生物降解性高分子材料

本文综述了国内外生物降解高分子材料的研究现状和发展方向，分析了国内外生物降解研究和生产中存在的几个问题，结合我国的国情，对我国未来生物降解高分子的研究和发展提出了几点建议。     

生物降解高分子材料

综述了近２０年来国内外生物降解高分子材料的研究进展及试验评价方法，初步探讨了生物降解的机理，并对现存的几个问题及开发前景提出了几点看法。     

生物降解高分子材料应用前景看好

塑料材料的大量应用，在给人们的生活带来许多方便的同时，也造成了许多困扰。而从根本上解决这一难题的途径就是生产可降解塑料等。可以预见，在21世纪降解性高分子材料将会取得长足发展，成为高分子工业不可分割的部分。     

生物降解高分子材料

简要介绍生物降解高分子材料的定义、降解机理及影响因素的基础上,较为全面的阐述了当前生物降解高分子材料的应用领域     

生物降解性高分子材料(续)

本文综述了国内外生物降解高分子材料的研究现状和发展方向，分析了国内外生物降解研究和生产中存在的几个问题，结合我国的国情，对我国未来生物降解高分子的研究和发展提出了几点建议。     

生物降解高分子材料的研究新进展

综述了生物降解高分子材料制备方法和降解机理的研究新进展 ,并讨论了结构、组成、形态和外界条件等因素对均聚物、共聚物和高分子共混物生物可降解性的影响 ,简述了生物降解高分子材料在生物医学、包装和农业领域的潜在应用。     

降解性高分子材料的研究开发进展

综述了生物降解高分子材料,光降解高分子材料和光－生物降解高分子材料的种类、制备方法、性能及其应用,指出了降解高分子材料存在的问题方向,通过比较认为光降解高分子材料技术比较成就,完全生物降解高分子材料和光－生物降解高分子材料发展前景看好,并对今后的发展提出了建议。     

生物降解高分子材料

介绍了高分子材料生物降解机理,概述了生物降解材料的研究和应用情况,并展望了将来的研究方向。     

生物降解高分子材料的研究进展

简要介绍了生物降解高分子材料的定义、分类和降解机理,较为全面地阐述了当前生物降解高分子材料的应用领域,并对其发展前景作出展望。     

生物降解高分子材料研究进展

介绍了生物降解高分子材料的概念和分类,并结合具体实例详细论述了目前国内外在天然、微生物合成、化学合成和掺混型等四类生物降解高分子材料方面的研究方向及最新研究进展。     

Review: Crystallization of Biodegradable Polymers

Understanding the crystallization behavior of polymer is significant both theoretically and practically as it decides the microscopic structure of polymer and determines final physical properties of the product. This article provides deep insight into the process of crystallization by exploring various models proposed for crystallization, factors determining crystallization, thermodynamics and kinetics in detail. The correlation of crystallinity with various properties is also discussed. For kinetics evaluation, the basic hypotheses of various models, as well as their relative drawbacks are also underlined. This article also reviews the crystallization behavior of widely useful biodegradable polymers such as poly(?-caprolactone) and poly(lactic acid).     

国外生物降解聚合物的改性添加剂

根据生物降解聚合物的性能、特征和使用要求,国外众多企业和研究机构不断开发新颖、适应的改性添加剂。和ＰＥ、ＰＰ、ＰＳ等常用塑料相比,用于降解聚合物的添加剂在生物降解性、生物相容性,无（低）生理毒性、以及在技术含量上都有较高的要求,研制这些添加剂涉及的知识和技术领域十分广阔。本文主要论述近期国外开发的用于降解聚合物的部分添加剂。它们包括：增塑剂、交关剂、增容剂、防水／防潮剂、粘合剂、引发剂等。     

Deformation and damage upon stretching of degradable polymers (PLA and PCL)

Microstructure and plastic behavior of poly(lactic acid), PLA, and poly(ε-caprolactone), PCL, are investigated. The injected molded specimens are analyzed as received. Thermomechanical properties are characterized by DSC and DMA and crystalline structure by WAXS. The results show that PLA samples are weakly crystalline (14 wt%) and that amorphous phase is glassy at room temperature. The PCL samples exhibit higher crystallinity (53 wt%) and contain a rubber-like amorphous phase. Mechanical behavior is investigated by means of novel video-controlled materials testing system specially developed to assess true stress vs. true strain curves and to record the volume changes upon stretching. While tested at 50 °C, PLA undergoes extensive plastic deformation with a dramatic yield softening followed by a progressively increasing strain hardening. Volume strain, which characterizes deformation damage, increases steadily over the whole plastic stage until reaching 0.27 for an axial strain of 1, 4. For its part, PCL exhibits at 23 °C a much progressive plastic response with a soft yield point, no softening, and moderate strain hardening at large strain. Volume change is delayed until axial strain reaches 0.4. Subsequent damage grows very quickly, eventually reaching 0.2 for an ultimate strain of 1, 3. Results are discussed on the basis of microscopic damage mechanisms observed in the stretched state.     

