FORMATION OF A COMPATIBLE COMPOSITE OF SILICA POLY(VINYL ALCOHOL) THROUGH THE SOL-GEL PROCESS AND A CALCINATED PRODUCT OF THE COMPOSITE/

A transparent composite film of poly(vinyl alcohol) (PVA) and silica w as obtained through the sol-gel process using tetraethoxysilane (TEOS) . By ESCA and X-ray diffraction measurements on the composite, it is c onfirmed that the PVA and silica were intimately mixed together. The Y oung's modulus increased with increasing silica content in the PVA, bu t the tensile strength decreased from 84 for pure PVA to 40 MPa (as th e PVA content reaches 50 wt%). A maximum value of 145 MPa was observed for the 80% PVA composite. The composite could be drawn to 2 similar to 3 times its original length under saturated humidity conditions. Th e modulus and the tensile strength were increased by a factor of two b y the drawing of the as-cast composite film. The residuals created by the removal of PVA from the composite films were transparent and showe d a surface area of about 500 m(2) g(-1) (in the case of 80% PVA as th e original material). The residuals showed permeability for gases. The gas permeability of the residuals rapidly increased with the PVA cont ent in the original materials.