INFLUENCE OF COCONUT SHELL ADDITION ON PHYSICO-MECHANICAL PROPERTIES OF WOOD PLASTIC COMPOSITES1

Éverton Hillig,Ignacio Bobadilla,Érick Agonso Agnes De Lima,Ademir José Zattera,Raquel Marchesan

doi:10.1590/1806-90882017000400012

Abstract

ABSTRACT In this study, composites with three types of thermoplastic matrix and cellulosic material in a proportion of 40% were produced. The three thermoplastic matrices were high density polyethylene (HDPE), polypropylene (PP) and low density polyethylene (LDPE), and the cellulosic materials were pure wood flour (Pinus taeda L) or a mixture of wood flour and coconut shell flour (Cocus nucifera L) in equal ratios. The objective was to evaluate the influence of addition of coconut shell on the physico-mechanical properties (density, strength and rigidity) and the distribution of the cellulosic material in the thermoplastic matrix of the manufactured composites. It was found that the composites had a satisfactory distribution of wood flour in thermoplastic matrices, but the addition of coconut shell promoted bubble formation in the resulting pieces and, thus, interfered with the material properties. The use of a coupling agent promoted interfacial adhesion (cellulose - thermoplastic matrix), which was better in high density polyethylene composites, followed by polypropylene and low density polyethylene. In general, the coconut shell addition caused a decrease of all properties compared to composites made with Loblolly Pine. In addition, the interactions between thermoplastic type and cellulosic matrix type have been statistically confirmed, which caused variations in the studied properties

Highlights

In accordance with SIMPLÁS (2008), wood plastic composites (WPCs) are combinations of plastics and natural fibers manufactured by thermoplastic processing technology
This study aimed to evaluate the effect of polymer type and the lignocellulosic material, especially the coconut shell, in the physico-mechanical properties of composites with different plastic matrix (HDPE, low density polyethylene (LDPE), PP), and the effect of using high density polyethylene (HDPE) graphitized with maleic anhydride as an coupling agent
For the production of the analyzed composites, coconut shell flour (Cocus nucifera L.) and Loblolly Pine wood flour (Pinus taeda L.) were used, both being of fine grain type, and they were provided by a company that produces these materials

Summary

Introduction

In accordance with SIMPLÁS (2008), wood plastic composites (WPCs) are combinations of plastics and natural fibers manufactured by thermoplastic processing technology This technology, which results in a new product with new properties, remains one of the fastest growing segments within the plastics industry. The polymers commonly used for the composites production are high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), and polyvinyl chloride (PVC), which can be used virgins, recycled or in mixtures (El-Haggar and Kamel, 2011). Additives, such as lubricants, pigments, stabilizers, coupling agents and biocides, as well as inorganic fillers, are added to the polymer and fibers

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Conclusion