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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T_m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X_c从54.3%下降到50.2%,熔融结晶温度T_(mc)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(T_(max1))从281.5℃上升到285.3℃;第二步热解中的最快分解温度(T_(max2))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。
In order to investigate the effect of polyethylene glycol (PEG) on the properties of cellulose nanocrystals (CNCs) / polyhydroxybutyrate valerate (PHBV) composites, PEG-CNCs / PHBV composites were prepared by melt blending. The morphology, crystallinity and mechanical properties of the composites were characterized by scanning electron microscopy (ESEM), differential scanning calorimetry (DSC), polarizing microscope (POM), TG and mechanical testing machine. The results show that the cross section of CNCs / PHBV composites is smooth and rough, and the fracture surface is irregular. The spherulite size of PEG-CNCs / PHBV composites decreases and the spherulitic structure has defects. The melting process is changed into two melts Peak, the melting temperature T_m decreased from 167.8 ℃ to 165.1 ℃. In addition, the addition of PEG increased the mobility of the molecular chain of the composite materials and the crystallization became difficult, the crystallinity X_c decreased from 54.3% to 50.2%, the melting temperature T mc ) Decreased from 99.8 ℃ to 73.5 ℃. The addition of PEG increased the impact strength and tensile elongation at break of CNCs / PHBV composites. The maximum increase of pure PHBV was 56.4% and 96.3% when 25wt% PEG was added, However, Young’s modulus and tensile strength decreased continuously. When PEG was added, the pyrolysis of the composite material was converted from one step to two steps. When 25wt% PEG was added, the fastest decomposition temperature ( T max max increased from 281.5 ℃ to 285.3 ℃. The fastest decomposition temperature in the second pyrolysis (T max2) increased from 371.5 ℃ to 394.3 ℃. Therefore, the addition of PEG can improve the interfacial compatibility and crystallinity of CNCs with PHBV, so as to improve the toughness, plasticity and thermal stability of CNCs / PHBV composites.