Biphenyl Epoxy Research Articles

Thermal conductivity of epoxy/multilayered graphene composites prepared with different curing agents

Epoxy/multilayer graphene (ML-graphene) composites were prepared using different curing agents to control the graphene dispersion by changing the curing reactivity. With increasing initial reactivity, the aggregation size of the ML-graphene decreased and their thermal conductivity increased. In particular, the thermal conductivity of the composite prepared with p-phenylenediamine showed a maximum value of 1.46 W/(m·K) at 25 wt% ML-graphene loading because of the highest initial curing reactivity. The application of a magnetic field led to graphene alignment along the applied field, resulting in two times higher thermal conductivity than that of the corresponding system without magnetic field. The relationship between the interfacial affinity for epoxy/graphene and thermal conductivity was also investigated. As a result, resulting in a biphenyl epoxy composite showed higher thermal conductivity (6.17 W/(m·K)) than that of the bisphenol-A epoxy composite. This is derived that the π-conjugated and planar structure of biphenyl epoxy can easily interact with the surface of graphene.

Humid heat aging of biphenyl epoxy resin: a combined study of experiments and simulations

Epoxy resins are commonly used as external insulating materials for high-voltage outdoor applications. To improve the moisture and heat resistance of epoxy resin materials, this research carried out experimental tests and theoretical simulations on a variety of epoxy resin materials, including the biphenyl type. The theoretical simulation used the Materials Studio software to model the biphenyl epoxy resin and bisphenol A-type epoxy resin at different humidities. The simulation results show that the biphenyl epoxy resin has a higher glass transition temperature, at which the water molecules have a smaller root-mean-square displacement and a lower probability of forming hydrogen bonds. Experimental tests illustrated that biphenyl-type epoxy resins exhibit enhanced stability, lower hygroscopicity, and minimal changes in the permittivity in hot and humid environments. The agreement between the theoretical simulations and experimental tests indicates that the simulation calculation method is applicable to studying the hygrothermal resistance of epoxy resin materials. This study also lays the foundation for improving various aspects of the performance of epoxy resin materials through simulations, thereby providing a theoretical basis for the development of hygrothermal-resistant epoxy resins.

Dielectric and thermal properties characterisation and evaluation of novel epoxy materials for high‐voltage power module packaging

AbstractInternal insulation of high‐voltage power modules is facing interesting failure risks, including high temperature overheating, breakdown fault, material cracking etc., so it is imperative to urgently develop new dielectric materials with high thermal conductivity (λ), outstanding electrical insulation, and thermal stability properties. A method to construct controllable liquid crystalline cross‐linking networks based on the synthesis of biphenyl epoxy monomer and the change of curing agent structures and curing temperature is proposed. The uniform nematic rod‐like liquid crystalline domains were obtained by using 4,4‐diaminodiphenylmethane as a curing agent under a pre‐curing temperature of 105°C. The resulting film (abbreviated as TD‐105) exhibited λ up to 0.53 W m−1 K−1 and a dielectric breakdown strength of 57.69 kV mm−1, which showed a simultaneous enhancement of 178% and 16%, respectively, compared to traditional bisphenol A epoxy resin. Moreover, it also exhibited lower dielectric loss and magnitude of partial discharge while having higher glass‐transition temperature (190°C). A novel idea for the development of high‐performance epoxy insulating materials for the application of high‐voltage and large‐power electrical equipment is provided.

A Fluorine-Containing Main-Chain Benzoxazine/Epoxy Co-Curing System with Low Dielectric Constants and High Thermal Stability.

A fluorine-containing main-chain benzoxazine (BAF-M-TB) was co-cured with biphenyl epoxy for the integrated circuit industry. The benzoxazine precursor was synthesized using 4,4'-(Hexafluoroisopropylidene)diphenol (bisphenol AF), 2,2'-Dimethyl-[1,1'-biphenyl]-4,4'-Diamine(M-TB), and paraformaldehyde. In addition, the 3,3'-(Oxybis(4,1-phenylene))bis(3,4-dihydro-2H-benzo[e][1,3]oxazine) (Benoxazine ODA-BOZ), which is a commercialized benzoxazine, was co-cured with biphenyl epoxy as a control. The two co-curing systems were referred to as EP/BAF-M-TB and EP/ODA-BOZ. The curing kinetics, rheological behavior, and thermal stability of the two co-curing systems were studied. Poly-EP/BAF-M-TB and poly-EP/ODA-BOZ quartz fiber cloth reinforced composites (QFRPs) were prepared using the prepreg laminating method in order to determine their mechanical, thermal, and dielectric properties. Both of them showed good thermal properties and dielectric properties. The dielectric constant of poly-EP/BAF-M-TB QFRP is in the range of 3.25-3.54 at the low frequency of 10 kHz-10 MHz. At the high frequency of 5 GHz, its dielectric constant is 3.16, which is better than that of poly-EP/ODA-BOZ QFRP. Additionally, the Td5 of poly-EP/BAF-M-TB was 398 °C in a nitrogen atmosphere, which is higher than that of poly-EP/ODA-BOZ.

