Special Topics Review

Synthesis of polymer microspheres and their application in the field of adhesive

He Jingtao, Han Lu, Li Jiaxi, Kan Chengyou

(Department of Chemical Engineering, Tsinghua University, Beijing  100084, China)

【Abstract】Polymer microspheres have received extensive attention and application in the research and development of new adhesive due to their characteristics such as surface modifiability, easy dispersibility, adjustable particle size and high specific surface area. The common preparation methods of polymer microspheres were summarized in this article. The application of polymer microspheres in the field of adhesive, including their use as special functional fillers, the preparation of thermally detachable adhesive using thermally expandable microspheres, and the preparation of one-component adhesive using microcapsules was elaborated in details. Finally, the future development of polymer microspheres for adhesive was prospected.

【Keywords】polymer microsphere; adhesive; preparation method; application

Research Report

Study on the properties of epoxy resin modified by phosphorylated acrylate oligomer

Wu Yuan, Xue Gang, Zhang Xugang, Sun Mingming, Xue Shuangle, Li Jianhui, Zhang Bin

(Institute of Petrochemistry, Heilongjiang Academy of Sciences, Harbin  150040, Heilongjiang, China)

【Abstract】In order to improve the bonding performance of epoxy resin and regulate its thermal mechanical properties, modified oligomers in epoxy resin medium were synthesized in this study by using butyl acrylate, acrylonitrile, glycidyl methacrylate, as well as different types and contents of acrylate phosphate (PM1500, PM1520) as monomers. The effects of phosphate type and content on the properties of epoxy resin were systematically investigated. The research results showed that the introduction of PM1500 could significantly enhance the bonding performance of epoxy resin to metals such as aluminum alloy, steel, and titanium alloy, and its optimal addition amount was 1 part. At this time, the shear strength of modified epoxy resin on aluminum alloy, steel, and titanium alloy specimens at room temperature reached 37.32, 29.77, and 32.44 MPa, respectively, which was significantly higher than that of the blank specimen. The peel strength of aluminum alloy specimen was 8.38 N/mm, an increase of 6.75%. The bonding performance enhancement was mainly attributed to the chelation and P—O—M covalent bonding between phosphate groups and metal surfaces. However, excessive addition could lead to a decrease in bonding strength due to increased system acidity and hindered crosslinking. Dynamic thermomechanical and thermogravimetric analysis showed that with the increase of PM1500 content, the storage modulus, glass transition temperature, and thermal stability of modified epoxy resin exhibited a slight downward trend, indicating its limited impact on the material’s heat resistance. This study significantly improved the interfacial bonding and flexibility of epoxy resin by introducing phosphate groups while maintaining its good heat resistance, providing a reference for the development of high-performance epoxy resin composite materials.

【Keywords】phosphate; acrylate oligomer; epoxy resin; bonding property

Development and curing kinetics study of polyallyl aromatic sulfone ether ketone epoxy adhesive

Hu Siyu, Yu Xinhai

(College of Chemistry and Chemical Engineering, Donghua University, Shanghai  201620, China)

【Abstract】A series of modified epoxy adhesive (EPA-1 - EPA-5) were prepared by using bisphenol A type epoxy resin (E-51) as the main resin, introducing self-made toughening agent polyallyl aromatic sulfone ether ketone (PAEK), compounding with curing agents (4,4'-diaminodiphenyl sulfone, methyltetrahydrophthalic anhydride) and accelerator (2-ethyl-4-methylimidazole), and their properties and curing kinetics were studied. The research results showed that the addition of PAEK significantly improved the mechanical properties of the material. When the addition amount was 10 phr (EPA-4), the impact strength, tensile strength, and bending strength reached 26.1 kJ/m², 78.1 MPa, and 104.6 MPa, respectively. At the frequency of 1 000 kHz, the relative dielectric constant of each formula ranged from 3.46 to 4.18, with a dielectric loss of less than 2.19% and a water absorption rate of less than 0.20%, demonstrating excellent dielectric properties and hydrophobicity. The curing kinetics analysis showed that the apparent activation energy of EPA-2 was 73.41 kJ/mol, and the reaction order was 0.9. The adhesive system had excellent comprehensive performance and had potential applications in high-end electronics and aerospace fields.

