生物基全降解复合材料

淀粉/聚乳酸复合具有相对较好的力学性能和生物降解性能,价格也与石油基塑料最为接近,是极具应用前景的全生物降解塑性材料。在分析国内外聚乳酸、淀粉及其复合材料研究现状的基础上,对该类材料的技术发展方向和工业化前景进行了展望。     

食品包装淀粉基生物降解薄膜阻氧性研究

本文综述了国内外食品包装用淀粉基生物降解薄膜的研究进展,讨论了目前开发食品包装用淀粉基生物降解薄膜阻氧性能检测方法的必要性和紧迫性。     

羟基磷灰石/淀粉基复合生物材料

淀粉基(starch-based)材料是一类重要的生物降解聚合物,羟基磷灰石(HA)是人体骨骼的主要成分,以淀粉基材料为基体、以HA为增强材料的HA/淀粉基复合材料是一类新型的复合生物材料,其具有良好的生物相容性,在骨修复领域具有巨大的应用潜力.初步对该复合材料进行了归类,并介绍了其制备工艺、性能和应用等方面的研究近况,指出改进复合工艺、采用纳米级HA增强并进行表面改性是其发展趋势.     

淀粉基可生物降解塑料的研究现状

发展淀粉基可生物降解塑料有利于节省石油资源、保护环境.国内外这方面的研究较多,并且在技术的实用性方面也取得了较大进展.目前研究热点集中在3个方向:淀粉与其它可生物降解高分子的直接填充;对淀粉表面修饰使其能与合成高分子相容;在淀粉与合成高分子体系中加入增塑剂.虽然淀粉基可生物降解塑料在综合性能上还不能与合成高分子相比,但由于淀粉的综合优势,淀粉基可生物降解塑料的研究和发展极具潜力.     

热塑性淀粉基复合材料力学性能研究

热塑性淀粉(TPS)基复合材料因具有原材料绿色化、废弃后全降解的特点,成为国内外学者研究的热点。以甲酰胺、尿素、丙三醇、乙二醇作为塑化剂,制备热塑性淀粉基复合材料,通过静态压缩试验得到淀粉基复合材料的静态压缩缓冲曲线,分别研究了不同比例的单一塑化剂和复合塑化剂制备的热塑性淀粉对淀粉基复合材料静态压缩性能的影响。实验结果表明,塑化剂含量为15%时,4种单一塑化剂制备的淀粉基复合材料承压能力大小分别为:FPTPS基复合材料UPTPS基复合材料EGPTPS基复合材料GPTPS基复合材料。复合塑化剂的含量为15%时,不同质量的比甲酰胺和尿素制备的淀粉基复合材料(FUPTPS),其承压能力大小为2∶11∶11∶2;不同质量比的丙三醇和乙二醇制备的淀粉基复合材料(GGPTPS),其承压能力大小为1∶22∶11∶1。     

淀粉基可生物降解材料在食品包装中的研究进展

为了减少白色污染带来的环境伤害，可生物降解的环境友好材料是目前的研究热点。淀粉具有来源广、价格低、可再生、生物相容性高和成膜性强等优势，在食品包装领域中展现出巨大的应用前景。传统淀粉基材料在机械性能方面的不足可以通过新型制备技术或复合其他材料来改善。综述了淀粉基可生物降解材料的制备方法、用于改善性能的添加剂和在食品包装中的应用进展。最后，对淀粉基可生物降解材料的未来发展方向进行了展望。     

淀粉基可生物降解纤维的结构与性能

采用熔融纺丝法制备了淀粉基可生物降解纤维,利用差示扫描量热仪(DSC)、热分析仪(TG)以及单纤维强力仪等对纤维的热性能和力学性能进行了研究,借助数码相机以及环境扫描电子显微镜(SEM)对降解前后纤维样品的形貌特征进行了研究,通过土埋生物降解实验,研究了纤维的生物降解性能。结果表明,淀粉基可生物降解纤维具有较高的断裂强度与断裂伸长率;随生物降解时间的延长,降解率逐步增加,力学性能逐渐下降;纤维颜色逐渐变为褐色甚至黑色,纤维表面有微孔、裂缝出现,100天能达到完全降解,表明该纤维具有优异的可生物降解性。     

淀粉基生物降解发泡塑料的缓冲性能研究

通过淀粉基生物降解发泡塑料的静态压缩试验,处理得出该发泡材料的C-σ曲线,并讨论了材料中淀粉、甘油及发泡剂对缓冲性能的影响.     

