Rheological Behavior And Properties Of Nano-Lignin/PBAT Composites

With the continuous development of the social economy,plastic products have been widely used in various fields of society due to their low cost and excellent performance.While the serious“White Pollution”was emerged because of the improper management of plastic-waste disposal.As a kind of biodegradable plastic,Poly(butylene adipate-co-terephthalate)(PBAT)has drawn widespread attention recently,but lacking commercial competitiveness since its high price.Besides,lignin,a sort of ubiquitous,biodegradable,and regenerative natural source,has been wasted seriously in paper industry with the lower high added value utilization rate.Hence,for the sake of economic and environmental requirements,it requires that PBAT be blend with lignin to synthesize composites with high performance at low cost.In this thesis,a new kind of composite was fabricated by melt blending process using sodium lignosulfonate as filler and PBAT as matrix,and the rheological behavior and properties of the composites were studied.The main contents are as follows:(1)Lignosulfonate nanoparticles(LNPs)were prepared via precipitation method in order to enhance its dispersibility and weaken its hydroscopicity.In addition,in order to improve the interaction between the filler and the matrix,maleated lignosulfonate nanoparticles(MLNPs)were prepared via esterification modification of maleic anhydride.The MLNPs and LNPs have an analogously sphere-like morphology,which has a mean diameter of~100nm from the measurement of particle size.The successful grafting of maleic anhydride(MA)makes the thermal stability of MLNPs better than LNPs,and the initial decomposition temperatures are 244? and 216?,respectively.Moreover,the hydrophilicity of MLNPs is reduced.(2)LNPs and PBAT were used to produce LNPs/PBAT composites by melt blending method,and the prepared composites were pseudoplastic fluid in viscous flow state.The storage modulus(G?),loss modulus(G??),and complex viscosity(?~*)of the composites decrease with fill volume,temperature,and frequency increasing;the G'and G"of the composites increase with increasing frequency,and?~*decreases as the frequency increases.The properties test results show that:there is hydrogen-bond interaction between LNPs and PBAT,but LNPs have a negative effect on its thermostability;LNPs can enhance the crystallization property of PBAT without affecting its crystal structure;a suitable quantity of LNPs can improve the mechanical property of composite,the addition of 5%LNPs increased the tensile strength and elongation at break of the composites by 15%and 32%,respectively.However,agglomeration of the filler at high loadings results in a decrease in mechanical properties of the composites.In addition,the addition of LNPs increases the water absorption of the composites.(3)MLNPs and PBAT were used to produce MLNPs/PBAT composites by melt blending method.Compared with LNPs/PBAT composites,MLNPs/PBAT composites exhibit higher G?,G??,and?~*at a high fill ratio,since the higher degree of dispersibility of MLNPs.Plus,the thermal stability of MLNPs/PBAT composites is improved compared to LNPs/PBAT composites.Moreover,the graft modification in the melt blending process strengthens the interface interaction,and thus improves its mechanical performance.The addition of 5%MLNPs increased the tensile strength and elongation at break of the composites by 22%and40%,respectively.However,at high filling levels,the agglomeration of the filler also causes the mechanical properties to decrease.Due to the good compatibility of MLNPs with PBAT,there is no particle shedding and specimen defect in the cross section of the composites,so the mechanical properties of the composites were higher than those of LNPs/PBAT composites at high loadings.In addition,MLNPs/PBAT composites have lower water absorption than LNPs/PBAT composites.