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《高分子学报》2020,(9)
从淀粉的微观结构、加工过程中的相变及淀粉改性等基础理论出发,针对淀粉基材料存在的机械性能较低,对水敏感性高等缺陷,以及发泡材料制备的特点,介绍了最新的基础研究和应用研究成果.本文从淀粉基全天然高分子复合材料、纳米复合材料、自增强复合材料及功能性复合材料四个方面介绍了通过共混与复合制备淀粉基可生物降解材料,并且介绍了淀粉基材料防水改性的相关进展.指出使用可再生的天然高分子材料对淀粉进行改性,不仅能够提高材料的各种性能,而且由于所有组分都来源于天然材料,制备出的共混、复合和涂层材料也都环保安全,甚至可以用来制备可食用包装,为研制新型淀粉基材料提供有力的理论和技术支持.另外,目前对水在淀粉基发泡材料中如何同时担任增塑剂和发泡剂的机理研究取得突破性进展,发现并控制了泡孔结构由闭孔到开孔的转换临界点,研制并产业化了全淀粉发泡材料.基于上述讨论,指出淀粉基可生物降解材料既有机遇,同时也面临挑战. 相似文献
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完全降解聚乳酸共混复合材料的研究进展 总被引:1,自引:0,他引:1
聚乳酸(PLA)是可完全生物降解的材料,广泛应用于包装、纺织、生物医用等领域。但其具有性脆,价格较高,疏水性大等缺点,限制了应用发展。近年来对聚乳酸共混改性已成为研究热点。根据共混组分的生物降解性,聚乳酸共混体系分为完全生物降解体系和部分生物降解体系。文中综述了近年来完全生物降解聚乳酸共混体系的研究,主要阐述了PLA/淀粉、PLA/天然纤维复合材料,并简要介绍了PLA/甲壳素、PLA/蛋白等PLA/天然高分子复合材料,以及PLA/PCL、PLA/PPC、PLA/PEO等PLA/合成高分子复合材料。 相似文献
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综述了天然纤维、合成纤维以及无机纤维增强聚乳酸(PLA)复合材料性能及研究进展,天然纤维包括麦秆纤维、菠萝叶纤维、竹纤维和蔗渣纤维等,合成纤维包括粘胶纤维、微纤化纤维素等,无机纤维中的玄武岩纤维和碳纤维,还比较了多种纤维增强PLA复合材料的力学性能。同时,对比了物理改性、化学改性以及增塑改性三种不同方法,对常用到的电晕处理、碱处理、偶联剂处理以及新型的等离子体处理、热蒸汽处理等对复合材料的影响作简要的阐述。最后,展望新型改性方法和生产技术的出现,以获得性能更优的绿色材料。 相似文献
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Lignocellulosic fibers, such as henequen, sisal, coconut fiber (coir), jute, palm and bamboo, have been used as reinforcement materials for different thermosetting and thermoplastic resins because of their attractive physical and mechanical properties. Unlike the traditional engineering fibers, e.g. glass and carbon fibers, and mineral fillers, these lignocellulosic fibers are able to impart certain benefits such as low density, less machine wear, no health hazards, and a high degree of flexibility to the composite. The last attribute is especially true because these lignocellulosic fibers will bend rather than fracture, like glass fibers do, during processing of the composite. The mechanical properties and fracture behavior of a natural fiber reinforced polymer composite depend, not only on the properties of constituents, but also on the properties of the region surrounding the fiber, known as the interphase, where the stress transfer takes place. Moreover, the tailoring of the interphase by means of surface treatments, and carefully characterizing it, gives a better understanding of the performance of natural-fiber reinforced composites. The fracture toughness resulting from the use of natural fibers as reinforcing materials is quite different between ductile and brittle polymers, as well as between quasi-static and impact loading rates. The aim of this paper is to study the effect of the interphase properties, resulting from well controlled surface treatment of the natural fibers, on the behavior of a ductile polymer matrix composite under quasi-static loading using the essential work of fracture criteria. Specifically, the contribution of each of the different fiber-matrix interfacial adhesion levels towards the dissipation energy were analyzed and discussed. In the case of the plastic work βwp, there seems to be a synergy between the frictional and chemical interactions observed for both, low and high strain rates. The nonlinear mechanical behavior of the natural fiber under combined tensile-shear loads has also an effect on the fracture behavior of the composite. Additionally, different fiber surface treatments change the microstructural nature of the natural fiber, further affecting its behavior, particularly under high loading rates. 相似文献
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近年来,随着材料科学领域的发展,机械性能优异且具有特定功能的有机-无机复合材料成为了研究热点。而天然的生物矿化过程产生了在自然界中分布广泛、结构特征多样性、机械性能优异的天然生物矿物,比如牙齿、骨骼、珍珠、贝壳、海胆刺、海洋红虫颚等。这些天然复合增强材料中的矿化组织结构特点和矿化机理为仿生设计与合成具有特定结构、特定功能和优异机械性能的材料提供了理论依据。通过模拟天然过程的仿生矿化方法,利用有机基质调控无机矿物成核生长为固态矿物,最终能够定向组装具有特定有序结构和先进功能的有机-无机复合材料。本文主要综述了自然界中通过生物矿化过程得到的高强度、高韧性的天然复合增强材料,以及受生物矿化增强现象的启发,在化学与材料仿生矿化合成中出现的一些有机-无机复合的增强材料。 相似文献
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P. Vimalanathan S. P. Srinivasan V. Santhanam M. Rajesh 《International Journal of Polymer Analysis and Characterization》2018,23(2):99-112
Nowadays, the awareness of the public along with strict legitimate forces over the use of polymers, the manufacturing and automotive industries started using the renewable materials. Since, natural fiber reinforced composites play vital role in developing lightweight structural materials, this study focuses on utilizing sisal fiber as reinforcement in polyester matrix along with natural filler. The influence of fiber length and fiber volume fraction on the mechanical properties of sisal fiber was studied initially. Test results revealed that the composite with 20?mm fiber length and 20-volume fraction composite has better mechanical properties. Furthermore, the effect of fiber surface modification has been analyzed using various chemical solutions such as NaOH, KMnO4, stearic acid, and maleic acid. Of these, NaOH treatment enhances the mechanical properties of composite compared to all other cases. Finally, the influence of Acacia nilotica, a natural filler addition into the alkali-treated sisal fiber composite has been evaluated by mechanical and dynamic mechanical properties. It is found that the addition of natural filler and surface treatment has enhanced the properties of composites due to their synergetic effect. This effect improves the adhesion and uniform stress transfer among the reinforcements. The fiber surface morphology was evaluated using micrographs obtained from scanning electron microscope. 相似文献
