| Poly(lactic acid)is a kind of thermoplastic aliphatic polyesters with excellent biocompatibility.The processes from synthesis to use to disposal have no pollution to the environment and are consistent with the concept of sustainable development.However,the pure poly(lactic acid)has low mechanical strength,poor impact toughness,low heat distortion temperature and thermal stability.So it is urgently required to carry out modification research in order to expand the application field.In this paper,excellent performance 3D printable carbon fiber/biodegradable toughener/poly(lactic acid)composites were prepared by physical blending method using poly(lactic acid)as a matrix material,micron-length carbon fiber as a reinforcing material,and a biodegradable toughener as a tough material.Firstly,carbon fiber/poly(lactic acid)composites were prepared by hot pressing and the effects of carbon fiber content and length on the properties of the material system were studied.The results showed that compared with pure poly(lactic acid),when the carbon fiber content is 20wt%and the length is 300?m,the overall performance is the best,and the tensile strength,notch impact strength and heat distortion temperature are increased by 30%,36%and 11.1%respectively,TGA analysis shows that the thermal stability increased,DSC analysis shows that carbon fiber has a heterogeneous nucleation,crystallinity increased.Then carbon fiber/biodegradable toughener/poly(lactic acid)composites were prepared by hot-pressing and to the effects of toughener type and content on the properties of the material system were studied.The results showed that the modification effect of PBS was better than that of PBAT and PHA.Compared with 20CF/80PLA composites,when the PBS content is 4wt%,a balance between strength,toughness,and heat resistance is achieved,and its elongation at break,notched impact strength and thermal conductivity are increased by 31.8%,11.8%and 18.5%respectively,tensile strength and heat distortion temperature only decreased by 7.7%and 0.5%,SEM analysis shows that the material section appears drawing phenomenon,DSC analysis shows that PBS has a heterogeneous nucleation,crystallinity increased.On the basis of the above,pure poly(lactic acid)and carbon fiber/biodegradable toughener/poly(lactic acid)composites were prepared by 3D printing and the effects of molding process on the properties of the material system were studied.The results showed that the performance of the 3D printed samples was lower than that of the hot press.For the molded samples,for the carbon fiber/biodegradable toughener/poly(lactic acid)composites,the tensile strength,notched impact strength,and heat distortion temperature of the 3D printed samples were 79.2%,81.6,and 95.8%of the hot-pressed samples respectively.The retention rate is good.SEM analysisshows that there is delamination in the cross section of 3D printed samples.Then the carbon fiber surface modification,SEM analysis showed that the surface roughness of the carbon fiber was increased,XPS analysis showed that the O/C value of the carbon fiber surface was increased and the oxygen-containing functional group was increased,Raman analyzed that the graphitization structure of the carbon fiber surface was basically unchanged.Finally,passed through 3D printing,the modified carbon fiber/biodegradable toughener/poly(lactic acid)composite was molded to study the effect of carbon fiber surface modification on the properties of the material system.The results showed that the modified sample was higher than that of the unmodified sample.The tensile strength,notched impact strength and heat distortion temperature were increased by 5.3%,12.9%and 1.7%respectively,SEM analysis showed that the material section delamination phenomenon was weakened,DMA analysis showed that the storage modulus and glass transition temperature increased,TGA analysis showed that the thermal stability increased,DSC analysis showed crystallinity increased. |
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