一种改性氰酸酯预聚体的合成和性能研究

将聚砜树脂(PSF)和双酚A型氰酸酯树脂(BCE)在一定条件下进行预聚反应,通过红外光谱(FT-IR)、差热扫描(DSC)、扫描电镜(SEM)对所得到的预聚体树脂及其固化后产物进行分析和表征。结果表明改性后的氰酸酯预聚体具有优异的力学性能和良好的介电性能。     

共聚改性氰酸酯树脂及其性能

利用环氧树脂和双马来酰亚胺树脂做改性剂,对氰酸酯树脂进行共聚改性,通过对粘度的测量描述了共聚树脂的固化反应情况。性能测试表明内聚改性氰酸酯树脂的冲击强度比纯氰酸酯树脂自聚体提高了2倍多,可达12.3kJ/cm^2,热变形温度高达235℃,并具有优异的介电性能,如10kHz 介电常数为2.25,介电损耗角正切＜10^-4。共聚树脂中的配比和固化条件对性能有影响。     

环氧改性氰酸酯树脂体系反应特性研究

采用FTIR研究了环氧改性氰酸酯树脂体系的固化反应特性。通过归一化处理,得到不同官能团在固化过程中的变化规律。结果表明,环氧树脂在低温下可促进氰酸酯官能团自聚,高温下可与三嗪环共聚生成噁唑啉结构;环氧和氰酸酯的不同配比决定生成产物的相对含量。     

复合材料光学镜面用氰酸酯基体树脂评价

通过示差扫描量热分析以及粘温特性、吸水率、耐热性和力学性能测试对现有商品化氰酸酯预聚体CY-3W、CY-5W和CY-10W的性能进行了研究。结果表明:3种氰酸酯预聚体的固化反应温度较高,峰值温度均在250℃以上。3种预聚体的粘度差值较大,CY-10W较适合光学镜面预浸料的成型工艺要求。CY-3W、CY-10W的耐湿性能优异(饱和吸水率1%),且均具有良好的耐热性(T_g240℃),但3种预聚体固化后力学性能较差,其中拉伸强度均低于50 MPa。     

聚硼硅氮烷固化氰酸酯基耐高温胶粘剂的制备与性能研究

以氰酸酯为基胶,聚硼硅氮烷前驱体为固化剂,复配相应的填料,制备了氰酸酯基耐高温胶粘剂。研究了聚硼硅氮烷用量对氰酸酯固化特性、固化产物的结构变化及固化物热稳定性的影响。研究结果表明：与传统的氰酸酯胶粘剂相比,聚硼硅氮烷催化氰酸酯的固化温度降低了50～100℃;聚硼硅氮烷可以催化氰酸酯在150℃低温固化,20份聚硼硅氮烷催化氰酸酯固化物T_5%最高达到476.3℃。以此为基础制备的耐高温胶粘剂的室温粘接强度最高为16 MPa,400℃老化3 h后粘接强度仍达到12 MPa,表明该胶粘剂具有较好的粘接性能和耐老化性能。本研究制备的胶粘剂凭借较低的固化温度、良好的粘接性能和耐温性,有望用于航空、航天和电子等行业。     

CTBN改性氰酸酯在高温发泡胶中的应用研究

以端羧基液体丁腈橡胶（CTBN）对双酚A型氰酸酯（BCE）增韧改性,制备了一种性能优异、贮存期长的预聚体,用此预聚体制备发泡胶膜,得到了综合性能优良的耐高温发泡胶。     

氰酸酯树脂热聚合反应与控制

用差热扫描分析四甲基双酚F型氰酸酯树脂的固化反应特性,用红外光谱跟踪其聚合反应过程,用阿贝折射仪监控氰酸酯树脂聚合反应过程中折光系数的变化情况.结果表明,四甲基双酚F型氰酸酯树脂的热均聚过程在160～200℃环境下反应过程缓慢,便于制作预聚体的工艺操作;常温状态呈琥珀状透明胶体的预聚体适宜的氰基转化率为36～38%;预聚体制作过程可以用树脂折光指数的变化情况进行控制,适宜的折光指数范围为1.5760～1.5820.     

双马来酰亚胺/氰酸酯/聚芳醚砜预聚物固化机理和动力学研究

通过FT-IR和DSC等对N,N-4,4’-二苯甲烷型双马来酰亚胺树脂(BMI)、双酚A型氰酸酯(BADCy)和聚芳醚砜(PES-C)的共固化反应进行研究。结果表明,固化过程前期的主反应是氰酸酯和双马来酰亚胺的自聚反应,固化反应进行2h以后,氰酸酯和双马来酰亚胺共聚反应成为主反应。动力学研究确定了树脂固化反应的活化能(Ea=70.765k J·mol-1),频率因子(ln A=16.6)和反应级数(n=0.923)。并根据动力学数据确定了树脂的固化条件。     

