Experimental Research On Preparation And Properties Of Bagasse/Polyethylene Composites

Bagasse is a by-product of the sugar industry and has the advantages of large production and low cost,so it is a biomass resource with potential utility value.However,improper processing modes of bagasse not only lead to waste of resources but also cause serious pollution to the ecological environment.The use of bagasse reinforced polymer to produce green wood-plastic composites can realize resource utilization and higher value application of bagasse and also avoid environmental pollution.But the difference between plant fiber and plastic substrate surface polarity will result in poor interfacial compatibility of composite materials and weak mechanical property.Luckily,the use of deep eutectic solvents can effectively remove the non-cellulosic constituent of bagasse,thus improving the interfacial bonding of bagasse and polymer.In this study,different deep eutectic solvents(DES)were used to pre-treat bagasse,and then it recombined high density polyethylene(HDPE)to produce bagasse/HDPE composites.The main research contents were as follows:(ⅰ)Choline chloride-lactic acid(CC-LA),an acidic deep eutectic solvent,was used to pre-treat bagasse,and the influence of CC-LA pretreatment on the mechanical property,crystallization behavior,and heat stability of composite materials was explored.The research results showed that compared with untreated bagasse,CC-LA treatment had a good removal effect on impurities such as hemicellulose and lignin in the surface of bagasse.Moreover,the surface roughness of treated bagasse fiber increased and the crystallinity improved.However,strong acidity of CC-LA could destroy the surface structure of bagasse,reduce fiber strength,and affect the mechanical property of composite materials.The addition of CC-LA(1:2)to treat bagasse had good microstructure and high specific strength,and the composite materials filled and prepared by it possessed the best comprehensive mechanical property(max tensile strength of～24.84 MPa,flexural strength of～32.58 MPa,and impact strength of～8.51 k J/m~2),as well as better heat stability.(ⅱ)Choline chloride-glycerol(CC-G),a neutral deep eutectic solvent,was used to pre-treat bagasse,and the influence of CC-G pretreatment on the mechanical property,crystallization behavior,and heat stability of composite materials was explored.The research results indicated that compared with control samples,CC-G dissolved the crystalline region of bagasse cellulose,causing that the crystallinity of bagasse fiber reduced and fiber strength also decreased.With the increase of glycerol content in the CC-G,the viscosity of the system increased,the liquidity was poor,and the treatment effect became worse.The increased roughness and decreased crystallinity of bagasse resulted in a maximum increase of 22.4%in impact properties and a decreased bending and tensile strength of 26.1%and 8.9%in composites.The specific surface area of treated bagasse increased,thus promoting the crystallization of HDPE and improving the thermal property of composite materials.(ⅲ)Choline chloride-urea(CC-U),an alkaline deep eutectic solvent,was used to pre-treat bagasse,and the influence of CC-U pretreatment on the mechanical property,crystallization behavior,and heat stability of composite materials was explored.The research results revealed that compared with untreated bagasse,CC-U treatment could selectively remove lignin,retain holocellulose,and increase fiber surface polarity.The surface appearance of bagasse was smooth,the roughness decreased.The composites filled and prepared from the above pretreated bagasse showed a 9.3%and 18.2%decrease in tensile and flexural properties,but a maximum 24%increase in impact strength.Differential scanning calorimetry(DSC)analysis manifested that pretreatment of bagasse improved the heat stability and crystallization property of composite materials.CC-U pretreatment increased the smoothness and holocellulose contents,which was the reason for degradation in interfacial bonding strength of composite materials.In summary,the results showed that the use of DES pre-treated bagasse to prepare composites could improve the interfacial bonding ability between bagasse and polymer matrix,which paved an efficient and scalable biomass fibers pretreatment strategy to construct high strength wood-plastic composites and expanded its application areas.