Poly(vinyl alcohol)-collagen hydrolysate thermoplastic blends: I. Experimental design optimisation and biodegradation behaviour

Hybrid blends based on poly(vinyl alcohol) (PVA) and collagen hydrolysate (CH), an abundant, added value waste product of the leather industry, have been processed by melt blow extrusion to environmentally degradable films. Optimisation of the blend compositions was performed in respect of mechanical properties of the films. The experimental design method (DOE) was used for the understanding of the structure-property relationships in the hybrid blends using glycerol as a plasticiser. Parameters were selected from torque measurements, melt flow index, thermogravimetric analysis, as well as tensile strength and elongation at break of the plasticised blends. The use of the DOE method offers the possibility of identifying a range of blend compositions suitable to yield products with valuable mechanical and thermal properties. Biodegradation experiments performed under anaerobic conditions evidenced a positive effect of collagen hydrolysate on the mineralization rate of PVA/CH blends.