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Study on Phenolphthalein Poly(ether sulfone)-Modified Cyanate Ester Resin and Epoxy Resin Blends 关于酚酞聚醚砜改性氰酸酯树脂和环氧树脂混合物的研究In this work,the phenolphthalein poly(ether sulfone)(PES-C)-modified cyanate ester(CE)and epoxy(EP)blends were prepared.在本文中，制备了用酚酞聚醚砜（PES-C）改性的氰酸酯树脂（CE）和环氧树脂（EP）的混合物。This work mainly discusses the curing behaviors,fracture toughness,dynamic mechanical properties,and thermal and mechanical properties of the blends.主要探讨了体系的固化行为，断裂韧性，动态机械性能，以及其热的和机械韧性。The Fourier transform infrared and differential scanning calorimetric analyses are used to confirm the curing behaviors,demonstrating that the main reaction pathways are not varied with the addition of PES-C,but the reaction rate could be evidently accelerated.用傅里叶红外光谱仪和差示扫描量热仪来确定体系的固化行为，证明主要反应的途径不会随着 PES-C的增加而变化，但是反应速度会明显地改变。The fracture morphologies of the blends are observed by Scanning electron microscope(SEM)and the fracture causes of the failed surface are also analyzed.用 SEM来分析混合物的断口形貌和有缺陷表面的断裂原因。With the addition of PES-C,the modified blends display higher fracture toughness(KIc)and impact strength when compared with neat CE.随着 PES-C的增加，与纯 CE比较，改性混合物展示出了更高的断裂韧性（KIc）和冲击强度。Domain sizes of the blends first increase then decrease with the addition of PES-C.随着 PES-C含量的增加，晶体大小也会随之增加。The results of dynamic mechanical analysis and thermogravimetric anal-ysis show that the Tg,storage modulus,and thermal sta-bility of the crosslink network slightly decreases with the addition of PES-C.根据 DMA，TG 的测试结果，随着PES-C的增加，混合物的 Tg，储能模量以及热稳定性可以明显地增加。The mechanical strength of blends with the addition of PES-C is far better than that of the blends without PES-C both at ambient temperature and elevated temperature.在室温和高温下，含有PES-C混合物的机械性能都远远高与不含改性物混合物的。POLYM.ENG.SCI.,55:2591 2602,2015.VC 2015 Society of Plastics Engineers INTRODUCTION 简介Cyanate ester resins(CE,Tg:255 262C)are recently used as matrices for high-performance composites and as adhesive materials for advanced random structures in aerospace field because of their high-temperature resistance,good dielectric properties,outstanding mechanical properties,and low-volume shrinkage 1,2.氰酸酯树脂（CE，Tg，255-262）近年来因为它的高温稳定性、好的介电性能、杰出的机械特性和低的体积收缩率，被用作高性能复合材料的基体和航空领域先进结构的粘结剂。The excellent properties arise from the special crosslink ring structure of cured CE.这些杰出性能和CE 固化物中的特殊交联环状结构有关。A practical disadvantage of the highly crosslinked materials is poor resistance to crack propagation.这种高交联材料的实际缺点是在裂纹扩展时的低抵抗性。These materials cannot be used for damage-tolerant applications and need to be suitably modified before serving structural functions.这些材料不能用于损伤容限应用或者需要在使用前对其结构功能进行适当的改性。Several methods have been proposed to modify the CE resins 3 6.多种方法被用来改性CE树脂。The most common method is to incorporate rubber into CE resins.最常用的方式是向CE树脂中添加橡胶。Various reactive-functionalized butadiene acrylonitrile rubbers like carboxyl-terminated butadiene acrylonitrile and amine-terminated butadiene acrylonitrile were widely used for CE resins,which are advantageous to improve the toughness due to the dispersed rubber particles as a result of phase separation on curing 7 10.