Cyanate Ester Resin Composites Research Articles

Bismaleimide and Biobased Limonene Copolymer Microspheres as Reactive Fillers to Fabricate Low-k, High-Toughness Cyanate Ester Resin Composites

Bismaleimide and Biobased Limonene Copolymer Microspheres as Reactive Fillers to Fabricate Low-<i>k</i>, High-Toughness Cyanate Ester Resin Composites

Novel multifunctional microcapsule and its cyanate ester resin composites with self‐healing ability and gamma radiation shielding ability

Resin-based composites used in spacecraft face risks from space debris and high-energy charged particles during their long-term service in the space environment. This work proposes a novel microcapsule (MC) and its cyanate ester (CE) resin-based composites (CE/MCs) with self-healing ability and gamma radiation shielding ability. The multifunctional epoxy/lead tungstate (EP@PWO) microcapsules are developed through self-assembly method and in-situ precipitation method. These microcapsules and curing agent 4,4′-diaminodiphenylsulfone (DDS) are incorporated into the CE resin to form resin-based composites with low curing temperature, self-healing ability, and gamma radiation shielding ability. Various approaches including chemical characterizations (X-ray diffractometer, fourier-transform infrared, energy dispersive spectrometer), microscopy (optical microscope, scanning electronic microscope), and thermal analysis (differential scanning calorimeter, thermogravimetric analysis) are utilized to demonstrate the successful encapsulation of the EP resin by PWO shell and good thermal stability of this material. The mechanical property, self-healing ability, and gamma radiation shielding property are investigated via fracture toughness test and using a NaI (Tl) spectrometer. In comparison with pure CE resin, the fracture toughness of the CE/MCs composites can increase by 66.5%, and the self-healing efficiency can reach up to 56%, indicating that the microcapsules have good toughening and self-healing abilities. The microcapsules and their composites also exhibit good gamma radiation shielding properties.

The nature of the exceptional impact of ultra‐low silica contents on the properties of cyanate ester resin‐based nano‐ and subnanocomposites

AbstractOur study clarifies the nature of the exceptional impact of the ultra‐low content of silica (SiO2) units on the properties of the heterocyclic cyanate ester resin (CER) network matrix in the subnano‐ or nanocomposites. To this effect, we have performed a series of calculations of average distances between SiO2 units and the interfacial area values in the composites as functions of the content and size of SiO2 units. The estimates were made for the CER composites with SiO2 and POSS additives, based on these calculations and the composites' previously measured structural characteristics. It was found that the aforementioned unusual effect was controlled by the constrained interfacial matrix dynamics in the composites. Thus, when (a) the SiO2 content was 0.03–0.1 wt%, (b) SiO2 units and the matrix network had covalent bonding, and (c) SiO2 units had quasi‐regular distribution in the amorphous matrix (as found for the subnanocomposites), we found that distances between SiO2 units equaled 6 and 10 nm, that is, these distances were commensurable with the lengths of Kuhn segments in heterocyclic macromolecules.

Mechanical, thermal and ablative behavior of organo nanoclay added carbon fiber/cyanate ester resin composites and effect of heat flux on its ablative performance

Nanoclay added cyanate ester resin (Type I) composites were fabricated by adding different weight percentages (0,1,2,4 &amp; 6 wt%) of organo-modified Montmorillonite (o-MMT) and tested for dispersion by Small angle X-ray scattering(SAXS), thermal stability using Thermogravimetric analyser (TGA) and curing behavior using Differential scanning calorimeter (DSC). This data was correlated with the thermomechanical properties of nanoclay added carbon fiber reinforced cyanate ester resin composites (C-CE composites /Type II). Interlaminar shear strength (ILSS), flexural strength of type II composites increased by about17%, 21% respectively at 2 wt% addition of nanoclay although at this loading nanoclay was found to show intercalation.Thermal stability of type II composites got reduced whereas the ablation rate has increased for type II composites with increased loading of nanoclay. However, percentage increase in ablation rate was found to be lower when type II composites were tested at 5000 kWm−2as compared to the ablation testing carried out at 1250 kWm−2. Scanning electron microscopy studies indicates significant melting of nanoclay at high flux resulting in additional protection mechanisms for the composites at high flux. Present study indicates the possibility of using o-MMT nanoclay for improved mechanical properties of C-CE composites used in thermal protection systems (TPS).

