纳米CaCO3增强竹浆纤维/环氧树脂复合材料的动态力学性能

为探索碳酸钙(CaCO_3)无机颗粒界面增强机理,建立竹纤维表面微纳米颗粒的附载与界面增强技术的内在联系,该论文以竹浆纤维(bamboo pulp fiber,BPF)和环氧树脂为主要材料,采用纳米CaCO_3浸渍改性工艺,通过真空辅助树脂浸注技术制备BPF/环氧树脂复合材料,利用动态力学分析仪对其动态热机械性能和界面性能进行研究。结果表明:测试频率为单频(1Hz)时,在–20~120℃,纳米CaCO_3浸渍改性竹浆纤维(BPF treated by impregnation modification,IMBPF)增强环氧树脂复合材料的最大储能模量是BPF/环氧树脂复合材料的1.3倍;测试频率为多频(1,2,5,10和20 Hz)时,频率对BPF/环氧树脂复合材料和IMBPF/环氧树脂复合材料的影响规律相同,储能模量,损耗模量和损耗因子均随频率的增加而增加且逐渐向高温方向移动。BPF/环氧树脂复合材料和IMBPF/环氧树脂复合材料的玻璃化转变温度均随频率的增加而升高,而测试频率对损耗因子影响不大;IMBPF/环氧树脂复合材料的玻璃化转变表观活化能(369.0kJ/mol)低于BPF/环氧树脂复合材料(495.8 kJ/mol),但IMBPF/环氧树脂复合材料的频率和玻璃化转变温度倒数的相关性(决定系数0.987 6)优于对照样(决定系数0.965 9);在–20℃、40℃和100℃时,IMBPF/环氧树脂复合材料的储能模量对频率的依赖性高于对照样;纳米CaCO_3浸渍改性技术可改善复合材料的界面性能,从而为纳米增强复合材料的研究提供理论依据。

Improving dynamic mechanical property of bamboo pulp fiber reinforced epoxy resin composite treated by nano calcium carbonate

In this study, in order to make bamboo plastic composites develop toward the economizing, simplification and practicality, bamboo pulp fiber (BPF) and epoxy resin were served as the raw materials to manufacture the fiber reinforced composites by means of vacuum-assisted resin transfer molding (VARTM). The BPF was modified withnano calcium carbonate (CaCO3) using impregnation. The dynamic thermo mechanical property and interfacial property of the composites were analyzed using dynamic mechanical analysis. It was observed that when the test frequency was in the single digit (such as 1 Hz), the maximum storage modulus of the BPF treated by impregnation modification (IMBPF) reinforced epoxy resin composites(3421 MPa) increased by 30% in temperatures ranging from -20 to 120 °C compared to the control sample(2627 MPa). When the test frequency was multiple digits (1, 2, 5, 10 and 20 Hz) it had a similar effect on the BPF/epoxy resin composites and IMBPF/epoxy resin composites. Meanwhile, the storage modulus, loss modulus and loss factor all increased with the increasing of frequency and gradually moved to a higher temperature. The glass transition temperature of both BPF/epoxy resin composites and IMBPF/epoxy resin composites increased with the increase of the frequency, however, the loss factor had no significant change. In addition, the apparent activation energy of glass transition of IMBPF/epoxy resin composites (369.0 kJ/mol)with a lower glass transition temperature was lower than that of BPF/epoxy resin composite(495.8 kJ/mol), but the correlation between the logarithm of frequency and the reciprocal of the glass transition temperature for IMBPF/epoxy resin composites (R2=0.9876)was higher than BPF/epoxy resin composites(R2=0.9659), and at the same time, the determination coefficient of BPF/epoxy resin composites and IMBPF/epoxy resin composites was higher than 0.95. Moreover, when the composites were in glassy state and rubbery state at the selected temperature of –20, 40 and 100℃, the dependence of the storage modulus of IMBPF/epoxy resin composites on the test frequency was higher than the BPF/epoxy resin composites, which suggested that the loading of CaCO3 particles (15%) affected the dependence of the storage modulus of the composites on test frequency to a certain degree. In the test temperature range from -20 to 120℃, the variation of the interface performance parameter for IMBPF/epoxy resin composites was similar with that for BPF/epoxy resin composites, and was lower than the control sample.The interface performance parameterof BPF and matrix epoxy resin could reflect the temperature and the state of the composite interface. Therefore, the smaller the interface performance parameter, the better the interfacial adhesion, and thus the interfacial property of the composites was improved with nano CaCO3impregnation.