Homopolymer tailing method

These two characteristics are not always encountered, especially in the cases of addition polymerization of monomers with double bonds. Isomerization of the monomers may occur, or false bonding of monomeric units into the chain may take place during the actual step of adding monomer onto the polymer chain. Consequently the assumed chemical structure of the polymer must always be carefully verified by analytical methods. Analysis is especially important with industrial polymer production, since the preparation history is not often known exactly. The chemical names of industrial or commercial polymers are often nothing more than a kind of generic name. Commercial poly(ethylenes), for example, despite the ascribed name, are often not homopolymers, but copolymers of ethylene and propylene. As well as that, commercial polymers practically always contain additives such as antioxidants, uv absorbers, fillers, etc. In the addition polymerization of monomers with multiple bonds, head-to-head and tail-to-tail structures are always to be expected together with the normal head-to-tail bonding, as can be seen, for example, with vinyl compounds such as CH2=CHR ... 

Polyvinyl chloride (PVC) is a homopolymer of vinyl chloride. Eighty percent of commercial PVC in packaging is produced by chain-reaction polymerization using a suspension method. Other methods are emulsion and solution polymerization. Chain-reaction polymerization requires initiators to produce free radicals, then the reaction proceeds until the chain is terminated. The predominant configuration of the monomer in the polymer chain follows a head-to-tail alignment to yield a syndiotactic polymer. 

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