Dielectric and thermal properties of polymer network based on bismaleimide resin and cyanate ester containing dicyclopentadiene or dipentene. III

A series of bismaleimide‐triazine (BT) resins were prepared from commercial bismaleimide (DDMBMI) and 2,6‐dimethylphenol‐dicyclopentadiene dicyanate ester (DCPDCY) or 2,6‐dimethylphenol‐dipentene dicyanate ester (DPCY). The thermal properties of cured BT resins containing DCPD or DP were studied using a dielectric analyzer (DEA), dynamic mechanical analyzer (DMA), and thermal gravimetric analyzer (TGA). These data were compared with that of DDMBMI cured with bisphenol A dicyanate ester (BADCY). The cured DDMBMI/DCPDCY or DDMBMI/DPCY exhibits a lower dielectric constant, dissipation factor, and moisture absorption than those of DDMBMI/BADCY. The effects of blend composition on the glass transition temperatures and thermal stability are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1942–1951, 2007     

Dielectric behavior and properties of a cyanate ester containing dicyclopentadiene. I

2,6‐Dimethyl phenol dicyclopentadiene dicyanate ester (DCPDCY) was synthesized through the reaction of 2,6‐dimethyl phenol dicyclopentadiene novolac and cyanogen bromide. The proposed structure was confirmed by Fourier transform infrared, mass spectrometry, NMR spectrometry, and elemental analysis. DCPDCY was then cured by itself or cured with bisphenol A dicyanate ester (BADCY) to form triazine structures. The thermal properties of the cured DCPDCY resins were studied with differential scanning calorimetry, dynamic mechanical analysis (DMA), dielectric analysis, and thermogravimetric analysis; these data were compared with those of BADCY. The cured DCPDCY resins exhibited a lower dielectric constant (2.58 at 1 MHz), a lower dissipation factor (20.2 mU at 1 MHz), less thermal stability (the 5% degradation temperature and char yield were 430°C and 32.1%, respectively), a lower glass‐transition temperature (266°C by thermomechanical analysis and 271°C by DMA), a lower coefficient of thermal expansion (22.5 ppm before the glass‐transition temperature and 124.9 ppm after the glass‐transition temperature), and less moisture absorption (0.88% at 48 h) than BADCY, but they showed higher moduli (6.28 GPa at 150°C and 5.35 GPa at 150°C) than the bisphenol A system. The properties of the cured cocyanate esters (DCPDCY and BADCY) lay between those of cured BADCY and DCPDCY, except for the moduli. The moduli of some cocyanate esters were even higher than those of cured BADCY and DCPDCY. A positive deviation from the Fox equation was observed for cocyanate esters. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2079–2089, 2005     

Synthesis and properties of bismaleimide resin containing dicyclopentadiene or dipentene. VI

New aromatic bismaleimides (BMIs), bis(4‐maleimidophenoxy‐3,5‐dimethylphenyl)dicyclopentadiene (DCPDBMI) and bis(4‐maleimido‐phenoxy‐3,5‐dimethylphenyl)dipentene (DPBMI), containing a large dicyclopentadiene (DCPD) or dipentene (DP) and aryl ether linkage, were synthesized from diamine bis(4‐aminophenoxy‐3,5‐dimethylphenyl)dicyclopentadiene (DCPDA) or bis(4‐aminophenoxy‐3,5‐dimethylphenyl)dipentene(DPA) and maleic anhydride by the usual two‐step procedure that included ring‐opening addition to give bismaleamic acid, followed by cyclodehydration to bismaleimide. The monomers were characterized by Fourier transform infrared spectroscopy, proton NMR, elemental analyses, and mass spectra. Their thermal polymerization was investigated by DSC. The presence of a large cycloaliphatic moiety in the backbone of the bismaleimide increased the curing temperature and reduced the reactivity of the maleimide bond. Thermal and electrical properties of cured bismaleimide resins were studied using a dielectric analyzer, dynamic mechanical analyzer, and thermal gravimetric analyzer. These data were compared with that of commercial 4,4‐bismaleimidodiphenylmethane (DDMBMI). The cured DCPDBMI or DPBMI exhibits a lower dielectric constant, dissipation factor and moisture absorption than those of DDMBMI. Copyright © 2006 Society of Chemical Industry     

Thermal behavior and properties of naphthalene containing bismaleimide–triazine resins

