Toughening of cyanate ester resin by N‐phenylmaleimide–N‐(p‐hydroxy)phenyl‐maleimide–styrene terpolymers and their hybrid modifiers

N‐Phenylmaleimide–N‐(p‐hydroxy)phenylmaleimide–styrene terpolymer (HPMS), carrying reactive p‐hydroxyphenyl groups, was prepared and used to improve the toughness of cyanate ester resins. Hybrid modifiers composed of N‐phenylmaleimide–styrene copolymer (PMS) and HPMS were also examined for further improvement in toughness. Balanced properties of the modified resins were obtained by using the hybrid modifiers. The morphology of the modified resins depends on HPMS structure, molecular weight and content, and hybrid modifier compositions. The most effective modification of the cyanate ester resin was attained because of the co‐continuous phase structure of the modified resin. Inclusion of the modifier composed of 10 wt% PMS (M_w 136 000 g mol^?1) and 2.5 wt% HPMS (hydroxyphenyl unit 3 mol%, M_w 15 500 g mol^?1) led to 135% increase in the fracture toughness (K_IC) for the modified resin with a slight loss of flexural strength and retention of flexural modulus and glass transition temperature, compared with the values for the unmodified resin. Furthermore, the effect of the curing conditions on the mechanical and thermal properties of the modified resins was examined. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviour of the modified cyanate ester resin system. © 2001 Society of Chemical Industry     

Modification of cyanate ester resin by soluble polyarylates

Soluble polyarylates were prepared from the reaction of 2,2‐bis(4‐hydroxyphenyl)propane (bisphenol‐A) and aromatic acid dichlorides (phthaloyl chloride and related diacid dichlorides), and used to improve the brittleness of a cyanate ester resin. The polyarylates include poly[2,2‐di(4‐phenylene)propane phthalate] (PPA), poly[2,2‐di(4‐phenylene)propane phthalate‐co‐2,2‐di(4‐phenylene)propane isophthalate] (IPPA) and poly[2,2‐di(4‐phenylene)propane phthalate‐co‐2,2‐di(4‐phenylene)propane terephthalate] (TPPA). Furthermore, a commercial polyarylate, U‐polymer, was also used as a modifier. The morphologies of the modified resins depended on the polyarylate structure and concentration. The most effective modification of the cyanate ester resin could be attained because of the co‐continuous phase structure of the modified resin: 25 wt% inclusion of IPPA (50 mol% isophthalate units, weight average molecular weight (M_w) 38 500 g mol^?1) led to a 130% increase in the fracture toughness (K_IC) for the modified resin, with retention of its flexural properties and glass transition temperature, as compared with the values for the unmodified resin. Water absorptivity of the IPPA‐modified resin was smaller than that of the unmodified resin. Copyright © 2003 Society of Chemical Industry     

氰酸酯树脂的改性及应用研究

综述了热固性树脂、热塑性树脂、橡胶、不饱和化合物、晶须和纳米粒子等改性氰酸酯(CE)树脂的研究现状,并简要概述了改性CE树脂在工业中的应用。     

Modification of cyanate ester resin by poly(ethylene phthalate) and related copolyesters

Aromatic polyesters were prepared and used to improve the brittleness of the cyanate ester resin. The aromatic polyesters include poly(ethylene phthalate) (PEP) and poly(ethylene phthalate‐co‐1,4‐phenylene phthalate). The polyesters were effective modifiers for improving the brittleness of the cyanate ester resin. For example, inclusion of 20 wt % PEP (MW 19,800) led to a 120% increase in the fracture toughness (K_IC) with retention in flexural properties and a slight loss of the glass transition temperature compared to the mechanical and thermal properties of the unmodified cured cyanate ester resin. The microstructures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The thermal stability of the modified resins was lower than that of the unmodified resin as determined by thermogravimetric analysis. The water absorptivity of the modified resin increased significantly, compared to that of the unmodified cured cyanate ester resin. The toughening mechanism was discussed in terms of the morphological and dynamic viscoelastic behaviors of the modified cyanate ester resin system. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 208–219, 2000     

