Synthesis of MQ silicone resins through hydrolytic condensation of ethyl polysilicate and hexamethyldisiloxane

MQ silicone resins were synthesized through hydrolytic condensation of ethyl polysilicate and hexamethyldisiloxane. The structure of the MQ resins was characterized by NMR and GPC. The concentration of an acid catalyst was essential for the capping of functional groups with the monofunctional units. The acid-catalyzed resins had a narrow molecular weight distribution. After postcondensation catalyzed by a base, the molecular weight distribution became bimodal. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1753–1757, 1998     

MQ硅树脂的合成工艺研究

以正硅酸乙酯（TEOS）、六甲基二硅氧烷（MM）为主要原料,在浓盐酸的催化作用下,合成MQ硅树脂。讨论合成过程中影响MQ硅树脂性能的主要因素,如反应物配比、反应时间、反应温度等。最终确定MQ硅树脂的最佳合成工艺条件：反应时间为3h,反应温度为60-70℃,正硅酸乙酯、六甲基二硅氧烷、水、乙醇和盐酸（35％重量浓度）的质量比为40／12／8．8／5／2．4。     

加成型纺织商标用液体硅橡胶的配方设计

以D4或DMC、乙烯基双封头、乙烯基环体等为原料，以四甲基氢氧化铵为催化剂合成了不同摩尔质量的乙烯基硅油；以高舍氢硅油、舍氢双封头、六甲基二硅氧烷、D4合成实验所需的交联剂低舍氢硅油;以白炭黑、乙烯MQ树脂为补强填料，以二甲基硅油为稀释剂制备纺织商标用透明液体硅橡胶。分别探讨了乙烯基硅油的粘度、白炭黑的比表面积和用量、乙烯MQ树脂的用量、二甲基硅油用量与铂金络合物和抑制剂的用量、固化（硬化）剂的用量对纺织商标用液体硅橡胶物理力学和加工工艺性能的影响。实验表明，所制备的纺织商标用透明液体硅橡胶在物理力学和加工工艺性能上基本达到甚至超出国内外同类产品。     

有机硅压敏胶的合成与性能

以硅橡胶和MQ硅树脂为原料,通过羟基缩合反应制备了有机硅压敏胶。用FT—IR和GPC表征了其结构。讨论了硅橡胶和MO硅树脂的原料配比、硅橡胶的黏度、MQ硅树脂的分子质量等因素对压敏胶力学性能的影响：测定了压敏胶的初粘性、1800剥离强度和持粘性等性能。结果表明,用MQ硅树脂与运动黏度为100×10^-4m^2／s的硅橡胶在质量比为2：3时,可得到具有良好粘接性能的有机硅压敏胶。     

Synthesis of silicone–acrylic resins and their applications to superweatherable coatings

Silicone–acrylic resins were synthesized to prepare superweatherable paints for building materials. The raw materials used were n‐butyl acrylate, methyl methacrylate, and n‐butyl methacrylate as acrylic monomers and 3‐methacryloxypropyltrimethoxysilane (MPTS) as a silicone monomer reactive with the acrylic monomers. Acrylic copolymers were synthesized such that their glass‐transition temperatures were adjusted to 30°C and their MPTS contents were varied to 10, 20, and 30 wt %. As the content of silicone and MPTS increased, average molecular weight and viscosity increased, and thermal stability at high temperatures improved. When we tested the properties of coatings by blending the synthesized silicone–acrylic resins with a white pigment, adhesion was superior with various substrates, and their properties were suitable on the whole. Weatherability was tested by an outdoor exposure test with a weather‐ometer and an accelerated weathering tester, and their results showed that silicone–acrylic resin composed of 30 wt % MPTS was a superweatherable coating. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1614–1623, 2001     

溶剂型有机硅压敏胶的制备及性能研究

以正硅酸乙酯和六甲基二硅氧烷为原料制得MQ硅树脂,MQ硅树脂再与107硅橡胶进行缩合反应,制备了107-MQ;再加入过氧化苯甲酰（BPO）及辅料配成有机硅压敏胶。考察了MQ硅树脂与107硅橡胶的质量比、BPO用量、外加辅料对压敏胶性能的影响。较佳工艺为：MQ与107硅橡胶的质量比为0．75：1．1．75：1、BPO用量2份、丙烯酸羟乙酯用量0．5份（MQ与107硅橡胶总用量100份）,此时有机硅压敏胶液稳定,可长时间放置,初粘32#钢球,剥离强度12N／25mm。     

