and binders. Two common varieties of thermoplastic rubber adhesives are styrene-butadiene-styrene (S-B-S) and styrene-isoprene-styrene (S-I-S). ... 

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. ... 

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