纳米CaCO_3对CE及CE/EP基体的改性研究

通过力学性能测试和扫描电镜、热重分析以及红外光谱测试研究了纳米CaCO3的加入量对氰酸酯(CE)及CE/环氧(EP)基体力学性能及热性能的影响。结果表明,适量的纳米CaCO3的加入,可有效地改善CE或CE/EP基体的韧性和强度。当纳米CaCO3的质量分数为3%时,两改性体系的冲击强度和拉伸模量均达到最大值,CE/EP/CaCO3体系较CE/CaCO3体系具有更高的冲击强度(7.8kJ/m2)和较低的拉伸模量(100.5GPa)。纳米CaCO3的加入有利提高基体的热稳定性,但CE/EP/CaCO3三元体系的热稳定性仍明显低于纯CE或CE/CaCO3二元体系。     

氰酸酯树脂增韧改性研究

综述了采用热固性树脂(环氧树脂,双马来酰亚胺)、热塑性树脂(聚醚砜,聚苯醚)、橡胶弹性体(端羧基丁腈橡胶,端环氧基丁腈橡胶)、无机纳米粒子(SiO2,SiC)增韧改性氰酸酯树脂的机理及研究进展,并指出了今后氰酸酯树脂改性研究的发展方向。     

Novel modification of cyanate ester by epoxidized polysiloxane

A novel modification of cyanate ester (CE) resin by epoxidized polysiloxane (E‐Si) has been developed, and the modified system is coded as CE/E‐Si. E‐Si was prepared by the reactions among octamethylcyclotetrasiloxane, hexamethyldisiloxane, (3‐aminopropyl)‐methyldiethoxysilane, and diglycidyl ether of bisphenol‐A resin. Six formulations were designed to evaluate the effect of the weight ratio between CE and E‐Si on performance parameters. Results reveal that the addition of E‐Si in CE resin cannot only significantly decrease the curing temperature of the CE resin but also improve the water resistance and toughness of original CE resin. Moreover, these positive effects increase with the increase of E‐Si concentration in CE/E‐Si systems. Thermal property investigation shows that the glass‐transition temperature and initial degradation temperature of CE/E‐Si systems are lower than that of original CE resin. For the flexural properties of the CE/E‐Si systems, the E‐Si concentration in the system exists a threshold, that is, when the E‐Si concentration is smaller than the threshold, original CE and CE/E‐Si systems have similar flexural properties, whereas when the E‐Si concentration is higher than the threshold, CE/E‐Si systems have lower flexural properties than original CE resin. All these changes of properties are closely correlated to the structure alteration from neat CE to CE/E‐Si networks. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

氰酸酯改性环氧树脂耐热性研究

采用热变形仪和红外光谱研究了氰酸酯树脂(CE)改性环氧树脂(EP)体系的4种不同配比和不同固化温度对产物的耐热性的影响。结果表明:加入CE树脂能显著提高EP的耐热性,但固化温度对CE树脂含量不同体系的热变形温度(HDT)影响程度有明显差别。CE/EP体系中EP过量时,提高固化温度,产物的HDT显著提高,在230℃以上固化反应才能完成;两者相当或CE过量时,固化温度在180～200℃时产物的HDT最高,提高固化温度,产物的HDT反而下降。CE含量不同时,反应生成的产物各异,这是造成固化物HDT差异的根本原因。     

Performance of aluminum borate whisker reinforced cyanate ester resin

Aluminum borate whisker (AlBw) treated with γ‐methacryloxypropyltrimethoxy silane (KH550) and borate ester (BE4) was adopted to modify bisphenol A dicyanate/epoxy resin (BADCy/E‐51) system, in this article. The influence of coupling agent and content of whisker on reaction activity were investigated by gel time and differential scanning calorimeter (DSC) and the results showed that addition of whisker enhances reaction activity of BADCy/E‐51 system slightly. The dispersion of whisker in matrix and reinforcement mechanism was investigated by scanning electron microscope (SEM). Results reveal that whisker treated with BE4 had better dispersing than that treated with KH550 in resin. The thermal stability, mechanical properties, and hot–wet resistance of AlBw/BADCy/E‐51 resin system were also studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

