The Effect of Thermal Oxidation on Biodegradation of Isotactic Polypropylene, Polyamide 6/66-4 and Their Mixtures

摘要

The characteristics of isotactic polypropylene (PP), polyamide 6/66-4 (PA) and their blends in the range of 0-100 wt% of PA after soil burial for 4 months are studied. Some thin films of blends were exposed to thermal degradation in air for estimation of the effect of preoxidation on biodegradation. The temperatures and the enthalpies of melting and crystallization of the PP, PA and composites are determined, depending on the PP/PA ratio both for oxidized and unoxidized films. An increase in the enthalpies of melting and crystallization, and the crystallization temperatures of the mixtures after biodegradation in the soil was found. Samples were also investigated by IR spectroscopy and optical microscopy. It has been shown that PP/PA films undergo fouling by micromycetes in the soil, and the concentration of amide, carbonyl and amino groups decrease. Preoxidation of specimens was shown to accelerate the biodegradation of PP/PA mixtures. It was concluded that the PA studied can be characterized as a biodegradable polymer under natural conditions.