Mechanical behaviour and stress-strain recovery characteristics of expanded polypropylene

Abstract

Expanded polypropylene (EPP) foam has been widely recognized as an energy absorbing material, and it is routinely used for variety of industrial applications. However, EPP foam has a relatively limited scope in the construction industry, especially for load-bearing applications. To address this aspect, the mechanical behaviour of EPP foam was examined under unconfined conditions in this study, and the effects of different preloading/precompression strain histories (5% to 60%) on the stress-strain response and strain energy characteristics of EPP were evaluated. Additionally, the stress-strain recovery behaviour of EPP foam having different preloading histories was also studied while considering the effects of recovery time after preloading (0 to 28 Days). The results suggest that EPP foam subjected to different preloading histories has identical patterns of stress-strain response to other conventional closed-cell polymeric foams, such as expanded polystyrene (EPS) foam, and EPP can adequately be used for load-bearing applications under the recommended design limits. Furthermore, noticeable recovery in the stress-strain response of EPP was also witnessed during the initial 14 days after preloading. Based on these findings, it is anticipated that the promising stress-strain recovery characteristics of EPP foam enable it to be reused, even after experiencing large in situ deformations.