氰酸酯树脂改性研究进展

氰酸酯树脂(CE)具有优异的介电性能、较高的玻璃化转变温度和强度、良好的耐化学腐蚀性和耐热性等优点,然而其固化物脆性较大,并且其韧性常常不能满足使用要求。从提高CE韧性角度,介绍了各种CE的改性方法(包括橡胶弹性体改性、热固性树脂改性、热塑性树脂改性和互穿聚合物网络改性等)及其应用研究进展。针对改性过程中存在的问题,提出了CE改性的未来发展方向。     

酚醛型环氧树脂改性氰酸酯复合材料性能的研究

通过DSC分析,粘度、介电性能、力学性能及耐油性测试对酚醛型环氧树脂改性氰酸酯树脂复合材料的性能进行了研究。结果表明,改性氰酸酯树体系在70～160℃具有较低的粘度,理想工艺是在125～130℃下30～45min后开始加压;改性氰酸酯树脂表观活化能和反应级数分别为60.81kJ/mol和0.8846。改性氰酸酯复合材料具有良好的力学性能、介电性能和耐油性能。     

Enhancement of processability of cyanate ester resin via copolymerization with epoxy resin

Two new matrices with enhanced processing characteristics, made from bisphenol A cyanate ester (BCE) and diglycidyl ether of bisphenol A epoxy resin or o‐cresol formaldehyde novolac epoxy resin, were developed. Solubility, differential scanning calorimetry (DSC), gel time, and tack experiments were used to detect the processing characteristics of the two new systems and neat BCE. Results show that the two new systems have enhanced processability compared with neat BCE, especially improved tack and drape properties of prepregs, and faster thermal polymerization rate. In addition, the two new cured systems have more than two times improved impact strength without a great decrease in excellent dielectric properties or thermal and hot–wet resistance of neat BCE resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2377–2381, 2002     

纳米碳化硅改性氰酸酯树脂研究

采用纳米碳化硅(nm-SiC)对氰酸酯树脂(CE)进行了改性,通过静态力学性能测试,TGA和DMA分析考察了nm-SiC含量对CE/nm-SiC复合材料性能的影响。结果表明,经硅烷偶联剂KH-560表面处理的nm-SiC更能有效地改善CE的力学性能和耐热性:相对纯CE,经KH-560表面处理的nm-SiC质量分数为1.00%的CE/nm-SiC复合材料的冲击强度和弯曲强度分别提高86.26%和29.56%,玻璃化转变温度由246℃提高到287℃,5%热失重温度由388℃提高到455℃。     

端羟基聚丁二烯改性氰酸酯体系固化反应动力学

采用示差扫描量热法(DSC)研究了端羟基聚丁二烯(HTPB)改性双酚A型氰酸酯树脂(BADCy)体系的固化反应动力学,根据Arrhenius方程对固化过程动力学参数进行了求解,建立了固化反应动力学模型。结果表明,随着HTPB含量的增大,动态DSC固化反应放热峰向低温方向移动,说明HTPB可以催化固化反应并降低体系的反应温度。纯BADCy和BADCy/15%HTPB体系等温固化符合自催化反应模型。纯BADCy体系以及BADCy/15%HTPB体系的表观反应活化能分别为59.67 kJ/mol、56.91 kJ/mol。     

Modification of cyanate ester resin by soluble polyimides

Soluble polyimides (PIs) were prepared as random or multiblock types with 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (s‐BPDA) as acid dianhydride components and 4,4′‐bis(m‐aminophenoxy) diphenyl sulfone (m‐BAPS) as a diamine component by a one‐pot process and used to improve the brittleness of the cyanate ester resin. Random‐type PIs were more effective as modifiers than multiblock‐type PIs. The morphologies of the modified resins depended on PI structure, molecular weight, and concentration. The most effective modification of the cyanate ester resin was attained because of a heterogeneous phase structure composed of a flat matrix phase and phase‐inverted structures of the modified resin; a 15 wt % inclusion of a random PI (weight‐average molecular weight = 63,400) composed of 6FDA, s‐BPDA, and m‐BAPS (0.5/0.5/1.0 molar ratio) led to a 65% increase in the fracture toughness for the modified resin with a slight loss of flexural strength and a retention of flexural modulus and glass‐transition temperature, compared with the values for the unmodified resin. Water absorptivity of the modified resin was comparable to that of the unmodified resin up to 400 h, and then, water absorption of the modified resins increased considerably. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1–11, 2003     

