Processability of Biobased Thermoset Resins and Flax Fibres Reinforcements Using Vacuum Assisted Resin Transfer Moulding

Biocomposite panels consisting of biobased thermoset resins (EP, PU, UP, and tannin) and flax fibre reinforcements were produced using the vacuum assisted resin transfer moulding process. Panels based on a conventional chemical-based resin matrix were also produced, and investigated comparatively. Rheometric analyses were performed to evaluate the suitability of these resins for liquid composite moulding. Tensile, shear, and impactbending tests have been carried out to assess the quality and mechanical performance of manufactured laminates. The impregnation quality was assessed by means of ultrasonic-C-scanning and microscopy. It turned out that the properties of the biobased composite panels made of biobased epoxy resin and a biobased UP-resin from the company Nuplex in New Zealand were onlay slightly inferior to those produced with a conventional epoxy resin. A biobased PU-resin from the company USSC in the USA developed voids during curing. A tannin-based resin containing of formaldehyde was not processable.

Mechanical properties of short carbon/glass fiber reinforced high mechanical performance epoxy resins

To research the relationship between epoxy and fiber inherent property and mechanical properties of composite,we prepared a series of composites using three kinds of high mechanical performance epoxy resins as matrices and reinforced by the same volume fraction(5%)of short carbon and glass fiber.Their mechanical properties were investigated from the perspective of chemical structure and volume shrinkage ratio of epoxy.We analyzed their tensile strength and modulus based on the mixing rule and Halpin-Tsai eq...

Properties of a New Dental Photocurable Resin based on the Expanding Monomer and Threecomponent Photoinitiator System

The purpose of this study was to use. a three-component photoinitiation system comprising 1wt% CQ （camphorquinone）, 2wt% DMAEMA （2-（dimethylamino） ethyl meth acrylate） and 2wt% ph^2I^＋PF6^- （diphenyliodonium hexafluorophosphate） to initiate the copolymerization of the matrix resins which combine bisphenol-S-bis （3-methacrylate-2-hydroxy propyl） ether （BisS-GMA） with the expanding monomer unsaturated spiro orthoesters 2-methylene-l,4,6-tdspiro[4,4] nonane （MTOSN）, for minimizing the volumetric shrinkage that generally occurs during polymerization. It was hypothesized that MTOSN would expand volumetrically during polymerization under the three-component photoinitiator system and further reductions in volumetric shrinkage would be obtained. The performance study which consists of degree of conversion and condition of the ring-opening reactions of MTOSN, volumetric shrinkage and mechanical properties including tensile bond strength, compressive strength and Vicker＇s hardness were carried out respectively by Fourier transfer infrared, the dilatometer and the universal testing machine. The results supported that the dental composites based on the expanding monomer and three-component photoinitiator system engendered a greater decrease of volumetric shrinkage and better mechanieal properties.

Mechanical Properties of RTM-made Composite Cross-joints

Tension and shear tests are carried out on composite cross-joints, produced by resin transfer moulding (RTM), stitch-RTM and cobonding techniques separately, to investigate the influences of different production methods on their mechanical properties and their failure mechanism. It is concluded from test results that, in terms of mechanical properties, the RTM-made cross-joint holds superiority over other two, and both stitch-RTM and cobonding methods have significant adverse effects on mechanical proper- t...

Static Pull and Push Bending Properties of RTM-made TWF Composite Tee-joints

This paper deals with static pull and push bending tests on two-dimensional （2D） orthogonal EW220/5284 twill weave fabric （TWF） composite tee-joints processed with the resin transfer moulding （RTM） technique. Static pull and push bending properties are determined and failure initiation mechanism is deduced from experimental observations. The experiments show that the failure initiation load, on average, is greater for push bending than for pull bending, whereas the scatter is smaller for push bending than for pull bending. The failure mode of RTM-made tee-joints in pull bending tests can be reckoned to be characteristic of debonding of resin matrix at the interface between the triangular resin-rich zone and the curved web of tee-joint until complete separation of the curved web from the bottom plate. In contrast, as distinct from the products subject to pull bending loading, the RTM tee-joints in push bending tests experience matrix cracking and fibre fracture from outer layers to inner layers of the bottom plate until catastrophic collapse resulting from the bending. Three-dimensional finite element （FE） models are presented to simulate the load transfer path and failure initiation mechanism of RTM-made TWF composite tee-joint based on the maximum stress criterion. Good correlation between experimental and numerical results is achieved.

