30 Pages

Degradation Mechanisms in Polyethylene=Starch Blends

WithR.P. Wool, J.S. Peanasky, J.M. Long, S.M. Goheen

This chapter focuses on the microorganism and macroorganism degradation mechanisms in polymer/starch blends and comment on the photo- and chemical degradation mechanisms. It reviews a computer simulation of a percolating microbial invasion system on a cubic lattice and compares to acid hydrolysis and other degradation studies with PE/starch blends. With simulated bilateral invasion of microbes from the top and bottom borders, the authors examine the connectivity or accessed starch. The percolation threshold for the three dimensional cubic lattice simulation was determined from the maximum of the second moment of the cluster distribution as pc = 31.17" volume fraction. The acid hydrolysis experiments were carried out by refluxing samples. The chemical degradation mechanism being used in commercial films containing 6" starch is easily perturbed by both the processing conditions and the environment. A major objective is to examine the biodegradability of the blends via accessibility and connectivity of starch particles in a polyethylene matrix by the use of a percolation model.