Premium
Free radical degradation of polypropylene: Random chain scission
Author(s) -
Triacca V. J.,
Gloor P. E.,
Zhu S.,
Hrymak A. N.,
Hamielec A. E.
Publication year - 1993
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.760330802
Subject(s) - bond cleavage , chain scission , polypropylene , materials science , molar mass distribution , degradation (telecommunications) , chain reaction , chain (unit) , degree (music) , beta scission , thermodynamics , polymer chemistry , radical , chemistry , composite material , polymer , photochemistry , organic chemistry , physics , computer science , telecommunications , catalysis , astronomy , radical substitution , acoustics
Free‐radical reactions, which are relevant in the chemical modification of polymeric materials, are discussed in relationship to their influence on random chain scission. A mathematical model is developed to calculate the entire molecular weight distribution (MWD) with the degree of chain scission as the sole parameter. This expression is identical to the one derived by Saito for the case of scission initiated by irradiation. An expression for the variation of molecular weight averages with the degree of chain scission is derived and compared with those calculated with the methods of moments found in the literature. The validity of empirical closure conditions used with moment methods is discussed. Experimental data for polypropylene (PP), degraded with organic peroxides in a single screw extruder, are compared with predictions when fitting the degree of chain scission. For a specific degradation process, the degree of chain scission is found to be proportional to the initiator level.