Characterization of Highly Filled Wood Flour–Polyvinyl Chloride Composites: Dynamic Mechanical and Dielectric Analysis D.S. Marathe, P.S. Joshi Department of Polymer Engineering, Maharashtra Institute of Technology, Kothrud, Pune 411038, India Viscoelastic and dielectric properties of composites with polyvinyl chloride as major matrix constituent, eth- ylene vinyl acetate (EVA) as polymeric plasticizer, and wood flour (WF) and fly ash (FA) as filler have been stud- ied. The effect of variation of WF, FA, and EVA on stor- age modulus E 0 , loss modulus E 00 , and glass transition temperature, T g has been evaluated using dynamic mechanical analysis (DMA). Effect on permittivity e 0 and conductivity is evaluated using dielectric analysis. The results show considerable influence of constituents of the composite on the properties evaluated. DMA shows that WF contributes to an increase in T g , E 0 , and E 00 and a decrease in loss tangent, tan d. The FA content has insignificant effect on these properties. Increasing WF content increases e 0 . POLYM. ENG. SCI., 50:1253–1260, 2010. ª 2010 Society of Plastics Engineers INTRODUCTION Wood plastic composites (WPC) have been growing at a very fast pace in the last few years. The acceptance of WPC in the market is due to high stiffness-to-weight ratio, low cost over conventional reinforcements, superior proper- ties over wood and plastics alone and above all, easy adap- tation to existing plastic processing techniques [1, 2]. Applications of WPC include decking, railings, automotive interiors, and furniture. Most commonly used thermoplastic matrix materials include polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC). PE, which has the major market share of 83%, is used in decking applications; PP with 7% is predominantly used in automobile industry, whereas PVC with 10% market share is used in furniture applications [3]. PVC, which has been used as matrix mate- rial in this experimental work, is commonly used for furni- ture applications because of its good mechanical properties, chemical resistance and water resistance, low flammability, and low cost. Also, PVC-based wood composites can be cut, sawed, screwed, and nailed like standard wood materi- als using conventional tools [4]. Effective interfacial adhe- sion between PVC and wood flour (WF) is important for processing and performance of the composites. Various coupling agents have been used to enhance the adhesion between hydrophobic PVC and hydrophilic WF. Shah et al. [5] used two natural polymers, chitin and chitosan, as cou- pling agents. Composites showed significant improvement in flexural strength and modulus. Also, DMA studies indi- cated increase in the storage modulus and loss modulus on addition of WF regardless of the coupling agent and tem- perature used. Addition of coupling agents significantly improved the storage modulus and loss modulus. Guffey and Sabbagh [6] used chlorinated polyethylene (CPE) as a compatibilizer. Addition of CPE significantly increased the melt strength. Ge et al. [7] studied the tensile and thermal properties of composites with WF content up to 50 phr of PVC. Addition of WF increased the stiffness but decreased the strength and elongation at break for the composites. There was no appreciable change in T g . The composites under consideration are designed for structural applications in building and construction, furni- ture applications, as a replacement for commercial ply- wood, and electrical conduit applications. The goal was development of low cost environmentally friendly compo- sites. PVC at present is used in conduit application, and its purpose is to find if substantial deviation results when WF and fly ash (FA) are added to PVC. WF and FA are both waste products, one from the lumber industry and the other from thermal power plants. Therefore, the cost of the fillers is low, which in turn reduces the cost of the composites. The composites can be termed environmen- tally friendly for utilization of the waste material, espe- cially FA. In the present composites, minor matrix com- ponent Ethylene vinyl acetate (EVA) acts as a polymeric plasticizer and also as an impact modifier. Polymeric plas- ticizers can ease processing without the disadvantages of low–molecular-weight plasticizers, which include leaching over a period of time. MATERIAL Suspension PVC of grade 57 GE R01 manufactured by M/s Reliance India was used. EVA (Escorene Ultra EVA Correspondence to: P.S. Joshi; e-mail: drvsj@yahoo.com DOI 10.1002/pen.21656 Published online in Wiley InterScience (www.interscience.wiley.com). V V C 2010 Society of Plastics Engineers POLYMER ENGINEERING AND SCIENCE—-2010