PBS-Grafted Surface Modification Of Nano-SiO₂ Based On Melt Blending And Its Application

Polybutylene succinate（PBS）is a aliphatic polyester with excellent biocompatibility and biodegradability.It has a good prospect for biomedical applications.However,low mechanical properties、poor thermal stability and slow crystallization rates which restrict its application.Nano-SiO₂ is considered as ideal reinforcing filler for polymer matrices due to the high strength,good thermal stability,and non-toxicity.However,nano-SiO₂ has high surface energy,and can be easily agglomerate to big granularity,which affects its dispersibility in the PBS matrix and the Interfacial Binding Properties with the PBS matrix.The surface modification of nano-SiO₂ can effectively solve those problems.we prepared modified nano-SiO₂ by melt blending strategy and Use the chemical reaction between the silanol groups on the surface of nano-SiO₂ and PBS molecular chains during the melt-blending process,to covalently grafted PBS onto the surface of nano-SiO₂,an efficient and low-cost nano-SiO₂ surface modification method was explored.studied we used the modified nano-SiO₂ to prepare PBS/SiO₂nanocomposites,and focu on the mechanism and influence of modified nano-SiO2on mechanical properties,thermal stability and crystallization performance of PBS composites.Firstly,surface PBS graft nano-SiO₂ was prepared by melt-blending strategy.Then,repeated centrifugation and washing process were also occurred to obtain modified nano-SiO₂.The modified nano-SiO₂ was characterized by thermogravimetric analysis（TGA）,Fourier transform infrared spectroscopy（FTIR）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）.The results showed that:（1）PBS chains were successfully grafted onto the surface of nano-SiO₂,the appropriate melt blending time（about 10 min）favored more PBS chains grafted on the surface of nano-SiO₂ about 24.3%.（2）It was found that the transesterification reaction between silanol groups of nano-SiO₂ as well as the ester group of PBS chains、the condensation reaction between silanol groups of nano-SiO₂ and hydroxyl group of degraded PBS chains were supposed to the mechanism of PBS chains grafted onto nano-SiO₂.Then,nano-SiO₂ with different raw material ratios（0.5-3wt%）was used to prepared PBS nanocomposites by melt blending and compression molding.The prepared PBS/SiO₂ nanocomposites were characterized by using scanning electron microscopy（SEM）,impact testing machine,as well as differential scanning calorimeter（DSC）、thermogravimetric analyzer（TGA）and electronic universal testing machine.The effects of nano-SiO₂ before and after modificated with different content on the the mechanical properties,thermal stability and crystallization properties of PBS/SiO₂ nanocomposites were studied.The results show that:（1）The modified nano-SiO₂ has excellent dispersibility and interfacial compatibility in the polymer matrix,and effectively improves the tensile strength and impact strength of the composite material,and the strength is the best when the content is 0.5%.（2）The modified nano-SiO₂ can effectively improve the thermal stability of the composites.With the increase of the particle content,the initial degradation temperature and the maximum degradation rate of the composites gradually increase.（3）The modified nano-SiO₂ plays a key role in heterogeneous nucleation in the PBS matrix,and heterogeneous nucleation effect improves the crystallization temperature and crystallinity of the composites.