Title

The investigation of the degradation mechanism from the kinetic parameters of dehydrochlorinated polyvinyl chloride decomposition

Date of Completion

January 2000

Keywords

Chemistry, Polymer|Engineering, Chemical|Engineering, Materials Science

Degree

Ph.D.

Abstract

Kinetic theory in regards to the basic understanding of reaction order as it relates to polymer degradation is discussed. The theory is then tested by determining the kinetic parameters for dehydrochlorinated polyvinyl chloride using thermogravimetric analysis. Four different mechanisms of degradation were deduced from four sets of kinetic parameters. The calculated kinetic parameters were apparent reaction order, apparent activation energy, and apparent frequency factor as determined by the original Freeman and Carroll model. A method for obtaining the optimal heating rate from a set of heating rates is also discussed. The product distributions for polyvinyl chloride, polyethylene, polypropylene, and polystyrene are also discussed. When the product distributions are separated into two divisions (volatile and non-volatile) two different modes of degradation are observed for each polymer. The non-volatile product distribution is characterized by random chain scission kinetics while the volatile product distribution is either controlled by some other kinetic phenomenon, thermodynamically controlled, or a combination of the two. ^