Creep analysis of thermoplastics using stress relaxation data

• Published in: Polymer engineering and science 1995-12, Vol.35 (24), p.1931-1937
• Main Authors: GRZYWINSKI, G. G, WOODFORD, D. A
• Format: Article
• Language: English
• Subjects: Analysis; Applied sciences; Exact sciences and technology; Mechanical properties; Physical properties; Polycarbonates; Polymer industry, paints, wood; Polyphenylene oxide; Properties and testing; Strains and stresses; Stress relaxation (Materials); Stress relieving (Materials); Technology of polymers; Thermoplastics
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.760352404

One of the major factors limiting the use of thermoplastics in engineering applications is the inadequacy of existing design data. Much of the data do not span appropriate ranges of stress, strain, time, or temperature. This study addresses the need to develop an accelerated method for generating long-time design data to support the innovative use of engineering thermoplastics. In particular, stress relaxation tests (SRT) were performed on polycarbonate (PC) and modified poly(phenylene oxide)(PPO), and used to generate time-dependent design data through the short-time measurement of the material's current state without dependence on elastic modulus. The test results and analyses reported here indicate the SRT method to be an efficient means of generating accurate and repeatable creep and secant modulus data which may be directly used in design. Therefore, SRT shows great potential both as a design parameter development tool, and as a quality control instrument for assessing batch-to-batch variability.