各种活性的丁二烯丙烯腈橡胶像端羧基丁二烯丙烯腈橡胶和端氨基丁二烯丙烯腈橡胶被广泛地用于CE树脂，由于在相固化的过程中分散橡胶颗粒的形成，使得加入的橡胶可以提高体系的韧性。Even though rubber toughening is effective in CE,it significantly decreases modulus and thermal stability of CE matrix and limits scopes of the application of modified CE resin at elevated temperature 11.尽管橡胶增韧对于CE是很有效的，它大幅度地提高了CE基体的模量和热稳定性，但是也限制了 CE树脂在高温下的使用范围。Additionally,epoxy(EP)resins are also used to modify CE resins for matrix of high-performance composites and adhesives applications 12.此外，环氧树脂（EP）也被用来 CE树脂基体的高性能复合材料和粘结应用来改性。Grenier-Loustalot and Lartigau 13 found that the initial reaction temperature of CE and EP co-curing was lower than that of neat CE.Grenier-Loustalot 和 Lartigau 13 发现 CE和EP共固化的初始反应温度比纯CE的低。Qi et al.14 have reported that the mechanical properties of EP-modified CE networks are improved.Qi et al.14发现 EP改性后的 CE的机械性能会提高。Although the addition of EP can improve the processability and impact strength of CE,they are still deficient in toughness.尽管随着 EP的增加，可以提高CE的加工性能和冲击强度，但其在韧性上仍显不足。Meanwhile,the thermal properties of CE matrix are also influenced.并且，CE基体的热稳定性仍然被影响了。To get improved toughness without losing thermal and mechanical properties of CE resins,high-performance thermo-plastics are often used.为了在提高 CE树脂的韧性的同时不损失其热学和机械特性，高性能的热塑性塑料被用来改性CE。The advantage of thermoplastic is that the mechanical and thermal properties of CE resin may be most retained even after blending 15.使用热塑性塑料的优点是就算在混合后CE树脂的机械和热学性能也能被保留。The high-performance thermoplastics such as polysulfone(Tg:190 2008C)and poly(ether imide)(Tg:2152278C)are usually used 16 19.通常用的高性能热塑性树脂有PSF（Tg：190-200）和 PEI（Tg：215-227）。However the toughened CE networks by the above manners would still suffer the setback in use temperature.然而，通过上述方法增韧过的CE体系依然存在使用温度的限制。Hence,it is most interesting to research the addition of a suitable thermoplastic which must have high Tg corresponding to neat CE and good fracture toughness to the uncured CE 20.因此，寻找一种合适的热塑性材料，使得其与纯 CE树脂的 Tg 相一致，并且使固化CE树脂的断裂韧性更好，就变得很重要了。Phenolphthalein-based poly(ether sulfone)(PES-C)has drawn increasing attention because of its excellent thermal stability(Tg=262C)and good fracture toughness.酚酞基 PES-C以其杰出的热稳定性（Tg=262）和高的断裂韧性受到越来越多的重视。Srinivasan and McGrath21,22 reported that CE networks can be effectively toughened by introducing PES-C.Srinivasan and McGrath21,22 报道用 PES-C可以有效地增韧CE树脂体系。In their researches,the blends exhibited enhanced toughness depending on the formation of microphase-separated structure.在他们的研究中，因为宏观相分离结构的形成，混合物展示出了很好的韧性。Toughened multiphase networks of CE and PES-C were generated without sacrificing the Tg of polycyanurate;however,the cured blends needed to undergo a process at 2508C.CE 和 PES-C增韧多相体系的形成没有以聚氰酸酯的Tg 为代价；然而，混合体系需要在250下才能固化。They reported that the Tg of PES-C-modified CE is about 2608C and that the maximum value of fracture toughness(KIc)is 2.0(M N m23/2).