环氧改性氰酸酯树脂固化动力学的研究

采用示差扫描量热法(DSC)对缩水甘油醚类环氧树脂(E-51)与脂环族环氧树脂(R-122)共同改性的双酚A型氰酸酯(BADCy)树脂的固化反应历程进行了研究。由Kisserger方程求得共聚体系固化反应的表观活化能为60.5 kJ/mol,根据Crane理论求得固化反应级数为0.89,接近于1级反应。该体系起始固化温度为132.1℃,峰顶固化温度为168.7℃,终止固化温度为246.0℃。研究表明,环氧树脂可促进BADCy的固化,改性体系可在177℃以下实现较完全固化。     

氰酸酯树脂增韧改性研究

主要评述了目前氰酸酯树脂的几种增韧改性途径,其中包括与热固性树脂(EP、BMI、BMI/EP/CE)、热塑性塑料(PSU、PEI)、橡胶弹性体、含不饱和双键的化合物以及纳米粒子的插层增韧改性。同时,还讨论了改性氰酸酯树脂的发展方向及应用前景。     

Preparation and properties of maleimide‐functionalized hyperbranched polysiloxane and its hybrids based on cyanate ester resin

A new hyperbranched polysiloxane containing maleimide (HPMA) was synthesized through the reaction between N‐(4‐hydroxyphenyl) maleimide and 3‐glycidoxypropyltrimethoxysilane, which was then used to prepare cyanate ester (CE) resin‐based hybrids (coded as HPMAx/CE, where x is the weight fraction of HPMA in the hybrid). The curing behavior of uncured hybrids and the typical properties (impact strength and dielectric properties) of cured hybrids were systemically investigated. Results show that the performance of hybrids is greatly related with the content of HPMA. Hybrids have obviously lower curing temperature than CE, overcoming the poor curing characteristics (higher curing temperature and longer curing time) of neat CE, for example, the curing peak temperature of HPMA20/CE is about 65°C lower than that of CE. In the case of cured resin and hybrids, the hybrids exhibit decreased dielectric constant and loss than CE resin; moreover, the former also exhibits lower water absorption than the latter. Specifically, the dielectric loss of HPMA15/CE hybrid is only about 27% of that of neat CE resin. In addition, the hybrids with suitable contents of HPMA have significantly improved impact strengths. The overall improved properties suggest that HPMAx/CE hybrids have great potential in applications needing harsh requirements of curing feature, dielectric properties, and toughness. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Toughening of aromatic diamine-cured epoxy resins by modification with hybrid modifiers composed of N-phenylmaleimide–styrene copolymers and N-phenylmaleimide–styrene–p-hydroxystyrene terpolymers

Hybrid modifiers composed of N-phenylmaleimide–styrene copolymers (PMS), and N-phenylmaleimide–styrene–p-hydroxystyrene terpolymers (PMSH) containing pendent p-hydroxyphenyl groups as functionalities, were used to improve the toughness of bisphenol-A diglycidyl ether epoxy resin cured with p,p′-diaminodiphenyl sulphone. The hybrid modifiers were effective in toughening the epoxy resin. When using the modifier composed of 10 wt% PMS (M?_w 313000) and 2.5 wt% PMSH (2.5 mol% p-hydroxystyrene units, M?_w 316000), the fracture toughness (K_IC) for the modified resins increased 100% with no deterioration in the flexural properties and the glass transition temperature. The improvement in toughness of the epoxy resins was attained because of the co-continuous phase structure and the improvement in interfacial adhesion. The toughening mechanism is discussed in terms of the morphological characteristics of the modified epoxy resin systems.     

Morphology of pyrolysed polystyrene–isoprene–styrene and polystyrene–butadiene–styrene block copolymers

The surface morphology of thermooxidative degraded polystyrene–isoprene–styrene (SIS) and polystyrene–butadiene–styrene (SBS) thermoplastic block copolymers was studied by scanning electron microscopy. Surface changes caused by heating the samples in a pyrolyzer for 15 and 30 min were presented in different micrographs. The morphological changes occurring due to the formation of polar groups and their crosslinking during the thermooxidative degradation are discussed. Morphological study of these thermally degraded polymer samples shows very good correlation with the thermodegradation results. The rate of thermodegradation is fast in case of SBS when compared with SIS block copolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2549–2553, 2006