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Michael R. Kessler - One of the best experts on this subject based on the ideXlab platform.
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multifunctional Cyanate Ester nanocomposites reinforced by hexagonal boron nitride after noncovalent biomimetic functionalization
ACS Applied Materials & Interfaces, 2015Co-Authors: Michael R. KesslerAbstract:Boron nitride (BN) reinforced polymer nanocomposites have attracted a growing research interest in the microelectronic industry for their uniquely thermal conductive but electrical insulating properties. To overcome the challenges in surface functionalization, in this study, hexagonal boron nitride (h-BN) nanoparticles were noncovalently modified with polydopamine in a solvent-free aqueous condition. The strong π–π interaction between the hexagonal structural BN and aromatic dopamine molecules facilitated 15 wt % polydopamine encapsulating the nanoparticles. High-performance bisphenol E Cyanate Ester (BECy) was incorporated by homogeneously dispersed h-BN at different loadings and functionalities to investigate their effects on thermo-mechanical, dynamic-mechanical, and dielectric properties, as well as thermal conductivity. Different theoretical and empirical models were successfully applied to predict thermal and dielectric properties of h-BN/BECy nanocomposites. Overall, the prepared h-BN/BECy nanocomp...
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injection repair of carbon fiber bismaleimide composite panels with bisphenol e Cyanate Ester resin
Composites Science and Technology, 2014Co-Authors: Amy Bauer, Mahendra Thunga, Kristine Obusek, Michael R. Kessler, Mufit Akinc, Ray MeilunasAbstract:Resin injection of bisphenol E Cyanate Ester, a low viscosity resin that cures into a high temperature thermoset polymer, is investigated as a reliable repair method to restore strength and stiffness in delaminated carbon fiber/bismaleimide composites used in aircraft panels. The influence of temperature on the viscosity of the uncured resin was measured to optimize the injection conditions for high resin infiltration into the delaminations. The repair efficiency of the resin was evaluated by varying the panel thickness and the method by which the delamination damage was created in the composite specimens. Ultrasonic scanning (C-scan), flash thermography images, and cross-section analysis of repaired panels revealed excellent resin infiltration into the damaged region. Evaluation of mechanical repair efficiency using both bending stiffness and in-plain compressive strength of the composite panels as the repair metrics showed values exceeding 100%.
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low viscosity Cyanate Ester resin for the injection repair of hole edge delaminations in bismaleimide carbon fiber composites
Composites Part A-applied Science and Manufacturing, 2013Co-Authors: Mahendra Thunga, Mufit Akinc, Wilber Y Lio, Kelsey Larson, Thilina Weerasekera, Michael R. KesslerAbstract:M. Thunga, K. Larson, W. Lio, T. Weerasekera, M. Akinc, M. R. Kessler: Low Viscosity Cyanate Ester Resin for the Injection Repair of Hole-edge Delaminations in Bismaleimide/Carbon Fiber Composites, Composites Part A: Applied Science and Manufacturing, 2013, 52, 31-37. doi:10.1016/j.compositesa.2013.05.001.
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bisphenol e Cyanate Ester as a novel resin for repairing bmi carbon fiber composites influence of cure temperature on adhesive bond strength
Polymer, 2013Co-Authors: Amy Bauer, Mahendra Thunga, Kristine Obusek, Michael R. Kessler, Mufit AkincAbstract:A. Bauer, M. Thunga, K. Obusek, M. Akinc, M. R. Kessler: Bisphenol E Cyanate Ester as a Novel Resin for Repairing BMI/Carbon Fiber Composites: Influence of Cure Temperature on Adhesive Bond Strength, Polymer, 2013, 54 (15), 3994-4002. doi:10.1016/j.polymer.2013.05.030.
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multifunctional properties of Cyanate Ester composites with sio2 coated fe3o4 fillers
ACS Applied Materials & Interfaces, 2013Co-Authors: Weixing Sun, Michael R. Kessler, Wuzhu Sun, Nicola Bowler, K W Dennis, William R Mccallum, Xiaoli TanAbstract:SiO2 coated Fe3O4 submicrometer spherical particles (a conducting core/insulating shell configuration) are fabricated using a hydrothermal method and are loaded at 10 and 20 vol % into a bisphenol E Cyanate Ester matrix for synthesis of multifunctional composites. The dielectric constant of the resulting composites is found to be enhanced over a wide frequency and temperature range while the low dielectric loss tangent of the neat Cyanate Ester polymer is largely preserved up to 160 °C due to the insulating SiO2 coating on individual conductive Fe3O4 submicrometer spheres. These composites also demonstrate high dielectric breakdown strengths at room temperature. Dynamic mechanical analysis indicates that the storage modulus of the composite with a 20 vol % filler loading is twice as high as that of neat resin, but the glass transition temperature considerably decreases with increasing filler content. Magnetic measurements reveal a large saturation magnetization and negligibly low coercivity and remanent m...