Thermo-mechanical properties of RTM-made carbon fibre/polyimide composite attaching collar under transient heating

This study focuses on the thermo-mechanical properties of Carbon Fibre/Polyimide Composite(CFPC)attaching collars under transient heating.The CFPC attaching collars were fabricated by a high-temperature resin transfer moulding process,and their thermo-mechanical properties under the conditions of simultaneous transient heating and bending load were investigated.The results show that the attaching collar tends to fail at 118% of the limit load.The failure mode includes the fracture of the connecting screws,local extrusion damage of the hole edges,and slight ablation damage at the outer plies.And there is no observable residual deformation in the composite attaching collar.Furthermore,considering that the material properties vary with temperature,a progressive damage model based on the sequential thermo-mechanical coupling method was established to study the failure mechanism of the attaching collar.Finally,the damage factor of the CFPC was calculated to assess the safety status of the attaching collar.The results show that the primary damage modes of the composite attaching collar are intralaminar failure,which mainly occurs at the heat insulation layer and the hole edges,and these slightly affect the structural bearing capacity.A good correlation between the experiment and FEA is obtained.The test methods and analysis models proposed contribute to the safety assessment of composite structures under transient heating.

改性纳米氮化硼对纤维金属层板的性能影响

纤维金属层板是一种由金属薄板与纤维层依次交替铺叠而成,在一定的温度与压力下粘结固化形成的一种混合复合材料。因为其中有金属与纤维两种材料,因此它既有金属的富延展性、韧性强与导热性好等优点,又具有复合材料纤维的抗疲劳、耐高强度与低密度等特点。文章以提升环氧复合材料基体的拉伸与断裂韧性性能和改善FMLs的性能,尤其是冲击与弯曲性能为主要目的,采用向FMLs环氧树脂基体中添加纳米氮化硼(h-BN)的方法,来提升纤维金属层板的力学性能。先对氮化硼材料进行一系列的球磨改性处理,分成不同含量的组分依次加入环氧树脂基体中,确定用量最好的四组,再将这四组环氧树脂复合材料基体用湿法铺层的方法铺在铝薄板与碳纤维布之间,使用硫化机固化的方式制备FMLs试件,利用水切割技术切割成标准试样,并进行冲击与弯曲测试。实验结果表明,向FMLs的环氧树脂基体中添加一定量的纳米氮化硼对FMLs的性能有着积极的影响。

常见结构材料低温性能研究进展

随着深空探测、极地科考、低温贮运等低温领域的快速发展,对低温材料的要求越来越高,低温材料逐渐成为目前国内外的研究热点。本文综述低温钢、铝合金、钛合金、铝基复合材料以及树脂基复合材料等常见结构材料的低温性能,归纳不同晶体结构、合金种类、合金元素等因素对结构材料的低温强度、塑性与韧性等力学性能的影响及低温变形和强韧化机理,介绍不同种类低温结构材料在国内外重要领域的应用,提出了低温材料未来的研究展望。

