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

• Published in: Journal of polymer science. Part B, Polymer physics Vol. 35; no. 4; pp. 545 - 552
• Main Authors: Brooks, N. W., Unwin, A. P., Duckett, R. A., Ward, I. M.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01-03-1997; Wiley
• Subjects: Applied sciences; deformation; Exact sciences and technology; Mechanical properties; Organic polymers; Physicochemistry of polymers; polyethylene; Properties and characterization; strain; yield; Strain rate sensitivity; Short chain; Polyethylene; Deformation; Branched polymer; Temperature effect; Property structure relationship; Experimental study; Elongation (mechanics)
• ISSN: 0887-6266; 1099-0488
• DOI: 10.1002/(SICI)1099-0488(199703)35:4<545::AID-POLB2>3.0.CO;2-P

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. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 545–552, 1997