Guozheng Liang - One of the best experts on this subject based on the ideXlab platform.
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self constructed nanodomain structure in thermosetting blend based on the dynamic reactions of Cyanate Ester and epoxy resins and its related property
Composites Part B-engineering, 2019Co-Authors: Song Chen, Li Yuan, Zehao Wang, Guozheng LiangAbstract:Abstract A new strategy to obtain nanodomain structure in thermoset/thermoset blends was developed via different dynamic reactions of Cyanate Ester (CE) and epoxy (EP) resins in the presence of zinc (II) acetylacetonate and glutaric anhydride. The resulting polymer systems show high mechanical property mainly attributed to EP nanophase and the excellent interfacial interaction between EP nanophase and CE matrix. Owing to the broad glass transition, the polymer systems display thermally activated triple shape memory effects in the temperature ranges of 150–225 °C. Moreover, the systems exhibit thermal self-healing behavior resulting from the transEsterification and possible reactions between the residual Cyanate Ester and epoxy groups, and a 78–83% recovery of fracture toughness for the resulting polymers can be achieved after the first healing schedule of 200 °C/2 h.
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preparation and mechanism of high energy density Cyanate Ester composites with ultralow loss tangent and higher permittivity through building a multilayered structure with conductive dielectric and insulating layers
Journal of Physical Chemistry C, 2019Co-Authors: Ruijua Gong, Li Yua, Guozheng LiangAbstract:High energy density polymer composites with ultralow loss tangent and higher permittivity for embedded capacitors are urgently required by new generation printed circuit boards. Herein, starting from a conductive layer (C-layer) with negative dielectric permittivity, a dielectric layer (D-layer) with positive dielectric permittivity, and insulating layer (I-layer), six multilayer composites, coded as DCI, CDI, IDCI, DCICD, DCIDC, and CDIDC according to their spatial stacking order, were prepared; among them, the C-layer is a graphite/polyvinylidene fluoride composite, the D-layer is a reduced graphene oxide–(K0.5Na0.5)NbO3/Cyanate Ester composite, and the I-layer is a boron nitride/Cyanate Ester composite. The effects of relative position and spatial stacking order of three-, four- and five-layer structures on performances were intensively discussed for the first time. Results show that CDIDC has the highest dielectric permittivity (886, 100 Hz) and biggest dielectric ratio of dielectric permittivity to l...
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cure kinetics of Cyanate Ester resin using microencapsulated dibutyltin dilaurate as catalyst
Polymer Bulletin, 2017Co-Authors: Yi Zhang, Feng Chen, Li Yuan, Guozheng LiangAbstract:Dibutyltin dilaurate (DBTDL) catalyst-filled microcapsules (MCs) were used to catalyze the reaction of thermosetting Cyanate Ester (CE) resins. Dynamic differential scanning calorimetry (DSC) experiments were performed at multiple heating rates (β) to investigate the effects of the MC content (0.125, 0.25, and 0.5 %) on the cure kinetics of CE resins. The kinetic parameters of CE/MC systems, including activation energy (Ea), preexponential factor (A), and reaction order (n), were analyzed using the Flynn–Wall–Ozawa method, Kissinger method, Crane method, Ozawa isoconversional method, and Coats–Redfern method. The results indicate that, as the MC content increases, the reaction temperature of CE/MC system gradually shifts to low temperature owing to the increase of the DBTDL catalyst released from MCs under heating conditions. Compared to the unencapsulated DBTDL, the encapsulated DBTDL can decrease the Ea, A, and the reaction rate constant of CE resins due to the gradual release of DBTDL from MCs and the homogeneous dispersion of the released DBTDL in CE resins. The Ea, A, and the reaction rate constant of CE/MC systems are effectively adjusted by the MC content and heating process. The reaction orders for all CE/MC systems are close to 1. The reaction model of CE/MCs is considered as a two-dimensional nucleation (A2).