氰酸酯树脂结晶性研究

对氰酸酯树脂结晶性进行了研究。通过折光指数测试监控氰酸酯树脂预聚反应过程,采用凝胶色谱研究了预聚前后树脂的结构变化,通过差热扫描分析了氰酸酯体系结晶物的熔融相变。结果表明,随着预聚时间的延长,折光指数不断增加,氰酸酯树脂出现大量多聚体,结晶时间推迟;双酚E型单体的引入可降低氰酸酯树脂的熔点、增加熔限,阻止氰酸酯结晶过程。在双酚A型氰酸酯树脂中加入25%双酚E型单体,并在130℃下预聚55 m in,折光指数达1.5842时,共混体系可在室温下长时间保持液态,未出现结晶。     

一种双酚A型氰酸酯树脂流变特性及其改性研究

本文采用平板法研究了一种双酚A型氰酸酯树脂的流变特性,通过恒温预固化的方法对其进行改性,并借助红外光谱、差示扫描量热法(DSC)和凝胶渗透色谱法(GPC)等手段分析了预固化对氰酸酯树脂化学结构的影响.在此基础上,针对S-2玻璃纤维/氰酸酯复合材料层板,采用热压机工艺考察了加压时机和预固化对层板成型质量的影响.研究结果表明,该氰酸酯树脂反应活性低且流动性高,热压工艺中树脂流动不易控制;预固化可使氰酸酯树脂发生一定程度的自聚反应,从而降低其流动性,可明显改善氰酸酯树脂的工艺性,提高了层板的成型质量.     

双酚A氰酸酯和酚类的反应机理研究

通过高效液相色谱、质谱分析和核磁共振等方法研究双酚A型氰酸酯单体和酚类的反应机理,提出可能的反应方程式。研究结果表明,酚类在体系反应初期起到了催化作用,但在反应后期以亚胺碳酸酯的结构形式留在三维网络中,实际起到的是改性作用。酚类不仅可催化氰酸酯基团三环化,还可改性氰酸酯树脂。     

Triazine reaction of cyanate ester resin systems catalyzed by organic tin compound: kinetics and mechanism

The mechanism and kinetics of the thermal cure reaction of two cyanate esters (CEs), 1,1′bis(4‐cyanatophenyl)ethane (AroCy L‐10) and bisphenol A dicyanate ester (BADCy), in the presence of dibutyl tin dilaurate (DBTDL) has been investigated using Fourier‐transform infrared spectroscopy (FTIR) and High‐performance liquid chromatography (HPLC). It was found that the organic tin compound (H₉C₄)₂Sn(NCO—R—OCN)₂, an active catalyst, has high catalytic efficiency in the polymerization of cyanate esters. The consuming rate of cyanate concentration showed a first‐order dependence on both active catalyst and the cyanate ester monomer concentration. The apparent activation energies (E_a) and frequency factors of both AroCy L‐10 and BADCy were calculated. A mechanism of cyclotrimerization was proposed, based on the kinetic data and FTIR spectra, which involves the formation of an active catalyst and the catalysis of the active catalyst. Copyright © 2004 Society of Chemical Industry     

Cyanate ester polymerization catalysis by layered-silicates

This work examines the effect of Na montmorillonite (Na MMT) and cation exchanged layered montmorillonite on the polymerization of a cyanate ester monomer (1,1-bis(4-cyanatophenyl)ethane). The cyanate ester polymerization reaction is examined using a traditional catalyst and several montmorillonites. Thermal properties of the liquid monomer mixtures and final polymers were investigated, along with the montmorillonite structural changes that occur during the various stages of polymerization. It was found that Na montmorillonite catalyzed the polymerization reaction and that the catalytic activity increased upon sodium cation exchange in the montmorillonite gallery. Montmorillonite catalyzed systems were found to have superior properties (cross-link homogeneity and extent of polymerization) compared to traditionally catalyzed cyanate ester-montmorillonite polymers. Evidence suggests that the montmorillonite structure is a mixture of exfoliated layers and intercalated tactoids. The intercalated montmorillonite was found to undergo a two-step layer expansion process beginning with monomer permeation into the gallery, followed by expansion possibly caused by monomer/polymer reorientation within the gallery.     

Determination of thermal cure kinetics of thin films of photocatalysed dicyanate ester by FTIR emission spectroscopy

Emission Fourier transform infrared (FTIR) spectroscopy has been found to be a suitable technique for monitoring the thermal cure of thin films of photocatalysed dicyanate ester resins. The kinetics of the polymerization of a commercial cyanate ester resin (AroCy RTX‐366) catalysed by an organometallic compound, tricarbonyl cyclopentadienyl manganese (CpMn(CO)₃), have been determined using this technique and the results compared with those obtained from transmission FTIR. The trimerization reaction rate of the resin is found to have a first order dependence upon both the cyanate fraction and the active catalyst concentration until diffusion control occurs. To elucidate the mechanism, a system with premade catalyst, which was the photoreaction product of the resin and the organometallic compound, has also been studied. The activation energy for this system is 91 ± 10 kJ mol⁻¹ compared to 72 ± 8 kJ mol⁻¹ for the directly irradiated system. This may arise from different distributions of three photoproducts identified as complexes between manganese and the cyanate ester. © 2000 Society of Chemical Industry     