A series of bismaleimid·triazine (BT) resins were prepared from various dicyanate esters and 2,7-bis(4-maleimidophenoxy)naphthalene (BMPN), which contains a naphthalene group and an aryl ether linkage in the backbone. Their curing behaviors were characterized by differential scanning calorimetry. The exotherm temperature and polymerization reactivity were strongly affected by the chemical structure of the various dicyanate ester monomer. Thermal behaviors were investigated by thermogravimetric analyses and dynamic mechanical analyses. The glass transition temperatures (T_g) of these cured resins with bismaleimide/dicyanate ester at the 1/2 molar ratio were in the range of 250–322°C, and exhibited excellent thermal stability up to 400°C in nitrogen. These results provided a structure–properties relationship for the cured bismaleimid·triazine resins. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1199–1207, 1998     

二烯丙基双酚A改性双马来酰亚胺三嗪树脂的固化工艺及性能

以烯丙基化合物改性的方法制得了改性双马来酰亚胺三嗪(BT)树脂,研究了改性BT树脂体系的固化动力学,求得表观活化能为45.9 kJ/mol,反应级数为0.842,确定了固化工艺,并采用力学性能分析和动态热机械分析等手段对树脂浇铸体的性能进行了研究.结果表明,对于烯丙基化合物改性BT树脂体系,二烯丙基双酚A具有改善双马来...     

Synthesis and properties of novel dicyanate with low dielectric and water absorption performance

The 1,4‐bis (3,5‐dimethyl‐4‐cyanatobenzyl) benzene (BBZCy) was synthesized successfully by the reaction of 1,4‐bis (3,5‐dimethyl‐4‐hydroxybenzyl)benzene(BBZ) with cyanogen chloride in the presence of triethylamine at −5–0°C. Its structure was confirmed by means of FTIR, elemental analysis, MS, and ¹H NMR spectra. The monomer of BBZCy was cured by itself or cured with catalysts to form sym‐triazine structure. Thermal properties of cured BBZCy were studied using DSC, DMA, TMA, and TGA. Compared with the commercial bisphenol A dicyanate resin (BADCy), the cured BBZCy resin exhibited a lower dielectric constant (2.66 at 1 GHz), a lower dissipation factor (0.0054 at 1 GHz), lower water absorption (0.8% at 100 h), less thermal stability, and lower glass transition temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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     

新型的单官能团氰酸酯改性氰酸酯树脂的研究

本文制备了新型的腰果酚型氰酸酯单体(CNSLCY),并用红外和质谱进行表征,研究了双酚A型氰酸酯(BADCY)/CNSLCY树脂改性体系.通过研究CNSLCY改性BADCY树脂性能发现,CNSLCY的引入可以提高BADCY的韧性、介电性能和耐吸水性能,而对其热性能降低则影响不大.     

Study on cure reaction of the blends of bismaleimide and dicyanate ester

In this work, the cure reaction of the blends of bisphenol A dicyanate ester (BADCy) and 4,4′-bismaleimidodiphenylmethane (BMI) was investigated by using DSC, in situ FTIR, DMA and generalized 2D correlation analysis. The results clarified that there existed different kinds of cure mechanism in the blends of bismaleimide and dicyanate ester. In non-catalyzed blends, the dicyanate ester and bismaleimide cured independently and formed two kinds of network: polycyanurate and polybismaleimide. A cyanate curing catalyst accelerated the cure of dicyanate ester but did not change the independent cure mechanism of two components. Moreover a commercial ring closure catalyst, which was usually used in the synthesis of bismaleimide, resulted in the co-reaction between two components and formed a homogeneous network. Thus, the cure mechanism of the blends of dicyanate ester and bismaleimide was related to the catalyst presented in the blends systems.     

