Study On The Preparation And Properties Of Bamboo Flour/PVC Composites

Natural cellulose has numerous advantages, such as low cost, low density, high toughness and biodegradability, and the cellulose can be used as reinforcements for thermoplastic matrix composites. But the incompatibility of the hydrophilic natural cellulose and the hydrophobic thermoplastic matrix can actually lead to a reduction in the strength of the composite material. Taking these aspects into account, the coupling agents are additives used in the cellulose reinforced thermoplastics, in order to increase the incompatibility of bamboo flour and PVC, grafting copolymerization of MMA onto cellulose under microwave irradiation is one of the most effective methods to improve the incompatibility of bamboo flour and PVC, and the effect of nano-TiO2 on the bactericidal activity of bamboo flour/PVC composites are investigated in this paper. The main contents and conclusions are as follows:1. The optimal level of DOP is 10%, the optimal level of CPE is 12%, the optimal level of titanate coupling agent is 2%.The tensile strength and impact strength have an increase with increasing titanate coupling agent content. The maximum tensile strength and impact strength are achieved at 2% titanate coupling agent, and then decrease. Treatment of bamboo flour with titanate coupling agent shows a decrease of the moisture absorption properties as compared to untreated bamboo flour. The modified bamboo flour is characterized by FTIR, and the result indicates that the surface of bamboo flour is modified successfully with titanate coupling agent. Scanning electron microscopy revealed good compatibility and adhesion between the plastic and the bamboo flour for crosslinked composites.2. The process of grafting is optimized by response surface methodology (RSM) to obtain the optimum conditions for grafting percentage. It is indicated that the optimum reaction condition is as follows:the microwave power,133.6 W; initiator concentration, 3.67×10-3mol/L; exposure time,8.01 min. The regression equation describing process of grafting is obtained by response surface methodology: Y= 46.79667+1.07375X1+1.00000X2+0.28875X3-3.68583X1X1+0.07250X1X2+ 1.66500X1X3-6.05833X2X2+0.70750X2X3-0.64583X3X3 The graft copolymer is characterized by FTIR, SEM, which elucidated the structure changes in comparison with bamboo cellulose, these results indicate that the surface of bamboo cellulose was grafted successfully with MMA copolymer. The crystallinity of the graft copolymers decrease in comparison with that of bamboo cellulose, and TGA revealed that copolymer had more thermal stability. Furthermore, the moisture absorption capacity of the graft copolymers decreased significantly with the increase in grafting percentage.A comparison with the composites filled with the untreated bamboo flour showed that the tensile strength and impact strength increased, with the incorporation of the graft copolymers into the bamboo flour/PVC composites. Scanning electron microscopy revealed good compatibility and adhesion between the plastic and the bamboo flour with the incorporation of the graft copolymers into the bamboo flour/PVC composites.3. The results exhibit that nano-TiO2 can obviously improve the mechanical properties of the composites. The tensile strength and impact strength have an increase with increasing nano-TiO2 content. Tensile strength reached the maximum value when the content of nano-TiO2 is at 3.2 wt%.The minimum inhibitory concentration of nano-TiO2 to E. coli and S. aureus are 400mg/L and 800mg/L respectively. The composites possess excellent bactericidal activity on the E. coli and S. aureus. The bactericidal activity of the composites is more than 90% when the content of nano-TiO2 is at 1.2 wt%. When the content of nano-TiO2 is at 1.6 wt%, the bactericidal activity of the composites is more than 99%. The prepared PE was treated by means of accelerated aging, and the results showed the composites had good long-time bactericidal activity.