Preparation And Properties Of Polyhydroxybutyrate Oriented Nanofibers And Their Composite Membrane Materials

Electrospinning is a very effective method to prepare polymer nanofibers.However,the fibers collecting by tlhe traditional electrospinning method are randomly arranged that lead to the decrease of the fiber orientation.Thus,the crystallinity and mechanical properties of nanofibers membrane are low,which limits the further application and development of electrospinning.In this study,three methods were used to improve the mechanical properties of electrospun nanofibers for the preparation of PHB parallel nanofibers.Firstly the parallel nanofibers is obtained by improving the receiving device,secondly the orientation and crystallinity of the nanofiber membranes with the hot stretching were improved that lead to the higher mechanical properties,thirdly addition of inorganic nanoparticles in the polymer solution enhanced the mechanical properties of nanofibers.For the preparation of PHB parallel nanofibers and PHB/CMWCNT parallel nanofibers,a rotating drum was used as the collecting device,and the parallel nanofibers with different orientation were prepared by changing the speed of the rotating drum.The influences of the drum speed on the morphology and mechanical properties of the PB parallel nanofibers and PHB/CMWCNT parallel nanofibers were investigated.The best conditions for the two enhanccements were determined by comparing the interaction between CMWCNT and the drum speed.On the basis of preparation of PHB parallel nanofibers and PHB/CMWCNT parallel nanofibers with the best mechanical properties,the orientation of the nanofibers was improved by the hot-strctch post process.The orthogonal experimental design were used to study the effects of the differcent hot stretching conditions(the stretching temperature,stretching time,tensile pressure)on the morphology and imcclianical properties of nanofibers.The effects of hot-stretch post process on PHB nanoflbers were studied on the basis of the other two enhancement methods.The preparation of PHB/CS and PHB/SA composite membranes were investigated using the electrospun PHB parallen nanofibers as reinforcing material,which lead to expand the applications of the PHB nanofibers.