Fabrication and properties of CTBN/Si3N4/cyanate ester nanocomposites

Hybrid fillers of carboxyl‐terminated liquid butadiene‐acrylonitrile/silicon nitride (CTBN/Si₃N₄) are performed to regulate the mechanical properties, heat resistance properties, dielectric properties and thermal conductivities of the bisphenol A dicyanate ester (BADCY) resins. With the 10 wt% addition of CTBN/Si₃N₄ hybrid fillers, the maximum impact, and flexural strength of the CTBN/Si₃N₄/BADCY nanocomposite is increased to 15.4 kJ/m² and 144.3 MPa, respectively. And the corresponding thermal conductivity value of the CTBN/Si₃N₄/BADCY nanocomposite is increased to 0.622 W/mK with 18 wt% addition of CTBN/Si₃N₄ hybrid fillers. Moreover, with the addition of CTBN/Si₃N₄ hybrid fillers, the heat resistance properties of the CTBN/Si₃N₄/BADCY nanocomposites are increased, but the dielectric properties get worse slightly. POLYM. COMPOS., 37:2522–2526, 2016. © 2015 Society of Plastics Engineers     

Catalyst effect on cure reactions in the blend of aromatic dicyanate ester and bismaleimide

Catalyst effects on cure reactions of a bismaleimide [4,4′‐bismaleimidodiphenylmethane (BMI)] associated with a liquid aromatic dicyanate ester [1,1′‐bis(4‐cyanatophenyl)ethane (BEDCy)] and with a powder type of aromatic dicyanate ester [bisphenol A dicyanate (BADCy)] were thoroughly investigated by in situ FTIR and DSC dynamic scanning. In noncatalyzed blend systems, coreactions between the dicyanate ester and bismaleimide always occur, and thus the formation of the pyrimidine and/or pyridine structures occurs. The pyrimidine structure always predominates. The use of a dicyanate‐sensitive catalyst facilitates the formation of a sequential interpenetrating network (IPN). The extent of the sequential IPN depends on the level of catalyst and the type of matrix materials, and thus the extent of coreactions. Probable reaction paths were also proposed for various formulations of hybrid blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 345–354, 2004     

High glass transition temperature bismaleimide‐triazine resins based on soluble amorphous bismaleimide monomer

A novel bismaleimide (DOPO‐BMI) with unsymmetrical chemical structure and DOPO pendant group has been prepared. The particular molecular structure makes DOPO‐BMI show an intrinsic amorphous state with a T_g about 135°C and excellent solubility in most organic solvents, which is beneficial to the processability of bismaleimide composite materials. A series of bismaleimide‐triazine (BT) resins have been prepared based on DOPO‐BMI and 2,2‐bis(4‐cyanatophenyl)propane at various weight ratios. The prepared BT resins show outstanding solubility in organic solvent and low viscosity about 10–671 mPa s at 180°C. The cured BT resins exhibit high glass transition temperature (T_g) over 316°C. As the weight ratio of DOPO‐BMI increases to 80% (BT80), the T_g can rise to 369°C (tan δ). The cured BT resins also show good thermal stability with the 5% weight loss temperature over 400°C under both nitrogen and air atmosphere. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42882.     

Low dielectric thermoset. I. Synthesis and properties of novel 2,6‐dimethyl phenol‐dicyclopentadiene epoxy

A 2,6‐dimethyl phenol‐dicyclopentadiene novolac was synthesized from dicyclopentadiene and 2,6‐dimethyl phenol, and the resultant 2,6‐dimethyl phenol‐dicyclopentadiene novolac was epoxidized to 2,6‐dimethyl phenol‐dicyclopentadiene epoxy. The structures of novolac and epoxy were confirmed by Fourier transform infrared spectroscopy (FTIR), elemental analysis, mass spectroscopy (MS), nuclear magnetic resonance spectroscopy (NMR), and epoxy equivalent weight titration. The synthesized 2,6‐dimethyl phenol‐dicyclopentadiene epoxy was then cured with 4,4‐diaminodiphenyl methane (DDM), phenol novolac (PN), 4,4‐diaminodiphenyl sulfone (DDS), and 4,4‐diaminodiphenyl ether (DDE). Thermal properties of cured epoxy resins were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), dielectric analysis (DEA), and thermal gravimetric analysis (TGA). These data were compared with those of the commercial bisphenol A epoxy system. Compared with the bisphenol A epoxy system, the cured 2,6‐dimethyl phenol‐ dicyclopentadiene epoxy resins exhibited lower dielectric constants (～3.0 at 1 MHz and 2.8 at 1 GHz), dissipation factors (～0.007 at 1 MHz and 0.004 at 1 GHz), glass transition temperatures (140–188°C), thermal stability (5% degradation temperature at 382–404°C), thermal expansion coefficients [50–60 ppm/°C before glass‐transition temperature (T_g)], and moisture absorption (0.9–1.1%), but higher modulus (～2 Gpa at 60°C). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2607–2613, 2003     

