Emulsifier‐free emulsion polymerization of tetrafluoroethylene by radiation. IV. Effects of additives on polymer molecular weight

摘要

AbstractPoly(tetrafluoroethylene) (PTFE) of high molecular weight, 4.5 × 107, was incidentally obtained at earlier study of an emulsifier‐free emulsion polymerization of tetrafluoroethylene by radiation. In order to clarify this phenomenon, the effects of additives, in particular radical scavengers, on the molecular weight of PTFE and its polymerization behavior were studied. It was found that the molecular weight of PTFE is increased by the addition of hydroquinone, benzoquinone, α‐pinene,dl‐limonene, and ethylenediamine but is decreased by oxygen and triethylamine. A PTFE latex with molecular weight higher than 2 × 107was obtained in the presence of hydroquinone. It is concluded that additives such as hydroquinone and benzoquinone, which rapidly scavenge the primary radicals (OH·, H·, andeaq−) in the aqueous phase but not the growing polymer radicals in PTFE particles, are most effective in increasing the mole