高性能纤维增强树脂基复合材料湿热老化研究进展

高性能纤维增强树脂基复合材料具有卓越的结构整体性及抗分层等特性,在诸多工业领域中具有广泛适用性。在其储藏及使用时,制件强度会不可避免地因湿热老化造成降解和退化。探讨和揭示高性能纤维增强树脂基复合材料在不同湿热老化环境下的力学响应,对其结构件的耐久性、安全服役性能和寿命预估具有至关重要的意义。综述了国内外高性能纤维增强树脂基复合材料湿热老化方面的研究进展,介绍了其吸湿机理以及在湿热环境下的老化机理。梳理了湿热老化环境对于高性能纤维增强树脂基复合材料力学性能的影响,寿命预测模型等。最后指出了高性能纤维增强树脂基复合材料老化研究存在的问题、面临的挑战,对未来研究发展方向提出了展望。

聚吡咯共轭结构对碳纤维增强树脂基复合材料热循环稳定性能的影响

为解决碳纤维增强树脂基复合材料(CFRPs)存在的碳纤维与基体间界面黏结性较弱和在热循环过程中因热膨胀系数不匹配而产生界面破坏的问题,通过低温聚合得到含有较多共轭结构的聚吡咯(PPy)对预处理后碳纤维(CF)进行表面改性,分别在0、30、60℃下制得碳纤维/聚吡咯复合纤维(PPy/CF),并研究了不同聚合温度下制备的CFRPs的界面结合性能、热膨胀性能和热循环稳定性能。结果表明:PPy/CF-0纤维的表面粗糙度与CF相比增加了2.09倍,这有利于树脂锚定在碳纤维表面,从而提高界面结合性能;并且PPy/CF-0纤维表面的聚吡咯层具有较完善的共轭结构,整体表现为负热膨胀系数,使得复合材料的层间剪切强度和界面剪切强度分别达到了CF的1.56倍和1.70倍;此外还使得CFRPs的热循环稳定性有了较明显的提升,经100次热循环实验后,其剪切强度仍能保持在初始数值的70%以上。

微胶囊型自修复环氧树脂材料的力学性能及修复效率

为了探究自修复环氧树脂微胶囊的引入对树脂基复合材料的力学性能和修复性能的影响,将由原位聚合法制得的环氧树脂微胶囊和潜伏型固化剂邻苯二甲酸酐组成的修复体系加入到E51环氧树脂和固化剂改性聚醚胺中,通过实验研究了混合体系的剪切黏度,并进一步分析了材料的力学性能和修复效率。结果表明,复合材料的力学性能随着自修复组分含量的升高而降低,复合材料的修复效率随着自修复组分含量的升高与而升高,但修复后复合材料的抗拉强度并不是随着自修复组分含量的升高而递增的。综合分析实验结果得出的最优选择为自修复组分的比例为3/2,含量为8%(质量分数,下同),此时复合材料的抗拉强度为15.32 MPa,断裂修复后抗拉强度10.13 MPa,修复效率66.12%。

自修复与阻燃功能一体化玄武岩纤维增强环氧树脂基复合材料的制备及性能

纤维增强环氧树脂基复合材料(FREPC)在实际应用中常因裂纹失效和燃烧破坏而受到限制。文中将自制的DA加合物(DOPO-FU-BMI)与糠胺(FA)配合,引入到环氧树脂DGEBA中,通过热压成型工艺制备了兼具自修复和阻燃双重功能的玄武岩纤维增强环氧树脂基复合材料。结果表明,DA加合物在复合材料中实现了均匀分布,提升了材料的热稳定性和玻璃化转变温度;复合材料通过动态可逆化学键的可逆Diels-Alder(DA)反应实现了裂纹的修复,当DA加合物质量分数为20%时,经2次“冲击-修复”循环后复合材料的强度保留率仍高达92.5%;同时,复合材料发挥了玄武岩纤维的阻燃特性优势,引入DA加合物后使其阻燃性能进一步增强,极限氧指数最高可达44.5%,较未改性复合材料提升25.4%。

