Cardo poly (ether sulfone) toughened E51/DETDA epoxy resin and its carbon fiber composites

A toughener that can effectively improve the interlaminar toughness in carbon fiber composites is crucial for various applications.We investigated,the toughening effects of phenolphthalein-based cardo poly(ether sulfone)(PES-C)on E51/DETDA epoxy and its carbon fiber composites(CFCs).Scanning electron microscopy showed that the phase structures of PES-C/epoxy blends change from island(of dispersed phase)structures to bi-continuous structures(of the matrix)as the PES-C content increased,which is associated with reaction-induced phase separation.After adding 15 phr PES-C,the glass transition temperature(T_(g))of the blends increased by 51.5℃,and the flexural strength,impact strength and fracture toughness of the blends were improved by 41.1%,186.2%and 42.7%,respectively.These improvements could be attributed to the phase separation structure of the PES-C/epoxy sys-tem.A PES-C film was used to improve the mode-II fracture toughness(G_(IIC))of CFCs.The G_(IIC) value of the 7μm PES-C film toughened laminate was improved by 80.3%compared to that of the control laminate.The increase in G_(IIC) was attributed to cohesive failure and plastic deformation in the interleaving region.

Toughness Effect of Graphene Oxide-Nano Silica on Thermal-Mechanical Performance of Epoxy Resin

A graphene oxide/nano-silica(GOS)hybrid was rapidly and easily synthesized using graphene oxide(GO)and nano-silica(nano-SiO_(2))as raw materials,and the synthesized GOS was used to improve the mechanical properties of epoxy resin(EP).The modified EP with different mass fractions of GOS(0,0.1%,0.2%,0.3%and 0.4%)were prepared and studied.The structure,thermal stability,mechanical properties,fracture toughness and failure morphology of the modified EP were analyzed.The results showed that the tensile strength of GOS modified EP increased from 40.6 MPa to 80.2 MPa compared with EP,the critical stress intensity factor of GOS modified EP increased by 65.9%from 0.82 MPa·m^(1/2)to 1.36 MPa·m^(1/2),indicating a significant enhancement in fracture toughness.In addition,failure morphology was observed by scanning electron microscopy(SEM)observation.The toughness mechanism of the modified EP was also discussed.Finally,the thermal stability of the modified EP was improved by the addition of GOS.Compared with neat EP,the initial thermal degradation temperature and glass transition temperature of GOS modified EP increased by 4.5℃and 10.3℃,respectively.

Polybutylacrylate/poly (methyl methacrylate) Core-Shell Elastic Particles as Epoxy Resin Toughener: Part Ⅱ Toughness on DGEBA/DDM system

Mechanlcal properties of epoxy resin were investigated by adding core-shell elastic particles (CSEP). The results indicated that optimized core-shell ratio was 60/40 and the loading volume of CSEP was 10 phr (per hundred parts of epoxy resin by weight). The impact strength of modified systems increased apparently with the decrease of core sizes. However, the shearing strength changed gently with the particle sizes. CSEP with lightly crosslinked rubbery core showed more effectiveness on toughness than others. With solution blending, CSEP could be dispersed in epoxy matrix well, and the morphologies of dispersed rubber domains were controlled perfectly by CSEP whose structure was predesigned. A cavitation-shearing band toughness mechanism was observed from the SEM micrographs of fracture surface. It also was found that the deforming temperature (DT) of modified epoxy did not decline apparently.

Effect of Hyperbranched Polyester on Modification of Epoxy Resins Cured with Anhydride

The synthesis and characterization of hyperbranched polyester （HBP） with different molecular weight are studied. The effect of HBP on the modification of epoxy resins cured with anhydride is mainly discussed. The characteristics of HBP and the morphologies of cured system are determined by nuclear magnetic resonance spectroscopy （NMR）, gel permeation chromatography （GPC） and scanning electron microscope （SEM）. The impact strength of cured system is detected and Fourier transform infrared （FTIR） measurements were used to pursue the curing process. The investigation shows that HBP can improve the toughness by forming copolymer networks between epoxy resins, HBP and anhydride. Moreover, when the molecular weight of HBP is 1342g/mol the toughening effect is the best, and the changes of toughness are small with the increase of molecular weight of HBP to 3500 g/mol.

