| The structure and performance of the scaffold material,equipped with the function of a biomimetic extracellular matrix carrier,directly determines the cell culture,reproduction and differentiation as well as the tissue regeneration.The scaffold materials were studied and developed which is provided with the ideal structural characteristics and fulfilling the performance requirements,in order to promoting the deepening of tissue engineering research.Biodegradable material PHBV has been widely recognized by scholars and industry due to its excellent mechanical properties and biocompatibility,and it has become a research hotspot in the field of polymer molding engineering.However,the further application has been limited due to some disadvantages of PHBV itself,such as the brittleness,poor thermal stability and difficult processing.In this paper,the properties of the PHBV-based blend/composite materials were systematically studied,including the microstructure,mechanical,thermal,rheological and foaming properties,by means of melt blending with the industrialized biodegradable polymers.The preparation method and the structure-property evolution at large deformation of the PHBV based materials with excellent performance were investigated.On this basis,the research contents of this paper are as follows:(1)A series of blends of PHBV and PBAT with different mass fraction were prepared by melt mixing,and the structure and properties of the system were studied.It was found that the addition of PBAT inhibited the crystallization of PHBV matrix and improved its thermal stability.With the increase of PBAT content,the storage modulus,loss modulus and complex viscosity of the blends increased.The results of the microstructure characterization showed that PHBV and PBAT were incompatible,and the co-continuous phase structure was presented when the proportion of the two phases is equal.With the increase of PBAT content,the elastic modulus and tensile strength of the blends decreased,but the fracture strain increased.The fracture strain reached 1000%when the content of PBAT is 75%.(2)The inorganic nanoparticles hydroxyapatite(HA)were composited with PHBV/PBAT blends,which acted as a filling enhancer.And The preparation and performance study of the composites were carried out.The results showed that the grain size of the blends decreased with the addition of HA.The enhancement effect of HA depended on its dispersion in the PHBV/PBAT matrix.The phase separation of the(50/50/HA)composite deteriorated in consequence of the concentration of the HA.The elastic modulus of PHBV/PBAT blends increased after composited with HA,but the tensile strength and strain at break decreased.HA can acted as the nucleating agent when it was well dispersed in the blends,and promoted the cell nucleation.(3)Biodegradable polymer PLA was introduced with PHBV/PBAT blends to further modulate the properties.The large deformation condition and performance variation of the PHBV/PBAT/PLA blend were investigated.It was found that,with the increase of thePLA content,the thermal stability and the mechanical property were improved.The dispersion of each phase become more uniform.The elastic modulus of(35/35/30)blend was 645MPa,the yield strength was 28MPa,and the strain at break reached 13%.At the same time,it was found that(35/35/30)had a large deformation capacity at a temperature of 60℃.(4)The stress-strain behavior and structural evolution of PHBV/PBAT/PLA(35/35/30)blend at different tensile ratios and rates were studied.During the stretching process,the blend underwent the crack and the hole expansion,and finally formed a fibrous single phase structure of highly oriented.The crystallinity of the samples increased and then decreased with the increase of strain.It was found that the stress fluctuation occured at the low strain rate,and decreased with the increase of the tensile rate. |
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