Preparation technique of Eichhornia crassipes-based composite packaging materials

Abstract: With the increase in industrial activity and the modernization of society, large quantities of waste (both solid and liquid) flow into rivers, which cause eutrophication to take place. As a result, a huge amount of algae develop and cause pollution and environmental degradation. Unusual proliferation of algae may induce the disruption of natural ecosystems, insufficient oxygen in the seabed, and the destruction of scenery, as well as generate an awful smell. Moreover, with the development of a social economy, land resources are becoming increasingly scarce; therefore, much scientific research has focused on the world's oceans and rivers in the search for new resources. In this study, a new method for producing biomass packaging material is proposed; using Eichhornia Crassipes based on the hot compression processing technology. The purpose of this study is to utilize the algae Eichhornia Crassipes to produce biodegradable biomass packaging material. Through structure and feature analysis of fiber, the refining technique of Eichhornia Crassipes is determined. The process of producing biodegradable biomass packaging material involves refining, adding additives, and compression molding and drying technologies. First, Eichhornia Crassipes is pulverized, and the long fibers are cut during refining. This changed the macromolecule fibers into microfibers, exposed more active hydroxy groups, and laid the foundation for physical adsorption. Second, the adhesives are added into pulverized Eichhornia Crassipes to increase performance of the biomass packaging material. Third, the materials are compressed with a hot presser. While preheating the mold and the materials, pressure is gradually applied. The hot press temperature and hot press pressure finally reach 160℃ and 5 MPa, respectively, and the hot compression time is about 20 min. During the hot compression, another connection opportunity is obtained. Since the moist algae are primarily dehydrated, the water in the experimental material is pressed and the many exposed active hydroxyl groups in the cellulose are more active with the heat, which causes them to reunite with the hydroxy and hydro groups. Finally, Eichhornia Crassipes is dried in the hot presser, and the hot press temperature and hot press pressure have remained at 160℃ and 5 MPa, respectively. In this study, three kinds of safety and environmental protection adhesives and a waterproof additive are employed. Technical evaluation shows that the produced biomass boards, which are added sodium alginate and guar gum, have high mechanical performance. Average rupture stresses of the biomass boards are 32.54 and 44.05 MPa, and average elastic moduli of the biomass boards are 3.69 and 4.77 GPa, respectively. Moreover, the biomass composite packaging material that is added to emulsion paraffin has good waterproof performance, and the contact angle is greater than 100°. This material produced by the method proposed in this study is a green environmental protection and degradable material. Its production, utilization, and disuse do not have negative impacts on the environment. Research on biomass packaging material makes waste resource reasonable to use and is in accordance with national sustainable strategy. Therefore, the biomass composite packaging board using Eichhornia Crassipes has a wide application prospect as a substitute for oil-based plastic materials in food packing containers, wood packaging transportation, food and farming products packaging, etc.