静电纺丝法加速聚乳酸水解机理研究

本研究通过静电纺丝法将聚乳酸制成纳米纤维材料,并通过X射线衍射、红外光谱等手段研究其在中性、酸性及碱性水相环境下的水解机理。结果表明,静电纺丝技术确实可以加快PLA的水解速率。研究分析可知,PLA样品的水解过程包括水解-溶胀-进一步水解等三个阶段,且会导致PLA样品结晶度增大。     

聚乳酸类材料的应用研究进展

对聚乳酸类材料在塑料、纤维和医学等领域的应用作了广泛而深入的总结和评述,预示了聚乳酸类材料的演技开发前景。     

聚乳酸类可吸收手术缝合线的研究进展

介绍了国内外聚乳酸手术缝合线的研究情况,分析了其在体内的降解机理,并对其发展提出了自己的观点。     

聚乳酸纤维的耐酸碱性

针对织物在加工、后处理以及服用过程中经常会遇到化学试剂作用的问题,研究了聚乳酸纤维在不同pH值、温度、时间等条件下的耐酸碱性。利用强力仪、扫描电镜(SEM)等测试仪器,测试分析了经酸碱液处理的聚乳酸纤维。结果表明:在影响聚乳酸纤维耐酸碱性的温度、时间和pH值三个因素中,pH值和温度起主要作用;热碱液对聚乳酸纤维强度影响很大,高温长时间的强酸性条件对纤维的损伤也较大;100℃、pH值为11、处理90 min时,纤维已失去纤维功能。从化学原理上分析了酸碱对聚乳酸纤维性能的影响,并从理论上解释了聚乳酸经酸碱水解的机制。     

聚乳酸类高分子材料的扩链合成法

综述了聚乳酸类生物降解材料的扩链合成法,重点总结使用聚乙二醇、二异氰酸酯类、二嚼唑啉类扩链剂的合成进展。     

绿色高分子材料--聚乳酸

本文概述了聚乳酸的基本性质和市场状况,着重论述了聚乳酸的工艺原理与应用,指出了聚乳酸是一种新型的绿色环保高分子材料。     

聚乙二醇改性聚乳酸类材料的合成及应用

介绍了丙交酯与环氧乙烷开环共聚合、丙交酯与聚乙二醇(PEG)开环共聚合，以及在其基础上的扩链3种主要的聚乙二醇改性聚乳酸(PELA)合成方法，并概括了各种PELA合成材料的性能与应用。为了得到功能化和亲水性理想的聚乳酸类生物降解高分子，聚乳酸树脂的PEG改性合成T作越来越引人注目。以PEG、乳酸等为原料，通过简单易行的直接聚合法合成PELA类材料，降低PELA类材料的成本，是未来研究的重要方向。     

可生物降解性高分子材料——聚乳酸

主要介绍了可生物降解高分子材料－聚乳酸的合成、基本性能,聚乳酸纤维和聚乳酸塑料的成型加工及主要用途。     

竹原纤维增强聚乳酸完全可降解材料的性能研究

以竹原纤维、聚乳酸为原料,采用非织造结合模压成型工艺制备了完全可降解材料。研究了材料降解随时间的变化规律及材料中增强纤维体积分数对材料拉伸、弯曲及降解性能的影响,采用扫描电子显微镜和傅立叶变换红外光谱仪研究了材料的降解机理。结果表明,当纤维体积分数为50%时,材料的纵横向拉伸强度和弯曲强度均达最大,分别为20.60、15.12MPa和27.47、21.27MPa;材料的降解速率随时间增加呈加快趋势,且纤维含量高的材料降解较快;降解首先发生在材料界面的缝隙处,随后产生了树脂开裂和纤维降解。     

新型生物降解材料聚乳酸综述

简介了可生物降解高分子材料聚乳酸的性能特点,综述了其合成方法的研究现状,发展趋势和应用前景.     

二甲基二氯硅烷浓酸与恒沸酸水解方法比较

聚二甲基硅氧烷主要由二甲基二氯硅烷水解制得,介绍了二甲基二氯硅烷水解的两种方法,即浓酸水解法与恒沸酸水解法,以60 kt/a二甲基二氯硅烷水解为例,对两种水解工艺过程的用能、设备投资、占地投资等进行了计算分析。结果表明,浓酸水解方法具有成本低、能耗低、流程短等优点,将逐渐取代恒沸酸水解方法成为聚硅氧烷生产的新的发展趋势。     

Effect of Chain-Extenders on the Properties and Hydrolytic Degradation Behavior of the Poly(lactide)/Poly(butylene adipate-co-terephthalate) Blends

Biodegradable poly(lactide)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends were prepared by reactive blending in the presence of chain-extenders. Two chain-extenders with multi-epoxy groups were studied. The effect of chain-extenders on the morphology, mechanical properties, thermal behavior, and hydrolytic degradation of the blends was investigated. The compatibility between the PLA and PBAT was significantly improved by in situ formation of PLA-co-PBAT copolymers in the presence of the chain-extenders, results in an enhanced ductility of the blends, e.g., the elongation at break was increased to 500% without any decrease in the tensile strength. The differential scanning calorimeter (DSC) results reveal that cold crystallization of PLA was enhanced due to heterogeneous nucleation effect of the in situ compatibilized PBAT domains. As known before, PLA is sensitive to hydrolysis and in the presence of PBAT and the chain-extenders, the hydrolytic degradation of the blend was evident. A three-stage hydrolysis mechanism for the system is proposed based on a study of weight loss and molecular weight reduction of the samples and the pH variation of the degradation medium.     

