超临界正丁醇对回收碳纤维复合材料的降解及表征

Degradation and Characterization of Recycling Carbon Fiber/Epoxy Resin Composites in Supercritical n-Butanol

采用响应面分析方法设计超临界正丁醇降解废弃的碳纤维/环氧树脂(CF/EP)复合材料降解实验,用以回收碳纤维.通过Design-Expert V8.0建立环氧树脂降解率和工艺参数之间的数学模型,获得了最优工艺参数;通过图形优化研究了工艺参数对环氧树脂基体降解率的影响规律;通过场发射电子扫描显微镜、原子力显微镜、X射线光电子能谱仪、显微共焦激光拉曼光谱仪及单丝拉伸等分析最优工艺参数下回收的碳纤维的表面形貌、表面化学、石墨化程度及力学性能.结果表明,建立的数学模型拟合误差范围为±5.5%,实现了回收工艺参数的预估;单因素对环氧树脂基体降解率的影响程度为:反应温度>保温时间>添加剂浓度>正丁醇含量;最优工艺参数为:反应温度330℃,保温时间60 min,添加剂浓度0.0538 mol/L,投料比0.024g/mL.回收的碳纤维表面无残留树脂,没有发生明显的石墨化,且表面平均粗糙度与原碳纤维相近;与原始碳纤维相比,回收的碳纤维的拉伸强度约为原碳纤维的93.58%,杨氏模量约为原碳纤维的94.87%.

Recycling carbon fibers from carbon fiber/epoxy resin（ CF/EP） composites using supercritical n-butanol were reported. The quantitative relationship between the degradation rate of epoxy resin and recycling process parameters was proposed through response surface methodology. The influence of process parameters on the degradation rate of epoxy resin was investigated by graphical optimization. Besides,the microstructure,the graphitization degree,the surface chemistry and the mechanical properties of the recycled carbon fibers were analyzed by scanning elcetron microscopy（ SEM）,atomic force microscopy（ AFM）,X-ray photoelectron spectrometry（ XPS）,Raman spectrum and single-filament tensile strength testing. The results show that the error between the actual and the theoretical degradation rate is within ±5. 5%,and the reaction temperature has the greatest impact on the degradation rate of epoxy resin,followed by the reaction time,KOH concentration and n-butanol volume. Given the optimal process parameters（ i. e.,reaction temperature at 330 ℃,reaction time at 60 min,KOH concentration at 0. 0538 mol/L,and feed ratio at 0. 024 g/mL）,there were no residual resin and graphitization on the surface of the recycled carbon fibers; the average roughness（ Ra） and O/C ratio showed little change comparing with those of the original carbon fibers; and the average tensile strength and Young＇s modulus were about 93. 58% and 94. 87% of those of the original carbon fibers,respectively.