Time-resolved small-angle X-ray scattering study of void fraction evolution in high-density polyethylene during stress unloading and strain recovery

Authors

F. Addiego, S. Patlazhan, K. Wang, S. André, S. Bernstorff, and D. Ruch

Reference

Polymer International, vol. 64, no. 11, pp. 1513-1521, 2015

Description

By means of time-resolved small-angle X-ray scattering, we developed an analysis methodology to assess the void volume fraction ϕ_v in high-density polyethylene (HDPE) during tensile testing. The specimens were first drawn up to different imposed strains, and subsequently were subjected to stress unloading and strain recovery stages. During the loading stage, ϕ_v progressively increased with the strain level, starting from a well-defined onset strain prior to the yield point. In particular, ϕ_v reached a maximum of 8.75 vol% for a strain of 12.5% in the case of a HDPE grade with a molecular weight of 105 000 g mol⁻¹. Stress unloading and strain recovery caused a decrease in ϕ_v attained at the end of the loading stage. For a HDPE grade with a molecular weight of 55 000 g mol⁻¹, ϕ_v was more important during the loading stage and the decrease in ϕ_v was less marked during the stress unloading stage when compared to the HDPE with molecular weight of 105 000 g mol⁻¹. The residual and reversible components of void volume fraction were revealed. © 2015 Society of Chemical Industry

Link

DOI: 10.1002/pi.4928