可生物降解聚酯复合材料吹膜湿热老化性能研究

采用GB/T12000—2003方法,在温度50℃和相对湿度95%条件下利用恒温恒湿箱对聚丁二酸己二酸丁二酯与聚乳酸共混改性材料的吹塑薄膜进行检测,研究了湿热老化时间对力学性能与热封性能变化的影响,总结了简单水解降解和酶解降解反应在PBSA/PLA体系薄膜降解过程中的作用过程。     

可生物降解高分子材料研究进展

简要说明了可生物降解高分子的降解机理及其种类,介绍了可生物降解高分子材料及其在生物医药方面的应用。表明可生物降解高分子具有良好的应用前景。     

全生物降解高分子材料的发展现状

生物降解高分子材料因医药、医学、环境等方面的需求而迅速发展起来,在近几十年,世界先进国家非常重视该领域的研究和开发工作,并取得一些重要进展。在简要介绍生物降解高分子材料的降解过程后,着重对全生物降解高分子材料的发展现状作了综述,其中包括化学合成高分子和天然高分子的研究和开发,同时对生物降解高分子材料存在的问题及其将来发展趋势等方面进行了讨论。     

Solution-based synthesis of a four-arm star-shaped poly(L-lactide)

The mechanical properties of biocompatible poly(L-lactide) (PLA) could be dramatically enhanced by cross-linking and interesting network structures might be achieved via the formation of branched and star-shaped structures prior to such cross-linking. However, the synthesis of a four-armed star-shaped PLA is limited to bulk melt polymerization at relatively high temperatures that may degrade the monomer and render the reaction kinetics difficult to control. In this work, a solution-based polymerization approach is introduced with dimethylformamide as the solvent for the initiator and all other reactants. Varying the reactant concentrations and reaction temperature, four-arm PLA star structures were produced in solution and their properties were analyzed. The progress of the polymerization reaction was studied using the ¹H NMR and Fourier transform infrared spectroscopy. The quantitative evaluation of the monomer conversion was discussed on theoretical basis. The thermal properties and the crystallinity of the product polymers were evaluated using differential scanning calorimetry. Results indicate polymerization and cross-linking of the four-armed PLA were successful. The introduced solution-based method could open venues for better controlled and more economic reactions of star-shaped and cross-linked PLA.     

Preparation of block copolymer of ?-caprolactone and 2-methyl-2-carboxyl-propylene carbonate

A block copolymer PCL-b-PMBC of ?-caprolactone (ε-CL) and 2-methyl-2-benzyloxycarbonyl-propylene carbonate (MBC) was synthesized by sequential ring-opening polymerization of the ε-CL and MBC monomers with amino isopropoxyl strontium (Sr-PO) as an initiator. It was debenzylated by catalytic hydrogenation to obtain a linear block copolymer PCL-b-PMCC with pendant carboxyl groups. WAXD showed that the presence of PMBC segment in PCL-b-PMBC influenced obviously the crystallizability of PCL block, in agreement with the DSC results. Diffraction peak of PCL-b-PMCC after debenzylation was hardly observed and moreover, melting enthalpy ΔHm of PCL-b-PMCC was 10.9 J/g compared to 68.0 J/g of PCL-b-PMBC, due to the replacement of the benzyl ester by the carboxyl group. The presence of carboxyl groups is expected to enhance the biodegradability of the copolymer and to facilitate a variety of medical applications.     

Film Blowing of Biodegradable Polymer Nanocomposites for Agricultural Applications

Films for agricultural applications, such as greenhouses films or mulching films are generally made of polyolefins such as linear low-density polyethylene (LLDPE) or low-density polyethylene. However, the use of biodegradable and/or compostable polymers is increasing, which enjoy the additional advantage that they can be left on the site since a fine life would be gradually assimilated to the underlying soil. Nevertheless, biodegradable polymeric films often do not have suitable mechanical performances. In this work, biodegradable polymer-based nanocomposite films are prepared by film blowing and compared with traditional LLDPE based nanocomposites. In particular, a biodegradable polymer blend and two different inorganic nanofillers (an organo-modified clay and a calcium carbonate with a hydrophobic coating) are used for the preparation of the nanocomposites. A detailed investigation of obtained materials is performed through rheological, mechanical, and optical characterizations. Adding nanofillers led to an increase of rigidity and tear strength of blown films without negatively affecting their ductility.     

PLA及其复合材料高效预结晶动态干燥工艺

研究了生物高分子PLA及其复合材料高效预结晶动态干燥的方法。在物料干燥过程中引入高速搅拌和真空工艺,使其在干燥过程中加快脱水,避免由于水分蒸发导致的物料黏结。考察了高效预结晶动态干燥和传统干燥两种方法对PLA及其复合材料的干燥温度、干燥时间、力学性能、加工性能、扭矩和热焓的影响。结果表明:高效预结晶温度以不超过95℃为宜,此方法可使生物高分子PLA及其复合材料最大扭矩降低20%～40%,热焓升高,性能有所改善,除湿干燥时间由原来的6～14h缩短为1～2h,而且不会出现黏粒和下料困难的现象。