可生物降解聚酯的结构与性能

以聚丙交酯为代表讨论了可生物降解聚酯纤维的结构特征与生物降解性能，对聚酯类纤维生物降解的机理，影响因素进行分析，指出聚合物的分子质量及分子链结构、聚集态结构、环境的温度，湿度，ｐＨ值及酶种类等因素对其降解性能有明显的影响，合理控制这些因素，可对其降解速度实现人为控制，以适应不同用途的需要。     

聚酯链结构定制及其构效关系

聚酯材料的物理性能与可生物降解性为其聚集态结构所决定,而聚合物链的化学组成、序列和拓扑结构又是决定聚合物聚集态结构的最关键因素。为此,本文从基于聚合过程调控的聚酯链结构定制出发,总结了嵌段、长支链、梳状、星型、超支化与树枝状结构聚酯的定制方法;评述了链结构与聚酯热与力学性能之间的构效关系,探讨了链结构对聚酯降解性能的影响规律,前人的研究表明共聚物嵌段长短影响着结晶聚集态结构,长支链的存在有助于聚酯结晶温度与结晶度的提高;链的结晶能力、链长及亲疏水性决定了聚酯的降解性能。文中还对高性能可生物降解聚酯材料的开发进行了展望。     

可降解聚酯酰胺新材料研制成功

以聚烯烃类高分子/淀粉共混物等可光降解或生物降解的包装材料、农用材料,不可能实现百分之百的生物降解,从而形成白色污染和二次白色污染。脂肪族聚酯可生物降解高分子材料,则由于只能采用特殊的合成方法和工艺获得,致使材料价格昂贵,难以推广。中国科学院成都有机化学所研究人员最近研制出可完全降解的聚酯酰胺新材料,并成功应用于一次性餐具、薄膜、纤维等。该技术具有连续化、制品质量稳定的特点,研究人员用可生物降解聚酯酰胺及共聚物制备了一次性餐具、可生物降解薄膜、纤维和各种色母料,其力学性能、生物降解性、毒性等都符合应用要…     

聚酯类生物降解塑料的降解行为

开发可完全生物降解的高分子材料是解决环境污染问题的一种有效途径。其中,脂肪族聚酯是公认的一类最有发展前景的可完全生物降解聚酯,由于可在自然环境中被降解成CO2和H2O而受到青睐。降解塑料在微生物作用下的降解行为受到外部环境和聚酯自身特性的影响。外部环境包括菌种、温度、湿度等;聚酯特性包括分子结构、分子量、熔点、结晶度等。从生物降解微生物、生物降解实验方法及生物降解机理三方面对PBS类降解塑料的降解行为进行论述。     

PBS基共聚酯降解性能的研究概述

简要分析了结晶能力、链段柔顺性和化学组成等对聚丁二酸丁二醇酯(PBS)基共聚酯降解性能的影响。结果表明,柔软的链结构易于被生物降解,有规晶态结构阻碍生物降解,脂肪族聚酯比芳香族聚酯易于生物降解,并指出提高PBS基共聚酯的降解性能仍然是一项具有挑战性的工作。     

以反丁烯二酸合成的不饱和脂肪族聚酯的生物降解性研究

以反丁烯二酸、一缩二乙二醇和1,4-丁二醇为原料,采用熔融缩聚法合成了不饱和脂肪族聚酯和共聚酯,在37℃下,用含有脂肪酶的磷酸缓冲溶液对聚酯的生物降解性进行了研究,讨论了聚酯结构、组成及C=C双键的交联度对生物降解性的影响。结果表明,对于粘稠液体状的聚酯,C=C双键的引入,没有明显的改变其生物降解性;对于固体状的聚酯,C=C双键引入后,熔点(Tm)和结晶度增加;聚酯部分降解后,其热力学性能(Tm、-ΔHm)和结晶度都升高;对于交联后的聚酯,交联度越高,生物降解性越差。     

聚酯型可生物降解弹性体的表征及其降解

用丙三醇和癸二酸通过熔融共缩聚反应合成了具有一定热塑性、可生物降解的弹性体（tp-PGS）,并对其结构进行了表征,同时讨论了该弹性体的力学性能、亲水性能和降解性能。结果表明,tp-PGS属于一种交联网络型聚酯,具有以非晶相为软区、晶相为硬区的微观相分离结构。tp-PGS具有一定程度的热塑性,可模压成型。tp-PGS分子结构中所具有的羟基和酯基赋予其良好的生物降解性能。     

