CF表面改性对注塑PLA/CF复合材料性能的影响

Effect of Carbon Fiber Surface Modification on Properties of PLA/CF Composites by Injection Molding

采用硝酸、硝酸+KH550分别对碳纤维(CF)进行表面改性处理,以聚乳酸(PLA)为基体,改性前后的CF为增强体,配制CF质量分数为10%的PLA/CF混合料,通过双螺杆挤出机进行造粒以及注塑机注塑得到拉伸、弯曲和冲压试样。采用扫描电子显微镜、能谱仪、傅立叶变换红外光谱仪对改性前后的CF进行表征,采用万能材料测试机和悬臂梁冲压试验机进行力学性能测试。结果表明,硝酸处理之后的CF表面产生沟槽,表面粗糙度增加,N和O元素含量增加,产生C—N键和C=O键;硝酸+KH550处理之后的CF表面产生层状KH550薄膜,O和Si元素含量增加,出现Si—O键;同时,硝酸和KH550共同处理CF时PLA/CF复合材料力学性能达到最佳,拉伸强度、弯曲强度以及冲击强度分别达到了84.09 MPa,131.47 MPa,36.54 k J/m2。

The surface of carbon fiber （CF） was treated with nitric acid and nitric acid＋KH550 respectively,polylactic acid （PLA） was used as matrix and CF before and after modification were used as reinforcement to prepare PLA/CF mixture when CF mass fraction was 10%, the mixture was pelletized by a twin-screw extruder and molded by an injection molding machine to obtain tensile,bending and stamped specimens. Scanning electron microscope,energy disperse spectroscopy,Fourier transform infrared spectrometer were used to characterize the CF before and after modification,the mechanical performance test was carried out by using universal material testing machine and cantilever beam stamping machine. The experimental results showed that after the treatment of nitric acid,the grooves on the surface of CF appeared, the surface roughness was increased,the contents of N and O were increased, and C-N bonds and C=O bonds appeared; after the treatment of nitric acid ＋KH550,layered KH550 films were produced on the CF surface,and the content of O and Si elements were increased, and the Si-O bond appeared; at the same time,PLA/CF composites treated with nitric acid and KH550 presented the desirable mechanical properties,the tensile strength, fiexural strength and impact strength were 84.09 MPa, 131.47 MPa and 36.54 kJ/m2 respectively.