Microstructure evolution of ammonia‐catalyzed phenolic resin during thermooxidative aging

The thermooxidative aging of ammonia‐catalyzed phenolic resin for 30 days at 60–170°C was investigated in this article. The aging mechanism and thermal properties of the phenolic resin during thermooxidative aging were described by thermogravimetry (TG)–Fourier transform infrared (FTIR) spectroscopy, attenuated total reflectance (ATR)–FTIR spectroscopy, and dynamic mechanical thermal analysis. The results show that the C? N bond decomposed into ammonia and the dehydration condensation between the residual hydroxyl groups occurred during the thermooxidative aging. Because of the presence of oxygen, the methylene bridges were oxidized into carbonyl groups. After aging for 30 days, the mass loss ratio reached 4.50%. The results of weight change at high temperatures coincided with the results of TG–FTIR spectroscopy and ATR–FTIR spectroscopy. The glass‐transition temperature (T_g) increased from 240 to 312°C after thermooxidative aging for 30 days, which revealed the postcuring of phenolic resins. In addition, an empirical equation between the weight change ratio and T_g was obtained. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Novel Self-Assembling Silane for Abhesive and Adhesive Applications

The potential benefits from using a novel vinyl-terminated long alkyl-chain self-assembling silane (VTS) have been investigated. A relatively high water contact angle of 83° was found for water on the VTS-pretreated soda-lime glass surface. This revealed that the degree of hydrophobicity of this surface was far more pronounced than for the ultrasonically-cleaned glass surface or the γ-glycidoxypropyltrimethoxy silane (GPS)–pretreated glass surface, which gave contact angles of 14° and 42°, respectively. Further, good agreement between the measured and the theoretical contact angles for a fully adsorbed vinyl-terminated self-assembled monolayer surface implied that the VTS molecules were adsorbed with the vinyl-terminal groups orientated away from the glass surface. Indeed, X-ray photoelectron spectroscopy (XPS) analysis confirmed that the VTS molecules were adsorbed as a monolayer with the vinyl-terminal groups orientated away from the glass surface. Double-cantilever beam joints were prepared using these various pretreated-glass substrates, using an epoxy adhesive, and they were tested employing a fracture-mechanics approach. The adhesive fracture energy, G _C , of the VTS-pretreated glass/epoxy joints was found to be far lower in value than for the ultrasonically cleaned joints or the GPS-pretreated joints. The potential applications of this novel long alkyl-chain silane are twofold: (a) the relatively very poor adhesion of the VTS pretreatment enables this silane to be used as an excellent abhesive layer, i.e., as a release agent, and (b) the presence of reactive vinyl-terminal groups might allow this silane to be activated to form functional groups that may then react with an adhesive, such as an epoxy resin, and so act as an excellent adhesion promoter to increase the durability of the adhesive joint.     

Low-stress encapsulants by vinylsiloxane modification

Dispersed silicone rubbers were used to reduce the stress of cresol–formaldehyde novolac epoxy resin cured with phenolic novolac resin for electronic encapsulation application. The effects of structure, molecular weight, and contents of the vinylsiloxane oligomer on reducing the stress of the encapsulant were investigated. Morphology and dynamic mechanical behavior of rubber-modified epoxy resins were also studied. The dispersed silicone rubbers effectively reduce the stress of cured epoxy resins by reducing flexural modulus and the coefficient of thermal expansion (CTE), whereas the glass transition temperature (T_g) was hardly depressed. Electronic devices encapsulated with the dispersed silicone rubber modified epoxy molding compounds have exhibited excellent resistance to the thermal shock cycling test and have resulted in an extended device use life. © 1994 John Wiley & Sons, Inc.     

Fourier transform infrared analysis of plasma-polymerized hexamethyldisiloxane

The plasma-induced polymerization of hexamethyldisiloxane onto solid surfaces is studied by FTIR. An inductively coupled RF reactor was used to produce the thin polymer coatings. Analysis of the plasma polymer indicates a long chain polysiloxane structure resulting from the removal of some methyl groups from the monomer structure. Increasing the plasma power level from 30 to 100 W increased the chain length in the resultant polymer as indicated by the widening and splitting of the Si–O stretching absorptions. Thermal aging of the vapor phase polymer at 120°C for 1 h in vacuum and at 410°C for 30 min in a nitrogen atmosphere revealed the removal of some methyl groups from the polymer structure with temperature. TGA runs on the vapor phase polymer at 20°C/min in air showed the polymer retaining almost 65% of its weight at 1000°C. The residue remaining after the TGA run had very little organic content and may represent a glass type silicate network. Wettability values determined on coated glass slides revealed the hydrophobicity of the coatings with water contact angle values > 100°. SEM micrographs showed uniform and featureless coating on glass fibers which was etched by boiling water and was attributed to the loss of vapor phase polymer on the surface.     

