Viscoelastic properties of plasticized PVC reinforced with cellulose whiskers

New nanocomposites are processed with a plasticized poly(vinyl chloride) ma trix reinforced by cellulose whiskers whose characteristics are a high aspe ct ratio and a large interface area. Dynamic mechanical analysis performed on samples reinforced with a filler fraction of up to 12.4 vol % gives the viscoelastic properties of the composite above and below its glass transiti on temperature. Different theoretical predictions are proposed to describe this behavior, but none of them is found wholly satisfactory for describing the reinforcing effect of these fillers. A model based on the Halpin-Kardo s equation, with the assumption of an immobilized phase around the whiskers , is developed to account for significant decrease in the modulus drop, on passing above the glass transition temperature. The small discrepancy betwe en this model and the experimental modulus measured in the rubber plateau i s discussed as a possible effect of a percolating whisker network whose cro sslinks are assured by chains adsorbed onto the whisker surface. Swelling e xperiments support this hypothesis. (C) 1999 John Wiley & Sons, Inc.