ABSTRACT
This paper discusses how molecular data, obtained by gel per meation chromatography (GPC), may be utilized for the elucidation of degradation kinetics. All procedures applied required accurate determinations of molecular weight averages or molecular weight dis tributions. Two systems were investigated in detail: (1) the re petitive extrusion of polycarbonate in a capillary rheometer and (2) the freezing and thawing of solutions of ultrahigh molecular weight polystyrene. Molecular scission was evaluated according to a method devised by Scott. It compares the relative decreases in M ¯ w https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003065081/c17910f6-7d69-4e95-a799-194ca99cfe28/content/ieq0167.tif"/> and M ¯ n https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003065081/c17910f6-7d69-4e95-a799-194ca99cfe28/content/ieq0168.tif"/> with those expected from theory. The nature of chain fracture was w n further elucidated by applying a general equation for scission kin etics proposed by Simha. This analysis made it possible to deter mine the scission frequency as a function of the position in the macromolecule.