他们报道 PES-C改性 CE的 Tg 大约为 260，并且其断裂韧性（KIc）达到了最大值 2.0（M N m-3/2）。However,the above-modified blends show a negative impact on processability because of rigor cure temperature,and the fields of application were limited.Meanwhile,the toughness effect of single PES-C-modified CE was deficient.然而，因为严苛的固化温度，上述改性混合物的加工性能不是很好，并且其应用领域也得到了限制。同时，只用PES-C改性的 CE的韧性尚有不足。The above questions led us to investigate the feasibility of tailoring methods to improve the rigor cure conditions and further satisfied requirements in manufacturing,the premise being that the thermal stability and strength are not substantially deteriorated and that the toughness is further increased.上述的问题引导我们探索另外的方法来提高严苛的固化条件和在工业生产中更好的需求品。这个的前提是体系的热稳定性和强度不会大幅下降和其韧性可以大幅度提高。It was well known that the polyether chains of EP introduced into CE can improve the ability of plastic deformation in crosslink network and enhance toughness of CE resins.我们都知道在 CE中加入 EP聚醚链可以提高交联结构的塑性应变和CE树脂的韧性。This study is devoted to developing hybrid composites of CE/EP modified with PES-C for decreasing the postcured temperature of CE resins and further enhancing toughness.这个理论被用来发展PES-C改性的CE/EP混杂复合材料，可以降低CE树脂的后固化温度以及大幅度提高其韧性。Consequently,it is aimed to develop a high-performance material for the aerospace structural applications under the continuous high temperature(200 2508C).因此，现在的目的是发展一种能在持续高温下（200-250）航天结构应用的高性能材料。The prime objective of this investigation is to find out the effect of content of PES-C on cure behavior,morphology,toughness,and thermal mechanical properties of CE/EP blends.本次研究的主要目的就是想找出CE/EP混合物中 PES-C的含量对其固化行为，形貌，韧性以及热机械性能的影响。Finally,it was found that PES-C is both a very effective cure accelerator and an excellent toughening agent for the CE/EP networks.最后，我们发现 PES-C是一种很好的固化促进剂和一种杰出的CE/EP树脂的增韧剂。FIG.1.Chemical structural formulas of raw materials.图 1.原材料的化学结构式EXPERIMENTAL 实验Materials 材料Bisphenol A dicyanate(BADCy)was used(Ciba-Geigy,Swiss).双酚A 二氰酸酯。Diglycidyl ether of bisphenol F was used(Dow Chemi-cal).二缩水甘油醚双酚F。The phenolphthalein PES-C with an intrinsic viscosity of 0.78 dL g-1was used(Xuzhou Chemical Factory,China).特性黏度为 0.78 dL g-1的酚酞 PES-C。It was dried at 1508C for 2 3 h before use.使用前在 150下干燥 2-3h。The chemical structural formulas of raw materials are shown in Fig.1.原材料的化学结构式如图.1。Preparation of Different Blends 不同混合物的准备Table 1 provides the blend mass ratios for PES-C-modified CHshjC-CHCMj-0OCHj-CCHjViDLilcitj;IcihirofbisphcmlFrefillCE/EP blends in this study.表 1.给出了本研究中 PES-C改性 CE/EP混合物的质量比。The mass ratio of CE/EP to PES-C was variable in blends,while the mole ratio of cyanate etser groups to epoxy groups was about 6:1(calculated from Eq.1),在混合物中，PES-C和 CE/EP的质量比是可变的，其中CE和 EP的摩尔比是 6:1（从下式中导出Eq.1）Ratio=MCE/MEP1.27 （1）where MCE and MEP are the mass of CE and EP components,respectively.分别在 CE和 EP的体系中，CE和 EP的质量是多的。The blending processes were performed in two steps.混合过程是通过两步来执行的。In the first step,PES-C was dissolved in BADCy at 1608C with constant stirring for 1 h(except CYEP0 formulation);and in the second step,the system was cooled below 1308C,and bisphenol F EP resin was immediately added to the above system with constant stirring until the mixture turns into a transparent homogeneous state.