Synthesis of Bio-based Epoxy Containing Phosphine Oxide as a Reactive Additive Toward Highly Toughened and Fire-retarded Epoxy Resins

The integration of high mechanical toughness,impact strength as well as excellent flame-retardant properties toward epoxy resins(EPs)have always been a dilemma.The inadequate overall performance of EPs severely restricts their sustainable utilization in engineering aspects over long-term.Herein,a new bio-based agent(diglycidyl ether of magnolol phosphine oxide,referred as DGEMP)derived from magnolol(classified as lignan),extracted from natural plants Magnolia officinalis,was successfully synthesized and further employed as a flameretardant reactive additive to diglycidyl ether of bisphenol A(DGEBA).As demonstration,the composite resin,DGEBA/15DGEMP(15 wt%DGEMP),achieved an Underwriters Laboratories-94 V-0 rating with a high limiting oxygen index(LOI)value(41.5%).In cone calorimeter tests,it showed that heat release and smoke production were effectively inhibited during combustion,wherein the peak heat release rate(PHRR)value of DGEBA/15DGEMP was reduced by 50%compared to neat DGEBA.Additionally,it exhibited a superior tensile strength(82.8 MPa),toughness(5.11MJ/m^(3))and impact strength(36.5 k J/m^(2)),much higher than that of neat DGEBA(49.7 MPa,2.05 MJ/m^(3)and 20.9 k J/m^(2)).Thus,it is highly anticipated that DGEMP imparts significantly improved mechanical and fire-retarded properties to conventional EPs,which holds a great potential to address the pressing challenges in EP thermosets industry.

Bisphenol-A epoxy resin reinforced and toughened by hyperbranched epoxy resin

The study on toughening and reinforcing of bisphenol-A epoxy resin is one of important developmental direction in the field.This paper reports a one-pot synthesis of aromatic polyester hyperbranched epoxy resin HTDE-2,an effect of HTDE-2 content on the mechanical and thermal performance of the bisphenol-A(E51)/HTDE-2 hybrid resin in detail.Fourier transform infrared(FT-IR)spectrometer,scanning electronic microscopy(SEM),differential scanning calo ri metry(DSC),thermogravimetric analysis(TGA),dynamic mechanical thermal analysis(DMA)and molecular simula tion technology are used to study the structure of HTDE-2,performance and toughening and reinforcing mech-anism of the HTDE-2/E51 hybrid resin.It has been shown that the content of HTDE-2 has an important effect on the performance of the hybrid resin,and the performance of the HTDE-2/E51 blends has maximum with the increase in HTDE-2 content.The impact strength and fracture toughness of the hybrid resin with 9 wt-%HTDE-2 are almost 3.088 and 1.749 times of E51 performance respectively,furthermore,the tensile and flexural strength can also be enhanced about 20.7% and 14.2%,respectively.The glass transition tem-perature and thermal degradation temperature,however,are found to decrease to some extent.

2—甲苯缩水甘油醚协同提升环氧复合物韧性及刚性研究

电气及电子设备集成度的不断提高,对环氧复合物的热学与力学综合性能提出了更高需求。环氧复合物的耐热性能、刚性与韧性三者之间存在“跷跷板”现象,难以协同提升。该文提出将六氢邻苯二甲酸酐/四氢邻苯二甲酸酐/邻苯二甲酸酐3种固化剂复配提升环氧复合物热学性能,并采用2—甲苯缩水甘油醚协同提升环氧复合物韧性及刚性的方法。研究表明:固化剂复配的方法将环氧复合物的玻璃化转变温度Tg及热分解温度T5%分别提升了17.93%、7.72%;2—甲苯缩水甘油醚改性使得环氧复合物冲击强度和弯曲强度分别提升了123.03%、61.71%。采用分子动力学模拟,从分子角度揭示了2—甲苯缩水甘油醚提升环氧固化物性能的机理,其刚性苯环基团增强了环氧体系分子结构稳定性,柔性—C—O—C—链段改善了交联体系柔韧性。该研究提出一种不降低环氧复合物热学性能,并协同提升其韧性与刚性的可行方法,可为具备高综合热学与力学性能环氧复合物配方的设计提供新思路。

