改性淀粉/PVA生物降解材料性能的研究

以BPO为引发剂、正庚烷为溶剂在66℃下制得马来酸酐接枝淀粉。将其与聚乙烯醇(PVA)、增塑剂及加工助剂等于HAAKE密炼机中共混,制备了可生物降解热塑性淀粉塑料。研究了接枝改性淀：粉／PVA共混物的力学性能、生物降解性能及热性能等,并用SEM研究了共混物的微观形态。结果表明接枝改性淀粉／PVA共混物拉伸强度为27．57Mpa,60d失重率达65．1％。     

淀粉基生物降解聚合物

本文阐述了生物降解聚合物的降解机理、淀粉基生物降解聚合物的制造、淀粉基生物崩解型和完全生物降解型聚合物的研究现状和发展趋势。     

淀粉-醋酸乙酯-甲基丙烯酸甲酯接枝共聚物的合成及生物降解研究

用硝酸铈铵为引发剂,合成了淀粉 醋酸乙烯酯 甲基丙烯酸甲酯接枝共聚物,用质子核磁共振谱研究了接枝支链的化学组成,用Ｘ 射线粉末衍射研究了接枝共聚物的结晶结构变化,分别用实验室酶分解法和室外土壤掩埋法测定了接枝共聚物的生物降解性能,结果说明,仅接枝共聚物中的淀粉部分能被微生物降解,接枝支链部分不能被降解．     

淀粉与聚丁二酸己二醇酯的反应及其生物降解性研究

合成了一种新型的完全生物降解型材料－淀粉－聚丁己二醇酯共聚物，对影响聚丁二酸己二醇酯的分子量及淀粉与聚丁二酸己二醇酯反应接枝率的主要因素进行了研究，当聚丁二酸己二醇酯酰氯化物与淀粉投料重量比为４：１时，聚酯的接枝率达到３８．２０％，接枝共聚物用枯草芽孢杆菌和金黄色葡萄球菌降解４０ｄ，其失重率达８９．６０％，在土壤中堆埋９０ｄ，接枝共聚物基本完全被降解。     

化学改性淀粉的研究进展

综述了化学改性淀粉的研制及应用现状,评价了各种改性淀粉的应用性能并预测了其今后的发展趋势.     

可生物降解高分子的酶法合成和改性

介绍了新型功能高分子材料－可生物降解高分子材料的研究概况，并重点评述了这一领域研究的新分支－酶法合成可生物降解高分子材料的新进展。     

淀粉基高分子材料的研究进展

概述了近5年国内外在淀粉的化学、物理改性及其作为一种材料使用方面取得的最新研究进展.淀粉的化学改性主要介绍了淀粉的酯化、醚化、氧化、交联、接枝共聚等,而物理改性主要介绍了淀粉分别与黏土、脂肪族聚酯、聚乙烯醇以及纤维素等天然大分子的共混改性,同时还介绍了通过酸化制备淀粉纳米晶.淀粉基材料除了用于制备可生物降解塑料、吸附材...     

淀粉衍生物的研究及应用

简要介绍了淀粉的结构和特点,以及物理改性、化学改性和酶法改性的基本原理,着重介绍了化学改性的基本原理,详细介绍了氧化淀粉、醚化淀粉和酯化淀粉的制备及应用,并对淀粉衍生物的研究方向作了展望,认为复合改性淀粉是未来淀粉化学品的发展趋势。淀粉衍生物可广泛应用于食品、纺织、造纸、医药等众多领域,具有广阔的发展前景。     

