The Preparation Optimization And Micro-mechanism Of The Biomass Cushion Packaging Composites

Currently, the industrial fields, such as household appliances, precision instruments, electronics, food packaging, used extensive petroleum-based buffer plastic packaging in the domestic and international markets. The plastic packaging wastes were hardly biodegradable and recyclable, causing serious environmental pollution and depletion of non-renewable resources. The widely used green cushion packaging products, involving pulp molding class, corrugated board type, honeycomb etc., consumed so much wood resources. And their comprehensive performance could not meet the various needs. Therefore, the development of new biomass cushion packaging materials reinforced with plant fibers was important, and this research had become a hot topic in food packaging, industrial packaging, fast-food packaging and other packaging fields.The biomass cushion packaging material was prepared by a molding-foaming process, reinforced with natural plant fibers and other additives. The composites, who had the advantages like wide raw material resources, simple preparation process, low cost and no pollution through its life cycle, belonged to green environment-friendly packaging materials. However, as a new kind of green materials, the research on biomass composites was still in the primary period. The immature composition and molding process seriously limited the standardization and industrialization of the biomass composites. The lack of research on raw materials pre-treating process and micro-mechanism directly affected the improvement of the mechanical and cushion properties. In order to solve these problems, this paper carried out several researches below.(1) The thermoplastic starch (TPS) matrix prepared by single/compound plasticizers was analyzed through infrared spectroscopy experiment and X-ray diffraction experiment. According to the strength of intermolecular hydrogen bonds and the crystallinity of TPS matrix, the best content of plasticizer was obtained, which was starch:plasticizer as 10:3. Furthermore, the best compound plasticizer ratio of formamide to urea was 2:1. By differential scanning calorimetry and thermal gravimetric analysis, the thermal stability of TPS was studied, which indicated that the starch plasticization process increased the melting point and decreased the glass transition temperature of natural starch.(2) Owing to the immature composition and molding process of the biomass composites, this paper used orthogonal experiment method to develop a four factors three levels orthogonal experiment, aiming at the composition and molding process optimization. This orthogonal experiment studied the effect of fiber length, fiber content, foaming agent content and additive content on the mechanical properties of biomass composites, where the plant fiber used was sisal fiber. The effect strong-to-weak sequence of four factors on the mechanical properties and the best combination of four factors were obtained.(3) Using sisal fiber, paper pulp, straw fiber, lignin fiber as the reinforced skeleton respectively, this paper prepared four kinds of biomass cushion packaging materials. For the first time, the infrared spectroscopy experiment was adopted in to analysis the intermolecular hydrogen bonds between fiber molecules and TPS molecules, which contributed to the building of molecular connection model. The molecular connection model divided into two phases, paste mixed phase and molding phase. Among four kinds of composites, the composites reinforced with sisal fiber had the strongest hydrogen bonds between sisal fiber and TPS matrix. And the mechanism analysis was verified by SEM investigation, mechanical experiment and thermal stability analysis.This project gave intensive researches on TPS matrix preparation, composition process optimization, micro mechanism of the biomass cushion packaging material. These researches provided theoretical basis for preparation optimization, overall properties improvement and the bubble growth mechanism of the biomass composites, and provided basic data and technology support for developing industry standards, promoting industrialization of the biomass composites.