bisphenol-A Cyanate Ester Research Articles

Fast pyrolysis bio-oil from lignocellulosic biomass for the development of bio-based cyanate esters and cross-linked networks

Fast pyrolysis of pine wood was carried out to yield a liquid bio-oil mixture that was separated into organic and aqueous phases. The organic phase (ORG-bio-oil) was characterized by gas chromatography–mass spectroscopy, 31P-nuclear magnetic resonance spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. It was further used as a raw material for producing a mixture of biphenolic compounds (ORG-biphenol). ORG-bio-oil, ORG-biphenol, and bisphenol-A were reacted with cyanogen bromide to yield cyanate ester monomers. Cyanate esters were characterized using FTIR spectroscopy and were thermally cross-linked to develop thermoset materials. Thermomechanical properties of cross-linked cyanate esters were assessed using dynamic mechanical analysis and compared with those of cross-linked bisphenol-A-based cyanate ester. ORG-biphenol cyanate ester was observed to have a superior glass transition temperature (350–380°C) as compared to bisphenol-A cyanate ester (190–220°C). Cyanate esters derived from bio-oil have the potential to be a sustainable alternative to the bisphenol-A-derived analog.

Calixarene–based cyanate ester resin for high-temperature material

p-tert-Butylcalix[4]arene-derived cyanate ester resins, both single and binary systems, were synthesized and studied for their thermal properties. The results showed that pure calixarene cyanate ester can be thermally cured at comparatively high temperature, which remains in original powder state after thermally cured. So the pure calixarene cyanate ester resin fails to meet the processing demands of resin-matrixed composite. In this work, p-tert-butylcalix[4]arene cyanate ester was chemically functionalized to have highly decreased thermal cure temperature (by copolymerization with epoxy, bisphenol A cyanate ester (BPACE), and polysilazane (PSZ), respectively). The binary resins were thermally cured into monolithic materials. The optimal acceleration of thermal cure reaction was achieved with an addition of 10% PSZ. The addition of epoxy resin decreased thermal resistance and carbon yield of p-tert-butylcalix[4]arene cyanate ester and addition of BPACE slightly decreased thermal resistance and carbon yield, while PSZ highly improved thermal resistance and carbon yield. Glass transition temperature of the co-cured resin of calixarene cyanate ester with 10% PSZ was much higher than that of conventional BPACE. Calixarene cyanate ester possesses much better property than that of conventional BPACE resin.

Toughening of cyanate resin with low dielectric constant by glycidyl polyhedral oligomeric silsesquioxane

In this article, a high-performance hybrid material was prepared by melt blending from glycidyl polyhedral oligomeric silsesquioxane (G-POSS) and bisphenol-A cyanate ester (CE), using triethylamine as the curing agent. The structure of the hybrid was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM), and the transparency properties, mechanical properties, dielectric properties, thermal performance, and wet fastness were studied. The results showed that G-POSS was uniformly distributed in the CE matrix and could obviously accelerate the curing reaction of the resin. Large amounts of corrugated and scaled structures were observed on the fractures of G-POSS/CE by the SEM photos. When the G-POSS content increased to 7 phr, the tensile strength (75.45 MPa), elongation at break (3.19%), and impact strength (23.76 kJ m−2) reached maximum values, representing increases of 21.75%, 27.6%, and 157.98% relative to that of pure CE, respectively, which indicated that the addition of G-POSS can significantly improve the toughness of G-POSS/CE composites. When the G-POSS content increased to 4 phr, the dielectric constant decreased from 3.27 to the minimum value of 3.05. The heat resistance and wet fastness of G-POSS/CE hybrid materials decreased with increasing G-POSS content.

Cyanate ester tethered POSS/BACY nanocomposites for low-k dielectrics

Low-k dielectrics have been developed as an interlayer insulating material in the large scale integrated circuitry devices by the copolymerization of various weight percentages (10, 20, 30, and 40 wt%) of cyanate ester tethered POSS (POSS-OCN) and bisphenol-A cyanate ester (BACY) to obtain BACY/POSS-OCN nanocomposites. The reinforcement of POSS-OCN significantly contributes to the reduction in the value of dielectric constant and dielectric loss as well, which might be due to the presence of porous structured POSS-OCN. The 30 wt% POSS-OCN/BACY nanocomposite possesses the lowest value of dielectric constant of 1.81 at 1 MHz. Copyright © 2016 John Wiley & Sons, Ltd.

Fabrication and properties of BADCy/Ni0.5Ti0.5NbO4/ZnNb2O6 composites for dielectric device application

In this study, we developed a new route to fabricate polymer/ceramic composites. This method mainly involves tape casting and vacuum assist infiltration (called TC-VI). Composites, using Bisphenol-A cyanate ester resin (BADCy) as matrix and mixed dielectric ceramic powders (1−x) Ni0.5Ti0.5NbO4 + x ZnNb2O6 (x = 0–100 vol. %) as fillers, were prepared successfully by this route. Dielectric properties and thermal conductivity of the composites were tested. Furthermore, the migration of silver (Ag) electrodes in the composites was investigated. Results show that the composites exhibit excellent dielectric properties. Dielectric constant of the composites can be adjusted continuously from 13.49 to 22.46 (at 9045 MHz). Dielectric loss is lower than 3.68 × 10−3 (at 7320 MHz). The addition of ceramic fillers can significantly enhance the thermal conductivity of BADCy resin. Moreover, no obvious Ag element migration can be detected in the composites. Due to the good performances of the composites, this method could be widely used in the fabrication of multilayer devices.

