Branching (polymer chemistry) Branching (polymer chemistry) In polymer chemistry, branching occurs by the replacement of a substituent, e.g., a hydrogen atom, on a monomer subunit, by another covalently bonded chain of that polymer; or, in the case of a graft copolymer, by a chain of another type. Branched polymers have more compact and symmetrical molecular conformations, and exhibit intra-heterogeneous dynamical behavior with respect to the unbranched polymers. In crosslinking rubber by vulcanization, short sulfur branches link polyisoprene chains (or a synthetic variant) into a multiply branched thermosetting elastomer. Rubber can also be so completely vulcanized that it becomes a rigid solid, so hard
Rubber technology 1844, but is a process restricted to polymer chains having a Double bond in the backbone. Such materials include natural rubber and polybutadiene. The range of materials available is much wider however, since all polymers become elastomeric above their Glass transition temperature. However, the elastomeric state is unstable because chains can slip past one another resulting in creep or stress relaxation under static or dynamic load conditions. Chemical cross links add the stability to the network that is needed for most practical applications. WORKER PROCESSING RUBBER Methods for processing rubber include mastication and various operations like mixing, calendering, extrusion, all