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Polymerization as a means of stabilization for polystyrene
Author(s) -
Howell B.A.,
Cui Y.,
Chaiwong K.,
Zaho H.
Publication year - 2006
Publication title -
journal of vinyl and additive technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.295
H-Index - 35
eISSN - 1548-0585
pISSN - 1083-5601
DOI - 10.1002/vnl.20091
Subject(s) - polystyrene , monomer , polymerization , polymer chemistry , materials science , styrene , polymer , thermal stability , radical polymerization , chemistry , copolymer , organic chemistry , composite material
General purpose polystyrene prepared by conventional radical techniques contains a head‐to‐head unit as a consequence of polymerization termination by radical coupling. As has been previously demonstrated, thermal stress promotes homolysis of the bond linking the head‐to‐head components. The macroradicals that were generated depolymerize rapidly to generate styrene monomer. This decomposition during processing can lead to finished articles containing objectionable levels of styrene monomer, particularly for food packaging applications in which even low levels of monomer can promote objectionable taste and aroma. Polymer containing no head‐to‐head units should not be prone to this facile decomposition. In this instance, polystyrene has been prepared by nitroxyl‐mediated polymerization of styrene monomer followed by reductive removal of nitroxyl end groups. Polymer prepared in this manner contains no head‐to‐head units and displays thermal stability much greater than that observed for conventional polystyrene. A direct comparison of the stability for the two polymers is readily available by thermogravimetric techniques. A quantitative reflection of the difference in stability is available from the rate constants for the respective decompositions. decompositions. J. VINYL ADDIT. TECHNOL., 12:198–203, 2006. © 2006 Society of Plastics Engineers