Hydrolytic extraction of glue from femoral bone

A minimum of five hydrolytic extractions in a total of 3.5 litres of water at 130°C was found sufficient to recover more than 95% of the glue present in a fresh femoral bone. Computerized analysis shows a parabolic mathematical relationship between the amount of glue extracted and the number of extractions under given conditions.     

Hydrolytic Depolymerization of PET in a Microwave Reactor

Recycling of PET was examined using hydrolytic depolymerization in an alkaline solution under microwave irradiation. The reaction was carried out in a sealed microwave reactor in which the pressure and temperature were controlled and recorded. The main products were the monomers TPA and EG. The effect of reaction temperature, time, amount of PET and alkaline concentration on the degree of PET depolymerization and TPA recovery was investigated. Microwave irradiation was found to reduce the time needed to achieve a specific degradation of PET significantly, with almost complete depolymerization occurring in 30 min at 180 °C and only 46 W of microwave power. Using a phase transfer catalyst (TOMAB) resulted in the same amount of unreacted PET but at significantly lower depolymerization temperatures.

     

Effects of Sterilization and Hydrolytic Degradation on the Structure,Morphology and Compressive Strength of Polylactide-Hydroxyapatite Composites

Composites based on polylactide (PLA) and hydroxyapatite (HA) were prepared using a thermally induced phase separation method. In the experimental design, the PLA with low weight-average molar mass (M_w) and high M_w were tested with the inclusion of HA synthesized as whiskers or hexagonal rods. In addition, the structure of HA whiskers was doped with Zn, whereas hexagonal rods were mixed with Sr salt. The composites were sterilized and then incubated in phosphate-buffered saline for 12 weeks at 37 °C, followed by characterization of pore size distribution, molecular properties, density and mechanical strength. Results showed a substantial reduction of PLA M_w for both polymers due to the preparation of composites, their sterilization and incubation. The distribution of pore size effectively increased after the degradation process, whereas the sterilization, furthermore, had an impact on pore size distribution depending on HA added. The inclusion of HA reduced to some extent the degradation of PLA quantitatively in the weight loss in vitro compared to the control without HA. All produced materials showed no cytotoxicity when validated against L929 mouse skin fibroblasts and hFOB 1.19 human osteoblasts. The lack of cytotoxicity was accompanied by the immunocompatibility with human monocytic cells that were able to detect pyrogenic contaminants.     

1-乙酰氨基-3,5-二甲基金刚烷的水解反应研究

通过对酰胺水解反应的机理的分析,针对1乙酰氨基3,5二甲基金刚烷空间位阻大、取代基为推电子基团的特点,对其水解反应对收率的影响进行了研究。结果表明:此化合物的水解适宜在碱性条件下进行,且在n(反应物)∶n(苛性钠)=1∶5,溶剂为水:乙二醇=1∶10,150℃下反应12h,得到最终产品盐酸美金刚的收率为92.5%,纯度为99.5%     

Hydrolytic decomposition of dichlorodifluoromethane on modified zirconium oxide surfaces

The hydrolytic decomposition of dichlorodifluoromethane (CFC-12) on various modified zirconium oxide surfaces has been studied. The reaction was carried out under flow conditions at 500°C. Complete CFC-12 conversion and long-time stability of the catalysts were achieved accompanied by a limitation of the undesired CFC-13 formation. A maximum CFC-12 conversion was observed on catalysts of sulfated zirconia or zirconia obtained from temperature-controlled calcination of zirconium oxide hydrate. The reaction depends on the presence or in situ formation of Brønsted acid sites. FTIR-photoacoustic measurements were performed on pyridine complexes chemisorbed on the catalyst surface in order to analyze the changes in the catalyst's acidity. The effects of the temperature and water in the reaction gas on the catalyzed decomposition of CFC-12 are examined.     

羟基磷灰石/聚乳酸类复合材料

聚乳酸(PLA)类高分子是一类重要的生物降解聚合物，羟基磷灰石(HA)是人体骨骼的基本成分，以PLA类高分子为基体、以HA为增强材料的HA／PLA复合材料是复合生物材料中无机／有机复合材料的典型代表，其具有良好的生物相客性，在骨修复领域有重要的应用。笔者在介绍HA／PLA类复合材料的制备、性能和应用等研究近况的基础上，指出使用新型的复合工艺，采用纳米级和改性的HA增强是其发展趋势。     

废尼龙66水解再资源化及其动力学分析

以硫酸为催化剂,对废尼龙66（PA66）水解反应进行了研究,采用红外光谱（FTIR）和核磁共振氢谱（¹H NMR）对产物结构进行了表征研究,并确认为己二酸（AC）和己二胺（HMD）。采用L₉（3⁴）正交实验方法,考察了反应温度、反应时间、催化剂用量及水用量等因素对水解反应结果的影响,并获得较佳的工艺条件：PA66和硫酸的摩尔比1∶2.5;PA66和甲醇的摩尔比1∶30;反应温度为110℃;反应时间为4h。在此工艺条件下,PA66转化率为100%,AC和HMD的摩尔收率分别达到98.06%和97.15%。动力学实验表明,PA66水解为一级反应,活化能为145.31kJ/mol。同时,对PA66在此条件下的水解反应机理进行了初步探讨。