As PVA is the largest synthetic water-soluble
polymer produced in the world, it can be blended with soy protein
polymers to form biodegradable composites, which would be
partially crystalline. The enhanced mechanical properties (tensile
strength of 49.2 MPa and percentage elongation at break of
50.4 MPa) can be attributed to the long-chain PVA molecules,
which contain manyeOH groups forming strong intra- and intermolecular
interactions with protein molecules. Evidence for the
specific chemical interaction occurring between SPI and PVA is
obtained from the FTIR analysis of the composite film where the
strong hydrogen bond association appearing both in SPI and PVA at
2918e3565 cm1 shifts to a new absorption band at
2900e3100 cm1 (Fig. 7). Analysis of heat sealing properties of SPI/