生物降解聚酯降解性能调控研究进展

综述了聚合物分子结构设计、聚合物共混改性以及复合材料配方设计等生物降解聚酯降解速率调控方法,分析了生物降解聚酯降解性能调控面临的问题并展望其前景,以期为制备具有高性能、时控性和完全降解性的生物降解聚合物材料提供理论基础。     

熔融共混工艺制备的聚(乳酸)弹性体共混体及其表征

<正>研究可生物降解聚合物的理由很多。上涨的油价和环境问题迫使很多研究人员用生物基聚合物开发容易降解的材料。近十年来,潜在自然资源的探索与合成一直是令人感兴趣的课题。有2类可生物降解聚合物:(1)农业聚合物(多糖、蛋白质等);(2)聚酯(芳香族和脂肪族聚酯)。脂肪族聚酯由于其性能,所以无论是均聚物还是共聚物都具有用作可生物降解聚合物的潜力。     

生物可降解聚丁二酸乙二醇酯的合成与降解性能研究

以丁二酸和乙二醇为原料,直接熔融聚合,合成了高相对分子量的聚丁二酸乙二醇酯(PES),用FTIR,1H-NMR表征其结构;考察了不同聚酯反应催化剂对其聚合反应的影响,结果表明:三氧化二锑的催化效果是最佳的。同时,利用酶降解和体外水解的方法,对聚合物降解性能进行研究,结果表明:PES是一种可生物降解的聚合物,且在体外具有一定的降解性。     

生物可降解材料——聚乳酸的研究进展

聚乳酸具有良好的生物相容性、降解性和可吸收性,已经广泛用于医药包覆、缓释药物、手术缝合线、骨折固定材料。综述了聚乳酸的主要合成方法,以及通过与其它材料的复合,改进聚乳酸的结构及性能,以进一步扩大应用范围。     

低毒金属配合物催化丙交酯开环聚合研究进展

可生物降解材料聚丙交酯主要通过丙交酯开环聚合反应制备,金属配合物催化剂由于具有结构易调变、催化活性高和立体选择性等优点,成为丙交酯开环聚合反应中应用最多的催化剂。近年来,低毒金属配合物催化剂引起了人们的极大关注。本文详细评述了低毒锂、钠、钾、钙、镁和锌配合物催化剂的最新研究进展,重点阐述了配体类型、配体上不同取代基的结构、电子效应对催化剂催化性能的影响,分析了溶剂对配合物在溶液中的状态以及对单体的配位、插入和聚合反应的影响。本文还对该领域发展趋势进行了展望,随着对低毒金属配合物催化丙交酯开环聚合机理研究的深入,未来将从配体结构设计出发,开发催化活性更高、性能更好的配合物催化剂,进而制得高质量的聚丙交酯。     

Synthesis of ultrafine fibers from L- and D,L-isomers of polylactide by electrospinning

This paper is devoted to study of the process of electrospinning fiber materials based on biodegradable and biocompatible polylactides in L and D,L isomer forms. We assess the effect of the rheological properties of the polymer solutions on the course of the process and we establish the optimal synthesis parameters and conditions for obtaining microfiber materials. We examine the effect of the properties of the polymer solution and technological characteristics of the spinning process on the structure and functional properties of material made from polylactide. Therapeutic drugs are incorporated into the fiber structure.     

可生物降解聚乳酸纳米复合材料的研究进展

聚乳酸具有良好的机械性能、热塑性、生物相容性和生物降解性等,广泛应用于可控释材料、生物医用材料、组织工程材料、合成纤维等领域.将填充剂以纳米尺度分散在聚乳酸基体中形成聚乳酸纳米复合材料,能显著提高聚乳酸的机械性、气体阻隔性能、热性能及生物降解性能,受到国内外学者及工业界的广泛关注.本文针对近年来在聚乳酸纳米复合材料的制备方法、结构表征与性能测试等方面取得的研究成果进行综述,并对今后的研究方向进行了展望.     