双马来酰亚胺／氰酸酯树脂的研究进展

双马来酰亚胺树脂／氰酸酯树脂（BT树脂）是一种高性能热固性树脂,综合了氰酸酯树脂与双马来酰亚胺树脂的优良性能,应用领域广泛。阐述了BT树脂的固化机理及现有的改性研究思路。并且对我国BT树脂的发展进行了展望。     

Thermal and dielectric properties of bismaleimide‐triazine resins containing octa(maleimidophenyl)silsesquioxane

Octa(maleimidophenyl)silsesquioxane (OMPS) was synthesized, characterized, and employed to modify the BT resin which composed of 4,4′‐bismaleimidodiphenylmethane (BMI) and 2,2′‐bis(4‐cyanatophenyl)propane (BCE). The curing reaction between OMPS and BT resin was first investigated. It was found that OMPS accelerate the curing reaction of BCE, and the onset temperature of the cyclotrimerization was reduced up to 95.5°C (by DSC). As demonstrated by DSC and FTIR, there was no evidence that indicated the coreaction between maleimide and cyanate ester. 2,2′‐diallyl bisphenol A (DBA) and diglycidyl ether of bisphenol A (E‐51) (Wuxi Resin Factory, Jiangsu Province, China) were also used to enhance the toughness of BT resin, and the formulated BTA (containing DBA) and BTE (containing E‐51) resins were obtained. The thermal properties of BT, BTA, and BTE resins incorporated with OMPS were then investigated. The results of DMA and TG showed that the BT, BTA, and BTE resins containing 1 wt % of OMPS exhibit enhanced thermal properties in comparison with their pristine resins respectively, while more contents of OMPS may impair the thermal properties of the polymer matrix, though the effect of OMPS was slight. Finally, the dielectric constant of these hybrid materials were detected, and their dielectric constant were distinctly reduced by the incorporation of OMPS, while overmuch contents of OMPS were disadvantageous for dielectric constant because of the aggregation of OMPS. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Blends of bisphenol A‐based cyanate ester and bismaleimide: Cure and thermal characteristics

A dicyanate ester, namely, 2,2‐bis‐(4‐cyanatophenyl)propane, and a bismaleimide, namely, 2,2‐bis[4‐(4‐maleimido phenoxy)phenyl]propane, possessing closely resembling backbone structures, were cured together to derive bismaleimide–triazine network polymers of varying compositions. The blend manifested a eutectic melting behavior at a 1 : 1 composition with a eutectic melting point of 15°C. The cure characterization of the blends was done by DSC and dynamic mechanical analyses (DMA). The near simultaneous cure of the blend could be transformed to a clear sequential one by catalyzing the dicyanate cure to lower temperature using dibutyl tin dilaurate. The two‐stage, independent cure of the components of the blend evidenced in DSC was confirmed by DMA. The cure profile of the bismaleimide component predicted from the kinetic data derived from nonisothermal DSC was found to be in league with the isothermal DMA behavior. Both techniques led to optimization of the cure schedule of the blends. The cured polymers were characterized by FTIR and TGA. The cured blends underwent decomposition in two stages, each corresponding to the polycyanurate and polybismaleimide. Enhancing the bismaleimide component did not alter the initial decomposition temperature, but led to reduced rate of thermal degradation at higher temperature. Interlinking of the two networks and enhancing crosslink density through coreaction of the blend with 4‐cyantophenylmaleimide unaffected the initial decomposition properties but was conducive for increasing the char residue significantly. Computation of activation parameters for the thermal decomposition of the polymers confirmed that the first step in the degradation of the blends is caused by the polycyanurate component. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3365–3375, 1999     

Synthesis of novel phosphorus-containing cyanate esters and their curing reaction with epoxy resin