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dielectric properties and mechanism of composites by superposing expanded graphite Cyanate Ester layer with carbon nanotube Cyanate Ester layer
Composites Science and Technology, 2014Co-Authors: Binghao Wang, Guozheng Liang, Yicheng Jiao, Li YuanAbstract:Abstract Electronic conductor/polymer composites with high dielectric constant have great potential in many cutting-edge fields, but they usually show high dielectric loss. Here, new composites (MWCNT/CE–5.0EG/CE) were prepared by superposing a multi-wall carbon nanotube (MWCNT)/Cyanate Ester (CE) composite layer with another expanded graphite (EG)/CE composite of which the loading of EGs is set as the percolation threshold (5.0 wt%) through a two-step curing procedure. No resin fault is observed at the interface between the two layers. The electrical and dielectric properties of MWCNT/CE–5.0EG/CE composites with different loadings of MWCNTs were studied. Results show that the conductivity of MWCNT/CE–5.0EG/CE composite intervenes between those of the two layers, and closes to the value of the layer with lower conductivity. Besides, when the loading of MWCNTs is 0.5 wt%, the 0.5MWCNT/CE–5.0EG/CE composite has the highest dielectric constant (up to 486 at 1 Hz) among the two-layer composites, about 4 and 1.5 times that of 0.5MWCNT/CE and 5.0EG/CE composite, respectively. Meanwhile the dielectric loss tangent of the 0.5MWCNT/CE–5.0EG/CE composite is only 1.2% or 50% of that of 0.5MWCNT/CE or 5.0EG/CE composite. The nature behind these interesting data was elucidated by investigating space charge distributions, discussing the space charge polarization and establishing equivalent circuit.
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a Cyanate Ester microcapsule system with low cure temperature and self healing capacity
Composites Science and Technology, 2013Co-Authors: Guozheng Liang, Li Yuan, Sidi Huang, Feng Chen, Steven NuttAbstract:Abstract Microcapsules filled with epoxy resin were blended into Cyanate Ester resin to produce systems with low cure temperature and self-healing capacity. A 4,4′-diaminodiphenylsulfone (DDS) curing agent was adopted for the systems. The mechanical properties, thermal stability and self-healing ability of the system cured at low temperature were investigated. Cyanate Ester systems with 2.5 wt% and 5.0 wt% microcapsules (MCs) demonstrated an 11~43% increase in fracture toughness ( K IC ) relative to the neat resin cured at high temperature, and exhibited slightly lower thermal stability than the neat resin. The self-healing ability of Cyanate Ester with MCs was influenced by MC content and healing temperature, although for a formulation with 5.0 wt% MCs, recovery of 85% of the original fracture toughness was achieved by heat treatment of fractured samples for 1 h at 220 °C.
Guanhui Wang - One of the best experts on this subject based on the ideXlab platform.
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Blends of Cyanate Ester and Phthalonitrile–Polyhedral Oligomeric Silsesquioxane Copolymers: Cure Behavior and Properties
MDPI AG, 2019Co-Authors: Fei Zhou, Ting Zheng, Ziqiao Wang, Heng Zhou, Haoran Chen, Lin Xiao, Dongxing Zhang, Guanhui WangAbstract:Blends of Cyanate Ester and phthalonitrile–polyhedral oligomeric silsesquioxane copolymers were prepared, and their cure behavior and properties were compared via differential scanning calorimetry (DSC) analysis, thermogravimetric (TG) analysis, dynamic mechanical analysis, Fourier-transform far-infrared (FTIR) spectroscopy, and rheometric studies. The copolymer blends showed high chemical reactivity, low viscosity, and good thermal stability (TG temperatures were above 400 °C). The glass-transition temperature of the blends increased by at least 140 °C compared to Cyanate Ester resin. The blends are suitable for preparing carbon-fiber-reinforced composite materials via a winding process and a prepreg lay-up process with a molding technique. The FTIR data showed that the polymerization products contained triazine-ring structures that were responsible for the superior thermal properties
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blends of Cyanate Ester and phthalonitrile polyhedral oligomeric silsesquioxane copolymers cure behavior and properties
Polymers, 2019Co-Authors: Fei Zhou, Ting Zheng, Ziqiao Wang, Heng Zhou, Haoran Chen, Lin Xiao, Dongxing Zhang, Guanhui WangAbstract:Blends of Cyanate Ester and phthalonitrile–polyhedral oligomeric silsesquioxane copolymers were prepared, and their cure behavior and properties were compared via differential scanning calorimetry (DSC) analysis, thermogravimetric (TG) analysis, dynamic mechanical analysis, Fourier-transform far-infrared (FTIR) spectroscopy, and rheometric studies. The copolymer blends showed high chemical reactivity, low viscosity, and good thermal stability (TG temperatures were above 400 °C). The glass-transition temperature of the blends increased by at least 140 °C compared to Cyanate Ester resin. The blends are suitable for preparing carbon-fiber-reinforced composite materials via a winding process and a prepreg lay-up process with a molding technique. The FTIR data showed that the polymerization products contained triazine-ring structures that were responsible for the superior thermal properties.