全降解淀粉基塑料

近年来,基于天然大分子的生物降解性和环境友好性,引起了学术界和工业界的兴趣。淀粉的产量丰富,降解性能优异,生物降解材料中淀粉的使用占比已超过40%。然而淀粉的结构、形貌和晶型复杂多样,天然淀粉作为材料使用还面临许多挑战。本文介绍了淀粉的结构并总结了制备全降解淀粉基塑料的物理改性和化学改性方法。     

淀粉基可生物降解纤维的研究进展

淀粉基可生物降解材料已成为材料研究的热点.概述了淀粉的结构与性能,介绍了几种常见的淀粉改性方法,着重综述了淀粉纤维的研究现状,指出了目前淀粉纤维的应用领域,更为广阔的应用领域尚待开拓,研究亟待深入.最后阐明了淀粉纤维与传统的可降解高分子成纤材料的结合使用,将是淀粉基生物可降解纤维的发展方向.     

Research progress of starch-based biodegradable materials: a review

With the enhancement of global environmental protection awareness, new eco-friendly packaging materials have gained more and more attention since the new century. Starch is one of the most potential natural biodegradable materials due to its abundant source, low price, and completely degradable characteristics. Starch-based materials with excellent biodegradability can be widely used by improving their properties. This review starts with the structure of starch and summarizes its phase transition during processing related to the packaging materials. Then, we expound on the development stage of starch-based biodegradable materials and starch modification. This part focuses on the research of starch-based composites formed by starch derivatives, including nano-starch. Besides, extrusion molding and other modern molding methods are described in detail. Through the systematic elaboration of the above contents, the connection among structure, phase transition, and processing can be found, which can better broaden the application of starch-based biodegradable materials. Finally, various applications of starch-based materials and prospects for its future research are discussed. It is hoped to provide the basic theory and reference for the research of starch-based biodegradable materials.

     

氧化淀粉基复合材料的制备及力学性能

为提高淀粉基复合材料的力学性能,采用对原生淀粉进行氧化改性,通过模压发泡工艺制备了氧化淀粉基复合材料(OS复合材料)。力学测试结果表明,OS复合材料在力学性能方面有很大程度的提升,且最佳氧化比为m(淀粉)∶m(H_2O_2)=10∶1.5。此时拉伸强度为3.05 MPa,压缩强度6.724 MPa,与原生淀粉基复合材料相比分别提高21.03%、14.65%,缓冲性能最佳;其压缩强度明显优于聚苯乙烯发泡塑料(EPS),缓冲系数与EPS接近。为揭示性能变化的内在机理,通过红外光谱分析发现,氧化过程使得淀粉内部官能基团改变,形成更强的氢键,与剑麻纤维的结合更紧固;通过X射线衍射分析得到,淀粉氧化改性后,结晶度降低,内部形成更均匀的相,裸露的支链增多,其与剑麻纤维结合得更好。为探究复合材料的界面结合情况,采用扫描电镜观察,图像显示OS复合材料内部生成了较好的泡孔结构,并且其淀粉基质均匀地附着在纤维的表面,淀粉和纤维形成了很好的结合。     

Compression Behavior of Biodegradable Thermoplastic Plasticizer-Containing Composites

Strength of Materials - Thermoplastic starch-based composites generate worldwide interest as they are based on green raw materials and undergo complete degradation. The composites were first...     

