Time-dependent properties of graphene nanoplatelets reinforced high-density polyethylene

• Published in: Journal of Applied Polymer Science
• Main Authors: Al-Maqdasi, Zainab, Pupure, Liva, Gong, Guan, Emami, Nazanin, Joffe, Roberts
• Format: Article in Journal/Newspaper
• Language: English
• Published: Polymera material och kompositer 2021
• Subjects: graphene and fullerenes; mechanical properties; theory and modeling; thermoplastics; viscosity and viscoelasticity; Aliphatic compounds; Creep; Graphene; Graphene Nanoplatelets; High density polyethylenes; Advanced applications; Classical techniques; Design and evaluations; High density polyethylene(HDPE); Nano-reinforcements; Reinforced high density polyethylene; Time dependent behavior; Time-dependent properties; Reinforcement; Composite Science and Engineering; Kompositmaterial och -teknik; Carrasco; Luleå; Norrbotten
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:ri:diva-52973; https://doi.org/10.1002/app.50783

The deformation of polymers at constant applied stress is one of their major drawbacks, limiting their use in advanced applications. The study of this property using classical techniques requires extensive testing over long periods of time. It is well known that reinforced polymers show improved behavior over time compared to their neat counterparts. In this study, the effect of adding different amounts of graphene nanoplatelets (GNPs) on the time-dependent properties of high-density polyethylene (HDPE) is investigated using short-term creep tests and load/unload recovery tests. The results are discussed in terms of the test profile and the influence of loading history. Viscoplasticity/viscoelasticity analysis is performed using Zapas model and by comparing creep, creep compliance and pure viscoelasticity curves. The results show that the reinforcement of 15 wt% GNP have the most significant effect on the time-dependent behavior, reducing the strain by more than 50%. The creep compliance curves show that nano-reinforced HDPE behaves nonlinearly viscoelastically even at very low stresses. In addition to demonstrating the effect of nano-reinforcement, the discussion of the results concludes that the influence of loading history can be quite significant and should not be neglected in the design and evaluation of material behavior. © 2021 The Authors. Funding details: 777810; Funding details: European Commission, EC; Funding text 1: Part of this study was financially supported by Interreg Nord project “Smart WPC” (funded by EU and Region Norrbotten) and project Smart Machine and Materials (SMM) within the excellence and innovation area at Luleå University of Technology. The project Nano2Day (grant agreement no. 777810) is also acknowledged. Authors would like to thank Runar Långström and Robert Westerlund at RISE SICOMP for composites processing and the help from Diego Carrasco Fernández (project student at LTU) in performing the creep experiment. See also front cover of the issue. DOI:10.1002/app.50783