【Keywords】polyallyl aromatic sulfone ether ketone; epoxy resin adhesive; curing kinetics

Research on toughening epoxy resin with isocyanate-based polyurethane

Feng Hao, Xiao Wanbao, Zheng Shuai, Zhao Liwei, Chen Wuying, Liu Changwei, Wang Dezhi

(Institute of Petrochemistry, Heilongjiang Academy of Sciences, Harbin  150040, Heilongjiang, China)

【Abstract】Polyether and polyester isocyanate-based polyurethane were synthesized in this study by the one-step method using toluene-2,4-diisocyanate, polytetrahydrofuran diol and polyester diol as raw materials, and then they were applied to toughen epoxy resin. The effects of polyurethane types (polyether/polyester) and their contents on the thermal properties, microstructure, and mechanical behavior of modified epoxy resin were systematically investigated through differential scanning calorimetry, dynamic thermomechanical analysis, thermogravimetric analysis, scanning electron microscopy, and mechanical property testing. The research results showed that the introduction of isocyanate-based polyurethane shifted the curing exothermic peak towards higher temperature zone, reduced the glass transition temperature, and significantly improved the peel strength, effectively improving the resin toughness. Microscopic morphology analysis showed that the modified fracture surface was rough, exhibiting microcracks and plastic deformation characteristics. Compared to polyether polyurethane, polyester polyurethane formed a more complete microphase separation structure due to its higher proportion of hard segments and internal energy, resulting in better overall mechanical properties. However, its thermal stability was slightly inferior to polyether polyurethane. This study provided a reference for the design and application of polyurethane toughened epoxy resin system.

【Keywords】isocyanate; polyurethane; epoxy resin; toughening; thermal property; microstructure; mechanical property

Preparation and characterization of waterborne hydroxyl acrylic latex

Dong Lizhi¹, Guo Yu¹, Yu Ningya², Guo Xiaoming³, Zhong Ximing⁴

(1. Zhuhai Zhanchen New Materials Co., Ltd., Zhuhai  519050, Guangdong, China; 2. Hunan Normal University, Changsha  410081, Hunan, China; 3. Hubei University of Automotive Technology, Shiyan  442002, Hubei, China; 4. Zhongkai University of Agriculture and Engineering, Guangzhou  510225, Guangdong, China）

【Abstract】In this study, a low VOC waterborne hydroxyl acrylic latex was prepared by free radical emulsion polymerization. The effects of emulsifier type and amount, initiator amount, molecular weight modifier (AMSD) amount, functional monomer (allyl methacrylate, diacetone acrylamide) amount and other factors on the performance of emulsion and the water resistance of paint film were systematically investigated. The research results showed that when the reactive emulsifier SR-1025 was compounded with ABEX WR45 at a total dosage of 1.1% of the total monomer mass, the initiator ammonium persulfate dosage was 0.20%, the molecular weight modifier AMSD dosage was 0.32%, the allyl methacrylate dosage was 4.4%, and the diacetone acrylamide dosage was 5.0%, the comprehensive performance of the prepared latex was optimal. Its particle size was stable at around 100 nm, the water resistance of the paint film reached the "non whitening" level, and the drying speed was fast. The industrial scale test showed that the latex synthesis process was stable, and its performance was consistent with the results of small-scale tests. It could be used as a base resin for high-performance waterborne two-component anti-corrosion coatings.