淀粉基塑料购物袋性能表征研究

目的 通过对淀粉基塑料购物袋的理化性能表征,了解淀粉基塑料购物袋使用特性,为改善淀粉基塑料购物袋使用性能提供一些理论依据。方法 采用热重分析(TG)、热机械分析(TMA)等手段对淀粉基塑料购物袋的淀粉含量及耐热性能进行分析,借助电子万能材料试验机对淀粉基塑料购物袋的力学性能进行分析,以及利用霉菌培养、总迁移行为探究等方法对淀粉基塑料购物袋霉变程度、卫生性能进行分析。结果 样品A、B、C淀粉质量分数分别为15.72%、23.97%、30.36%,耐热性能比传统PE塑料袋要低;淀粉基塑料购物袋的拉伸强度随淀粉含量的增大而减小,断裂伸长率随淀粉含量的增加而增加,总迁移量结果随淀粉含量增加而增大,但经三氯甲烷处理后均低于限量要求;淀粉基塑料购物袋不适宜盛装酸性和低乙醇类食品。结论 通过对淀粉基塑料购物袋深入研究,发现淀粉基塑料购物袋在力学性能、总迁移量、霉变程度存在缺陷,望研究者们可以从这几个方向入手,改善淀粉基塑料购物袋的理化性能。     

国外可降解淀粉发泡材料最新研究进展

主要综述了国外可降解环保型淀粉发泡材料的研究现状,阐述了淀粉挤出发泡和烘焙发泡以及淀粉基聚氨酯泡沫塑料的最新研究进展.同时也概述了超临界熔体挤出法应用于淀粉发泡的最新研究成果和淀粉发泡过程的模型建立,为淀粉发泡材料的进一步工业化应用提供了一定的参考.     

Hydroxyapatite reinforcement of different starch-based polymers affects osteoblast-like cells adhesion/spreading and proliferation

The aim of this study was to determine which, from a range of the starch-based biomaterials, would be more suitable to be used in orthopaedic applications. This included blends of corn starch and ethylene vinyl alcohol (SEVA-C), corn starch and cellulose acetate (SCA), corn starch and polycaprolactone (SPCL) and its composites with increasing percentages of hydroxyapatite (HA). Osteoblast-like cells (SaOs-2) were cultured in direct contact with the polymers and composites and the effect of the incorporation and of increasing percentages of the ceramic in osteoblast adhesion/proliferation was assessed. In the evaluation of cell adhesion and proliferation rate, two variables were considered; cells adhered to the bottom of the tissue culture polystyrene wells (TCPS) and cells adhered to the surface of the materials, in order to distinguish, respectively: (i) the effect of possible degradation products released from the materials to the culture medium and (ii) the effect of the surface properties on the osteoblast-like cells. In addition, the morphology of cells adherent to the surface of the starch-based polymers was analysed and correlated with their topography and with other chemical properties previously evaluated.The proliferation rate was found to differ from blend to blend as well as with the time of culture and with the presence of HA depending on the material. SEVA-C and respective composites systematically presented the higher number of cells comparatively to the other two blends. SPCL composites were found to be less suitable for cell proliferation. The amount of cells quantified after 7 days of culture, both on the surface and on the wells showed a delay in the proliferation of the cells cultured with SPCL composites comparatively to other materials and to TCPS. SCA composites, however, did support cell adhesion but also induce a slight level of toxicity, which results in delayed proliferation on the cells adhered to the wells.Cell morphology on the surface of the materials was also, in almost every case, found to be appropriate. In fact, cells were well adhered and spread on the majority of the surfaces. Thus, starch-based biomaterials can be seen as good substrates for osteoblast-adhesion and proliferation that demonstrates their potential to be used in orthopaedic applications and as bone tissue engineering scaffolds.     

