Study On The Preparation And Properties Of Chitosan Modified Poplar Flour And High-density Polyethylene Composites

Wood plastic composites (WPC), usually made from wood fiber and thermoplastic, are biomass composite material, were prepared by using extrude or injection or mould pressure or heating pressure. First appeared in the Second World War, is considered a high added value, low carbon environmentally friendly composites. However, conventional wood plastic composite materials there are some shortages in flammable, ultraviolet ageing and bacteria corrosion, which restricted application field, wood plastic composite materials of new multi function has become the focus of future research one.This paper used boric acid and borax compounds(BA/BX) as the flame retardant antibacterial agent, chitosan(CS) as antibacterial and interface compatibility synergistic agent, poplar wood flour as substrate, high-density polyethylene (HDPE), adding other assistants, using twin-screw melt mixing and granulating, and then use single screw extrudes prepared the flame-retardant and antibacterial wood plastic composite material. Morphology of composite section analysis by SEM, and structure was using analysis by infrared spectroscopy, comparative studied the effects of chitosan, boric acid and borax compounds on the physical and mechanical properties, flame retardant, Thermal stability, antibacterial and the color of the surface of the ultraviolet aging resistance performance of composite materials. The results demonstrate that:(1) There are significantly effected of CS% on flexural strength, but were not significantly effected of the tensile strength, The comprehensive mechanical properties of CS adding amount was 6%,12%,18% is better, by adjusting the ratio of CS and the content of wood powder, composite materials could be prepared with different mechanical properties. With CS WPCs is significantly effect of BA/BX% on the flexural strength, flexural modulus and the tensile strength, without CS WPCs were not significantly effect except for the tensile strength, Mechanical Properties decreased with increasing BA/BX content, the mechanics of composite materials with 6%CS and 3%BA/BX is better. (2) SEM analysis results showed that good mechanical properties, section variable fuzzy, empty less, among them, add 6%CS and 3% BA/BX occur tearing, interfacial binding force better, occur esterification reaction, accord with the front mechanical properties consistent results. (3) Infrared spectrum analysis results showed that, CS and BA/BX mixture has an effect on the composite structure, accord with the front on the mechanical properties and fracture morphology analysis of SEM results, add 6%CS and 3%BA/BX sample appeared ester bond absorption peaks in 1660cm-1, indicating that CS and BA/BX mixture has synergistic effect. (4) The density of the composites increases with the increase of CS content and then tends to a certain value, density variation range is 1.16g/cm3 to 1.21g/cm3; effect of CS and BA/BX mixture combination on the density is smaller, density variation range is 1.20 g/cm3 to 1.24 g/cm3; the water absorbency of the composite increased with the increase of CS content and changes in volatility, add 16%CS and adding 12%CS with 3%BA/BX combination is smaller; effect of CS, BA/BX mixture on absorbent thickness expansion rate consistent on absorption water rate. (5) Effect is significantly of MAPE on the mechanical properties of the composites, physical and mechanical properties of 4% MAPE is best. (6) Adding the BA/BX mixture can improve the flame retardant of the composite, heat release rate decreases, the mass loss rate gradually decreased, the ignition time decreases first and then increases and then decreases, CO and CO2 conversion rate and generation decreases with the increase of BA/BX content. The flame retardant of 12%BA/BX mixture is best, heat release rate, mass loss rate and smoke production rate than without BA/BX mixture sample decreased by 17.68%,10.71% and 9.07% respectively; and ignited time of 9% BA/BX mixture have the longest time is 44S, than without added 37S increased by 18.9%.(7) With 6%CS and without CS, with different amount BA/BX of TGA and DTG curve variation is similar. Wood plastic composite materials residual rate of 600℃ increase with increase BA/BX mixture, the residual rate of 12%BA/BX is maximum, the residual rate with 6%CS is higher than without CS. (8) Composite △E and △L values change with the CS content is nonlinear, and the changes of volatility. The ultraviolet aging 300h and 500h △E and △L value of 8%CS is minimum; ultraviolet aging of 300h and 500h, △E and △L values with BA/BX mixture is higher than without BA/BX mixture in addition to 3%BA/BX sample. Overall, wood plastic composite materials surface color anti ultraviolet ageing performance with CS and BA/BX mixture is better than without CS only adds BA/BX mixture. (9) BA/BX mixture can obviously improve the antibacterial properties of composite materials, mass loss rate decreased with increase BA/BX; CS and BA/BX mixture combined antibacterial effect is the best, consistent with the results of SEM analysis of surface morphology.Summary, added suitable amount of CS and BA/BX mixture, not only can improve the compatibility of high density polyethylene and wood flour, but also improve the antibacterial flame-retardant of wood plastic composites materials. This indicates that use CS and BA/BX mixture prepared antibacterial and flame retardant function wood plastic composites materials is a feasible method.