高分子材料的生物降解性能表征

生物降解能够使高分子材料回归自然界物质循环,被认为是解决塑料污染的一大重要途径.高分子材料的生物降解性能表征对相关材料开发、改性和产业应用十分重要.本文针对高分子材料的需氧生物降解,从降解产物和降解残留材料两个方面介绍常用表征方法 .降解产物的表征主要从CO2生成量、O2消耗量和小分子产物三方面开展,降解残留材料的表征围绕其组成结构变化和性能变化.介绍了各表征方法的简单原理和典型案例,并对未来发展进行了展望.     

医用可生物降解高分子材料

对目前医用可生物降解高分子材料的研究及应用状况分化学合成，天然和生物技术合成三类作了综述。对材料的生物相容性、可生物降解性及物理机械性能进行了分析和比较。并就医用生物降解高分子材料的发展趋势作了预测。     

聚乳酸类生物降解性高分子材料研究进展

本文综述了近年来乳酸类合成生物降解材料的合成及应用研究进展。     

PBS基生物降解材料的研究进展

PBS(聚丁二酸丁二醇酯 )是一种具有良好生物降解性的聚酯塑料。本文简述了PBS的基本特性、降解机理和制备方法 ,对各种PBS基生物降解材料的特性进行了分析 ,介绍了PBS基生物降解材料的研究进展     

应用于药物控释系统中的生物降解高分子材料

生物降解高分子材料具有良好的生物相容性和生物降解性而成为人们关注的药物控释材料。本文简要介绍了生物降解高分子材料的降解机理，综述了生物降解高分子材料的发展现状，展望了今后的发展方向。     

生物降解材料

本文介绍了生物降解材料的含义、作用机理、影响微生物降解的因素、以及生物降解材料的应用,并列举了几种主要的可生物降解的材料。     

可生物降解材料聚天冬氨酸的研究进展

综述了可生物降解材料聚天冬氨酸及其衍生物的特点及合成和结构表征，并介绍了聚天冬氨酸及其衍生物在水处理和药物控制释放等领域的研究进展。     

新型可生物降解医用高分子材料-聚膦腈

聚磷腈是一族由交替的氮、磷原子以交替的单键、双键构成无机主链的新型可生物降解聚合物。聚膦腈具有独特的性质和显著的合成多样性,降解产物为磷酸、氨、氨基酸和乙醇等无毒物质。通过改变聚膦腈侧链结构和组成,可调节聚膦腈的降解速度,控制药物释放的速度。本文主要综述了聚膦腈的合成、降解及其在药物控释系统中的应用。     

生物降解高分子/羟基磷灰石复合材料研究进展

由于高分子/HA复合材料兼具HA优良的生物性能和高分子材料良好的力学性能而受到了广泛的重视.本文综述了近年来生物降解高分子/羟基磷灰石复合材料的研究进展,介绍了胶原及其衍生物、聚酯、甲壳素及其衍生物、淀粉等可降解高分子材料与羟基磷灰石复合作为骨修复材料的研究进展,并对此类材料存在的问题和发展前景进行了讨论.     

用于基因传递系统控制释放的可生物降解高分子材料

综述了用于基因传递系统控制释放的各类高分子材料包括天然高分子及其衍生物、合成高分子,并介绍了它们在基因治疗和组织工程领域中的应用.     

改性淀粉材料生物降解性分析体系的建立及应用

测定了热塑性淀粉(TPS)和热塑性双醛淀粉(TPDAS)在堆肥条件下的生物降解能力。根据ISO 14855建立了一套新的测试体系并且验证了这个体系测定高分子材料生物降解性能的可行性。对热塑性淀粉材料生物降解性的测试结果发现化学改性对于淀粉的降解速率和降解速度都有很大的影响。在可控堆肥条件下TPS比TPDAS降解的要快。TPDAS的降解速度和最终的生物降解百分率和双醛淀粉(DAS)的氧化度有密切的关系。文中讨论了存在这种关系的可能原因。有不同降解速率的TPS和TPDAS的降解过程呈现出三个阶段,即迟滞阶段。降解阶段和平稳阶段。     

Thermal analysis techniques for characterization of polymer materials

Routine DSC and TGA techniques, used to characterise polymer thermal stability, have been further used for assessment of comparative thermal stability of various polymer materials and for prediction of material lifetimes. The following materials were investigated: (1) commercial and experimental polymer materials - results for poly(vinyl chloride) (PVC) and bisphenol A polycarbonate (PC) are presented; (2) a polydimethylsiloxane-polytetrafluoroethylene (SIL-PTFE) coating system; and (3) commercially available linear low density polyethylene (PE-LLD), unmodified and modified chemically and physically. The plot of reciprocal temperature of initial decomposition 1/T_di vs log heating rate β has been recommended for assessment of comparative thermal stability. The lifetime of polymer materials was calculated from the plots of log time-to-failure, log t_f, vs reciprocal temperature 1/T, where t_f values were obtained using T_di from TGA measurements or directly from the oxidation induction time (OIT) data as criteria for initial deterioration of polymer thermal stability. The following sequences of increasing thermal stability were found for investigated materials:

(1)

PVC ? PC;

(2)

SIL < SIL-PTFE 20% < SIL-PTFE 50% ? PTFE;

(3)

(B) PE-LLD, grafted < (A) PE-LLD, unmodified < (C) PE-LLD, filled.

