Structure and Properties of Polypropylene Nanocomposites with Poly(Vinyl Alcohol) Prepared via Crazing

Novel polymer-polymer nanocomposites have been prepared based on PP films deformed in solutions of PVA via the crazing mechanism. Mechanism of PP deformation in solutions of high-molecular compounds as well as structure, composition, thermophysical properties, and wetting of the composites have been investigated by means of AFM, DSC, gravimetry, mechanical tests, and measurement of contact angle of wetting and volumetric porosity. Draw ratio of PP and concentration of PVA in the solution have affected the nanocomposites composition. The content of PVA has been up to 45 wt % at the PP draw ratio of 300%. Upon the liquid medium removal, PVA has been crystallized in the confined space of the PP mesoporous matrix, the degree of crystallinity being reduced to 12‒14%. Introduction of the hydrophilic component has improved wetting of PP with water, and the contact angle has been decreased from 98° (starting PP) to 42° (the composite). Hydrophilization via crazing can be considered an approach for modification, processing, and recycling of the large-tonnage polymer.