Thermoforming of HDPE

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The thermoforming process involves a previously extruded sheet of material being reheated to a softened state below the melting temperature and then forced into a mould either by a plug, air pressure or a combination of both. Thermoplastics such as polystyrene (PS) and polypropylene (PP) are commonly processed via thermoforming for products in the packaging industry. However, high density polyethylene (HDPE) is generally not processed via thermoforming and yet HDPE is extensively processed throughout the packaging industry. The aim of this study was to investigate the potential of thermoforming HDPE. The objectives were to firstly investigate the mechanical response under comparable loading conditions and secondly, to investigate the final mechanical properties post-forming. Obtaining in-process stress-strain behavior during thermoforming is extremely challenging if not impossible. To overcome this limitation the processing conditions were replicated offline using the QUB biaxial stretcher. Typical processing conditions that the material will experience during the process are high strain levels, high strain rates between 0.1-10s-1 and high temperatures in the solid phase (1). Dynamic Mechanical Analysis (DMA) was used to investigate the processing range of the HDPE grade used in this study, a peak in the tan delta curve was observed just below the peak melting temperature and hence, a forming temperature was selected in this range. HPDE was biaxially stretched at 128°C at a strain rate of 4s-1, under equal biaxial deformation (EB). The results showed a level of biaxial orientation was induced which was accompanied by an increase in the modulus from 606 MPa in the non-stretched sample to 1212MPa in the stretched sample.

Original languageEnglish
Title of host publicationProceedings of the 20th International ESAFORM Conference on Material Forming (ESAFORM 2017)
EditorsDermot Brabazon, Inam Ul Ahad, Sumsun Naher
PublisherAmerican Institute of Physics Inc.
ISBN (Electronic)9780735415805
Publication statusPublished - 16 Oct 2017
Event20th International ESAFORM Conference on Material Forming, ESAFORM 2017 - Dublin, Ireland
Duration: 26 Apr 201728 Apr 2017

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


Conference20th International ESAFORM Conference on Material Forming, ESAFORM 2017

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Ecology
  • Plant Science
  • General Physics and Astronomy
  • Nature and Landscape Conservation


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