A resveratrol based active ester cured epoxy film with low dielectric loss and high thermal performances

The production of epoxy resins with low dissipation factor (Df) remains an alluring yet challenging task. In this work, we successfully synthesized a novel resveratrol based active ester (ResE) by a one-step method using the renewable resveratrol as raw material. The structure of ResE was characterized using FTIR and NMR techniques. The phenol biphenyl epoxy (SQXN-324) was cured with ResE, the SQXN/ResE system boasted a favorable dielectric constant (Dk) of 2.78 and dissipation factor (Df) of 3.5 × 10−3 at a high frequency of 10 GHz. Additionally, the SQXN/ResE system exhibited impressive thermal performances, with a 5 % weight loss temperature (T5%) of 368 °C, a residual carbon of 34 wt% at 800 °C in N2 atmosphere, a glass transition temperature (Tg) of 154 °C, a coefficient of thermal expansion (CTE) of 61.9 ppm/°C from 25 °C to Tg and the CTE of 130 ppm/°C from Tg to 250 °C. These findings suggested that a biomass curing agent for epoxy with low Df and high thermal performances were successfully developed, it had potential applications in the high frequency communication field and microelectronics industry.

Thermal Tunable Tribological Behavior of Shape Memory Biphenyl Epoxy Resin

Although polymer-based self-lubricating materials have rapidly developed recently, intelligent lubricating materials with self-adaptable lubrication with external conditions changing are highly demanded, especially for harsh conditions. Herein, a shape memory epoxy resin based on the biphenyl units (BPEP) with tunable tribological behavior was systematically studied. X-ray diffraction (XRD), field emission scanning electron microscope (SEM), laser confocal three-dimensional profiler, and optical microscope were applied to analyze the friction and wear mechanism. Due to the presence of the specific biphenyl structural units, which could be performed a switching phase between crystalline and amorphous, that allows the self-assembly of the polymer chain under π–π interaction. As a result, the improving mechanical properties enable the BPEP to perform outstanding self-lubricating in a wide temperature range, and the friction coefficient (COF) can be tuned in a wide range of 0.10~0.175 by adjusting the temperature. The shape memory effect of the polymer refers to modulus changing and heat conversion during the shape morphing, and a thermal tunable tribological was observed based on the physicochemical properties varying of polymer with temperature changing. The shape memory effect of BPEPs drives the wear self-compensation so that a low wear rate (6.94 × 10−5 mm3 N−1 m−1) at 110 °C was obtained. The superb lubricating properties of this BPEP could broaden the application scope of shape memory polymers in the field of intelligent lubricating materials, and it is expected to guide future studies on the thermal regulating of tribological behavior.

Thermal conductivity and closed-loop recycling of bulk biphenyl epoxy composites with directional controllable thermal pathways

The bulk epoxy composites are fabricated by film-stacking method based on covalent adaptable networks. Directional controllable high thermal conductivity is realized by altering stacking mode.

Thermal and Dielectric Properties of Cyanate Ester Cured Main Chain Rigid-Rod Epoxy Resin.

Thermal and dielectric properties of rigid-rod bifunctional epoxy resin 4,4-bis(2,3-epoxypropoxy) biphenyl epoxy (BP) and commercial epoxy resin diglycidyl ether of bisphenol A (DGEBA) were studied using differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), dynamic mechanical analyzer (DMA), thermal mechanical analyzer (TMA) and dielectric analyzer (DEA). These two epoxies were cured with cyanate ester hardener 2,2’-bis(4-cyanatophenyl) propane (AroCy B10). The BP/B10 system consisting of a rigid-rod structure exhibited better thermal properties than the DGEBA/B10 system with a flexible structure. Anisotropic BP/B10 (2:1) had the highest 5% weight loss temperature, the highest amount of residue and a smaller thermal expansion coefficient than the commercial DGEBA/B10 system. The BP/B10 system, which cured at the LC phase temperature, had higher Tg than the commercial DGEBA/B10 system, as found from dynamic mechanical analysis. The BP/B10 system also demonstrated better dielectric properties than the commercial DGEBA/B10 system when enough curing agent was provided.