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.     

MQ硅树脂及其压敏胶粘带的研究

用FT -IR、2 9Si-NMR和GPC对适用于合成硅酮压敏胶的自制MQ硅树脂进行了表征 ,研究了硅酮压敏胶的合成配比和工艺对PET压敏胶带“三物性的影响 ,并优选出最佳配比     

Adhesion property of novel polyimides with 1‐[3′,5′‐bis(trifluoromethyl)phenyl] pyromellitic dianhydride

Novel polyimides were synthesized from 1‐[3′,5′‐bis(trifluoromethyl)phenyl] pyromellitic dianhydride (6FPPMDA) by a conventional two‐step process: the preparation of poly(amic acid) followed by solution imidization via refluxing in p‐chlorophenol. The diamines used for polyimide synthesis included bis(3‐aminophenyl)‐3,5‐bis(trifluoromethyl)phenyl phosphine oxide, bis(3‐aminophenyl)‐4‐trifluoromethylphenyl phosphine oxide, and bis(3‐aminophenyl)phenyl phosphine oxide. The synthesized polyimides were designed to have a molecular weight of 20,000 g/mol by off‐stoichiometry and were characterized by Fourier transform infrared, NMR, differential scanning calorimetry, and thermogravimetric analysis. In addition, their intrinsic viscosity, solubility, water absorption, and coefficient of thermal expansion (CTE) were also measured. The adhesion properties of the polyimides were evaluated via a T‐peel test with bare and silane/Cr‐coated Cu foils, and the failure surfaces were investigated with scanning electron microscopy. The 6FPPMDA‐based polyimides exhibited high glass‐transition temperatures (280–299°C), good thermal stability (>530°C in air), low water absorption (1.46–2.16 wt %), and fairly low CTEs (32–40 ppm/°C), in addition to good adhesion properties (83–88 g/mm) with silane/Cr‐coated Cu foils. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1801–1809, 2005     

Crosslinking reaction and properties of two‐component waterborne polyurethane from terpene‐maleic ester type epoxy resin

A two‐component waterborne polyurethane (2K‐WPU) is prepared with the terpene‐maleic ester type epoxy resin‐based polyol dispersion and a hydrophilically modified hexamethylene diisocyanate tripolymer. Laser particle size analyzer and transmission electron microscopy are used to characterize the particle size distribution and the micromorphology of the 2K‐WPU. Crosslinking reaction kinetics of the 2K‐WPU is examined by fourier transform infrared spectrometry (FTIR) spectra. In the preliminary stage of the crosslinking reaction, it shows a very good fit with a second order reaction kinetics, and the apparent activation energy is 94.61 kJ mol^?1. It is also shown from the FTIR spectra that the complete crosslinking reaction of the 2K‐WPU needs 7 h at 70°C. The crosslinked products of the 2K‐WPU have good thermal resistant properties, with glass‐transition temperatures (T_g) in the range of 35–40°C and 10% weight loss temperatures (T_d) in the range of 275–287°C. The films obtained from the crosslinked products have good water‐resistance, antifouling, blocking resistance properties and impact strength of >50 cm, flexibility of 0.5 mm, adhesion of 1 grade, pencil hardness of HB‐2H. The pencil hardness and thermal‐resistant properties of the crosslinked products increase with the molar ratio of isocyanate (? NCO) group to hydroxyl (? OH) group. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation,solubility and thermal behaviour of new bismaleimides containing silicone linkages

A series of new bismaleimides containing silicone linkages have been prepared via Diels–Alder reaction of bismaleimides containing silicone and bisfurans containing silicone; their molecular structures have been characterized by FTIR, NMR and elemental analysis. The solubility of the prepared bismaleimides was tested in six types of solvent of different boiling point and polarity, and their curing temperatures were determined by DSC. The thermal-oxidative stability of the cured networks was investigated by TGA and their glass transition temperatures were measured by DSC, revealing that the bismaleimides are soluble in low boiling point solvents and their curing temperatures are in the range 206–285°C. The DSC and TGA traces of cured networks show that the glass transition temperatures are in the range 287–331°C and that these resins are stable up to 353–384°C. © 1999 Society of Chemical Industry     

