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聚乳酸降解性能研究进展 总被引:1,自引:0,他引:1
聚乳酸是典型的绿色塑料,因其良好的生物相容性、完全可降解性及生物可吸收性,是生物降解医用材料领域中最受重视的材料之一。本文介绍了聚乳酸的降解机理,着重对近年来有关聚乳酸降解性能的研究进行了综述。 相似文献
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针对生物可降解材料聚乳酸的一些缺点,提出了几种改性的方法,并对聚乳酸成型加工常用的两种方法,即挤出成型和注射成型做了介绍,最后对聚乳酸的应用进行了展望. 相似文献
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液压脉动注射成型聚乳酸力学性能及生物降解性能的研究 总被引:1,自引:1,他引:0
在不同振动工艺参数下,研究液压脉动注射成型对聚乳酸(PLA)制品力学性能、结晶性能及生物降解性能的影响.结果表明,与普通注射成型相比,液压脉动注射成型的PLA制品拉伸强度提高了10.6%,冲击强度提高了29.7%,结晶度提高了11.9%.在蛋白酶K催化降解下,其生物降解过程是从表面侵蚀到内部整体侵蚀的逐步演变过程,制品总降解速率比普通注射成型的小. 相似文献
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聚乳酸生物复合材料降解性能的研究 总被引:1,自引:0,他引:1
研究了使用土埋法降解后,经聚乙二醇400改性前后的聚乳酸/热塑性淀粉复合材料其质量和力学性能的变化,进而分析聚乳酸生物复合材料的降解性能。结果表明:在改性前,样条的降解性能随着热塑性淀粉含量的增加而变得更好;经过PEG400改性后,样条的降解率随着PEG400含量的增加而增加,说明PEG400在一定程度上促进了复合材料的降解。 相似文献
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以聚乳酸(PLA)为原料,乙酰柠檬酸三丁酯(ATBC)为增塑剂,利用竹纤维作为增强体,加入聚磷酸铵/淀粉/甲酰胺、双氰胺(APP/TS/FD)混合膨胀型阻燃剂,制备阻燃型竹纤维/PLA复合材料,通过分析土埋、热老化两种条件下,复合材料表面形貌、燃烧性能、热性能、吸水性能、力学性能的变化,研究竹纤维增强PLA复合材料的降解性能。研究表明,在热老化情况下,复合材料的力学性能变化更为明显,在80℃下热老化12天后复合材料的拉伸强度和弯曲强度分别降低了86.6%和77.1%,而土埋3个月后的拉伸强度和弯曲强度分别降低了71.9%和61.8%,处理前后复合材料的燃烧性能和热性能均无明显变化。 相似文献
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为了了解聚L-乳酸(PLLA)自身结构特点,更好地控制其成型加工过程,研究了PLLA的非等温结晶行为、熔融行为和热失重过程。结果表明:降温速率对PLLA的非等温结晶过程具有显著影响,在1℃/min的降温速率下,PLLA的结晶起始温度为121℃,结晶焓为3.363 J/g;PLLA的熔融双峰遵循熔融-再结晶的机理;PLLA热分解温度在300℃左右,且随升温速率的增加而增大。 相似文献
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Effect of the addition of poly(D-lactic acid) (PDLA) as stereocomplex (SC) on crystallization behavior of poly(L-lactic acid) (PLLA) had been systemically investigated. The result indicated that the inclusion of PDLA with higher MW into PLLA exhibited lower t 1/2 and showed accelerated crystallization behavior. Meanwhile, SC formed in blends with higher MW of PDLA exhibited enhanced nucleation activity. In combination with both DSC and WAXD analysis, it was believed that nucleation process was more related to the crystalline size of SC. The result in this study would provide guidance for the application of SC as nucleating agent for the PLA-based products. 相似文献
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以纳米二氧化钛对聚L-乳酸进行共混改性,并对所得PLLA/TiO2复合材料的结构与性能进行了分析表征。实验结果表明,所得复合材料处于无定型态,退火处理后结晶,TiO2不改变PLLA基体结晶的α晶型,但结晶衍射峰强度随TiO2添加量增加而减弱。TiO2对PLLA基体的结晶性能和熔融行为影响较小,表明TiO2对PLLA的异相成核作用有限。 相似文献
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The kinetics of crystal nucleation of poly(L-lactic acid) (PLLA) has been analyzed by fast scanning chip calorimetry in a wide temperature range between 313 and 383 K, that is, between temperatures about 30 K below and 40 K above the glass transition temperature. The relaxed melt was rapidly cooled to the analysis temperature and subsequently aged between 10−1 and 104 s, to permit formation of nuclei. The number of formed crystal nuclei has been probed by analysis of the crystallization rate at 393 K. The nucleation rate is maximal at 370–375 K and decreases monotonously with decreasing temperature in the analyzed temperature range. The observation of a monomodal dependence of the nucleation rate on temperature points to predominance of a single nucleation mechanism in the analyzed temperature range, regardless nucleation occurs in the glassy or devitrified amorphous phase. The collected data suggest that nuclei formation at ambient temperature requires a waiting time longer than about 108 s. The performed study is considered as a quantitative completion of nucleation-rate data available for PLLA only at temperatures higher than 360 K, suggesting that the nucleation mechanism is independent on temperature in the analyzed temperature range between 313 and 383 K. 相似文献
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Homo-crystallization and melting behavior of poly(L-lactic acid) (PLLA) with poly(D-lactic acid) (PDLA) (≤10 wt.%) was studied. The different thermal history had been applied to exert structural variation on stereocomplex (SC). The PLLA/PDLA blend showed different crystallization and melting behavior when cooled from 250°C or 200°C. Double melting peaks were observed after the blend was cooled from 250°C. SC annealing at different temperatures exhibited significant effect for melt-crystallization of PLLA. Influence of initial melting condition before cooling was also investigated. The cold crystallization of amorphous blend initially was studied and some novel results had been observed. 相似文献