【Keywords】waterborne hydroxyl acrylic latex; emulsifier; water resistance;fast drying; influence factor

Process and Application

Research on the preparation and application of anti-mildew functionalized modification of polythioether rubber

Peng Yuqing, Wu Songhua, Qin Pengbo

(BAIMTEC Material Co., Ltd., Beijing  100095, China)

【Abstract】In response to the problem of mildew growth in polythioether sealant in hot and humid environments, through the Michael addition reaction of thiol-double bond, using 3-iodo-2-propynyl-butyl-carbamate (IPBC) fungicide to functionally modify polythioether rubber, a series of polythioether rubber with anti-mildew functional groups were synthesized, and corresponding anti-mildew sealant materials were further prepared. The effects of different IPBC feeding ratios on product structure, molecular weight, mechanical properties, and mildew resistance were systematically investigated. The research results showed that the modification reaction successfully introduced anti-mildew functional groups into the polythioether rubber molecules. The molecular weight of the reaction product was directly related to the feeding ratio. A higher proportion of IPBC fungicide added would result in a decrease in the elongation at break of the polythioether sealant. The raw rubber with anti-mildew functional modification exhibited the best anti-mildew effect, achieving an anti-mildew grade of 0. This method effectively solved the problems of poor dispersibility and easy migration of fungicide in traditional physical addition methods, providing a new approach for the development of high performance, long lasting anti-mildew sealant.

【Keywords】polythioether rubber; sealant; anti-mildew; functional modification

Exploration of the strength of conductive adhesive bonded components in environmental testing

Xu Qiang, Huang Jianbang, Tian Chenghao, Lin Guang, Cao Zhixue, Gong Yixia

(Chengdu Hongke Electronic Technology Co., Ltd., Chengdu  610100, Sichuan, China)

【Abstract】In the electronic manufacturing industry, components are typically installed through soldering. However, there are problems such as splashing and residual materials during the soldering process that affect the reliability of use. In order to solve the potential risks associated with soldering, some components are installed using conductive adhesive bonding. To investigate the impact of environmental testing on the reliability of conductive adhesive bonding, shear force testing and fracture morphology analysis were conducted in this study on multi-layer ceramic capacitors (MLCC) bonded with two-component silver-based conductive adhesive under two accelerated aging conditions of high-temperature baking and damp-heat with electrical bias. The research results showed that, ⑴ Under high-temperature baking condition, the bonding strength first increased slightly and then continuously decreased. The long-term degradation was primarily attributed to the aging of the polymer matrix and the accumulation of thermal stress. ⑵ Under damp-heat with electrical bias condition, the bonding strength showed a continuous decline accompanied by dendritic migration. The primary cause of strength deterioration was the plasticization of the matrix due to water infiltration. ⑶ Under both environmental conditions, the samples exhibited typical ductile fracture characteristics, with fracture morphology revealing that failure occurred within the conductive adhesive. This study revealed that high-temperature baking and damp-heat electric field environments significantly weakened the long-term bonding performance of conductive adhesive, providing an experimental basis for evaluating their application reliability in harsh operating conditions.

【Keywords】conductive adhesive; bonding strength; high-temperature baking; damp-heat with electrical bias

Preparation and properties of polyurethane-based hydrophobic low infrared emissivity coating

Lyu Dandan, Li Mengyu, Chen Siyi, Ma Ruoyu, Huang Xufeiyu, Zhang Weigang

(Chuzhou University, Chuzhou  239000, Anhui, China)

【Abstract】Using polyurethane as the matrix, flake aluminum (Al) powder and nano silicone dioxide (SiO₂) as functional fillers, a hydrophobic low infrared emissivity coating was prepared in this study by adding dispersant, coupling agent (KH-560) and adhesion promoter. The influence of each component on the microstructure, emissivity, hydrophobicity, and mechanical properties of the coating was systematically investigated. The research results showed that when the mass ratio of Al powder to nano SiO₂ was 60∶40, the coating had a lower emissivity (0.579) and better overall performance. Moderate additives could further optimize performance, with 1% dispersant reducing emissivity to 0.571, 1% coupling agent increasing water contact angle to 127°, and 4% adhesion promoter improving adhesion to level 2. When the total filler content in the coating was 50%, the mass ratio of Al powder to nano SiO₂ was 60∶40, the amount of dispersant added was 1% of the total filler, the amount of coupling agent added was 1% of the polyurethane mass, and the amount of adhesion promoter added was 4% of the polyurethane mass, the infrared emissivity of the prepared coating was 0.591, the glossiness was 3.6, the adhesion was level 2, and the water contact angle reached 126°, achieving a synergistic optimization of hydrophobicity, low infrared emissivity, and good adhesion.