核壳颗粒增韧改性环氧树脂基体研究评述

环氧树脂(EP)具有优异的性能,被广泛应用在涂料、胶黏剂、复合材料等领域,但是其交联密度大,抗裂纹萌生和扩展能力差,因此,EP的增韧改性一直是国内外学者的研究重点。核壳颗粒(CSP)作为第二相加入EP中能达到良好的增韧效果,同时不会引起热力学性能的大幅损失,相较于传统增韧剂有较大的发展前景。本文在阐述EP的不同增韧机理的基础上,介绍了CSP增韧剂的增韧机理、主要类型及制备方法,评述了CSP材料、颗粒粒径、核壳比等因素对EP力学性能影响的研究结果,并分析了使用CSP增韧方法对作为复合材料基体的EP流变行为和固化动力学等工艺性能的影响。

基于Al_(2)O_(3)/环氧树脂复合材料的盆式绝缘子在役态裂纹萌生及失效断裂机制研究

本文首先总结了近年盆式绝缘子失效破坏的一般规律和特征,然后截取典型失效区域试样,分析基体微观组织形貌和失效断口的形貌特征,最后采用纳米压痕力学技术对复合材料异质界面微观力学性能进行表征分析,阐释基于Al_(2)O_(3)/环氧树脂复合材料的裂纹萌生及失效断裂机制。结果表明:环氧树脂基体的断裂韧性值约为0.55 MPa·m^(1/2),在载荷作用下裂纹从环氧树脂基体中萌生,并不断扩展,当遇到高强度的Al_(2)O_(3)颗粒时因受阻而发生偏转,并沿着颗粒与基体的界面快速扩展。

橡胶作为环氧树脂增韧剂的研究进展

综述橡胶增韧环氧树脂的原理、方法和研究进展,并对其发展方向进行展望。橡胶作为增韧剂可以改善环氧树脂的韧性,其增韧原理主要包括橡胶颗粒撕裂变形、银纹-剪切带-空穴和银纹-钉锚理论。常见的橡胶增韧材料主要有功能化液体橡胶、核-壳橡胶(CSR)颗粒和复合橡胶增韧剂。复合橡胶增韧剂增韧技术可以在一定程度上解决功能化液体橡胶和CSR颗粒增韧技术在实现环氧树脂的加工性能、力学性能与热稳定性能平衡方面存在的问题。复合橡胶增韧剂增韧技术的研究需深入探索填料分散和橡胶与填料协同增韧机理,并开发高效和稳定的韧性环氧树脂的生产工艺以促进其产业化。

饱和电抗器用环氧树脂性能提升研究

针对饱和电抗器浇注用环氧树脂在受到电应力及机械振动时易出现老化开裂的问题,需要在保持其优良绝缘、抗腐蚀性能的基础上改善其力学性能及热学性能。本文以功能优化设计为原则,先通过热处理在碳化硅晶须(SiCw)表面形成二氧化硅介电层得到SiCw@SiO_(2),然后利用掺杂改性的方法制备SiCw@SiO_(2)/EP复合电介质,并对其介电性能、力学性能以及导热性能进行测试。结果表明:SiCw@SiO_(2)/EP复合电介质兼具高介电常数及低介质损耗,韧性也得到改善,且由于SiCw相互接触形成了连续导热网络,SiCw@SiO_(2)/EP复合电介质的导热系数相比纯环氧树脂提高了117%。

