ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
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.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760330802
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