The effect of micron sized wood fibers in wood plastic composites

Lance W Gallagher,Armando G Mcdonald

doi:10.4067/s0718-221x2013005000028

Lance W Gallagher, Armando G Mcdonald

Open Access

https://doi.org/10.4067/s0718-221x2013005000028

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Abstract

The popularity and demand for wood plastic composites (WPC) has focused research on fiber properties associated with performance. In this study, maple wood fibers (WF) were ball milled and classified into discrete size fractions. Fiber analyses showed only three distinct WF size classes (80-100, 100-200 and <200 mesh). High density polyethylene (HDPE) based WPC were made from classified WF (10 to 50%). The effect of WF size, loading, and maleated polyethylene (MAPE) coupling agent on WPC rheological behavior (torque rheometry and melt flow rate (MFR)) and flexural properties were examined. The WPC MFR decreased with wood loading, increased with a reduction in WF size. The modulus of rupture (MOR) was shown to increase with a reduction in WF size and increase with the addition of MAPE. The increase in MOR is likely due to an increase in the interfacial interaction between the polymer and WF. Modulus of elasticity (MOE) was shown to increase with an increase in wood loading and decrease with a decrease in WF size. The toughness of the WPC was shown to increase with a decrease in WF size and increase upon addition of MAPE.

Highlights

A growing trend in decking is the use of composite decking, which boasts several advantages over its natural competitor, wood
Wood Fiber Analysis Sieve analysis was performed throughout the ball milling process and after seven days milling over 90% of the wood fibers (WF) produced were < 200 mesh
The results suggest that as wood loading increases so does the effect of WF size on MFR and viscosity

Summary

Introduction

A growing trend in decking is the use of composite decking, which boasts several advantages over its natural competitor, wood. Composite decking is made up of two main ingredients, WF and a thermoplastic matrix (such as HDPE, polypropylene, or polyvinylchloride), as well as additives that aid processing of the product and add color, dispersants and coupling agents, ultra-violet/light stabilizers, and biocides (Clemons 2002) The makeup of these WPC allows decking to be highly durable and have lower maintenance associated with it (Morrell et al 2006, Fabiyi et al 2008, 2010, 2011). Li and Wolcott (2004, 2005) examined the effect of WF species, size, and content (30-70%) using capillary rheometry Their results have showed that WF content has a major positive effect in shear and extensional properties of the WPC melt. Properties of formulations were evaluated utilizing torque rheometry, melt flow indexer, thermal analysis and flexural properties in order to investigate the effect of wood loading, WF size, and MAPE coupling agent

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