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The commingled technology is one of the most effective and alternative methodologies for producing more sustainable as well as uniformly distributed natural fiber reinforced composite without inflecting the shearing strength on yarns or reinforcing natural fiber. The term commingled encompasses the materials consisting of both polymer matrix and reinforcing materials over the same fabric cross-section used for the production of highly flexible, continuous fiber-reinforced thermoplastic prepregs. Nonetheless, the increased pathlength and high melt viscosity around 500–5000 Pa s of the molten thermoplastic makes the processing more difficult compared with other thermoset plastic (usually 100 Pa s). Where the commingled hybrid yarns can be considered as one of the promising preforms employed for long fiber reinforced composite because of low cost, ease of storage and manipulation, excellent flexibility, molding capacity, reduced pressure consolidation as well as impregnation time while processing and the ability to form complex-shaped reinforced composite parts. The parameters that affect the process of commingling controls the consolidation of hybrid yarns thermoplastic composite; the degree of commingling depends on the pressure, temperature, and production speed during a fixed period. Recently commingled thermoplastic composite has become one of the possible destines for a wide array of applications in aircrafts, automotive, and sporting goods. This paper reviews types of commingled plastic composite, various processing routes, and the influence of the processing parameters, their properties, and their application. The manufacturing and development of hybrid yarns through air-jet texturing, intermingling process, are also discussed concerning the attributes of advanced composites. 相似文献
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《Surface and interface analysis : SIA》2018,50(1):111-116
The effects of polypyrrole coatings on the tensile and tribological properties of bamboo fiber reinforced polyamide 6 (PA6) composites were studied. Tribological tests were conducted using a block‐on‐ring arrangement. It was observed that the polypyrrole coatings played a main role in the tensile‐resistant and wear‐resistant properties of the PA6 composites. The tensile properties were ruled by the fiber‐matrix adhesion. And the excellent tribological performance of the fillers improved the tribological properties of PA6 composites. The optimum content of polypyrrole coating concentration is 7vol%. 相似文献
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Md. Rafiquzzaman Md. Maksudul Islam Md. Habibur Rahman Md. Saniat Talukdar Md. Nahid Hasan 《先进技术聚合物》2016,27(10):1308-1316
The natural fibers such as jute, coir, hemp, sisal etc. are randomly used as reinforcements for composite materials because of its various advantages such as low cost, low densities, low energy consumption over conventional fibers. In addition, they are renewable as well as biodegradable, and indeed wide varieties of fibers are locally available. In this study, glass–jute fiber reinforced polymer composite is fabricated, and the mechanical properties such as tensile, flexural and impact behavior are investigated. The materials selected for the studies were jute fiber and glass fiber as the reinforcement and epoxy resin as the matrix. The hand lay‐out technique was used to fabricate these composites. Fractured surface were comprehensively examined in scanning electron microscope (SEM) to determine the microscopic fracture mode. A numerical procedure based on the finite element method was then applied to evaluate the overall behavior of this composite using the experimentally applied load. Results showed that by incorporating the optimum amount of jute fibers, the overall strength of glass fiber reinforced composite can be increased and cost saving of more than 30% can be achieved. It can thus be inferred that jute fiber can be a very potential candidate in making of composites, especially for partial replacement of high‐cost glass fibers for low load bearing applications. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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Samson Rwawiire Blanka Tomkova Jiri Militky Bandu Madhukar Kale Petr Prucha 《International Journal of Polymer Analysis and Characterization》2015,20(2):160-171