Steven Nutt - One of the best experts on this subject based on the ideXlab platform.
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a Cyanate Ester microcapsule system with low cure temperature and self healing capacity
Composites Science and Technology, 2013Co-Authors: Guozheng Liang, Li Yuan, Sidi Huang, Feng Chen, Steven NuttAbstract:Abstract Microcapsules filled with epoxy resin were blended into Cyanate Ester resin to produce systems with low cure temperature and self-healing capacity. A 4,4′-diaminodiphenylsulfone (DDS) curing agent was adopted for the systems. The mechanical properties, thermal stability and self-healing ability of the system cured at low temperature were investigated. Cyanate Ester systems with 2.5 wt% and 5.0 wt% microcapsules (MCs) demonstrated an 11~43% increase in fracture toughness ( K IC ) relative to the neat resin cured at high temperature, and exhibited slightly lower thermal stability than the neat resin. The self-healing ability of Cyanate Ester with MCs was influenced by MC content and healing temperature, although for a formulation with 5.0 wt% MCs, recovery of 85% of the original fracture toughness was achieved by heat treatment of fractured samples for 1 h at 220 °C.
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hybrid network structure and mechanical properties of rodlike silicate Cyanate Ester nanocomposites
Macromolecules, 2008Co-Authors: Yongzheng Pan, Yuliang Yang, Wei Chen, Steven NuttAbstract:Silicate nanorods (attapulgite, ATT) were organically modified and homogeneously dispersed in a Cyanate Ester (CE) resin. ATT dispersions and networks were characterized by rheological and microscopic measurements. Amine groups grafted onto the particle surface catalyzed the cyclotrimerization of the CE monomers and enabled the CE monomers to enter the inter-rod spacing of loose aggregates easily, resulting in homogenization of the particle size distribution in the nanocomposites. The addition of nanorods decreased the density of organic networks and increased intracyclizations. Covalent bonding at the interface was confirmed by Fourier transform infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMA), which establishes a basis for enhancing/optimizing mechanical properties of CE resins. Nanocomposite modulus, strength, and toughness increased 40, 42, and 55%, respectively, relative to the neat resin, although high nanorod loadings (e.g., 8 wt %) showed negligible benefit. The interplay between...
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hybrid network structure and mechanical properties of rodlike silicate Cyanate Ester nanocomposites
Macromolecules, 2008Co-Authors: Yongzheng Pan, Yuliang Yang, Wei Chen, Steven NuttAbstract:Silicate nanorods (attapulgite, ATT) were organically modified and homogeneously dispersed in a Cyanate Ester (CE) resin. ATT dispersions and networks were characterized by rheological and microscopic measurements. Amine groups grafted onto the particle surface catalyzed the cyclotrimerization of the CE monomers and enabled the CE monomers to enter the inter-rod spacing of loose aggregates easily, resulting in homogenization of the particle size distribution in the nanocomposites. The addition of nanorods decreased the density of organic networks and increased intracyclizations. Covalent bonding at the interface was confirmed by Fourier transform infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMA), which establishes a basis for enhancing/ optimizing mechanical properties of CE resins. Nanocomposite modulus, strength, and toughness increased 40, 42, and 55%, respectively, relative to the neat resin, although high nanorod loadings (e.g., 8 wt %) showed negligible benefit. The interplay between nanorod and resin networks governed the mechanical properties of the nanocomposites. The curing reaction decreased the size of particle aggregates and thus reduced the percolation threshold of particle networks. Particle networks induced the formation of more linear or branching polymer molecular structures, resulting in weaker particle-matrix interactions. These factors reduced the stress transfer efficiency and crack propagation resistance, impairing the extent of reinforcing at high particle loadings.