基于珍珠层和凤凰螺内部结构的混合仿生设计

融合多种生物材料内部结构的混合仿生结构设计是近年来兴起的一种材料强韧化设计新策略。采用碳纤维增强环氧树脂设计了一种由贝壳珍珠层“交错”结构和凤凰螺“交叉”结构融合而成的新型“交错-交叉”复合结构材料。实验和理论研究发现,珍珠层“交错”结构和凤凰螺“交叉”结构在内部载荷传递和应力分布调控方面存在显著差异,将两者进行简单混合将会导致局部应力集中,进而使材料性能劣化。通过优化该复合结构,提出了一种新型小角度连续纤维“交叉”叠层仿生结构,该结构能够优化材料内部的全场应力分布、抑制局部应力集中,形成延迟整体结构断裂失效的强韧化机制,有效解决材料性能的劣化问题。该研究结果有望为解决材料的强韧矛盾提供有益参考。

一种添加自交联环氧树脂乳液的防腐韧性水泥浆

酸性气体中H_(2)S和CO_(2)要与硅酸盐水化物发生反应,导致水泥石的渗透率增大、抗压强度大幅降低,使油井水泥环受到严重腐蚀,影响井筒完整性。为此,合成一种自交联环氧树脂乳液,用于增强油井水泥耐H_(2)S和CO_(2)腐蚀的能力。在H_(2)S分压为2.0 MPa、CO_(2)分压为1.5 MPa下,对水泥石的防腐蚀性能和作用机理进行评价与分析。研究结果表明:①交联环氧树脂乳液加量增加,抗压强度增大,超过一定加量后抗压强度增加不明显甚至减小,而弹性模量降低显著,增幅逐渐减少;②自交联环氧树脂乳液能够提高油井水泥石耐H_(2)S和CO_(2)腐蚀的能力,随着自交联环氧树脂乳液加量的增大,水泥石受H_(2)S和CO_(2)的腐蚀深度、渗透率降低,抗压强度先增加后降低;③自交联环氧树脂乳液包裹水泥石的水化产物,阻隔了硅酸盐水泥石水化产物与H_(2)S和CO_(2)等酸性气体的接触,提高了水泥石对H_(2)S和CO_(2)等酸性气体的耐腐蚀能力;④自交联环氧树脂乳液防腐韧性水泥浆常规工程性能良好,固井水陈化时间、自交联环氧树脂加量、温度变化对稠化时间不敏感,现场应用可操作性强。在6口井开展了防腐韧性水泥浆试验,固井质量平均优质率达到90%以上,合格率为99%以上。结论认为,自交联环氧树脂乳液充填和成膜包裹水泥水化产物,使水泥石具有防腐韧性性能,在川东北高含硫区块具有良好的推广应用前景。

E-51环氧树脂改性混凝土桥梁应用效果与施工技术

为加强公路桥梁用混凝土的强度、韧性等性能,通过聚氨酯对E-51环氧树脂进行改性,制备了一种公路桥梁用C40混凝土,并对其性能进行研究。试验结果表明,在混凝土中掺入改性E-51环氧树脂,会降低材料的抗压强度,当掺入的改性E-51环氧树脂适量时,可以有效增强混凝土的粘接强度和弯曲韧性;当混凝土中掺入4%改性E-51环氧树脂时最佳,此时C40混凝土养护28d时的抗压强度为47.6MPa,其粘接强度以及弯曲断裂能达到最高,分别为2.81MPa和1135N·m,增幅达到23.1%、14.2%和46.3%。综合性能较好,符合实际应用标准,可以用于实际桥梁路面上的铺装应用。

Formation of Hybrid Ring Structure of Cyanurate/Isocyanurate in the Reaction be-tween 2,4,6-Tris(4-Phenyl-Phenoxy)-1, 3,5-Triazine and Phenyl Glycidyl Ether

Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.

