Synthesis of phenyl silicone resin with epoxy and acrylate group and its adhesion enhancement for addition-cure silicone encapsulant with high refractive index

A novel phenyl silicone resin with epoxy and acrylate group (PSREA) was successfully synthesized via the non-hydrolytic sol-gel condensation reaction of 3-glycidoxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, and diphenylsilanediol, and was employed as the adhesion promoter for addition-cure silicone encapsulant (ASE) with high refractive index. The structure of PSREA was confirmed by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance spectroscopy, and ²⁹Si nuclear magnetic resonance spectroscopy. The influence of PSREA on the properties of ASE was studied. It was found that PSREA could markedly enhance the adhesion strength of ASE to aluminum (Al) and poly(p-phenylene terephthamide) (PPA) substrate. When the content of PSREA was 1.5 phr, the shear strength of ASE was 4.43 and 2.27 MPa for Al and PPA substrate, which was about 71 and 266% higher than that of ASE without the adhesion promoter, respectively. In addition, PSREA had little effect on the mechanical properties, refractive index, and viscosity of ASE.     

Investigation of ureido-attached vinyl MQ silicone resin on tracking and erosion resistance of addition-cure liquid silicone rubber

With the growing incidence of extreme climate and serious pollution, the capability to resist high-voltage arc discharge has been considered as one of crucial performances for silicone rubber in the field of electrical power. Herein, to enhance the tracking and erosion resistance of addition-cure liquid silicone rubber (ALSR), a kind of ureido-attached vinyl MQ silicone resin [hydrolytic condensation products of monofunctional silane (M) and tetrafunctional silane (Q)] (U-VMQ) was synthesized. The chemical structure of U-VMQ was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance, and the effects of U-VMQ on the mechanical properties, thermal stability, and tracking and erosion resistance of ALSR were investigated. The results showed that U-VMQ was beneficial for the improvement of mechanical properties and thermal stability of ALSR. With 2 phr of U-VMQ containing 2.5 wt % of vinyl content, the ALSR successfully passed the inclined plane tracking at 4.5 kV, and the electrical erosion rate was only 0.13%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47360.     

加成型硅橡胶用含酯基有机硅增粘剂的制备及应用性能

以含氢硅油（PHMS）和1,6-己二醇二丙烯酸酯（HDDA）为原料,通过硅氢加成反应合成了含酯基的有机硅增粘剂（PHMS-g—HDDA）,并将其用于加成型液体硅橡胶（LSR）。采用傅立叶变换红外光谱（FT—IR）及核磁共振波谱（1HNMR）对PHMS—g—HDDA的结构进行了表征;研究了PHMS-g-HDDA用量对LSR的黏度、力学性能、硫化特性及与聚碳酸酯、对苯二甲酸乙二醇酯及热塑性聚氨酯粘接性能的影响。结果表明,PHMS—g—HDDA可显著提高LSR的粘接性能,且对LSR的黏度、力学性能和硫化特性有明显影响。当PHMS—g—HDDA用量为0．9份时,硅橡胶的综合性能较为理想。此时硅橡胶的拉伸强度为5．3MPa、拉断伸长率为380％、撕裂强度为14．7kN／m、邵尔A硬度为47．6度;焦烧时间及正硫化时间最小,分别为51S和68S;与各种基材的粘接性良好。     

Adhesive and thermal characteristics of maleimide-functional novolac resins

A novel, addition-curable maleimide-functional novolac phenolic resin was evaluated for adhesive properties such as lap shear strength and T-peel strength using aluminium adherends, when thermally self-cured and cocured with epoxy resins. The adhesive properties of the self-cured resin, although inferior at ambient temperature, improved at high temperature and were found to depend on the cure conditions. When cocured with epoxy resin, the adhesive properties improved significantly and showed a strong dependence on the nature of the epoxy resin used, on the stoichiometry of the reactants, on the concentration of imide groups in the phenolic resin, and on the extent of polymerization of the maleimide groups. Optimum adhesive properties were obtained for novolac resins with a moderate concentration of maleimide groups, taken on a 1 : 1 hydroxyl–epoxy stoichiometry with a novolac epoxy resin. In comparison to the conventional novolac, the imide–novolac contributed to improved adhesion and better adhesive property retention at higher temperature when cured with the novolac–epoxy resin. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 695–705, 1999     

Simulation of Curing Process for Propargyl Terminated Novolac Resins

Non-isothermal kinetic simulation analysis was carried for CFRP （carbon fiber reinforced plastic） based on PN （propargylated novolac） resins with various curing enthalpy. The simulation study was performed for CFRP with 40% mass resin content. It was shown that, curing enthalpy of PN resin must be less than 600 J/g to avoid uncontrolled heat emission causing destruction of composite sample.     

