EFFECTS OF WATER-CONTENT ON THE PROPERTIES OF STARCH POLY(ETHYLENE VINYL ALCOHOL) BLENDS

The physical properties of unmodified starch, poly(ethylene vinyl alco hol), glycerol, and water mixtures are reported. Thermal and melt-flow properties of the preprocessed, physically mixed materials were deter mined along with the tensile properties and morphology of injection-mo lded microtensile samples. Melt-flow properties were measured by a cap illary rheometer, and the water content was varied from 4 to 18%. The morphology, rheology, and tensile properties are all highly related to the percentage of water present. A transition in the tensile properti es and morphology of the blends was observed at approximately 11% mois ture content. (C) 1994 John Wiley & Sons, Inc.