The quest for sustainable materials as a consequence of a global drive to mitigate climate change has led to a focus on natural fiber–reinforced composite materials. In this study, skillful ply angle arrangement of bark cloth–reinforced laminar epoxy composites was carried out for the first time using vacuum-assisted resin transfer molding, and the composites fabricated were characterized for the effect of the layering pattern on their static and dynamic mechanical properties. Tensile strength and flexural strength were shown to be dependent on the ply angle arrangement. Dynamic mechanical analysis of the composites showed a glass transition temperature of 70°C, and the storage modulus and mechanical damping properties showed that the developed composites can withstand considerable loads and have excellent fiber-to-matrix adhesion. 相似文献
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Selecting the best brake friction composite composition amongst a set of natural fibres reinforced composites using hybrid optimization method - ELECTRE (elimination and choice translating priority) II - entropy is discussed in this article. Three sets of natural fibres containing different amounts of banana, hemp, and pineapple reinforced brake friction composites were tested according to IS 2742 (part-4) regulations on a chase friction testing machine. The experimental results have been discussed in terms of seven performance defining attributes such as coefficient of friction, fade, wear, friction stability coefficient, friction recovery, friction fluctuations, and friction variability coefficient. The composite containing 5 wt% pineapple fiber exhibit the highest coefficient of friction, whereas wear performance and friction stability remain highest for 5 wt% hemp fiber based composites. The recovery performance remains highest for the composite containing 15 wt% banana fiber, while fade, friction variability, and fluctuations remain lowest for 10 wt% banana fiber reinforced composites. The tribological results indicate that the inclusion of disparate natural fibers in varying amounts may differently affect the tribological performances and therefore to choose the best brake friction composite satisfying the maximum beneficial criteria hybrid ELECTRE II- entropy optimization technique is used. Brake friction composite containing ~10 wt% banana fibers was ranked first, in meeting the desired performance tribological properties. A comparison of this optimization approach with other multi-criteria decision-making techniques is also made for validating the performance ranking of these composites. 相似文献
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V. P. Kommula Mukul Shukla Tshilidzi Marwala A. Varada Rajulu 《International Journal of Polymer Analysis and Characterization》2014,19(8):693-708
Napier grass fiber strands were used as reinforcement to obtain composites with epoxy resin as matrix. To improve the surface, these fiber strands were treated with alkali solution. The composites were prepared by means of hand lay-up molding, then the effects of Napier grass fiber strand loading on mechanical properties such as tensile, flexural and impact, interfacial bonding, and chemical resistance were investigated. The composite with 20 wt.% Napier grass fiber strands gives excellent mechanical properties and chemical resistance, showing that it has the best bonding and adhesion of the composites. SEM micrographs of fractured and worn surfaces clearly demonstrate the interfacial adhesion between fiber and matrix. Alkali-treated Napier grass fiber strand–reinforced composites have better resistance to water and chemicals than the untreated fiber strand composites. 相似文献
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The mechanical properties and dynamic behavior of thermoplastic composites based on polypropylene/glass fibers and polypropylene/natural fibers (i.e. kenaf, hemp, flax) are presented. A survey is given on some aspects, crucial for the use of these composites in structural and non-structural components such as their vibration-damping response, in relation to the composite compaction level and the manufacturing procedure. In order to investigate a wide vibration frequency range, including acoustic frequencies, different testing techniques, both with forced and free vibrations, were applied. A comparison between natural fiber and glass fiber reinforced laminates is presented. Compaction levels, allowing to obtain the best compromise between mechanical performance and damping response, are investigated. 相似文献