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Effect of polypropylene morphology on thermal cis‐trans isomerization and photofading of some azo dyes: A kinetic study
Author(s) -
Beltrame Pier Luigi,
Paglia Ernestina Dubini,
Marcandalli Bruno,
Seves Alberto
Publication year - 1989
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1989.070380413
Subject(s) - isomerization , crystallinity , glass transition , kinetics , polypropylene , polymer , polymer chemistry , morphology (biology) , materials science , amorphous solid , chemistry , organic chemistry , composite material , catalysis , physics , quantum mechanics , biology , genetics
Five polypropylene films were prepared having different crystallinity and morphology, the latter having been modified by stretching. They were colored with azo dyes XC 6 H 4 NNC 6 H 4 N(C 2 H 5 ) 2 (where XH, OCH 3 , CN, and NO 2 ). The kinetics of the thermal cis‐trans isomerization of these dyes has been studied in the range 21–41°C, much above the glass transition temperature of the polymer. The isomerization process was found to be strictly first‐order; the kinetic parameter values have been correlated with the free volume extent in the amorphous regions of the matrix. Lightfastness of the dyes in the polymer matrices has been also investigated: It appeared to be more important for the unoriented samples with respect to the stretched ones and substantially independent on the crystalinity degree.