W.k. Goertzen - One of the best experts on this subject based on the ideXlab platform.
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thermal expansion of fumed silica Cyanate Ester nanocomposites
Journal of Applied Polymer Science, 2008Co-Authors: W.k. Goertzen, Michael R. KesslerAbstract:The thermal expansion behavior of a Cyanate Ester matrix reinforced by fumed silica nanoparticles with average primary particle diameters of 12 and 40 nm was investigated with thermomechanical analysis. All nanocomposites showed decreased coefficients of thermal expansion (CTEs) in comparison with the neat bisphenol E Cyanate Ester resin, but the 12-nm fumed silica nanocomposites had lower CTEs than the 40-nm nanocomposites for equal volume fractions. The largest decrease in CTE was 27.0% for 20.7 vol % 40-nm fumed silica. When the data were compared to applicable theory, the best fit of the data was given by Schapery's upper limit and Shi's model. Estimates of the interphase volume fraction and effective thickness surrounding the nanoparticles were made with the results of Shi's model, and the results showed that the interphase volume fraction was larger for the 12-nm fumed silica nanocomposites, given an equal fraction of silica. The glass-transition temperature of the nanocomposites from thermomechanical analysis varied only slightly with the volume fraction. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
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dynamic mechanical analysis of fumed silica Cyanate Ester nanocomposites
Composites Part A-applied Science and Manufacturing, 2008Co-Authors: W.k. Goertzen, Michael R. KesslerAbstract:Fumed silica particles with average primary particle diameters of 12 and 40 nm were combined with a low viscosity bisphenol E Cyanate Ester resin to form composite materials with enhanced storage modulus and reduced damping behavior, as evidenced by dynamic mechanical analysis (DMA). The storage modulus increased with volume fraction of fumed silica in both the glassy and rubbery regions, but the increase was more pronounced in the rubbery region. The maximum increase in storage modulus in the glassy region was 75% for 20.7 vol% of 40 nm fumed silica, while the same composition showed a 231% increase in the rubbery storage modulus. Furthermore, decreases in damping behavior were used to estimate the effective polymer-particle interphase thickness. The glass transition temperature of the nanocomposites was not changed significantly with increasing volume fraction.
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rheology and curing kinetics of fumed silica Cyanate Ester nanocomposites
Polymer Engineering and Science, 2008Co-Authors: W.k. Goertzen, Mufit Akinc, Xia Sheng, Michael R. KesslerAbstract:A low-viscosity bisphenol E Cyanate Ester (BECy) monomer was combined with fumed silica with average primary particle diameters of 12 and 40 nm to form high-temperature adhesives with processability at ambient temperatures. Rheological evaluation revealed that for silica loadings below 15 vol%, suspensions of both particle sizes exhibited shear thinning and thixotropic behavior. Samples with high silica loadings (>15 vol%) of 40-nm silica also showed intense shear thickening at shear rates above 10 s−1. Thixotropy was most pronounced for the 12-nm silica, but the formation of a gel was slow, indicating that the polar nature of the BECy monomer was responsible for disrupting hydrogen bonds between silica particles. Rheokinetic evaluation of catalyzed samples showed that increasing silica content reduced gel time and increased gel viscosity, and this effect was most pronounced for the 12-nm silica. Differential scanning calorimetry confirmed that the silica's hydroxyl groups have a minor catalytic effect on the polymerization kinetics, such that the activation energies of the catalyzed suspensions were decreased with increased nanoparticle loading and decreased particle size. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
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thermal and mechanical evaluation of Cyanate Ester composites with low temperature processability
Composites Part A-applied Science and Manufacturing, 2007Co-Authors: W.k. Goertzen, Michael R. KesslerAbstract:Abstract A low viscosity bisphenol E Cyanate Ester monomer was used as a reactive diluent in a bisphenol A/novolac Cyanate Ester to achieve a low viscosity prepolymer with a viscosity suitable for processing at room temperature. Dynamic mechanical analysis was conducted on carbon fiber composite specimens manufactured from two Cyanate Ester blends with varying catalyst compositions. It was shown that post-curing was needed to produce a polymer matrix with a single glass transition relaxation, but increases in post-cure temperature above 204 °C resulted in slight reductions in T g and modulus. Also, increasing catalyst composition was shown to have a negative effect on T g .