第一步，在 160时，连续搅拌1h 将 PES-C溶入 BADCy中；第二步，将体系冷却到130以下，立即在连续搅拌下把双酚F环氧树脂加入到上述体系中，直到混合物转变成透明均匀的状态。After complete mixing,air bubbles were instantly removed from the mixture under vacuum at 1008C.等完全混合后，在100的真空条件下快速除去体系中的空气泡。The hot resin was subsequently poured into preheated(1008C)steel molds for fracture toughness(KIc),impact strength,mechanical properties,and dynamic mechanical analy-sis(DMA).将热树脂灌入预加热（100）过的铁质磨具，然后测其断裂韧性（KIc），冲击强度，机械特性以及DMA。The samples were cured with the following procedure:1778C for 4 h 1 2008C for 2 h.样品以以下的固化程序进行固化：177*4h+200*2h。Characterization of Samples 样品的特性Fourier Transform Infrared Analysis.傅里叶变换红外光谱分析。Fourier transform infrared(FTIR)studies were conducted to investigate the curing reaction(Nicolet Magna 550).傅里叶变换红外光谱仪旨在研究固化反应（Nicolet Magna 550）。The samples were heated to melt and coat on the surface of KBr slice to form a thin film and were first scanned by FTIR at ambient temperature,and then,the samples were placed into an oven at a given temperature for certain time interval and scanned once again by FTIR 23.样品别加热融化然后浇铸在KBr 薄片的表面，形成一个薄膜。第一次在室温下用FTIR 扫描，然后将样品在烤炉中加热确定的时间，再来用 FTIR 扫描。Additionally,the residual content of characteristic groups at different time,X(t),was calculated as follows:(2)where Hi is the characteristic peak height,and H2965 is the methyl stretch vibration peak height used as internal reference.此外，在不同时间时官能团的残存量，x（t）由下式给出：(Hi!H2%5)t(/,/2965)05耶)（2）where Hi is the characteristic peak height,and H2965 is the methyl stretch vibration peak height used as internal reference.在标准谱图中，Hi是特征峰，H2965是甲基的拉伸振动峰。Differential Scanning Calorimetric Analysis.DSC。Curing kinetics was determined by using differential scanning calorimeter(DSC6220,Japan).用 DSC来测定其固化动力学（DSC6220，日本）。The samples were heated from 24 to 4008C at the rate of 2,5,10,15,and 208C min21(air atmosphere).样品分别在 2、5、10、15、20/min-1的升温速率下从 24升到 400（空气气氛）。The enthalpy of cure is directly proportional to the area under the DSC curve 24.固化焓变与在 DSC曲线下的面积成正比24。Thus,the fractional extent of conversion a could be expressed as follows:转变的部分范围可以从下式中算出来：where dHt is the reaction enthalpy of the sample heated to a(/,./2965),(/,/2965)0，mAH，given temperature T,and dH is the total enthalpy of reaction at the heating rate of 108C min21.dHt是样品被加热到一个特定温度T时的反应焓，dH 是在加热速率为 10/min-1下的反应总焓。Isothermal curing method was used to determine the conversion a of samples in the process of isothermal curing by using the following equation:在等温固化过程中探索样品的转变过程用等温固化模式，如下式：The samples are partially cured isothermally in the oven at a given temperature at a certain time,where dHr is residual reaction heat.特定温度特定时间下，在烘箱中等温过程的样品是局部固化的，dHr是残余反应的反应热。Impact Strength and Fracture Toughness(KIc)冲击强度和断裂韧性（KIc）The unnotched impact strength of cured blends was measured with Charpy impact tester(XCJD-5 pendulum impact machine,China)according to GB/T 2751-95 Standard of China.