高韧性低黏度1,8-辛二醇基环氧树脂的制备及其性能

以1,8-辛二醇、环氧氯丙烷为原料,苄基三乙基氯化铵为相转移催化剂,NaOH为闭环剂,通过两步法合成1,8-辛二醇基环氧树脂(ODOL-EP),并与普通双酚A型环氧树脂进行性能对比与结构表征。结果表明:ODOL-EP的环氧值高达0.676 mol/100 g,产率达90.95%,其黏度(0.0186 Pa·s)低于普通双酚A型环氧树脂(13.2721 Pa·s),降低了加工难度;当1,8-辛二醇与环氧氯丙烷摩尔比为1.0∶3.6时韧性达到最佳,冲击强度及断裂伸长率分别提高了279.96%,342.82%,拉伸强度有所降低;ODOL-EP固化物呈现良好的韧性断裂特征。

水性环氧树脂(WER)-丁苯橡胶(SBR)复合改性乳化沥青韧性性能

为了研究水性环氧树脂(waterborne epoxy resin,WER)-丁苯橡胶(styrene-butadiene rubber,SBR)复合改性乳化沥青(WER and SBR composite modified emulsified asphalt,WER-SCMEA)的韧性性能,选择改性剂WER和SBR对乳化沥青进行改性,通过低温拉伸性能和差示扫描量热试验对WER-SCMEA的韧性性能进行研究,并与SBR改性乳化沥青进行对比分析。结果表明:随着WER掺量的增加,WER-SCMEA的抗拉强度逐渐增大,断裂延伸率显著减小,但WER质量分数为10%的乳化沥青试件仍具有超过100%的断裂延伸率。沥青经过WER改性后,其玻璃化转变温度呈现先降后升的规律。当WER掺量高于8%时,其玻璃化转变温度上升到与基质沥青相当;继续增加WER掺量,玻璃化转变温度急剧上升;当WER掺量达到15%时,沥青的玻璃化转变温度仍小于所在地的最低服务温度。

SBR水性环氧树脂复合改性乳化沥青性能研究

文中将SBR与WER进行共混,通过先乳化后改性的工艺制备SBR-WER复合改性乳化沥青.采用针入度、延度、软化点、黏度、低温韧性、荧光显微镜等方法综合评价SBR的掺量和WER掺量对SBR-WER改性乳化沥青性能的影响.结果表明:在一定的掺配比例下,SBR的加入对SBR-WER复合改性乳化沥青的延度、黏度有所提升;观察低温弯曲裂缝发现,其低温韧性提高,并且对其高温性能和抗疲劳性能也起到一定的改善作用.荧光显微镜试验分析显示,当WER掺量为10%,SBR掺量为3%~4%时,复合改性乳化沥青内部分散形成交联网络结构,从而达到最佳的使用性能.

聚合物改性钢纤维再生混凝土抗冲击性能研究

目的研究水性环氧树脂质量分数、再生粗骨料取代率和超短微丝钢纤维体积分数对RAC抗冲击性能的影响,以促进其工程应用。方法对RAC进行抗压和落锤冲击试验,通过极差分析法研究各因素对RAC抗冲击性能的影响,并分析水性环氧树脂的改性机理;同时基于Weibull分布理论对冲击试验结果进行拟合检验和冲击寿命预测分析。结果钢纤维体积分数对RAC抗冲击性能的影响最大,纤维体积分数由0增至1.0%时,RAC初裂冲击耗能和破坏冲击耗能的增幅分别接近150%和900%;再生粗骨料取代率对水性环氧树脂的改性效果影响较大;双参数Weibull分布能较好地描述RAC抗冲击次数的分布特征。结论水性环氧树脂掺入后可改善界面过渡区的密实性;钢纤维掺入后能显著提升RAC基体的冲击韧性和延性。

高韧性环氧树脂体系的研究开发

使用了核壳粒子、聚醚砜、纳米颗粒及自制改性增韧剂对环氧树脂进行增韧,筛选出增韧效果较优的高韧性环氧树脂体系。通过进一步对高韧性环氧树脂体系浇铸体及其复合材料性能的表征分析,优化了体系配方并探讨了其增韧机理。对高韧性环氧树脂体系的性能进行了测试,结果表明:优化的树脂体系拉伸模量达到3.43GPa,拉伸强度达到83.00 MPa,断裂伸长率达到7.10%,冲击强度达到32.04 kJ·m^(-2);制备的碳纤维/高韧性环氧树脂基复合材料性能优异,其拉伸强度达到2.17GPa,拉伸模量达到140.00GPa。