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。     

改性淀粉/聚乳酸共混体系增容方法的研究

研究了聚乳酸和改性淀粉共混挤出前的固相酯化反应对共混体系的增容作用。比较挤出样条经二氯甲烷抽提后剩余物的固体13C-NMR光谱谱图,发现未经酯化反应时剩余物为淀粉,经酯化反应后剩余物的固体13C-NMR光谱谱图在20ppm和170ppm处出现聚乳酸特征的碳吸收峰,说明剩余物中含有聚乳酸和淀粉的接枝物。由共混物中聚乳酸的端羧基含量的测定结果也能说明酯化反应后共混物剩余物中含有聚乳酸和淀粉的接枝物。考察了生成的接枝物对共混体系相容性的影响,扫描电镜分析结果表明,经过预处理酯化反应后共混物相容性得到了提高。挤出样条取向拉伸后进行力学性能测试,发现酯化反应明显提高了力学性能。该方法可以通过设计共混挤出过程实现改变共混物相容性的目的,具有广阔的前景和很强的应用价值。     

高分子材料生物降解性能的分析研究进展

本文介绍了近年来生物降解材料降解方法的研究现状,主要从不同的降解环境,包括在堆肥环境、水性环境、惰性固体介质环境等进行的材料生物降解性能研究进行了比较、评述与展望。     

Synthesis, thermal properties, and biodegradability of propyl-etherified starch

High amylose corn starch (HACS) was etherified with 1-bromopropane in dimethyl sulfoxide. The structure of the products was characterized by infra-red and ¹H-NMR spectroscopy. The degree of substitution (DS) on glucose unit calculated from ¹H-NMR spectrum was varied from 0.9 to 2.7 by changing feed ratio of 1-bromopropane to HACS. Thermogravimetric analysis reveals that the etherified HACS has a higher decomposition temperature than unmodified HACS. Differential scanning calorimetry analysis reveals that the etherified starch has a clear glass transition temperature which decreased with increasing DS, and that no melting point is observed. This result demonstrates that the etherified HACS mainly consists of amorphous region. The biodegradation rate decreases with increasing degree of etherification.     

Studies on the properties and characteristics of starch-LDPE blend films using cross-linked, glycerol modified, cross-linked and glycerol modified starch

Corn starch was modified by cross-linking with epichlorohydrin and plasticizer glycerol. X-ray diffraction studies showed that relative crystallinity of the native and cross-linked starch were similar and were not affected by cross-linking. Different films were prepared by blending corn starch, cross-linked starch or glycerol modified starch in LDPE. The mechanical properties of the films were studied for tensile strength, elongation, melt flow index, and burst strength. The properties of the blend films were compared with LDPE films. It was observed that with the blending of 7.5% native starch, there was a decrease in tensile strength, elongation and melt flow index but burst strength increased. The tensile strength, elongation and melt flow index of the films containing cross-linked starch was considerably higher than those containing native starch but the burst strength showed a reverse trend. For native starch and cross-linked starch modified with glycerol, the elongation and melt flow index of the films increased but burst strength decreased. Surface scanning of the blend films were done by scanning electron microscope. Film containing cross-linked starch/glycerol modified starch in the blend was observed to be smoother than the native starch blend films.     

Structural and mechanical properties of edible films from composite mixtures of starch,dextrin and different types of chemically modified starch

Abstract

Recent regulations restricting the use of one-use-plastics open the possibility to develop starch-based edible packaging material. The objective of this work was to determine the effect of three different modified starches on starch and dextrin composite edible films by a mixture design approach on edible films’ mechanical properties. The amylose content of chemically modified starches influenced their swelling capacities, where higher amylose content was inversely related to water-power uptake and directly related to film thickness. CMS3 Nifrastarch-TS edible films, with higher amylose content, presented higher puncture force and tensile strength, but lower puncture deformation and elongation, related to a less smooth surface, according to atomic force micrographs. The use of CMS1 Gelamil-100, with lower amylose content, decreased stiffness but increased films’ stretching, presenting higher surface smoothness film topography. The use of commercial chemical modified starches in combination with starch and dextrin will allow to control of edible film thickness and hence, mechanical properties, depending on food covering necessities.     