Synthesis and characterization of mechanical-controllable polyurethane derived from tetramethybiphenyl epoxy acrylate

In this paper, a novel polyurethane copolymer (PU) derived from hexamethylene diisocyanate (HDI), polycaprolactone (PCL) and tetramethyl biphenyl epoxy acrylate (TMBPEA) was synthesized, characterized, and designed to have controllable mechanical properties and shape memory ability. The multifunctional PU contains cystallizable PCL segments, cross-linkable CC bonds in TMBPEA and urethane moieties. Both the PCL crystalline phase and photo-crosslinking of CC bonds play an important role in determining the mechanical properties of PU. Therefore, by adjusting the degree of crystallinity and the degree of crosslinking, the mechanical properties of PU could be easily controlled and varied. Before photo-crosslinking, the crystallinity of PU increases from 33.01% to 78.97%, as the content of PCL in PUs increases. However, after photo-crosslinking, the degree of crystallinity was significantly reduced to 11.09% as the UV irradiation time increased. In this way, the mechanical properties of PUs could be readily controlled by adjusting the ratio of PCL in the PUs and varying the UV irradiation time. As the ratio of PCL in PUs increases, the tensile strength and Young’s modulus of PUs increases from 9.04 ± 1.26 MPa to 12.98 ± 0.33 MPa and 89.79 ± 5.74 MPa to 224.88 ± 5.22 MPa, respectively. Meanwhile, the elongation at break increases from 499.09 ± 88.38% to 776.51 ± 67.39%. After crosslinking, the Young’s modulus of UV-cured PUs decreased from 224.88 ± 5.22 MPa to 18.74 ± 1.30 MPa as the UV irradiation time increased. Moreover, the elongation at break of UV-cured PUs was also dramatically reduced to around 60 MPa after photo-crosslinking compared to pristine PUs. Furthermore, shape memory tests indicated that uncrosslinking PUs samples have shape memory ability.

Hollow-glass-microsphere-based Biphenyl Epoxy Resin Composite with Low Dielectric Contant

In this study, rigid 4,4′-diglycidyl(3,3′,5,5′-tetramethylbiphenyl) epoxy(TMBP)-based composites were developed by the incorporation of varying percentages of commercial hollow glass microspheres(HGMs, QH-450) into the TMBP resin used for electronic packaging. The thermal and mechanical properties as well as the morphology of all the composites were characterized, and dielectric properties were characterized by advanced analytical techniques. The results reveal that a series of TMBP/QH-450 composites exhibits higher initial degradation tempera-tures(Td,5%>300 °C), and the residual char and glass transition temperature were clearly improved with QH-450 loading. In addition, all epoxy composites exhibited a lower dielectric constant ranging from 3.74 to 3.06 at 1.2 MHz because the lower dielectric properties of the inert gas used as the core of the QH-450 decreased molecule polarity. Hence, this developed TMBP/QH450 system demonstrates potential applications in electronic packaging.

Synthesis of a novel biphenyl epoxy resin and its hybrid composite with high thermal conductivity

ABSTRACTA novel biphenyl epoxy monomer of p‐methyl phenylhydroquinone epoxy resin (p‐MEP) was synthesized and characterized. We researched its potential in the area of thermal conduction application and prepared a series of hybrid composites based on it with different mass ratios of sphere Al2O3 filler. From the good mobility and low viscosity of p‐MEP, it allowed mixing with more Al2O3 fillers. The hybrid epoxy resins owned the advantages of traditional epoxy resins as well as quite considerable thermal conductivity. Therefore, the hybrid composite at the maximum mass fraction of 70% possess the highest thermal conductivity of 5.6 W mK−1, which is 5.6 times higher than that of pristine p‐MEP (0.1 W mK−1). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47078.

Controlled synthesis and evaluation of cyanate ester/epoxy copolymer system for high temperature molding compounds

ABSTRACTEpoxy molding compounds (EMCs) have become an integral component for high power electronics to work under harsh environment nowadays. For high temperature operation, polymer networks with high glass transition temperature (Tg) are required to ensure device stability. In this work, high Tg polymers were designed via controlled incorporation of in situ formed and thermally stable triazine structures into epoxy matrix. Reactions involved in the copolymer system of cyanate ester and epoxy (CE/EP) were investigated. Increasing ratio of cyanate ester dramatically promoted Tg of the copolymer up to 275 °C with improved heat resistance. High temperature aging and moisture absorption tests revealed that hydrolysis of polycyanurate network and rearrangement of cyanurate occurred during aging, especially for copolymers with higher than 75% of cyanate ester. Based on thermal properties and aging performance, the composition of CE/EP system was optimized. The formulated bisphenol A cyanate ester and biphenyl epoxy copolymer system has great potential to be applied as high temperature encapsulation materials in electronic packaging. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 1337–1345

