Short-chain branch, definition

The extent of short-chain branching in PE may be quantitatively determined by a variety of techniques including IR. 1 pyrolysis Ct., 7" and y-radiolysis."84 The most definitive information comes from l3C NMR studies.2S5"2 0 The typical... 

In long- and short-chain branching, according to definition, each of the branches has the same chemical constitution as the main diain, i.e., as in polyethylene ... 

As a more general structural definition, a polymer synthesized from only one type of monomer is referred to as a homopolymer. In contrast, a polymer that is formed from more than one type of monomer is known as a copolymer. The terms terpoly-mer, tetrapolymer, pentapolymer, etc. are used to designate a polymer derived from three, four, five, etc. co-monomers. Although homopolymers contain only one repeating chemical unit in their structure, this distinction is not always clear. For instance, polyethylene polymers often contain short-chain branched impurities as a consequence of the polymerization process. However, since this unintentional structural deviation results from a polymerization process involving only one type of monomer, the term homopolymer is still most appropriate. 

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