Dielectric properties of BADCy/Ni0.5Ti0.5NbO4 composites with novel structure fabricated by freeze casting combined with vacuum assisted infiltration process

Abstract Bisphenol-A cyanate ester resin (BADCy)/Ni 0.5 Ti 0.5 NbO 4 composites with novel structure, within which Ni 0.5 Ti 0.5 NbO 4 and BADCy are continuous directional distribution and parallel to the electric field direction (marked as composite-directional), were designed and fabricated using freeze casting combined with vacuum assisted infiltration process. Dielectric properties as well as the moisture absorption of the composites were studied. Theoretical models used to predict the dielectric properties of the composites were established. Results show that the novel structure can significantly improve the dielectric constant while decrease dielectric loss compare with traditional structure in which Ni 0.5 Ti 0.5 NbO 4 filler is homogeneously distributed (the composite marked as composite-homogeneous). Dielectric constant of composite-directional is as high as 19.93 while dielectric loss is only 4.07 × 10 −3 (at 7319 MHz) when Ni 0.5 Ti 0.5 NbO 4 content is 43.79 vol%. Furthermore, the dielectric constant of both composite-directional and composite-homogeneous can be predicted using Rother-Lichtenecker model when the fitting parameters ( n ) are −0.5188 and −0.1499, respectively. Distribution state of Ni 0.5 Ti 0.5 NbO 4 is the main reason for the difference of fitting parameters. Due to the excellent properties of composite-directional, this kind of composites can be used as printed circuit board (PCB) materials.

Fabrication and dielectric properties of BADCy/Ni0.5Ti0.5NbO4 composites for ultra-low-loss printed circuit board application

Ni0.5Ti0.5NbO4 was firstly reported as filler to adjust dielectric properties of polymer matrix composites for printed circuit board (PCB) application. In this study, the Ni0.5Ti0.5NbO4 filler was modified using γ-aminopropyl triethoxy silane (KH550). The effects of KH550 on particle lipophilicity and Bisphenol-A cyanate ester resin (BADCy) curing behavior were studied. BADCy/Ni0.5Ti0.5NbO4 composites were fabricated by the traditional casting method. The dielectric properties and moisture absorption of the composites were tested. Results show that most hydrophilic groups on the surface of Ni0.5Ti0.5NbO4 powder are replaced by lipophilic groups after modification, which results in the obvious improvement of Ni0.5Ti0.5NbO4 filler dispersion in BADCy. Beyond that, surface modification also greatly affects the curing behavior of BADCy resin. The BADCy/Ni0.5Ti0.5NbO4-KH550 composites exhibit excellent dielectric properties as well as low moisture absorption. Furthermore, the dielectric constant can be accurately predicted using Effective Medium Theory (EMT model) when the morphology factor is 0.1407.

High-k and ultra-low-loss BADCy/Ni0.5Ti0.5NbO4 composites for PCB application fabricated by cold isostatic pressing and vacuum assisted infiltration processes

A simple method, which include cold isostatic pressing and vacuum assisted infiltration, that can significantly improve the filler content, was employed to fabricate Bisphenol-A cyanate ester resin (BADCy)/Ni0.5Ti0.5NbO4 composites with high-k and ultra-low-loss. Results show that briquetting pressure and sintering temperature for fabricating Ni0.5Ti0.5NbO4 porous preforms have a great influence on the properties of BADCy/Ni0.5Ti0.5NbO4 composites. The optimal process for the fabrication of BADCy/Ni0.5Ti0.5NbO4 composites is fixing the briquetting pressure at 90 MPa and sintering temperature at 700 °C. The dielectric constant and loss of the composites are 22.79 and 4.17 × 10−3 at 9041 MHz, respectively. Properties of this kind of composites can meet the requirements for high-k and ultra-low-loss PCB application.

Preparation and characterization of carbon foams from cyanate ester mixtures

Carbon foams were prepared by direct pyrolysis of cyanate ester (CE) resins from the mixtures of phenol novolac cyanate ester (PNCE) and bisphenol A cyanate ester (BACE) at ambient pressure. Pyrolysis behaviors of the CE resins were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). In addition, influences of PNCE/BACE mass ratio on the characteristics of the resultant carbon foams were studied. Results show that the CE resin possesses better thermal stability with increasing PNCE/BACE mass ratio, whereas its self-foaming performance becomes worse during pyrolysis. The addition of PNCE to BACE leads to an increase in the bulk density of the resultant carbon foam but a decrease in both its porosity and open cell. Moreover, the compressive strength of the carbon foam increases with an increase in the PNCE/BACE. When the PNCE/BACE mass ratio varies from 0 to 0.75, the compressive strength of the carbon foam prepared increases from 3.25 to 9.6MPa.

A facile synthesis of cyanate ester silica hybrid nanocomposites by in situ sol-gel method

High performance cyanate ester—silica hybrid nanocomposites were prepared using the sol—gel method through in situ reaction. The methodology adopted here was the formation of a covalent bond between the bisphenol-A cyanate ester (CE) and silica matrix utilizing γ-aminopropyltriethoxysilane (γ-APS) as coupling agent. The covalent bond formation in the hybrid was confirmed by Fourier transform infrared analysis and solvent extraction. Thermal and morphological properties of the hybrid materials were investigated by differential scanning calorimetry, thermogravimetric analysis and scanning electron microscopy. The CE—silica hybrids show improved thermal properties. The double degradation curves observed from thermogravimetric analysis may be due to the weak adduct linkage and the cleavage of the triazine ring in the hybrid. The nitrogen porosimetry study confirmed the molecular level dispersion of cyanate ester in the cyanate ester—silica hybrid nanocomposites.

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

AbstractTwo 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