The Study of Low Moisture Molding Compound

This paper studied the moisture of the post-mold-cured packages with the effects of resin structure, equivalent ratio of epoxy resin to Phenolic resin (E/OH), coupling agent, stress modifier and release agent on the moisture are further studied. The results showed that the resin structure has significant effect on the moisture, the order is multifunctional epoxy resin>o-crosel novolac epoxy resin>biphenyl epoxy resin>Naphthalene epoxy resin. The moisture decreases while the ration of E/OH increased. The moisture decreases rapidly with increase of the ratio of E/OH from 0.3 to 1.0. The moisture decreases slowly when it is larger than 1.0. The highest moisture of catalyst are 2MZ-A and 2MAOK while the lowest are 2MZ and TPP. The highest moisture of wax are GMS and stearic acid, while the lowest are polyethylene wax, oxidized polyethylene wax, and Carnauba wax, and the moisture of E wax, OP wax and S wax are in the middle.

Biphenyl liquid crystalline epoxy resin as a low-shrinkage resin-based dental restorative nanocomposite

Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECH), the photoinitiator 4-octylphenyl phenyliodonium hexafluoroantimonate and the photosensitizer champhorquinone. The inorganic filler is silica nanoparticles (∼70–100nm). The nanoparticles were modified by an epoxy silane of γ-glycidoxypropyltrimethoxysilane to be compatible with the organic matrix and to chemically bond with the organic matrix after photo curing. By incorporating the BP liquid crystalline (LC) epoxy resin into conventional ECH epoxy resin, the nanocomposite has improved hardness, flexural modulus, water absorption and coefficient of thermal expansion. Although the incorporation of silica filler may dilute the reinforcing effect of crystalline BP, a high silica filler content (∼42vol.%) was found to increase the physical and chemical properties of the nanocomposite due to the formation of unique microstructures. The microstructure of nanoparticle embedded layers was observed in the nanocomposite using scanning and transmission electron microscopy. This unique microstructure indicates that the crystalline BP and nanoparticles support each other and result in outstanding mechanical properties. The crystalline BP in the LC epoxy resin-based nanocomposite was partially melted during exothermic photopolymerization, and the resin expanded via an order-to-disorder transition. Thus, the post-gelation shrinkage of the LC epoxy resin-based nanocomposite is greatly reduced, ∼50.6% less than in commercialized methacrylate resin-based composites. This LC epoxy nanocomposite demonstrates good physical and chemical properties and good biocompatibility, comparable to commercialized composites. The results indicate that this novel LC nanocomposite is worthy of development and has potential for further applications in clinical dentistry.

Copolymers of phenolphthalein-aniline-based benzoxazine and biphenyl epoxy: curing behavior and thermal and mechanical properties

In this work, the crosslink density and mechanical properties of phenolphthalein-aniline-based benzoxazine (BP-a) were enhanced through blending with biphenyl epoxy. The curing behavior of the blends was explored, and the thermal and mechanical properties of the corresponding copolymers were investigated in detail. The results showed that these copolymers possessed higher initial decomposition temperatures and better mechanical properties but slightly lower glass transition temperatures and coefficients of thermal expansion than those of BP-a.

Synthesis, morphology and physical properties of multi-walled carbon nanotube/biphenyl liquid crystalline epoxy composites

We have developed multi-walled carbon nanotube/liquid crystalline epoxy composites and studied the effects of incorporation carbon nanotubes (CNTs) on the morphology, thermal and mechanical properties of the composites. The CNTs are functionalized by liquid crystalline (LC) 4,4′-bis(2,3-epoxypropoxy) biphenyl (BP) epoxy resin for the ease of dispersion and the formation of long range ordered structure. The epoxy functionalized CNT (ef-CNT) were dispersed in the LC BP epoxy resin that can be thermal cured with an equivalent of 4,4′-diamino-diphenylsulfone to form composite. The curing process was monitored by polarized optical microscopy. The results indicate the LC resin was aligned along the CNTs to form fiber with dendritic structure initially then further on to obtain micro-sized spherical crystalline along with fibrous crystalline. With homogeneous dispersion and strong interaction between nanotubes and matrix, the composite containing 2.00 wt.% ef-CNT exhibits excellent thermal and mechanical properties. When the amount of ef-CNT exceeds 2.00 wt.%, vitrification stage of curing is fast reached, which lowers the degree of conversion. As compared with the neat resin, the composite containing 2.00 wt.% ef-CNT increases the glass transition temperature by 70.0 °C, the decomposition temperature by 13.8 °C, the storage modulus by 40.9%, and the microhardness by 63.3%.