固AH-AHrOLAHTABLELBlendratioofPES-C-modifiedCE/EPsystem(unit:wt%).RawmaterialsCYEP0CYEP5CYEPmCYEPl5CYEP2()CYEP25BADCyresinBisphenolFepoxyresinPES-C82.578.374.217.516.715.870.161.966.014914,013.10510152025化体系的无缺口冲击强度用Charpy 冲击试验机（XCJD-5 摆锤冲击试验机，中国）按照中国的GB/T2751-95 标准来测量。Fracture toughness of cured blends was determined according to ASTM D-5045-99 test method on 10 12 specimens of dimensions 60 mm*10 mm*3 mm.固化混合体系的断裂韧性用10-12 个60mm*10mm*3mm的样品通过 ASTMD-5045-99 测试方法 测得。A notch of 5 mm was made at one of edge of the specimen.在另一组样品的边缘开 5mm 的凹槽。A natural crack was made by pressing a fresh razor blade into the notch.用刀片在凹槽内开一个自然的缺口。With attention to the crack,it must propagate evenly through the specimen thickness.当测试缺口的时候，它必须通过试件厚度均匀地传导。The precracked specimens were loaded on a three-point bend mode at a rate of 2 mm min21.裂纹试样被载入 2mm/min-1的速率下的三点式弯曲模式。Dynamic Mechanical Analysis DMAThe dynamic mechanical properties of the cured blends were measured by using DMA 6100 dynamic mechanical analyzer(Japan).固化混合体系的动态机械性能用DMA6100 动态机械分析仪（日本）来测试。Rectangular specimens of 31 mm*10 mm*3 mm were used for the analysis.测试用的是 31mm*10mm*3mm的矩形样条。The analysis was done in three-point bending mode at a frequency of 1 Hz and at a heating rate of 58C min21.这个测试是用三点式弯曲模式在频率为1Hz以及在 5/min-1的加热速率下测得的。The samples were heated from room temperature to 3008C.样品从室温升温到300。Thermogravimetric Analysis 热重分析The thermal stability of the blends was analyzed by thermogravimetric with a TG/DTA 6300 thermogravimetric analyzer(Japan).混合物的热稳定性是用TG/DTA 6300 热重量分析仪（日本）测得的热重来分析的。The cured samples were heated from room temperature to 8008C at a heating rate of 108C min21in air atmosphere.固化样品是在空气气氛下从室温以10/min-1的加温速率升到800的。Mechanical Properties 力学性能The flexural properties and tensile properties of cured samples were tested by using INSTRON 5969 equipped a tempera-ture chamber in accordance with GB/T 2567-2008 Standard of China.固化样品的弯曲性能和拉伸性能是用INSTRON 5969 在室温下通过中国 GB/T 2567-2008 标准测试的。RESULTS AND DISCUSSION 结果和讨论Cure Behaviors of PES-C-Modified CE/EP Blends PES-C 改性 CE/EP 混合物的固化行为FTIR was used to monitor the curing reaction between CE and EP in the modified blends.用 FTIR 来监控改性混合物中CE和EP树脂的固化反应。The FTIR spectra of CYEP0,CYEP5,and CYEP 20 cured at 1778C and postcured at 2008C are shown in Fig.2.CYEP0,CYEP5,和 CYEP 20在 177下固化和在 200下后固化的 FTIR 如图 2.From Fig.2,in the initial stage(0 40min),the consumption of cyanate(2270 2235 cm21)monomers is accompanied with the increase of polycyanurate groups,namely,triazine rings(1565 and 1370 cm21),and then the absorption of alkyl isocyanurate groups(1680 cm21)increases with the further insert reaction of EP groups into polycyanurate groups.在最初阶段（0-40min），随着异氰酸酯（2270-2235cm-1）单体的消耗，伴随着聚异氰酸酯（1565 和 1370 cm-1）基团即三氮杂苯环的生成，烷基异氰酸脲酯基(1680 cm-1)的吸收会在 EP更进一步地插入聚异氰酸酯基团的过程中增加。We observed small amounts of polycyanurate groups in uncured samples;however,alkyl isocyanurate groups were not found.我们观测了少量在未固化样品中的聚异氰酸酯基团；然而，没有发现烷基异氰酸脲酯基。These findings suggest that EP groups(916 cm21