Novel phosphorus-containing cyanate esters with phosphorus contents between 1-4% (badcyp_x, x=1-4) were synthesized from the addition reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (dopo) and bisphenol A dicyanate (badcy). The structures of synthesized cyanate ester resins were confirmed by NMR and IR spectra. The modified cyanate esters were either self-curing (badcy and badcyp_x series) or curing with epoxy (badcye and badcyp_xe series). Thermal properties of cured cyanate ester were evaluated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermal gravimetric analysis (TGA), dielectric analyzer (DEA) and UL-94 vertical test. It was found that T_g and T_d (5%) decrease markedly with the phosphorus content for the self-curing system, while T_g and T_d (5%) decrease slightly with the increase of cyanate equivalent weight for the cyanate-epoxy curing system. The flame retardancy increases with the phosphorus content and a UL-94 V-0 rating can be achieved for cured badcyp₂-badcyp₄ and badcyp₃e-badcyp₄e. These flame retardant thermosets exhibit low moisture absorption as well as low dielectric constants and dissipation factors. Experimental results indicate that introducing the flame retardant phosphorus element into cyanate ester will not sacrifice its low dielectric characteristic.     

Flame retardancy and dielectric properties of dicyclopentadiene‐based benzoxazine cured with a phosphorus‐containing phenolic resin

A dicyclopentadiene‐based benzoxazine (DCPDBZ) was prepared and separately copolymerized with melamine–phenol formaldehyde novolac or phosphorus‐containing phenolic resin (phosphorus‐containing diphenol) at various molar ratios. Their curing behaviors were characterized by differential scanning calorimetry. The electrical properties of the cured resins were studied with a dielectric analyzer. The glass‐transition temperatures were measured by dynamic mechanical analysis. The thermal stability and flame retardancy were determined by thermogravimetric analysis and a UL‐94 vertical test. These data were compared with those of bisphenol A benzoxazine and 4,4′‐biphenol benzoxazine systems. The effects of the diphenol structure and cured composition on the dielectric properties, moisture resistance, glass‐transition temperature, thermal stability, and flame retardancy are discussed. The DCPDBZ copolymerized with phosphorus‐containing novolac exhibited better dielectric properties, moisture resistance, and flame retardancy than those of the melamine‐modified system. The flame retardancy of the cured benzoxazine/phosphorus‐containing phenolic resins increased with increasing phosphorus content. The results indicate that the bisphenol A and 4,4′‐biphenol systems with a phosphorus content of about 0.6% and the dicyclopentadiene system with a phosphorus content of about 0.8% could achieve a flame‐retardancy rating of UL‐94 V‐0. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis,cure kinetics,and thermal properties of the Bis(3‐allyl‐2‐cyanatophenyl)sulphoxide/BMI blends

A novel allyl functionalized dicyanate ester resin bearing sulfoxide linkage was synthesized. The monomer was characterized by Fourier Transform Infrared (FT‐IR) Spectroscopy, ¹H‐, and ¹³C Nuclear Magnetic Resonance (NMR) spectroscopy and elemental analysis. The monomer was blended with bismaleimide (BMI) at various ratios in the absence of catalyst. The cure kinetics of one of the blends was studied using differential scanning calorimetry [nonisothermal] and the kinetic parameters like activation energy (E), pre‐exponential factor (A), and the order of the reaction (n) were calculated by Coats‐Redfern method and compared with those calculated using the experimental Borchardt‐Daniels method. The thermal stability of the cured dicyanate, BMI, and the blends was studied using thermogravimetric analyzer. The initial weight loss temperature of dicyanate ester is above 380°C with char yield of about 54% at 800°C. Thermal degradation of BMI starts above 463°C with the char yield of about 68%. Inclusion of BMI in cyanate ester increases the thermal stability from 419 to 441°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of epoxy‐functionalized hyperbranched poly(phenylene oxide) and its modification of cyanate ester resin

High curing temperature is the key drawback of present heat resistant thermosetting resins. A novel epoxy‐functionalized hyperbranched poly(phenylene oxide), coded as eHBPPO, was synthesized, and used to modify 2,2′‐bis (4‐cyanatophenyl) isopropylidene (CE). Compared with CE, CE/eHBPPO system has significantly decreased curing temperature owing to the different curing mechanism. Based on this results, cured CE/eHBPPO resins without postcuring process, and cured CE resin postcured at 230°C were prepared, their dynamic mechanical and dielectric properties were systematically investigated. Results show that cured CE/eHBPPO resins not only have excellent stability in dielectric properties over a wide frequency range (1–10⁹Hz), but also show attractively lower dielectric constant and loss than CE resin. In addition, cured CE/eHBPPO resins also have high glass transition temperature and storage moduli in glassy state. These attractive integrated performance of CE/eHBPPO suggest a new method to develop high performance resins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012