Novel starch thermoplastic/Bioglass® composites: Mechanical properties, degradation behavior and in-vitro bioactivity

The present research aims to evaluate the possibility of creating new degradable, stiff and highly bioactive composites based on a biodegradable thermoplastic starch-based polymeric blend and a Bioglass® filler. Such combination should allow for the development of bioactive and degradable composites with a great potential for a range of temporary applications. A blend of starch with ethylene–vinyl alcohol copolymer (SEVA-C) was reinforced with a 45S5 Bioglass® powder presenting a granulometric distribution between 38 and 53 m. Composites with 10 and 40 wt % of 45S5 Bioglass® were compounded by twin-screw extrusion (TSE) and subsequently injection molded under optimized conditions. The mechanical properties of the composites were evaluated by tensile testing, and their bioactivity assessed by immersion in a simulated body fluid (SBF) for different periods of time. The biodegradability of these composites was also monitored after several immersion periods in an isotonic saline solution. The tensile tests results obtained indicated that SEVA-C/Bioglass® composites present a slightly higher stiffness and strength (a modulus of 3.8 GPa and UTS of 38.6 MPa) than previously developed SEVA-C/Hydroxylapatite (HA) composites. The bioactivity of SEVA-C composites becomes relevant for 45S5 amounts of only 10 wt %. This was observed by scanning electron microscopy (SEM) and confirmed for immersion periods up to 30 days by both thin-film X-ray diffraction (TF-XRD) (where HA typical peaks are clearly observed) and induced coupled plasma emission (ICP) spectroscopy used to follow the elemental composition of the SBF as function of time. Additionally, it was observed that the composites are biodegradable being the results correlated with the correspondent materials composition.     

Flexural properties of fully biodegradable alpha-grass fibers reinforced starch-based thermoplastics

This work has the aim of study the flexural properties of alpha-grass reinforced starch-based composites. The composite materials contain alpha-fibers in the range from 5 to 35 wt%. The reinforcing fibers were submitted to an alkali treatment to create a good interphase between the fibers and the matrix. It was observed that a mild 2.5 h cooking process was enough to create a good interphase, while longer periods rendered lesser improvements. The surface charges of the fibers and the matrix were determined by polyelectrolyte titration, and it was found that after the alkaline treatment both were similar. The composite materials were injection molded and tested under flexural conditions. All the flexural properties of the studies composites increased linearly with the reinforcement contents. The micromechanics of the flexural modulus and strength were studied and compared with that of tensile modulus and strength. It was established that the efficiency factors for the tensile and flexural properties were statistically similar. Three different methods were used to compute the intrinsic flexural strength from the available data. Finally the Weibull theory was used to study the best prediction of the standard deviation of the intrinsic flexural modulus.     

The effect of starch-based biomaterials on leukocyte adhesion and activation <Emphasis Type="Italic">in vitro</Emphasis>

Leukocyte adhesion to biomaterials has long been recognised as a key element to determine their inflammatory potential. Results regarding leukocyte adhesion and activation are contradictory in some aspects of the material's effect in determining these events. It is clear that together with the wettability or hydrophilicity/hydrophobicity, the roughness of a substrate has a major effect on leukocyte adhesion. Both the chemical and physical properties of a material influence the adsorbed proteins layer which in turn determines the adhesion of cells. In this work polymorphonuclear (PMN) cells and a mixed population of monocytes/macrophages and lymphocytes (mononuclear cells) were cultured separately with a range of starch-based materials and composites with hydroxyapatite (HA). A combination of both reflected light microscopy and scanning electron microscopy (SEM) was used in order to study the leukocyte morphology. The quantification of the enzyme lactate dehydrogenase (LDH) was used to determine the number of viable cells adhered to the polymers. Cell adhesion and activation was characterised by immunocytochemistry based on the expression of several adhesion molecules, crucial in the progress of an inflammatory response. This work supports previous in vitro studies with PMN and monocytes/macrophages, which demonstrated that there are several properties of the materials that can influence and determine their biological response. From our study, monocytes/macrophages and lymphocytes adhere in similar amounts to more hydrophobic (SPCL) and to moderately hydrophilic (SEVA-C) surfaces and do not preferentially adhere to rougher substrates (SCA). Contrarily, more hydrophilic surfaces (SCA) induced higher PMN adhesion and lower activation. In addition, the hydroxyapatite reinforcement induces changes in cell behaviour for some materials but not for others. The observed response to starch-based biodegradable polymers was not significantly different from the control materials. Thus, the results reported herein indicate the low potential of the starch-based biodegradable polymers to induce inflammation especially the HA reinforced composite materials.