The lifetime of polymer materials predicted from the plots of log t_f vs 1/T are in reasonable agreement with experimental data and users' observations, e.g. approximately 1 year for PC and unmodified PE-LLD both at 373 K (100 °C) and for PVC at temperature of outdoor conditions about 298 K (25 °C).     

A biostimulation-based accelerated method for evaluating the biodegradability of polymers

The high cost and long duration of the existing standard tests, such as ASTM D5338 and ISO 14855, represents an important drawback in evaluating the biodegradability of polymers. This works presents a new accelerated method for this purpose, based on the use of a Bartha respirometer and biostimulation with yeast extract. The new method was applied to microcrystalline cellulose (MCC), low density polyethylene (LDPE), poly(3-hidroxybutyrate) (PHB), poly(lactic acid) (PLA), poly(vinyl alcohol) (PVOH), polypropylene (PP) and poly(ethylene terephthalate) (PET). The results obtained with these polymers were consistent with those of the standard methods in terms of differentiating biodegradable and non-biodegradable polymers and relative order of biodegradation extent. Besides, a significant reduction of test duration was achieved (from 45 to 110 days with ASTM D5338 or ISO 14855 to 28 days). These results corroborate the potential of the proposed method as a fast test for assessment of biodegradation of polymeric materials.     

Optical analysis of polymer powder materials for Selective Laser Sintering

This study increases the basic understanding of optical material properties of polymer powders used in selective laser sintering (SLS). Therefore, different polymer powder materials were analyzed regarding their optical material properties with an integration spheres measurement setup. By the measurements a direct connection between the absorption behavior of the solid material and the overall optical material characteristics of the same material in powdery form could be shown. The results were used to develop an advanced explanation model for the optical material properties of powders. At present, existing explanation models only consider the occurring of multiple reflections in the gaps between the particles to explain the overall optical material properties of powder materials. Thus, by also considering the absorption behavior of the single particles, the basic understanding of the beam-matter interaction and their effect on the optical material properties of powder materials can be expanded.     

聚乳酸合成的研究现状

对生物降解可吸收材料聚乳酸的合成以及共聚改性等方面的研究现状作了综述     

聚乳酸的研究进展

本文对聚乳酸的合成、性能、共聚改性等方面的研究进展做了综述, 并讨论了聚乳酸类材料的应用现状和前景。     

Compostability of bioplastic packaging materials: an overview

Packaging waste accounted for 78.81 million tons or 31.6% of the total municipal solid waste (MSW) in 2003 in the USA, 56.3 million tons or 25% of the MSW in 2005 in Europe, and 3.3 million tons or 10% of the MSW in 2004 in Australia. Currently, in the USA the dominant method of packaging waste disposal is landfill, followed by recycling, incineration, and composting. Since landfill occupies valuable space and results in the generation of greenhouse gases and contaminants, recovery methods such as reuse, recycling and/or composting are encouraged as a way of reducing packaging waste disposal. Most of the common materials used in packaging (i.e., steel, aluminum, glass, paper, paperboard, plastics, and wood) can be efficiently recovered by recycling; however, if packaging materials are soiled with foods or other biological substances, physical recycling of these materials may be impractical. Therefore, composting some of these packaging materials is a promising way to reduce MSW. As biopolymers are developed and increasingly used in applications such as food, pharmaceutical, and consumer goods packaging, composting could become one of the prevailing methods for disposal of packaging waste provided that industry, governments, and consumers encourage and embrace this alternative. The main objective of this article is to provide an overview of the current situation of packaging compostability, to describe the main mechanisms that make a biopolymer compostable, to delineate the main methods to compost these biomaterials, and to explain the main standards for assessing compostability, and the current status of biopolymer labeling. Biopolymers such as polylactide and poly(hydroxybutyrate) are increasingly becoming available for use in food, medical, and consumer goods packaging applications. The main claims of these new biomaterials are that they are obtained from renewable resources and that they can be biodegraded in biological environments such as soil and compost. Although recycling could be energetically more favorable than composting for these materials, it may not be practical because of excessive sorting and cleaning requirements. Therefore, the main focus is to dispose them by composting. So far, there is no formal agreement between companies, governments and consumers as to how this packaging composting will take place; therefore, the main drivers for their use have been green marketing and pseudo-environmental consciousness related to high fuel prices. Packaging compostability could be an alternative for the disposal of biobased materials as long as society as a whole is willing to formally address the challenge to clearly understand the cradle-to-grave life of a compostable package, and to include these new compostable polymers in food, manure, or yard waste composting facilities.     

FRET-based polymer materials for detection of cellular microenvironments

Effective detection of cellular microenvironments and understanding of physiological activities in living cells remain a considerable challenge.In recent years,fluore scence(or Forster) resonance energy trans fe r(FRET) technology has emerged as a valuable method for real-time imaging of intracellular environment with high sensitivity,specificity and spatial resolution.Particularly,polymer-based imaging systems show enhanced stability,improved biodistribution,increased dye payloads,and amplified signal/noise ratio compared with small molecular sensors.This review summarizes the recent progress in FRET-based polymeric systems for probing the physiological environments in cells.     

UV curing polymer materials for making laser glass

Epoxy acrylate was synthesized by reacting epoxy resin with acrylic acid in the presence of quaternary ammonium salt. The effects of photoinitiators on the curing rate have been studied. UV curing polymer materials for making laser glass have been selected. The laser glass thus manufactured is a new decorative building material. Copyright © 1999 John Wiley & Sons, Ltd.