【Keywords】composite coating; low infrared emissivity; adhesion; hydrophobicity

Material Science

Study on properties of modified terpene resin

Yu Lei^1,2 Cao Jingpo¹, Long Xiujin¹, Wang Hongkui^1,2, Xuan Zhongcan^1,2, Jiang Xuejing^1,2, Xu Siming^1,2

（1.Shandong Yanggu Huatai Chemical Co., Ltd., Liaocheng  252300, Shandong, China; 2.National Engineering Technology Research Center for Rubber Chemicals, Liaocheng  252300, Shandong, China）

【Abstract】To improve the performance of terpene resin in rubber composite materials, styrene, α-methylstyrene, and phenol were used for chemical modification in this study. The influence of modification on its structure and rubber properties was systematically studied through dynamic mechanical analysis, vulcanization characteristics, mechanical properties, cutting resistance, abrasion resistance, hardness and other tests. The research results showed that modification could significantly increase the glass transition temperature of terpene resin, optimize molecular weight distribution, and enhance compatibility with rubber matrix. The wet skid resistance of the modified rubber material was improved, rolling resistance was reduced, vulcanization speed was accelerated, and crosslinking density was increased. The mechanical properties, abrasion resistance and cutting resistance of styrene and phenol composite modified rubber were excellent at room temperature, while the high temperature abrasion resistance of α-methylstyrene modified rubber was the best. However, the heat and oxygen aging resistance of the modified rubber material had decreased. Modified terpene resin had shown great potential for application in fields such as green tire tread rubber.

【Keywords】terpene resin; modification; wet skid resistance; rolling resistance

Preparation of multi-component modified epoxy resin for membrane enclosure system of MARK Ⅲ LNG carriers

Xie Qiongchun, Wang Yun, Gao Wentao, Lu Jinjun, Huang Yuquan, Xu Xiang, Chen Mingqi

(Zhejiang Tuanyuan Composite Materials Co., Ltd., Jiaxing  314200, Zhejiang, China)

【Abstract】In order to meet the stringent requirements of high toughness and strong interfacial bonding performance of structural adhesive for membrane enclosure system of MARK III LNG carriers, polyurethane (PU) prepolymer was synthesized in this paper by using diphenylmethane diisocyanate (MDI) and polytetrafluoroethylene (PTMG2000) through molecular design. Then it reacted with 3,4-dihydroxyphenylalanine (DOPA) and E-51 epoxy resin, and a multi-component modified epoxy resin with both catechol adhesive groups and flexible PU segments was prepared. The optimal modification ratio was determined through orthogonal experiment optimization: DOPA was 20% (proportion of epoxy resin mass, the same below), PU prepolymer was 5%, and polyetheramine curing agent was 120%. FT-IR characterization confirmed successful modification, and the color of the cured product changed from white to yellow, with the disappearance of the —NCO characteristic peak and the weakening characteristic peak of the epoxy group. Mechanical performance tests showed that the modified resin had significantly better tensile and shear strength with birch board and paint layers at 23 and -25 ℃ than the unmodified system, and met the GTT standard requirements. The performance improvement mainly came from the enhanced interface adhesion of DOPA coordination bonds and hydrogen bonds, as well as the internal toughening achieved by the “sea-island structure” formed by PU segments. The failure mode had shifted from interface failure to adhesive layer cohesion failure, further proving that both interface adhesion and bulk strength had been substantially improved.

【Keywords】LNG carrier; enclosure system; epoxy resin; DOPA; polyurethane; birch board