Study On The Biodegradable Film For Encapsulation Of Fertilizer And Its Properties

Biodegradable film material with slow release effect is a research hot in the field of coated slow release fertilizer. This paper used polyvinyl alcohol as the main material, and oxalic acid, sodium alginate, chitosan as modifiers to develop a variety of modified polyvinyl alcohol film materials with method of chemical synthesis. By measuring water absorption, stress and rate of dilatation-magnificationratio, set clear modified conditions of the film materials. By measuring Fourier infrared spectrum, and scanning electron microscopy, studied the modification mechanism and the degradation of films. Research results as follows:(1) With stress as the main reference index, three kinds of modifiers all make the stress decrease. With rate of dilatation-magnificationratio as the main reference index, the rate of dilatation-magnificationratio of all the film increased. The rate of dilatation-magnificationratio of sodium alginate-modified was highest With water absorption as the main reference index, The water absorption of films modified by oxalic acid and chitosan was reduced. When the process conditions were PVA concentration with 55g/kg, oxalic acid concentration with 32g/kg, reaction temperature with 90℃, reaction time with 2.5h, the water absorption of oxalic acid-modified was lowest, and it is most suitable for film material.(2) After adding silicon dioxide, water absorption was further reduced, particularly the treatment of high water absorption. Stress and rate of dilatation-magnificationratio were further decreased or unchanged.(3) Infrared spectroscopic analysis results indicated that after the modified, the absorbance peaks and transmittance had changed. It indicated polyvinyl alcohol was reacts with these modifiers.(4) Through study of quality changes, infrared spectroscopy and scanning electron microscopy, the degradation rates of same film after different incubation methods were different, and also the degradation rates of different films after same incubation method were different. Film O had the highest degradation rate, which was 37.8%. Silicon dioxide can increase the degradation rate of chitosan-modified polyvinyl alcohol film, while decrease it of oxalic acid-modified and sodium alginate-modified polyvinyl alcohol films.In a word, polyvinyl alcohol had some change after modified by oxalic acid, sodium alginate, chitosan and silicon dioxide. Depending on the requirements, changing technological conditions, it can be used to make film materials.