Preparation And Properties Of Cassava Straw/PPC Composites

At present,the research on cassava straw mainly focuses on bio-composting,bio-fuel,composition analysis,etc.,but there is little research on the use of cassava straw as wood-plastic composites,and there is no significant difference between the composition of4-year-old cassava straw and wood.It is used as a high-quality raw material for wood-plastic composites.Currently,the most common polymers for preparing wood-plastic composites are polyethylene,polypropylene,polyvinyl chloride,etc.Although these polymers have excellent mechanical properties,it is difficult to degrade and lead to pollution of the soil environment,which is not green especially the promotion of“Green mountains and clear water are equal to mountains of gold and silver”and the development of sustainable economy have being popular in china today.Therefore,the development of biodegradable new wood-plastic composites has become a research hotspot.In this research,the paper uses poly(propylene carbonate)(PPC)as the polymer matrix in wood-plastic composites,and innovatively combines cassava straw with PPC to develop a new,fully biodegradable wood-plastic.composites,and perform a series of characterization on their mechanical properties,rheological properties,thermal stability,micromorphology,etc.and made a comprehensive natural degradation analysis,the main findings of this paper are as follows:(1)The particle size and proportion of cassava straw were analyzed by single factor test method,The results show that the particle size does have a great influence on the mechanical properties of the composites.The reason is that the larger particle size is not conducive to blending,while the smaller particle size is short and thick,which cannot effectively provide strength support,and the optimal particle size range is 80-140 mesh;the proportion of cassava straw powder also has a great influence on the mechanical properties,and its mechanical properties first increase and then decrease,and reach the maximum when the added amount is 40%.The flexural strength,tensile strength and impact strength are 39.5 Mpa,34.94 Mpa and 2.99 KJ/m²,respectively.After adding cassava straw powder,the equilibrium torque is increased and the thermal stability is also improved.(2)Studying several silanes and addition amount by three-factor three-level orthogonal analysis method.The effects on the modification of composites are as follows:All three silane coupling agents play a positive role in the mechanical properties of composites.Fourier infrared spectroscopy shows that the characteristic peaks of cassava straw powder at 1110cm^-1 and 760cm^-1 are slightly strengthened.It also shows that silanol achieves a certain grafting effect in cassava straw powder.The best coupling agent is KH560,the optimum addition amount is 2%,and its flexural strength,tensile strength and impact strength are 39MPa,35.8MPa,2.75 KJ/m²;at the same time,the modification of the silane coupling agent also improves the thermal stability of the composite.The DMA results show that the addition of the coupling agent increases the maximum storage modulus of the composites and the vitrification of the composite.The glass transition temperature has also increased slightly.(3)Using the single factor test method separately studied several common calcium carbonates in the market,the effect of the type and amount of calcium carbonate on the properties of the composites was further analyzed.The results were as follows:the tensile and flexural strengths of the composites increased after the addition of calcium carbonate,while the nano calcium carbonate and active calcium carbonate composites have a greater increase in tensile strength and flexural strength of composites,and the nano-calcium effect was the most obvious.The addition amount reached the maximum at 15%,and the flexural strength,tensile strength and impact strength were 41.6 MPa,37.1 MPa,and 2.765 KJ/m²,compared with the control group,increased by 11%and 10%respectively;and the addition of calcium carbonate increased the equilibrium torque of the composite system,and also improved the thermal stability of the composites.(4)The degradation performance of cassava straw/PPC composites results are as follows:in the first 30 days,the soil burial weight loss rate of the composite material was0.1%,almost no weight loss,and after 30 days,The composites began to degrade the weight loss.By 60 days,the weight loss rate was 2%.By 150 days,the weight loss rate reached 8.9%.It can be seen that the surface of the composites was covered by reddish brown microorganisms.