Preparation And Properties Of PBS/mangesium Hydroxide Sulfate Whisker Composites

As one of the three largest biodegradable material,Poly(butylene succinate)(PBS)is becoming more and more popular because of its good comprehensive performance.However,PBS also has some defects such as high crystallinity and poor mechanical properties to limit the application.In this paper,magnesium hydroxide sulfate whisker(MHSH),was used as fillers to prepare PBS/UMHSH and PBS/MMHSH composites by one step and two-step methods,respectively.We studied the surface modification of MHSH and interfacial compatibilization effect on the performance of PBS composites,which provided an important experimental and theoretical basis for the preparation of high-performance PBS composites.One step method of preparing PBS/UMHSH was prepared by directly blending the unmodified whiskers and PBS.According to the defective compatibility between PBS and magnesium hydroxide sulfate whisker,in this paper,the two-step methods was adopted to prepare the PBS/MMHSH composites.That is,first focused on the modification of MHSH by KH560,and then prepared PBS oligomers grafted-whisker by in situ polymerization.The grafted-whisker oligomers were mixed with commercial PBS in a certain proportion to prepare the PBS/MMHSH composites by the second step(melt blending).The effect of oligomers on the interfacial compatibilization and the properties of PBS composites,as well as the effects of UMHSH on the properties of PBS composites were investigated.The mechanical performance test showed that,when the whisker content was 10%,the tensile strength,flexural strength and flexural modulus of PBS/MMHSH prepared by two-step were increased by 18.4%,71.3% and 119.7% compared to the pure PBS.SEM showed that the compatibility between the whisker and the matrix was enhanced obviously after in situ polymerization.According to the kinetic equation of Avrami and Jeziorny,the crystallization rate constant(Z)and Avrami index(n)of PBS and PBS/UMHSH composites were calculated.The crystallization activation energy(?E)of PBS composites was calculated by Kissinger method.The cooling rate function F(T)and the ratio of Avrami index and Ozawa index were studied by Mo method.Research showed that “Z” was increased with the increasing content of whiskers,and “n” was changed from 5.27 to 6.69.The ?E of composites were lower than the pure PBS(214.23 k J/mol).F(T)was increased with the increasing of relative crystallinity,but decreased with the increasing of whisker content.The value range of “a” for PBS and PBS/UMHSH composite materials were 0.972~1.092 and 1.293~1.699.Accordingly,magnesium hydroxide sulfate whisker can be used as a nucleating agent,and significantly improve the crystallization rate and crystallization ability of PBS.By TG-FTIR,the decomposition behavior of PBS and PBS/UMHSH composites was investigated and the thermal decomposition process was studied.The results showed that the ester bond in the molecular chain of PBS first broke into small molecules,like the olefin and carboxylic acid,then the carboxylic acid happened to decarboxylation reaction to produce carbon dioxide and alkanes.The pure PBS decomposed completely at 481°C.To investigate the biodegradability of PBS and its composite materials,the method of enzymatic degradation and natural degradation were adopted.With the increasing of the degradation time,the mass loss rate of PBS and the composites increased gradually.The degradation ability of PBS/MHSH composite was better than that of pure PBS.The degradation curve and SEM analysis showed that the more the whisker content are,the more obvious the degradation is.In this study,the PBS/MHSH composite materials were prepared for the first time by the one step and two-step method,which significantly improved the mechanical properties,decreased the crystallinity and enhanced biodegradation rate.Meanwhile,this study provides the theoretical basis for the preparation of high-performance PBS composites.