Biodegradable PVA/Gelatin Blends Prepared by Reactive Extrusion

摘要

Reactive extrusion was adopted to prepare poly (vinyl alcohol)/gelatin (PVA/gelatin) blends using PVA and collagen fibres derived from cattle hide limed split wastes as raw materials. The experimental results showed that during the reactive extrusion process, all the collagen fibres were degraded in-situ into gelatin under the thermal/physico-chemical effects of the extruder and thus exposed the reactive groups in gelatin and induced the esterification reaction between PVA and gelatin. Ascribing the effects to the plasticization of gelatin with low molecular weight, the crystallinity and the melting point of PVA were depressed and the thermal processing window for PVA was obtained. In this way, PVA/gelatin blends with good processibility, compatibility, mechanical properties and biodegradability were successfully prepared. When the ratio of PVA and gelatin was 7:3, the tensile strength and the elongation at break of the PVA/gelatin blend increased up to 34MPa and 320%, respectively, and its biodegradable ratio reached 37.2%, much higher than that of PVA after the 60-day incubation in respirometric tests of an aerobic aquatic environment. Compared with the conventional two step methods to prepare PVA/gelatin blends, the technology developed here is convenient, cost-efficient and environmentally-friendly and also provides a novel idea to recycle non-tanned solid leather wastes. The end note provides statistics and further details of the large possible usage of limed hide wastes in this application.