Outdoor performance of plastics:

Abstract

This is the second in a series of reports on outdoor performance of 20 plastics. Computer-aided analysis of tensile and flexural strength data is presented for 24-months exposure in Arizona, Florida and Washington, D. C. Ultimate elongation (tensile) and 5% stress (flexural) showed the greatest change of 11 parameters investigated. These changes characterized loss of elasticity and flexibility. Because of the exponential nature of the deterioration, an objective critical fai lure-point was defined, by which most of the change had occurred. This is reached at 36.87, retention of initial property-value. Classification systems were useful for quantitatively distinguishing physical performance. Generally, samples performed worst in Arizona and best in Washington, D. C. Actinic radiation and heat thus appear to be primary agents causing physical degradation.