Novel investigation based on cationic modified starch with residual anionic polymer for enhanced oil recovery

Cationic modified starch polymer (CMSP) is a newly developed green chemical agent designed to reutilize the residual anionic polymer found in reservoirs for enhanced oil recovery (EOR). In this study, a series of experiments were conducted to investigate the phase behavior of the residual anionic polymer, CMSP solution, and the flocculation generated from the mixture in plugging capacity and capability of enhancing oil recovery in heterogeneous reservoirs. The experiment results show that the phase behavior of the residual anionic polymer and CMSP solution could be divided into two parts: rapid flocculation reaction and dispersion reaction. The main mechanisms of the rapid flocculation reaction were charge neutralization and bridging. Based on the above results, an optimal amount of CMSP was chosen for plugging capacity, stability, and EOR study. Plugging tests in both parallel cores and EOR in three-layer heterogeneous square cores illustrate that the injected CMSP slug after polymer flooding can effectively block the high-permeability zone and initiate the remaining oil in middle- to low-permeability zones. The investigation results prove that the CMSP solution, injected after polymer flooding, reduces the pollution of produced fluid and further improves oil recovery.     

Improving polylactide/starch biocomposites by grafting polylactide with acrylic acid--characterization and biodegradability assessment

In this article, the properties of a polylactide and starch composite (PLA/starch) and an acrylic acid grafted polylactide and starch composite (PLA-g-AA/starch) were compared. The composite containing PLA-g-AA was found to have much better dispersion and homogeneity of starch in the polymer matrix than the composite containing PLA, indicating better compatibility between the two phases. Better mechanical and thermal properties of the PLA-g-AA/starch composite, notably an increase in tensile strength and elongation at breakpoint, evidenced its superiority to the PLA/starch composite. Furthermore, the lower viscosity of PLA-g-AA/starch makes it easier to process than PLA/starch. Weight loss on exposure to a soil environment over a period of three months showed that the starch in the composites was almost completely biodegradable, even at a high degree of substitution (60 wt.-% starch). After three months in soil, a reduction in the mechanical properties of the blends was observed, especially in those with higher starch contents.     

Anaerobic toxicity and biodegradability of hydrolysis products of chemical warfare agents

The toxicity and biodegradability of the main hydrolysis products of chemical warfare agents were investigated under methanogenic conditions. Among the tested substances, only MPhA does not have any toxic effect with regard to the aceticlastic methanogenic activity. The toxicity of other compounds varied between moderate (TDG, mercaptoethanol) to strong (ethanolamine, diisobutyl ester of MPhA). Biodegradability tests showed that all the products of chemical detoxification of mustard gas (ethanolamine, ethylene glycol, TDG, mercaptoethanol) can be biomineralized under methanogenic conditions. On the contrary, phosphorus-containing compounds from the chemical detoxification of nerve warfare agents (Sarin, Soman, V_x-gases) are quite persistent under these conditions.     

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.     

热塑性淀粉/PBS共混物的微生物降解性研究

以甘油作为增塑剂,采用玉米淀粉与改性后的聚丁二酸丁二醇酯(PBS)熔融共混制备出淀粉/PBS共混材料.对这种改善了两相相容性的共混材料在特定微生物条件下的降解行为进行了研究.结果显示,共混物降解28天后,含有30%PBS的共混物质量损失达到35%左右,其力学性能只有降解前的20%,甘油含量减小和PBS含量增加均能减缓材料的降解.且随着降解时间的延长,PBS的结晶度和熔点有所提高.     

Chemically modified electrodes for the determination of sulphydryl compounds

Under neutral conditions, the electrocatalytic oxidation of sulphydryl compounds at rotating graphite electrodes modified with tetracyano-p-quinodimethane, tetrathiafulvalene and 1,1′-dimethylferrocene proceeds at potentials higher than ?0.1 V vs. SCE. The sensitivity of the electrodes depends on the nature of both the modifier and the sulphydryl compounds, and in 0.1 M potassium phosphate buffer solution (pH 7) it reaches 0.16 A 1 mol^?1 cm^?2. The electrode sensitivity is higher in a weakly alkaline medium. The sensitivity is only slightly dependent on the electrode rotation speed.