摘要:
为了探讨聚乙二醇（PEG）对纤维素纳米晶体（CNCs）/聚羟基丁酸戊酸酯（PHBV）复合材料性能的影响规律，采用熔融共混法制备了PEG-CNCs/PHBV复合材料。采用环境扫描电镜（ESEM）、DSC、偏光显微镜（POM）、TG、力学试验机表征了复合材料的界面形貌、结晶性能、力学性能。结果表明，PEG的加入使CNCs/PHBV复合材料的断面由光滑变得粗糙，断口凹凸不平；PEG-CNCs/PHBV复合材料球晶尺寸减小，球晶结构产生缺陷，熔融过程转变成两个熔融峰，熔融温度Tm从167.8℃下降到165.1℃，此外，PEG的加入增加了复合材料分子链的移动性，结晶变得困难，结晶度Xc从54.3%下降到50.2%，熔融结晶温度Tmc从99.8℃下降到73.5℃；PEG的加入提高了CNCs/PHBV复合材料的冲击强度和拉伸断裂伸长率，25wt% PEG添加量时，较纯PHBV最大增幅分别为56.4%和96.3%，但杨氏弹性模量和拉伸强度不断下降；PEG的加入使复合材料热解过程由一步热解转化成两步，25wt% PEG添加量时，第一步热解中的最快分解温度（Tmax1）从281.5℃上升到285.3℃；第二步热解中的最快分解温度（Tmax2）从371.5℃上升到394.3℃。因此，PEG的加入可以改善CNCs与PHBV界面相容性和结晶性能，从而提高CNCs/PHBV复合材料韧性、塑性和热稳定性。
Abstract:
In order to investigate the effects of polyethylene glycol (PEG) on the properties of cellulose nanocrystals (CNCs)/poly 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) composites, polyethylene glycol (PEG)-CNCs/PHBV composites were prepared by the melt compounding method. The facture structure, crystalline properties, thermal stability, and mechanical properties of PEG-CNCs/PHBV composites were charactered by ESEM, DSC, POM, TG and material-testing machine, respectively. The results show that the cross section of CNCs/PHBV composites with the addition of PEG becomes rough and fracture suface becomes uneven. The addition of PEG make the spherulite sizes of PEG-CNCs/PHBV composites decrease, new spherulite structure defects emerge, and melting process transform into two melting peaks. The melt temperature Tm decreases from 167.8℃ to 165.1℃. In addition, the addition of PEG enhances the mobility of PHBV molecular chain, thus the crystallization of PHBV becomes more difficult. The melt crystalline temperature Tmc of composites decreases from 99.8℃ to 73.5℃ and the crystallinity Xc decreases from 54.3% to 50.2%. Compared with PHBV, the impact strength and tensile elongation at break of PEG-CNCs/PHBV composites keep increasing with the increase of PEG content, whose maximal promotion with 25wt% PEG are 56.4% and 96.3%, respectively, but the Young's modulus and tensile strength of PEG-CNCs/PHBV composites keep decreasing. Meanwhile the application of PEG improves the thermal stability of composite materials. The pyrolysis process of PEG-CNCs/PHBV composites transforms into two steps, and the fastest decomposition temperature (Tmax1) in the first and second step increases from 281.5℃ to 285.3℃, and from 371.5℃ to 394.3℃, respectively. The addition of PEG can improve the compatibilization and crystallinity between CNCs and PHBV, accordingly enhance toughness, plasticity and thermal stabilities of CNCs/PHBV composites.
百度学术
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