聚苯胺包覆纳米TiO_2/氰酸酯复合材料的介电性能

通过化学氧化原位聚合法制备了聚苯胺包覆纳米TiO2并将其通过溶液共混的方法添加到氰酸酯树脂中,制备了聚苯胺包覆纳米TiO2/氰酸酯复合材料。利用透射电子显微镜,观察了粒子在氰酸酯基体中的分散情况并采用FT-IR、XRD及TGA等手段对其进行了表征。研究了不同粒子添加量对氰酸酯复合材料介电性能的影响。结果表明,包覆了聚苯胺的纳米TiO2对氰酸酯复合材料的介电常数影响较小,但对介电损耗影响较大,粒子的添加量为3%时其介电损耗最大,且其最大吸收损耗峰从频率较低处转移到较高处。聚苯胺包覆纳米TiO2/氰酸酯复合材料有望成为1种新型吸波材料。     

Frontal polymerization of a cyanate ester

Thermal frontal polymerization is an exothermic process that uses a propagating wave to polymerize monomers via an external heat source, such as a soldering iron, to initiate front propagation. Herein, for the first time, the curing of a cyanate ester via thermal frontal polymerization is described with two different external heat sources. However, issues of bubbling due to vaporization of the amine catalyst generally resulted in incomplete frontal polymerization when a soldering iron was used as the external heat source. To counter this issue, dual‐strip polymerization systems were used, wherein the heat from the exothermic polymerization of a free‐radical system was used to initiate the frontal polymerization of a cyanate ester system with an amine catalyst. As a result, complete frontal polymerization occurred. Additionally, the effect of the width of the acrylate strip and its impact on the front temperature, initial velocity, and steady‐state velocity of the adjacent cyanate ester system were studied. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

氰酸酯树脂固化反应的研究概况

综述了目前氰酸酯树脂主要采用的几种固化反应类型以及反应机理,并简要指出了氰酸酯树脂今后的研究方向。     

Cure reaction and phase separation behavior of cyanate ester‐cured epoxy/polyphenylene oxide blends

The cure reaction and phase separation mechanism of a cyanate ester‐cured epoxy and its blends with polyphenylene oxide (PPO) were studied. An autocatalytic mechanism was observed for the epoxy and its blends. The reaction rate of the blends was higher than that of the neat epoxy at initial stage; however, the reached conversion decreased with PPO content. FTIR analysis revealed that the cyanate functional group reactions were accelerated by adding PPO and indicated that several coreactions have occurred. This was caused by the reaction of cyanate ester with the PPO reactive chain ends. But at a later stage of cure, the reaction could not progress further due to diffusional limitation of PPO. To understand the relationship between the cure kinetics and phase separation of the blends, the morphology of the blends during cure was examined. When the homogeneous epoxy/PPO blends with low PPO content (10 phr) were cured isothermally, the blends were separated by nucleation and growth (NG) mechanism to form the PPO particle structure. But at high PPO content (30 phr), the phase separation took place via spinodal decomposition (SD). SD is favored near critical concentration and high cure rate system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1139–1145, 2006     

Effect of cyanate ester on the cure behavior and thermal stability of epoxy resin

Epoxy resin (diglycidyl ether of bisphenol A, DGEBA)/cyanate ester mixtures were cured with a curing agent, 4,4′-diaminodiphenylsulfone, and the effect of cyanate ester resin on the cure behavior and thermal stability in the epoxy resin was investigated with a Fourier transform infrared spectrometer, a rheometer, a dynamic mechanical analyzer, and a thermogravimetric analyzer. Cure reactions in the epoxy/cyanate ester mixture were faster than that of the neat epoxy system. The cure reaction was accelerated by increasing the cyanate ester resin component. Glass transition temperature and thermal stability in the cured resins were increased with increasing cyanate ester resin component. This may be caused by the increase of crosslinking density due to the polycyclotrimerization of the cyanate ester monomer to form triazine rings and the reaction of cyanate ester resin with the epoxy network. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 85–90, 1997     

Synthesis and characterization of novel low‐dielectric cyanate esters. II

A novel cyanate ester, 2,6‐dimethyl phenol dipentene cyanate ester (DPCY), was successfully synthesized from cyanogen bromide with 2,6‐dimethyl phenol dipentene novolac, which was synthesized from dipentene and 2,6‐dimethyl phenol. For the purpose of increasing the mobility of residual DPCY during the final stage of curing and achieving a complete reaction of cyanate groups, a small quantity of a monofunctional cyanate ester, 4‐tert‐butyl phenol cyanate ester, was added to DPCY to form a cyanate ester copolymer. The thermal properties of the cured cyanate ester resins were studied by dynamic mechanical analysis, dielectric analysis, and thermogravimetric analysis. These data were compared with those of the commercial bisphenol A cyanate ester system. The cured modified cyanate ester exhibited a dielectric constant of 2.59–2.50, a dissipation factor of 0.0055–0.0089, and moisture absorption of 0.91–1.17%; these values were all lower than those of the as‐cured bisphenol A dicyanate system. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 369–379, 2005