Synthesis and Characterization of Cured Allyl/Propargyl Ether Novolac Resins

A new kind of modified thermoset resins were synthesized by phase-transfer Williamson reaction from novolac resin and mixtures of allyl- and propargyl-chlorides. The compositions of the resins were defined by 1H NMR （nuclear magnetic resonanse） spectroscopy and the dependence of the cured materials properties on the composition was established. Increase of a propargyl content resulted in char yield raise and the maximum value had been found for propargylated resin--58%. DSC （differential scanning calorimetry）-analysis of the resins has demonstrated that exothermic enthalpy of the curing process could be adjusted by varying the content of propargyl and allyl groups in the resin.     

Synthesis of a boron-containing adhesion promoter for improving the adhesion of addition-cure silicone rubber to PPA

Abstract

In this study, a boron-containing adhesion promoter PhBSiO with a high refractive index and MeBSiO with a low refractive index were synthesized by a non-hydrolytic sol-gel reaction. The chemical structures of the synthesized adhesion promoters were firstly characterized by infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC). Then, the effects of adhesion promoters on the bonding properties of the cured silicone rubber were analyzed and the compatibility of the adhesion promoters to the silicon rubber was further studied through light transmittance detection. The boron-containing silicone adhesion promoters significantly enhanced the bonding strength of the cured silicone rubber to poly-phthalamide (PPA). When the addition amounts of PhBSiO and MeBSiO was 3.0 phr, the shear strength between silicone rubber and PPA respectively reached 0.761?MPa and 0.809?MPa, which were 145% and 161% higher than that of silicone rubber without adhesion promoter. In addition, the adhesion mechanism of the boron-containing adhesion promoter was investigated. The microscopic morphology of the fractured surface of the cured silicone rubber further demonstrated that boron atoms in the adhesion promoters significantly improved the adhesion strength between silicone rubber and PPA.     

氢氧化铝对导热加成型有机硅灌封胶性能的影响

以粘度为300和1 000 mPa·s的端乙烯基硅油复配,含氢硅油为交联剂,三氧化二铝为导热填料,氢氧化铝[Al(OH)_3]为阻燃剂,制备了无卤阻燃导热加成型有机硅灌封胶,研究Al(OH)_3用量对导热加成型有机硅灌封胶性能的影响。结果表明:随着Al(OH)_3用量的增大,加成型有机硅灌封胶的阻燃性能和导热性能提高,粘度增大,体积电阻率和物理性能下降;当Al(OH)_3用量为60份时,加成型有机硅灌封胶的综合性能最佳。     

Synthesis of silane oligomers containing vinyl and epoxy group for improving the adhesion of addition-cure silicone encapsulant

Two types of silane oligomers containing vinyl and epoxy group (PTGM and PTGE) as adhesion promoters were synthesized by the reaction of trimethylolpropane monoallyl ether with 3-glycidoxypropylmethyldimethoxysilane and 3-glycidoxypropylmethyldiethoxysilane, respectively. Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance spectroscopy, and gel permeation chromatography were used to characterize their chemical structures. The effect of adhesion promoters on properties of addition-cure silicone encapsulant (ASE) with lots of alumina (Al₂O₃) particles as thermally conductive fillers was investigated. The results showed that PTGM and PTGE could significantly improve both the adhesive strength and mechanical properties of ASE. The viscosity of ASE with no more than 3.0 phr PTGM and PTGE was below 5000 mPa s so that they were suitable for encapsulating process. Observation using scanning electron microscopy revealed that PTGM and PTGE could improve the dispersion of Al₂O₃ particles in silicone rubber matrix and enhance the bond between the particles and the matrix.     

The synthesis,characterization and properties of silicone adhesion promoters for addition-cure silicone rubber

Two types of polysiloxanes, GVPMS and GVHMS, were synthesized through nonhydrolytic sol-gel reaction from vinyltrimethoxysilane(VTMS), 3-glycidoxypropyltrimethoxysilane(KH560) and diphenylsilandiol(DPSD) or hydroxyl silicone oil, respectively. The chemical structures were characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H nuclear magnetic resonance (¹H-NMR) spectroscopy and gel permeation chromatography (GPC). GVPMS and GVHMS were used as adhesion promoter for addition-cure silicone rubber. It was found that the adhesion promoters not only greatly improved adhesion strength but also had excellent compatibility with silicone rubber. Among them, GVPMS gave better adhesion strength in silicone rubber. The shear strength of silicone rubber reached 1.70 MPa with addition of 1.5 phr GVPMS, which was about 317% higher than that of silicone rubber without the adhesion promoter. Meanwhile, the shear strength of silicone rubber reached 1.14 MPa with addition of 2.0 phr GVHMS, which was 183% higher than that of silicone rubber without the adhesion promoter. Optical property test results revealed that the refractive indexes of GVPMS and GVHMS were 1.5185 and 1.4133 respectively and both of them had good compatibility with silicone rubber, which satisfied the application demand of high-refractive and low-refractive electron encapsulation. Thermal resistance test and SEM results further proved that adhesion promoter could significantly increase the adhesion between the copper substrate and silicone rubber, in which GVPMS had a better performance. Oxidation treatment experiment further explained the mechanism that adhesion promoter functioned as a bridge, linked silicone rubber and copper substrate through chemical bonds.