Optimization of technical parameters for making mulch from waste cotton and rice straw fiber

Abstract: The technology of plastic mulching was widely used, but its use depended on petroleum resources, which caused white pollution; straw was a rich resource in quantity, but large amount of waste straw was burned in the field, which caused the waste of resource and the environmental pollution at the same time. To solve the pollution of plastic film, plant fiber mulching has been developed, which was biodegradable mulching. There was lots of methyl cellulose in the biogas residue produced by anaerobic fermentation using ruminant feces. Crop residues, most often treated as waste material, could be used as raw material to produce biodegradable plastic membrane, and one technique may solve the white pollution brought by plastic mulching and the plant residue pollution. Waste cotton fiber came from human production and life with low price, so there was an urgent need to its re-utilization. Abandoned textiles were mostly disposed as garbage, and the recycle was very little, which resulted in serious waste of resource and environmental pollution. In abandoned textiles, cotton textiles were mostly confined, for cotton fiber was cut or broken, and through the re-processing, some low additional value products were produced, which hindered the establishment of the industrial chain of the waste textile recycling. In order to improve the utilization rate of waste cotton fabrics and crop straw, and provide technical support for making the biodegradable biogas residue fiber mulch, the processing and property of hybrid film produced by waste cotton and rice straw fiber were studied. The "skeleton" was waste cotton fiber, and filling material was rice straw fiber, with adding the additive that was environmental friendly. The method of four-factor and five-level quadratic regression orthogonal rotation center combination was applied. Beating degree, adding ratio, basis weight and wet strength agent were taken as influencing factors; dry tension strength and elongation, wet tension strength and elongation were objective variances. The results showed that: 1) The rank of the effect of 4 factors on dry tensile strength from high to low was as follows: adding ratio, wet strength agent, basis weight and beating degree; on dry elongation: basis weight, wet strength agent, adding ratio and beating degree; on wet tensile strength: basis weight, wet strength agent, beating degree and adding ratio; on wet elongation: wet strength agent, adding ratio, basis weight and beating degree; 2) Optimal technology parameters of hybrid film made from waste cotton-rice straw fiber were basis weight of 77-90 g/m2, wet strength agent of 1.5%-1.8%, beating degree of 45°SR and adding ratio of 25%; under this condition, dry tensile strength was greater than 32 N, dry elongation was greater than 2.0%, wet tensile strength was greater than 10 N, wet elongation was greater than 5.5%, and the film met the requirements of mechanical property for field mulching. Adding functional additives could make fibers' lap best, and reticular structure was formed so that the film was uniform and compact, and increased the intensity and stability; 3) Manufacturing film samples was according to the optimal process results, which were basis weight of 80 g/m2, wet strength agent of 1.6%, beating degree of 45°SR and adding ratio of 25%. Evaluation indicators were separately determined and 10 parallel tests were taken for the verifications. Experimental results indicated that dry tensile strength was 34.7 N, dry elongation was 2.19%, wet tensile strength was 11.4 N and wet elongation was 5.8%. The results were correct and credible. According to the standard of tensile strength and elongation, manufacturing environment-friendly biodegradable film with waste cotton and rice straw fiber is feasible.