Hybrid Composites Based on Polypropylene with Basalt/Hazelnut Shell Fillers: The Influence of Temperature, Thermal Aging, and Water Absorption on Mechanical Properties.

Anna Kufel,Stanisław Kuciel

doi:10.3390/polym12010018

Abstract

The aim of the research was to study the effects of adding natural fillers to a polypropylene (PP) matrix on mechanical and physical properties of hybrid composites. The 10%, 15%, and 20% by weight basalt fibers (BF) and ground hazelnut shells (HS) were added to the PP matrix. Composites were produced by making use of an injection molding method. Tensile strength, tensile modulus, strain at break, Charpy impact strength, and the coefficient of thermal expansion were determined. The influence of temperature, thermal aging, and water absorption on mechanical properties was also investigated. In addition, short-time creep tests were carried out. To characterize the morphology and the filler distribution within the matrix, a scanning electron microscope (SEM) was used. The results showed that the addition of the two types of filler enhanced mechanical properties. Furthermore, improvements in thermal stability were monitored. After water absorption, the changes in the tensile properties of the tested composites were moderate. However, thermal aging caused a decrease in tensile strength and tensile modulus.

Highlights

In recent years, natural fibers have increasingly been used as an alternative to traditional synthetic fibers, which have harmful effects on the environment
The results showed that acid treatment of basalt fibers (BF) improved tensile strength and impact strength
This study aimed to investigate the influence of an addition of natural fillers to a polypropylene matrix on mechanical properties

Summary

Introduction

Natural fibers have increasingly been used as an alternative to traditional synthetic fibers, which have harmful effects on the environment. Agricultural waste is used to manufacture composites due to an increasing demand for eco-friendly materials. Walnut shells are renewable lignocellulosic materials and they can be obtained as agricultural by-products. Gurbanow et al [7] studied polypropylene (PP) composites with hazelnut shell flour. The addition of HSs increased the stiffness of the composites. Basalt fibers (BFs) have been extensively used in various fields of engineering. BFs are mineral fibers with mechanical properties, similar to glass fibers, and low-cost compared to carbon fibers [9]. Basalt is a natural material, and no chemical additives, solvents, pigments, or other hazardous materials, are used in the production of its fibers.

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