电气胶带用有机硅压敏胶的研制

通过MQ硅树脂和端羟基聚二甲基硅氧烷(PDMS)的硅醇缩合反应制备有机硅压敏胶溶液,将合成的有机硅PSA压敏胶溶液涂布在基材上干燥后得到有机硅压敏胶胶带(PSA),研究了PSA的合成配料、工艺以及胶带生产工艺对压敏胶带性能的影响。结果表明,硅树脂/硅橡胶比例在1.2~1.4之间具有良好的初粘、持粘和剥离力,硅树脂含量增加胶带耐热性增强;此外,反应真空度低于0.07MPa,反应温度高于140℃,且添加2%~3%左右的BPO时所制备的PSA胶带具有良好的综合性能。     

MQ硅树脂/纳米TiO_2复合改性环氧树脂的结构与性能

以环氧树脂(EP)为基体树脂,以MQ硅树脂和纳米TiO_2(nano-TiO_2)同时作为EP的增韧改性剂,由此制备了nano-TiO_2/MQ硅树脂/EP复合材料。研究结果表明:MQ硅树脂已成功接枝在EP分子链上;当m(MQ硅树脂):m(nano-TiO_2):m(EP)=15:3:100时,nano-TiO_2/MQ硅树脂/EP复合体系的耐热性能明显提高,拉伸强度和冲击强度分别提高了66.6%和68.1%,其断面呈韧性断裂特征。     

Characterization of a rigid silicone resin

Silicone resins have been used as binders for ceramic frit coatings and can withstand temperatures of 650°C to 1260°C. Conceptually, silicone resins can potentially be used as matrices for high temperature fiber‐reinforced composites. The mechanical and thermal properties of a commercially available silicone resin, Dow Corning® 6‐2230, were characterized. Neat 6‐2230 resin was found to have inferior room temperature mechanical properties such as flexural, tensile and fracture properties when compared to epoxy. The room temperature flexural properties and short beam shear strength of the silicone/glass composites were also found to be lower than those of epoxy/glass composite with similar glass content. However, the silicone resin had better elevated temperature properties. At an elevated temperature of 316°C, the retentions of flexural modulus and strength were 80% and 40% respectively of room temperature values; these were superior to those of phenolic/glass. Unlike the carbon‐based resins, the drop in flexural properties of the silicon/glass laminates with temperature leveled off with increase in temperature beyond 250°C. The resin weight loss at 316°C in 100 cm³/min of flowing air was small compared to other carbon‐based resins such as PMR‐15 and LaRC TPI. Only Avimid‐N appeared comparable to Dow Corning® 6‐2230.     

Effects of molecular weight on phase structure of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends

The phase structure of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends was studied in relation to the molecular weight. The samples were prepared by both solution blends, which showed two glass‐transition temperatures (T_g), and melt blends (MQ), which showed a single T_g, depending on the composition of the blends. The T_g of the MQ series was independent of the molecular weight of the homopolymer, although the degree of transesterification in the blends was affected by the molecular weight. The MQ series showed two exotherms during the heating process of a differential scanning calorimetry scan. The peak temperature and the heat flow of the exotherms were affected by the molecular weight of the homopolymers. The strain‐induced crystallization of the MQ series suggested the independent crystallization of PET and PEN. Based on the results, a microdomain structure of each homopolymer was suggested. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2428–2438, 2005     

Copper particles/epoxy resin thermosetting conductive adhesive using polyamide resin as curing agent

Thermosetting conductive adhesive (TCA) comprised of epoxy resin E‐51 as matrix, Cu microparticles and nanoparticles modified by silane coupling KH550 as conductive fillers, polyamide resin with low molecular weight as curing agent, and some other additives. It was reported creatively a new liquid curing agent, which solved successfully some difficult problems during preparation of TCA, such as limit of quantity of conductive fillers. Therefore, application of this liquid curing agent decreased greatly the resistivity of TCA under the condition of keeping enough adhesion strength. Antioxidized and mixed Cu particles were developed as conductive fillers in place of expensive Ag. The results showed that optimum conditions of conductive adhesive composed of 16 wt % of epoxy resin E‐51, 8 wt % polyamide resin, 65 wt % of Cu microparticles and nanoparticles, 1.3 wt % of silane coupling agent, and 9 wt % of other additives with curing time for 4 h at 60°C. The adhesion strength reached 16.7 MPa and the bulk resistivity was lower than 3.7 × 10^?4 Ω cm. The variation of bulk resistivity was less than 15% at high temperature (100°C). © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012