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Rheological and mechanical relaxation behavior of a thermally crosslinkable poly(ethylene terephthalate)
Author(s) -
Mather Patrick T.,
Romouribe A.
Publication year - 1998
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10285
Subject(s) - comonomer , materials science , terephthalic acid , rheology , ethylene , polymer chemistry , activation energy , polyester , dynamic mechanical analysis , polymer , copolymer , composite material , chemical engineering , organic chemistry , catalysis , chemistry , engineering
A novel terephthalic acid derivative based on benzocyclobutene, XTA, has been used as a comonomer in the preparation of thermally crosslinkable poly(ethylene terephthalate) copolymers. We have examined the rheological properties of a series of such polymers containing varying monomer percentages of the XTA comonomer: 0, 1, 5, 10, and 20. Incorporation of XTA into PET is found to cause dramatic changes in the temperature and time dependence of the rheological material functions, all indicating that the rate of crosslinking between chains in the melt increases as the XTA percentage is increased. The impact of thermal crosslinking on mechanical properties is also examined using dynamic mechanical analysis (DMA) on samples molded at a selected crosslinking temperature for times yielding varying levels of crosslinking extent. DMA results show that the activation energy of the β mechanical relaxation increases significantly, indicating the importance of torsional mobility of the aromatic ring of PET.