Investigations on the effect of plasma treatment on the adhesive bonding behavior of ultra high modulus K13C2U/cyanate ester fiber composites

Surface preparation of ultra-high modulus fiber composites for adhesive bonding is challenging due to the subsurface damages that can occur during a standard abrasion operation that could weaken the laminate cohesion. Therefore, it is highly desirable to utilize a non-contact method that can clean and activate the composite surface without exerting an external force to eliminate potential damage. This investigation focuses on the use of atmospheric plasma treatment (APT) for the surface preparation of unidirectional ultra-high modulus, composites for adhesive bonding. The laminates were manufactured using Mitsubishi K13C2U pitch-based carbon fiber with Tencate’s RS-3C cyanate-ester resin and bonded with Henkel 9394 epoxy. Surface analysis of plasma-treated samples revealed a significant reduction of surface contamination and increased chemical modification of the matrix material resulting in improved wetting and the formation of chemical groups conducive to bonding. The plasma treatment also produced a minor increase in surface roughening, well below levels expected to contribute to mechanical interlocking. APT epoxy-bonded lap-shear specimens (LSS) exhibited a 50% increase in strength as compared to mechanically abraded samples. It was also shown that solvent rinsing after APT removed a highly-oxidized, poorly bonded carbonate component from the treated resin surface as evidenced by XPS. This surface ash is observed at fairly high concentrations after APT of cyanate ester resin composites limiting functional group contributions. The removal of this ash resulted in increases in LSS of 25% as compared to unrinsed APT surfaces. Lap shear strengths and GIC delamination resistance tests showed improvements over abrasion surface treated samples. Image analysis of the fracture faces for both surface treatments showed that abrasion treated surfaces resulted in sub-surface damage to the fibers that translated into brittle fracture through weak, highly aligned layers within these graphitic fibers. On the other hand, plasma treatment was successfully applied to minimize subsurface damage and resulted in crack propagation along with the more tortuous fiber-matrix interface. The degree of the improvements was ultimately limited by the interlaminar strength of these composites.

Dielectric and mechanical properties of polyimide fiber reinforced cyanate ester resin composites with varying resin contents

Polyimide (PI)/ bisphenol A dicyanate esters (BADCy) composite laminates with varying resin contents were prepared by filament winding and autoclave molding process. The laminates exhibited ultralow dielectric constant (e of 3.15–3.25) and dielectric loss (tanδ of 0.004–0.006) as well as excellent mechanical properties. When the resin content was 35.6%, the composite achieved outstanding comprehensive properties with tensile strength and modulus equal to 1485.1 MPa and 80.9 GPa, respectively, and the inter-laminar shear strength (ILSS) up to 66.2 MPa. The failure mode of laminates followed an explosive gage middle (XGM) mechanism, which suggested a favorable interface between fiber and resin. According to the mixed law equation, PI fiber at a frequency of 10.2 GHz exhibited dielectric constant of 3.41 ± 0.03 and dielectric loss of about 0.002–0.004. The successful preparation of PI fiber reinforced BADCy composite with low dielectric constant provides new ideas for material design and selection of lightweight high-strength structural-functional integrated composites.

Modulating topological structure of carbon nanotube/cyanate ester-boron nitride/cyanate ester multi-layered composites for enhancing dielectric properties, breakdown strength and energy density

Constructing multi-layered structures based on insulating layers and conductor/polymer composites is proved to be an effective strategy of preparing high dielectric constant conductor/polymer composites with suppressed dielectric loss, high breakdown strength and high energy density; however, up-to-date, researches are mainly focused on three-layer structures, the influence of the layer number on dielectric properties, breakdown strength and energy density of multi-layered composites has not been clearly elaborated yet. Starting from a typical three-layer structure composite (CBC) with outstanding integrated performance using carbon nanotube (CNT)/cyanate ester resin (CE) and hexagonal boron nitride (BN)/CE composites as C layer and B layer, respectively, new four-layer structure (CBCB) and five-layer structure (CBCBC and BCBCB) composites were fabricated to reveal the role and mechanism of layer number and BN content, consequently finding a new technique to get multi-layered composites with better integrated performances. Results show that when the content of BN in B layer is 20 wt%, the five-layer structure composite (CBC20BC) achieves the highest energy density, about 6264% higher than that of 0.4CNT/CE, this improvement of energy density is the maximum value among all multi-layered composites based on conductor/polymer layer reported so far. In addition, the dielectric constant of CBC20BC composite is as high as 352 (100 Hz), and the breakdown strength of CBC20BC composite is 1.4 times of that of CBC composite. The mechanism behind these excellent integrated performances is that the increase in layer number not only enhances the interfacial polarization, but also extends the length and tortuosity of breakdown path.

Adamantane-Modified Graphene Oxide for Cyanate Ester Resin Composites with Improved Properties

The conjugation of graphene and polymers has attracted great attention for the fabrication of functional hybrid nanomaterials. Here, we demonstrate the modification of graphene oxide (GO) with adamantane (AMT) through the diimide-activated amidation reaction. The modification of GO with AMT improves the dispersion and decreases the interfacial polarization of GO, causing a lower dielectric constant for the fabricated GO/AMT hybrid materials. The structures of GO/AMT were studied by Fourier transform infrared spectroscopy and Raman spectroscopy. Furthermore, the mechanical properties, thermal stability, and dielectric constant of GO/AMT composites were measured at a low cured temperature using various techniques, such as differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis. It was found that the synthesized GO/AMT materials with different contents were blended into cyanate ester (CE) resins, resulting in a lower cure temperature, smaller dielectric constant, higher thermal stability, and stronger water resistance. It is expected that this novel GO/AMT-CE material will have potential applications for replacing traditional thermosetting resins.