分层缺陷对CFRP层合板力学性能的影响

碳纤维增强树脂基复合材料(CFRP)具备高强度和高刚度,被广泛应用于航空航天和汽车等领域,然而碳纤维的分层缺陷会极大影响其力学性能。因此,研究分层缺陷对CFRP层合板拉伸、压缩、剪切和弯曲等力学性能的影响具有重大意义。采用复合成型工艺,将聚四氟乙烯片添加到复合材料中,经成型加工制备具有分层缺陷的CFRP层合板,考察了分层区域的尺寸和形貌,研究了分层缺陷对CFRP层合板力学性能的影响。研究发现,分层缺陷能显著降低CFRP层合板的压缩、剪切和弯曲强度,而且分层区域面积越大,CFRP层合板压缩和弯曲强度越小,但是分层区域面积的变化对拉伸强度影响较小。

石墨烯改性树脂材料的研究进展

讨论了石墨烯作为增强相制备石墨烯/树脂材料(graphene/resin materials,简称GR)的方法,分析不同制备工艺的特点。系统阐述了石墨烯改性树脂材料在力学、耐热、导电和耐摩擦等性能上的研究现状,分析了添加石墨烯对树脂材料性能产生影响的规律和机理。结果表明:添加少量石墨烯填料可全面提高树脂材料的综合性能,得到较佳的改善效果。最后基于石墨烯/树脂材料的优异性能总结了石墨烯/树脂材料的应用前景和未来着重探索的方向。

不同β树脂含量的沥青中间相炭微球的形态及其成型性能研究

通过控制吡啶的抽提次数得到一系列不同 β树脂含量的沥青中间相炭微球 ,并在SEM下观察其微观形态 ,结果表明随着抽提次数的增加 ,β树脂含量越来越低 ,并且微球分散越均匀。用这样得到的中间相炭微球在一定条件下热压成型制得各向同性炭块 ,生坯的弯曲强度随着 β树脂含量的降低也逐渐降低 ,但炭化后炭块的弯曲强度随 β树脂含量有一个极大值 ,说明要取得性能良好的整体炭块 ,需要有一个最佳的β树脂含量。

树脂基复合材料/泡沫塑料夹层结构成型技术研究进展

总结归纳了树脂基复合材料 /泡沫塑料夹层结构的五种典型成型工艺方法 ,并对其部分成型工艺的特点。

一种适用于树脂传递模塑工艺的双马来酰亚胺改性酚醛树脂

合成了一种双马来酰亚胺改性酚醛树脂 ,研究了加工性能 ,固化树脂的力学性能和耐热性。应用一种高温固化剂于该树脂体系中 ,并探讨了它对树脂性能的影响。制备了这类树脂与玻璃布的复合材料 ,评价了不同温度下的力学性能。结果表明 ,改性树脂具有适用于RTM工艺的良好加工性能。高温固化剂的使用能较大幅度地提高树脂的耐热性。在 30 0℃下 ,复合材料的弯曲强度和模量保持率分别为 73%和 83%。

耐高温聚酰亚胺材料研究进展

综述了耐371℃及以上高温聚酰亚胺材料的国内外研究现状与发展趋势,着重对以PMR-Ⅱ树脂为基础的聚酰亚胺材料的化学结构设计与制备方法,以及化学结构与综合性能之间的关系进行介绍。

RTM工艺及其在我国航空工业的应用前景

本文介绍了树脂传递模塑即ＲＴＭ工艺方法及其特点，并将其与手糊和ＳＭＣ成形工艺进行了对比；概括了ＲＴＭ在国外航空工业上的应用，进而提出我国航空工业迅速发展ＲＴＭ工艺的必要性和重要性。

有机硅树脂在SiO_2基复合材料中的应用研究

SiO2基复合材料是近年来发展起来的务性能多功能透波复合材料，广泛应用于弹头的防热—透波部件。本文介绍了由硅溶胶转化的SiO2基复合材料的结构特点和存在的主要问题，利用有机硅树脂进行应用研究。讨论了有机硅树脂对SiO2基复合材料的介电、烧蚀及力学性能的影响。试验表明有机硅树脂能够有效地提高SiO2基复合材料的各项性能。