生物降解塑料研究开发中的几个问题

列举了一些数据说明不同的微生物分解的高分子材料不同,这就为合成生物降解塑料提供了分子设计的依据。介绍了聚乳酸、PCL及Bionolle等较有发展前途的脂肪族聚酯。     

PBAT/PLA/cellulose nanocrystals biocomposites compatibilized with polyethylene grafted maleic anhydride (PE-g-MA)

The use of biodegradable polymers has grown exponentially due to their lower environmental impact when compared to conventional polymers. In this sense, biocomposites are an alternative due to their promising properties, maintaining biodegradability. For this purpose, in the present study, a biodegradable biocomposite of PBAT (poly [butylene adipate co-terephthalate]) and PLA (polylactide) blend containing cellulose nanocrystals (CNC) were obtained, using polyethylene grafted with maleic anhydride (PE-g-MA) as a coupling agent. Seven formulations were produced by extrusion and had their structure, morphology, thermal, and rheological properties analyzed. The results showed a significant improvement of adhesion among the components using PE-g-MA as a coupling agent. Moreover, CNC and PE-g-MA increased the PLA crystallinity degree and reduced the complex viscosity. These results are unprecedented in the literature using these compositions and extrusion processing conditions. Therefore, these new insights provide a vast horizon for the use of biodegradable mixtures using PBAT/PLA and CNC.     

Relationship between structure and rheological,mechanical and thermal properties of polylactide/Cloisite 30B nanocomposites

Melt‐state and solid state mechanical properties and thermal stability of polylactide layered silicate nanocomposites elaborated by melt intercalation were studied as a function of clay content. Wide angle X‐ray scattering results, transmission electron microscopy observations, and rheological measurements indicated that the clay was finely distributed in the polylactide matrix. Contrary to nonlinear mechanical properties, thermal and linear mechanical properties were shown to increase with increasing clay fraction. The nanoindentation measurements confirm the significant increase of linear mechanical properties previously observed by tensile tests. The good correlation of linear mechanical properties at the macrometric and nanometric scales is explained by the high dispersion degree of the nanofiller in the biodegradable polymer matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermal properties and characterization of surface-treated RSF-reinforced polylactide composites

The thermal, mechanical, and biodegradation properties of composite materials made from polylactide (PLA) and rice straw fibre (RSF) were evaluated. To improve the properties of PLA/RSF composites, glycidyl methacrylate (GMA)-grafted polylactide (PLA-g-GMA) and treated (crosslinked) rice straw fibre (TRSF) were used to prepare the composites. The result showed that PLA-g-GMA/TRSF had noticeably superior mechanical properties compared with PLA/RSF because of greater compatibility between the polymer and TRSF. The dispersion of TRSF in the PLA-g-GMA matrix was more homogeneous, because branched and crosslinked macromolecules formed via condensation of the glycidyl methacrylate groups of PLA-g-GMA and the hydroxyl groups in TRSF. In addition, the PLA-g-GMA/TRSF composites were more easily processed because of their lower melt viscosities. The water resistance of PLA-g-GMA/TRSF was higher than that of PLA/RSF, although the weight loss of composites buried in soil compost indicated that both were biodegradable, especially at high levels of RSF substitution. The PLA/RSF and PLA-g-GMA/TRSF composites were more biodegradable than was pure PLA.     

聚乳酸及其共聚物合成催化体系研究进展

综述了聚乳酸及其共聚物合成中催化体系的性能和催化效果以及催化体系对聚乳酸结构和性能的影响,探讨了聚乳酸合成的催化机理,并对聚乳酸合成中应用的催化体系的发展趋势进行了展望。     

Plasticizing polylactide—the effect of different plasticizers on the mechanical properties

Poly(lactide) (PLA), a biodegradable aliphatic polyester with excellent property profiles for different polymer applications, will play a major role in future markets for biodegradable polymers from renewable resources. PLA is a very brittle and stiff polymer with a glass transition temperature of around 58°C. The mechanical properties of PLA are comparable to those of polystyrene, with an elasticity modulus of 3500 MPa, a maximum tensile strength of 50 MPa, and an elongation at break of 4%. To introduce PLA into other applications requiring other mechanical property profiles, especially higher flexibility and higher impact resistance, it is necessary to use plasticizers. In this study the influence of several biocompatible plasticizer systems on the mechanical properties of PLA is determined. Poly(ethylene glycol), glucosemonoesters and partial fatty acid esters are introduced at 2.5, 5, and 10 wt% into polylactide. The mechanical properties, such as impact strength and the stress-strain-interrelationship of tensile tests, show changes, which are discussed.