On the mechanical preconditioning of ultrahigh-molecular-weight polyethylene at small uniaxial deformations

• Published in: Journal of polymer science. Polymer physics edition 1985-12, Vol.23 (12), p.2599-2610
• Main Authors: Crissman, J. M., Zapas, L. J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Rheology and viscoelasticity
• ISSN: 0098-1273; 1542-9385
• DOI: 10.1002/pol.1985.180231215

The results of creep and recovery experiments are reported for a sample of ultrahigh‐molecular‐weight polyethylene at three different temperatures and creep times in the range from 10 s to 1.47 X 10 6 s. In order to approximate constant‐true‐stress conditions all the experiments were carried out at the same value of applied stress (4 MPa) and the change in strain during creep was never more than about 2%. It was found that within the range of conditions used the creep and recovery data could be described quite well by a one‐dimensional constitutive equation consisting of two terms, one a single integral hereditary term and the other a plasticity term. Further, it was shown that to a very good approximation the idea of time‐temperature superposition can be applied to the description of the hereditary term Ĵ (σ, T , t ). We believe that the results described here provide greater insight into what constitutes “mechanical preconditioning” of semicrystalline polymers and further provide a relatively simple method for describing the uniaxial creep and recovery behavior of such materials.