Temperature and strain rate dependence of yield strain and deformation behavior in polyethylene

✍ Scribed by N. W. Brooks; A. P. Unwin; R. A. Duckett; I. M. Ward

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 190 KB
• Volume: 35
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(199703)35:4<545::aid-polb2>3.0.co;2-p

✦ Synopsis

The deformation behavior of a range of polyethylene materials which differ with respect to both their short-chain branch content and molecular weight has been studied. Mechanical measurements carried out over a wide range of temperatures have shown that there is a sudden transition in the measured tensile yield strain at a temperature which is dependent on both the grade of material and the applied strain rate. Above the transition temperature all of the materials behave in a nonlinear viscoelastic manner and the wide-angle X-ray scattering patterns obtained have shown that at low applied strains reorientation of the lamellae is observed before necking. Below the transition temperature the materials all behave in an elastic-plastic manner and there is no evidence of lamellar reorientation before necking. This transition in yield mechanism is not apparent when considering the yield stress data alone.