Investigation on thermal stability and tribological properties of ZrB2 particles filling cyanate ester resin composites by experiments and numerical simulation

The thermal stability and tribological properties of cyanate ester (CE) composites filled with Zirconium boride (ZrB2) particles were investigated by experimental and numerical simulation. The results of thermogravimetric analysis and differential scanning calorimetry showed that the thermal stability of composites was improved by introduction of ZrB2 particles. The tribological properties of composites including friction coefficient and wear rate measured by pin‐on‐disk friction and wear tester were enhanced. Friction coefficient and wear rate of composites were decreased significantly with an increase of ZrB2 particles content under dry and oil sliding conditions. The 5 wt% ZrB2 particles reinforced CE resin composite presented optimal thermal stability and tribological performance due to good dispersion of ZrB2 particles. The worn surfaces of composites were observed by scanning electron microscopy to explore wear mechanism, indicating that the dominant wear mechanism of composites was transformed from adhesive wear to abrasive wear after incorporation of ZrB2 particles. Finite element model was established to study the distribution of friction stress. The results revealed that filling ZrB2 particles in the friction process of composites could bear more friction stress than CE resin matrix, which further illustrated that abrasive wear is main wear mechanism of ZrB2/CE resin composites. POLYM. ENG. SCI., 59:602–607, 2019. © 2018 Society of Plastics Engineers

Influences of surface modification of nano-silica by silane coupling agents on the thermal and frictional properties of cyanate ester resin

Abstract The surface of nano-silicon dioxide (nano-SiO2) particles was modified by small molecular coupling agent KH-560 and macromolecular coupling agent SEA-171, respectively, to change the surface activity and structure. The modified nano-SiO2 was then used for reinforcing cyanate ester resin (CE). Influences of the content of nano-SiO2 and the interfacial structure over the thermal and frictional properties of nano-SiO2/CE composites were investigated. The mechanism of the surface modification of silicon dioxide by KH-560 and SEA-171 was discussed. The experimental results show that the addition of coupling agents increased the interfacial bonding between nano-SiO2 particles and the CE resin so that the heat resistance and friction properties of the composites were improved. After surface treatment of nano-SiO2 by SEA-171, the thermal decomposition temperature of the 3.0 wt% nano-SiO2/CE composites increased nearly by 75 °C and the frictional coefficient was reduced by 25% compared with that of the pure CE, and the wear resistance increased by 77%.

Research of Functional Graphene Nanosheets Modified Carbon Fiber Reinforced Cyanate Ester Resin Composites on Thermal and Electrical Conductivities Properties

Research of Functional Graphene Nanosheets Modified Carbon Fiber Reinforced Cyanate Ester Resin Composites on Thermal and Electrical Conductivities Properties

Unique pure barium titanate foams with three-dimensional interconnecting pore channels and their high-k cyanate ester resin composites at very low barium titanate loading

High-k ceramic/polymer composites containing very low ceramic loading were developed through synthesizing pure barium titanate foams with a unique structure.

Thermal Conductivity Cyanate Ester Resin Composites Filled with Boron Nitride

Boron nitride (BN) powder was modified by silane coupling agent, and a series of cyanate ester resin composites containing the modified BN were prepared. The effect of volume fraction of BN on the thermal conductivity, electrical insulation properties of these composites was investigated. Results show that addition of a little of BN powder can improve thermal conductivity of the composites effectively, while the composites still retain the relatively good electrical insulation and low dielectric constant. When the volume fraction of BN was 23.6%, the thermal conductivity of composite increased to 1.33 W/(m·K), which is 4.6 times that of pure resin.

Effects of moisture and thermal cycling on in-plane shear properties of graphite fibre-reinforced cyanate ester resin composites

The weight change and retention of in-plane shear (±45°) strength of graphite fibre-reinforced cyanate ester resin matrix composites have been estimated on exposure to high humidity and thermal cycling, respectively. Cyanate ester resin matrix composites absorbed a remarkably small amount of moisture on exposure to high humidity. However, the degree of moisture absorption underwent a rather sudden increase to a new equilibrium level after prolonged exposure. A morphology study showed the occurrence of extensive cracking in the matrix/interface region in the form of delamination between plies as well as translaminar cracking within plies. The phenomenon is believed to be caused by weakening of the fibre-matrix interface, which was confirmed by microscopic analysis of fracture surfaces. A sudden moisture gain associated with extensive matrix/interface cracking was found to reduce the in-plane shear strength and fatigue lifetime at a given stress amplitude. The slope of the S-N curve was lower for wet specimens, implying a higher growth rate of local cracks as well as delamination. The rate of in-plane shear strength degradation was also measured on static exposure to dry heat as well as after thermal cycling to a peak temperature of 150 or 204°C. At a frequency of 10 min/cycle and for a relatively short duration, the effect of thermal cycling seems to be represented by the cumulative sum of thermal oxidation effects at the peak temperature.