Deepti Marathe

Wood plastic composites (WPC) were made from polypropylene (PP), impact copolymer (ICP) and wood flour (WF) by varying the WF content from 10 to 40% with PP grafted maleic anhydride as a coupling agent. The effect of varying WF content was studied on rheological, thermal, mechanical properties and dynamic mechanical properties. Experimental small amplitude oscillatory shear (SAOS) data was compared with the Einstein–Batchelor and empirical Krieger–Dougherty relations. Significant dependence of mechanical and rheological properties on WF content was observed. Young’s modulus, flexural modulus and dynamic shear viscosity increased with WF content. Results of dynamic mechanical analysis (DMA) showed increase in storage modulus with WF content. Three millimeter thick compression molded composites sheets were thermoformed using axisymmetric molds with two draw depths. Sag observed visually during thermoforming decreased with increasing WF content. Components made from the composites showed close to uniform thickness distribution as compared to those from ICP.

Viscoelastic and dielectric properties of composites with polyvinyl chloride as major matrix constituent, ethylene vinyl acetate (EVA) as polymeric plasticizer, and wood flour (WF) and fly ash (FA) as filler have been studied. The effect of variation of WF, FA, and EVA on storage modulus E′, loss modulus E″, and glass transition temperature, T_g has been evaluated using dynamic mechanical analysis (DMA). Effect on permittivity ε′ 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′, and E″ and a decrease in loss tangent, tan δ. The FA content has insignificant effect on these properties. Increasing WF content increases ε′. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers

The present article evaluates the effect of variation of WF on the tensile strength, modulus, and elongation at break. The pin-bearing properties usually correlate well with tensile properties. Tensile strength and pin-bearing strength decrease but tensile modulus increases on addition of WF. The tensile strength, pin-bearing strength, and mode of pin-bearing failure also depends on the void content. Increase in void content has a detrimental effect on all the mechanical properties. Wide variation is observed in impact strength because of unpredictable void content due to use of non-vented extrusion process. TGA indicates insignificant effect of WF on thermal stability of composites. Infrared spectroscopy indicates some interaction between PVC and WF.

Composites with polyvinyl chloride (PVC) as major matrix constituent, ethylene vinyl acetate (EVA) as polymeric plasticizer and wood flour (WF) and fly ash (FA) as filler were extruded. Morphology of the samples was studied using scanning electron microscopy (SEM). Morphological study indicated good dispersion of the constituents. Infrared spectroscopy (IR) indicates interaction between EVA and PVC and also between the polymeric matrix and WF. The effect of various constituents on glass transition temperature (T_g) was evaluated using differential scanning calorimetry. Addition of EVA decreased the T_g, whereas T_g was increased due to addition of WF and FA. Study indicated that reduction in T_g on addition of EVA was compensated by increase in T_g due to addition of WF. The contribution of FA to change in T_g was not significant. Resulting composites have T_g close to that of PVC. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009