Relationship of Particle Content and Size of Spherical Silica with the Flowability of Epoxy Molding Compounds for Large-Scale Integrated Circuits Packaging

The melting viscosities of different kinds of epoxy resins have been investigated in this paper. The results showed that tetramethyl biphenyl epoxy resin(TMBP) has very low melting viscosity(0.02Pa•s at 150°C) and can be blended with ortho-cresol novolac epoxy resin(ECN) in order to decrease the melting viscosity of epoxy molding compound(EMC). When the content of TMBP in the blend of ECN/TMBP was up to 40wt%, the viscosity of the blend decreased to 0.15 Pa•s from 0.8 Pa•s of ECN. In addition, the effects of the content, particle size of silica on the flowability of EMC have been researched systematically in the paper. The results showed that the melting viscosity of EMC increased greatly with the filling increasing of silica, and the particle size and the match of silica with different particle diameter had markedly influenced on the flowability of EMC. The melting viscosity of system with higher filling content of silica changed complicatedly with the increasing of shear rate, i.e., the viscosity of the system decreased with the increasing of shear rate in the range of low shear rate, then increased with the increasing of shear rate in the range of high shear rate, but decreased again with the increasing of shear rate in the range of higher shear rate. The system filled by silica with small particle diameter had low melting viscosity at low shear rate and high melting viscosity at high shear rate, but the melting viscosity of the system filled by silica with large particle diameter changed by contraries.

Kinetic Analysis of UV-Curable Epoxy Resins for Micromachining Applications

Multifunctional epoxy resin series Epiclon HP-7200 is classified under the high performance series and is well known for its application in electrical encapsulation as it exhibits excellent mechanical and electrical properties. In addition, they have an advantage of an ultra low moisture absorption compared to other conventional cresol novolac (ECN) and biphenyl epoxy resins, which potentially makes it the next new mainstream of epoxy resins in electronics application. In this paper, kinetic study of various concentration of Epiclon HP-7200 (40-70 wt %) with divinyl ether (DVE) as the reactive solvent has been performed by Photo-Differential Scanning Calorimetry (DPC). The thermal stability of the Epiclon HP-7200 solutions has been analyzed by DSC and TGA.

Cure properties of self‐extinguishing epoxy resin systems with microencapsulated latent catalysts for halogen‐free semiconductor packaging materials

AbstractThe cure properties of self‐extinguishing epoxy resin systems with different microencapsulated latent catalysts were investigated, which are composed of YX4000H and NC3000H as a biphenyl epoxy resin, MEH‐7800SS as a hardener, and triphenylphosphine (TPP) microencapsulated with various polymers as a latent catalyst. The cure kinetics of these systems were analyzed by differential scanning calorimetry using an isothermal approach, and the kinetic parameters of all systems were reported in generalized kinetic equations with diffusion effects. Both the epoxy resin systems with microencapsulated latent catalysts showed lower cure conversion rate and higher critical cure reaction conversion than those with TPP. These different cure conversion rates could be explained by the decrease of crystallinity of the biphenyl epoxy resin and the activation energy of these epoxy resin systems. The cure conversion rates of the epoxy resin systems with the microencapsulated latent catalyst would be dependent on the activation energy of these systems. The storage stability tests for these systems were performed, and a good shelf‐life was observed in both the epoxy resin systems with EPCAT‐PAM, a core–shell‐type latent catalyst. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Reaction kinetics, thermal properties of tetramethyl biphenyl epoxy resin cured with aromatic diamine

AbstractEpoxy resins, 4, 4′‐diglycidyl (3, 3′, 5, 5′‐tetramethylbiphenyl) epoxy resin (TMBP) containing rigid rod structure as a class of high performance polymers has been researched. The investigation of cure kinetics of TMBP and diglycidyl ether of bisphenol‐A epoxy resin (DGEBA) cured with p‐phenylenediamine (PDA) was performed by differential scanning calorimeter using an isoconversional method with dynamic conditions. The effect of the molar ratios of TMBP to PDA on the cure reaction kinetics was studied. The results showed that the curing of epoxy resins contains different stages. The activation energy was dependent of the degree of conversion. At the early of curing stages, the activation energy showed the activation energy took as maximum value. The effects of rigid rod groups and molar ratios of TMBP to PDA for the thermal properties were investigated by the DSC, DMA and TGA. The cured 2/1 TMBP/PDA system with rigid rod groups and high crosslink density had shown highest Tg and thermal degradation temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007