Compression Molded Thermoplastic Composites Entirely Made of Recycled Materials

Petri Sormunen,Timo Kärki

doi:10.3390/su11030631

Abstract

Recycled post-consumer high-density polyethylene pipe plastic was agglomerated into composite samples with wood, glass fiber, mineral wool, gypsum, and soapstone as recycled particulate fillers. The tensile strength, tensile modulus, impact strength, and hardness were the mechanical properties evaluated. Scanning electron microscopy was performed on the broken surfaces of tensile strength samples to study the interfacial interactions between the composite matrix and the filler materials. Heat build-up, water absorption, and thickness swelling were the physical properties measured from the composites. The addition of particulate fillers demonstrated the weakening of the tensile and impact strength but significantly improved the rigidity of the post-consumer plastic. The composites filled with minerals had mechanical properties comparable to compression molded wood plastic composites but higher resistance to moisture. A lack of hot-melt mixing affected the mechanical properties adversely.

Highlights

The addition of organic and inorganic fillers to polymers has been an important industrial method in creating new materials with tailored properties for specific applications
The main aim of this paper is to study mechanical, moisture resistance, and heat build-up properties of compression molded high-density polyethylene (HDPE) composites filled with recycled wood fiber, glass fiber, mineral wool, gypsum, and soapstone particles by empirical testing in order to evaluate the effect of recycled low-cost fillers on the recycled plastic
Compression-molded composites were made of recycled materials, and their mechanical properties were examined

Summary

Introduction

The addition of organic and inorganic fillers to polymers has been an important industrial method in creating new materials with tailored properties for specific applications. The use of selected recycled particulates from post-consumer and industrial by-product waste currents as property changing fillers for polymers could be a way to reuse such materials in the manufacturing of new products. Properties of polymers such as corrosion resistance, light weight, and ease of processing into a variety of shapes can be combined with the unique properties of fillers to form composites with modified appearance, cost, mechanical strength, thermal and electrical conductivity, thermal stability, magnetic characteristics, flame retardant, electromagnetic shielding, dielectric, and barrier properties [1,2]. The use of low-cost filler content decreases the costs in thermoplastic composites when the relatively virgin plastic is replaced [6] It could be an economical way to change the properties of the recycled thermoplastics

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