The effect of annealing time on morphology, mechanical properties, and thermal conductivity of HDPE pipes produced by rotational shear

• Published in: Materials today communications Vol. 31; p. 103321
• Main Authors: Huang, Wei, Zhang, Yuxuan, Chen, Bin, Yang, Hao, Shen, Kaizhi, Gao, Xueqin, Fu, Qiang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2022
• Subjects: Different annealing times; HDPE pipe; Mechanical properties; Rotational shear; Shish-kebab; Thermal conductivity; Mechanical properties; Different annealing times; Thermal conductivity; HDPE pipe; Rotational shear; Shish-kebab
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2022.103321

The high-density polyethylene (HDPE) pipes containing a large amount of shish-kebab structures were produced by a self-developed rotational shear system (RSS). The effect of different annealing time on morphology, mechanical properties, and thermal conductivity of HDPE pipes with shish-kebab structures was studied. The results showed that there were two models for the change of shish-kebab structures after annealing at 125 ℃: partial melting and annealing recrystallization under short-term annealing conditions (< 120 min), and new elongated kebabs formation under long-term annealing conditions (≥ 120 min). Under short-term annealing conditions, the hoop tensile strength increased by 2.21% and thermal conductivities in both directions also increased slightly. However, under long-term annealing conditions, the hoop tensile strength increased by 19.12% (from 73.56 MPa to 87.63 MPa), and the thermal conductivity of out-of-plane increased by 7.77% due to the higher interlocking degree of shish-kebab. [Display omitted] •Shish-kebab with different annealing times is studied systematically.•There is the dimensional change of shish-kebab with heat treatment.•There are two models for the annealing of shish-kebab at 125 ℃.•The enhanced hoop tensile strength and thermal conductivity have been confirmed.