26‐Year creep and recovery of poly(vinyl chloride) and polyethylene

Abstract

Creep experiments on two thermoplastics at constant values of tensile stress, temperature, and relative humidity previously reported for 132,000 h were continued to about 230,000 h. An equation of the form ϵ = ϵ^o + ϵ⁺tⁿ was used to predict the creep, where t is time and ϵ^o, ϵ⁺, and n are constants for a given stress. ϵ^o, ϵ⁺, and n were determined from the first 1900 h of data and were used to predict the creep to 230,000 h. The subsequent recovery on unloading was predicted using the same equation together with the superposition principle. Also reported are creep and recovery of companion specimens aged for about 98,000 h.