Morphological, thermal and mechanical properties of recycled HDPE foams via rotational molding.

Denis Rodrigue,Yao Dou

doi:10.1177/0021955x211013793

Abstract

In this study, foamed recycled high density polyethylene (rHDPE) parts were produced by rotational molding using different concentration (0 to 1% wt.) of a chemical blowing agent (CBA) based on azodicarbonamide. From the samples produced, a complete morphological, thermal and mechanical characterization was performed. The morphological analysis showed a gradual increase in the average cell size, while the cell density firstly increased and then decreased with increasing CBA content. As expected, increasing the CBA content decreased the foam density as well as the thermal conductivity. Although increasing the CBA content decreased both tensile and flexural properties, the impact strength showed a similar trend as the cell density with an optimum CBA content around 0.1% wt. Finally, neat rHDPE samples were also produced by compression molding. The results showed negligible differences between the rotomolded and compression molded properties indicating that optimal rotomolding conditions were selected. These results confirm the possibility of using 100% recycled polymers to produce rotomolded foam parts.

Highlights

In the last decades, rotational molding received a great deal of interest due to its simple processing tools, low machinery cost and limited waste generation.[1,2,3,4] The main reason is the technology allowing to produce large one-piece hollow and seamless products such as industrial storage tanks, automotive parts, furniture and several other items
We reported that increasing the chemical blowing agent (CBA) content led to lower tensile and flexural moduli, and to lower tensile strength and elongation at break, which can be associated with lower density and larger cell size.[25]
There is about 4.9% weight of residues which can be related to the presence of inorganic components in the recycled high density polyethylene (rHDPE) powder

Summary

Introduction

Rotational molding (rotomolding) received a great deal of interest due to its simple processing tools, low machinery cost and limited waste generation.[1,2,3,4] The main reason is the technology allowing to produce large one-piece hollow and seamless products such as industrial storage tanks, automotive parts, furniture and several other items. Rotomolding can more handle complex shaped articles with uniform wall thicknesses. These features make rotomolding one of the fastestgrowing polymer processes in the plastic industries over the last few years.[5,6,7]. The hollow structure of rotomolded products can be used to overcome some limitations related to low mechanical and shock mitigation properties.[11,12,13]

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Results

Conclusion