Presented by Dr. William R. Dougherty

4th International Conference on Advanced Engineered Wood & Hybrid Composites
Harborside Hotel and Marina
Bar Harbor, Maine, U.S.A.

Sunday, July 6, 2008 to Thursday, July 10, 2008

Session:  To be determined
 

Paper Abstract

Wood plastic composites based on soft pine wood flour and high density polyethylene (HDPE) are currently being used in commercial decking applications. As manufacturers attempt to broaden the use of these types of composites, improved strength is required to reduce board profiles and weight to make them suitable for complex geometries required for applications like fencing and railing. Simultaneously, manufacturers attempt to control costs by increasing the wood to HDPE ratio to offset the increasing cost of HDPE, and by running at faster production rates.

To meet these needs, coupling agents such as maleinized polyolefins and processing aids such as zinc stearate, are often used. The maleinized polyolefins help crosslink the composite matrix and increase compatibility between the wood and the HDPE, resulting in increased flexural strength and flexural modulus. However, the maleinized polyolefins often decrease the melt flow of the composite resulting in the need for processing aids. Zinc stearate improves the flow properties of the blend, allowing for faster production rates, but usually decreases the flexural properties of the composite.

In this study, new coupling agents are introduced which can be used at reduced levels compared to conventional maleinized polyolefins while maintaining the same improvement in flexural properties. In addition, a new processing aid is introduced which significantly improves the flexural properties. Compounding and property testing data will be shown in a composite containing 65% wood flour to support the effectiveness of these new additives.