Rudolph D. Deanin

Controlled UV Degradation in Plastics

I. INTRODUCTION When plastic products reach the end of their useful life, most of them are discarded by open dumping, sanitary landfill, or simple litter. In order to maintain the quality of our environment, it would be highly desirable if the litter portion were readily degradable by sunlight. Whereas earlier efforts were concerned primarily with increasing the ultraviolet-stability of plastics, the emphasis in recent years has turned increasingly toward our ability to use the same understanding and skill to increase the rate of ultraviolet degradation of such materials. The purpose of the present review is to summarize the present status of our efforts in this direction.

Breathable, Permanent Water-Repellent Treatment of Cotton 1

Cotton fabric was esterified with C4-18 aliphatic monobasic acid chlorides in dimethyl formamide, with pyridine as acid scavenger, at temperatures of 30-85°C. Reaction for 15-60 min at 85°C produced 0.02-0.36 ester groups per monomer unit, which provided water-repellency ratings of 50-80 in the AATCC spray test; water-repellency generally improved with increasing chain length and reaction temperature. Dry-cleaning resistance was good in perchloroethylene alone, but addition of alkaline soap required longer chain lengths and preferably an aqueous post-rinse to retain water repellency. Air permeability decreased during the reaction, but this was due primarily to shrinkage rather than inherent in the pro duction of water repellency. Tensile strength decreased gradually with increasing chain length, temperature, and time, but it was possible to produce a maximum spray rating of 80 with a tensile loss of only 33% and spray ratings of 70 with tensile losses as low as 12%.

Practical Properties of Multi-Phase Polymer Systems

Theoretical polymer chemists traditionally prefer to study simple systems which exist in a single homogeneous phase. For theoretical study of solid state properties, in addition, they prefer polymers which are linear and amorphous as well. In actual practice, however, most important polymer systems are much more complex than this.