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N,N′-bis(benzoyl) hexanedioic acid dihydrazide (BHAD), and N,N′-bis(benzoyl) terephthalic acid dihydrazide (BTAD) were synthesized as the organic nucleating agents for poly(L-lactic acid) (PLLA). These two organic compounds exhibited different nucleating effect to PLLA. When the concentration was very low, BTAD was able to nucleate PLLA, while BHAD was not. When the concentration was adequate, BHAD showed better nucleating effect than BTAD. The experiments showed that, BHAD had the ability of dissolving into PLLA melt matrix, while BTAD was insoluble in PLLA. The optical microscope images revealed the quite different PLLA crystal morphologies nucleated by BHAD and BTAD. As BTAD could not dissolve in PLLA melt, it only induced a mass of small grain crystals of PLLA, the morphology of which is the same as neat PLLA. BHAD had relatively different nucleation and crystallization behaviors. Upon heating, BHAD could partially or totally dissolve in PLLA melt, which depended on the final heating temperature and its concentration. Upon cooling, BHAD separated from PLLA matrix and formed needle like or dendritic structures. Moreover, totally dissolved BHAD could finally exhibit dendritic structures, which had an excellent nucleation effect to PLLA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46851. 相似文献
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Shuenn-Kung Su Jhih-Wun Siao Fu-San Yen Jane-Yii Wu Chien Ming Huang 《Polymer-Plastics Technology and Engineering》2013,52(13):1361-1370
Biodegradable polycaprolactone/poly(glutamic acid) (PCL/PGA) blends were prepared by a melt blending method. Additionally, acrylic acid-grafted polycaprolactone (PCL-g-AA) was studied as an alternative to PCL. The samples were characterized using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), an Instron mechanical tester, and scanning electron microscopy (SEM). Because of poor compatibility between PCL and PGA, the mechanical properties of PCL/PGA blends were worse than of PCL alone. The PCL-g-AA/PGA blends had obviously improved mechanical properties over PCL/PGA ones, and the former provided a plateau tensile strength at break when the PGA content was up to 20 wt%. Biodegradation tests of blends were also conducted in a soil environment; the results showed that the mass of blends declined by about the PGA content within 4 weeks. 相似文献
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Ling Chang 《Polymer》2011,52(1):68-76
Effects of poly(3-hydroxybutyrate) (PHB) on crystalline morphology of stereocomplexing capacity of poly(L- and D-lactic acid) (PLLA and PDLA) were studied by differential scanning calorimetry (DSC), polarizing-light optical microscopy (POM), atomic-force microscopy (AFM) and wide-angle X-ray diffraction (WAXD). When crystallized at high Tc (130 °C or above), morphology transition of stereocomplexed PLA (sc-PLA) occurs from original well-rounded Maltese-cross spherulites to dendritic form in blends of high PHB contents (50 wt.% or higher), where PHB acts as an amorphous species. Microscopy characterizations show that morphology of sc-PLA in PHB/sc-PLA blends crystallized at Tc = 170 °C no longer retain original complexed Maltese-cross well-rounded spherulites; instead, the spherulites are disintegrated and restructured into two types of dendrites: (1) edge-on feather-like dendrites (early growth) and (2) flat-on wedge-like crystal plates (later growth) by growing along different directions and exhibiting different optical brightness. The concentration and/or distribution of amorphous PHB at the crystal growth front, corresponding to variation of the slopes of spherulitic growth rates, is a factor resulting in alteration and restructuring of the sc-PLA spherulites in the blends. Despite of spherulite disintegration, WAXD result shows that these two PHB-induced dendrites still retain the original unit cells of complexes, and thus these two new dendrites are sc-PLA. 相似文献
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熔融缩聚法合成高分子量聚L-乳酸 总被引:5,自引:0,他引:5
以L-乳酸为原料,采用分步除水、丙交酯回流、优选催化剂等工艺,通过熔融缩聚法制备了高分子量聚L-乳酸(PLLA),研究了脱水产物、反应装置、催化剂、聚合工艺等对产物分子量、产率及色泽的影响,并对产物分子结构进行了表征。在加装丙交酯回流装置后,以Sn(Ot)2/SnC l2.2H2O/TSA为催化剂,在170℃,反应12h所得PLLA黏均分子量(Mη)可达10.6万,产率为76%。 相似文献
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Poly(L-lactic acid) (PLLA) microfibers were obtained by a carbon dioxide (CO2) laser-thinning method. A laser-thinning apparatus used to continuously prepare microfibers was developed in our laboratory; it consisted of spools supplying and winding the fibers, a continuous-wave CO2-laser emitter, a system supplying the fibers, and a traverse. The laser-thinning apparatus produced PLLA microfibers in the range of 100-800 m min−1. The diameter of the microfibers decreased as the winding speed increased, and the birefringence increased as the winding speed increased. When microfibers, obtained through the laser irradiation (at a laser power of 8.0 W cm−2) of the original fiber supplied at 0.4 m min−1, were wound at 800 m min−1, they had a diameter of 1.37 μm and a birefringence of 24.1×10−3. The draw ratio calculated from the supplying and winding speeds was 2000×. The degree of crystal orientation increased with increasing the winding speed. Scanning electron microscopy showed that the microfibers obtained with the laser-thinning apparatus had smooth surfaces not roughened by laser ablation that were uniform in diameter. The PLLA microfiber, which was obtained under an optimum condition, had a Young's modulus of 5.8 GPa and tensile strength of 0.75 GPa. 相似文献