Scientific Research Report
Research on self-repair and bonding properties of polyurethane based on hydrogenated hydroxyl-terminated polybutadiene and catechol group
Zhu Jun1,Chang Chun1, Wei Liuhe2, Li Yuhan2
(1.College of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, Henan, China; 2. College of Chemistry, Zhengzhou University, Zhengzhou Key Laboratory of Elastic Sealing Materials, Zhengzhou 450001, Henan, China)
【Abstract】Chain extender containing catechol group was synthesized from 3,4-dihydroxybenzaldehyde (DBA) and serinol, and then linear polyurethane (HHPB-DS) was synthesized with hydrogenated hydroxyl-terminated polybutadiene (HHPB) and isophorone diisocyanate (IPDI). The research results showed that the polyolefinic HHPB had a higher degree of microphase separation than that of polytetramethylene ether (PTMEG). The viscous flow transition temperature of HHPB-DS was 81 ℃, which not only exhibited self-repair properties but also could be used for hot melt bonding. The introduction of catechol group endowed the material with good bonding to a variety of substrates, especially to improve the bonding strength to steel plate. The HHPB with low surface energy played a role in protecting the hard segment phase and reducing the interference of water molecule on the hydrogen bond between carbamate group and catechol group so that the bonding strength of substrate could still be maintained even after immersed in water for 3 d.
【Keywords】catechol; hydrogenated hydroxyl-terminated polybutadiene; water resistance; self-repair; bonding
Preparation and properties of novel chain extender and its modified waterborne polyurethane acrylate
Luo Qinghong1, Wu Shufang1,2, Zhang Yushu1, Mo Zhaohong1, Wen Xinyu1, Liu Xiaoxuan1
（1.Guangdong University of Technology, Guangzhou 510006, Guangdong, China; 2.Guangdong Shenzhan Industry Co., Ltd., Jieyang 522061, Guangdong, China）
【Abstract】A chain extender with cyclic side chain was synthesized from ethylenediamine and isobornyl acrylate, and its structure was characterized by infrared and nuclear magnetic hydrogen spectroscopy. A series of modified waterborne polyurethane acrylate were prepared by modifying polyurethane acrylate with the synthetic chain extender. The effects of different photoinitiators (JRCure500, 1173 and L-TPO) on the curing kinetics of modified waterborne polyurethane acrylate were investigated, and it was found that JRCure500 had relatively high double-bond conversion and photopolymerization rate. The effects of the amount of chain extender on the particle size of modified waterborne polyurethane acrylate emulsion, the tensile strength of cured film, the glass transition temperature, the water absorption and the thermal weight loss were studied. The research results showed that with the increase of the amount of chain extender, the particle size of emulsion gradually increased, the tensile strength of cured film gradually increased, the glass transition temperature gradually increased, the water absorption gradually decreased, and the temperature of maximum thermogravimetric rate gradually decreased.
【Keywords】waterborne UV curing; polyurethane acrylate emulsion; chain extender
Research on bonding of polytetrafluoroethylene thin sheet and aluminum alloy by epoxy adhesive film
Yang Haidong1, Wang Shuai2, Wang Dezhi1, Li Hongfeng1, Xiao Wanbao1, Zhao Liwei1, Qu Chunyan1, Kang Wenshuang1
(1.Institute of Petrochemistry Heilongjiang Academy of Sciences, Harbin 150080, Heilongjiang, China;2.China Academy of Launch Vehicle Technology, Beijing 100076,China)
【Abstract】The curing process, heat resistance and microscopic morphology of the new epoxy-arylamine structural adhesive film were studied. The research results showed that the glass transition temperature (tanδ method) of the adhesive film was about 202 ℃. The TGA curve showed that the temperature of 5% mass loss of cured adhesive film was about 372 ℃, and the DTG curve showed that the fastest thermal weight loss rate of adhesive film was about 400 ℃. Scanning electron microscopy photos showed that the fracture surface of adhesive film was ductile failure mode.
The adhesive film was used to study the bonding of wear-resistant polytetrafluoroethylene thin sheet and aluminum alloy. The effects of curing time, pressure and surface treatment of aluminum alloy on bonding strength of them were analyzed. The research results showed that when the curing process was 180℃/3h and the pressure was 0.3MPa, the bonding strength of wear resistant polytetrafluoroethylene thin sheet and aluminum alloy was relatively good, the shear strength was 12.7 MPa at room temperature (23 ℃) and 5.6 MPa at high temperature (177 ℃). The adhesive film had potential application value in aeroengine.
【Keywords】wear-resistant polytetrafluoroethylene thin sheet; aluminum alloy; heat resistance; bonding strength
Preparation of one-component moisture curing polyurethane adhesive for wood and selection of optimal R value
Gu Hao, Xu Zhen, Gu Jiyou
(Northeast Forestry University, Harbin 150000, Heilongjiang, China)
【Abstract】One-component moisture curing polyurethane adhesive for wood was prepared by one-step reaction of polyether polyol, chain extender and isocyanate. The properties of samples were analyzed, and the optimal —NCO/—OH (R value) was explored. The research results showed that when R value was 10.38, the adhesive applied to birch wood had relatively best bonding strength, and at this time the adhesive had excellent wettability, thermal stability and open time performance on birch wood.
【Keywords】wood adhesive; polyurethane; bonding strength; single factor test
Development and Application
Study on environmental reliability of ionic conductor structural adhesive
Wu Min, Wei Yong
(School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang 621010, Sichuan, China)
【Abstract】A kind of high-strength ionic conductor epoxy structural adhesive that could be quickly peeled off by electricity was prepared by introducing polyethylene glycol (PEG1000) and 1-butyl-3-methylimidazolium bis[(trifluoromethyl) sulfonyl]imide ([BMIM]TFSI) into epoxy adhesive. The initial bonding strength reached 21.65 MPa, the residual strength was only 0.02 MPa after applying 60 V/60 s, and the peeling efficiency was 99.91%. The influence of aging environment with temperature of 55 ℃ and relative humidity of 95%RH on the bonding strength of I-EP was emphatically studied. The research results showed that the bonding strength of I-EP reduced by 49.28% after aging for 48 h in this environment. The study on the failure mechanism of its environmental reliability found that under high temperature and high humidity environment, [BMIM]TFSI in I-EP body was prone to physical migration to the bonding interface and spontaneous electrochemical corrosion with the bonding substrate, leading to the destruction of strong interaction between adhesive and substrate, which led to a significant decline in the bonding strength.
【Keywords】ionic conductor; structural adhesive; environmental reliability
Prediction of dynamic viscosity of epoxy resin system in curing process by using aggregate
Zhu Xiaoxia1, Liang Guoxing1,2, Lyv Ming1,2, Zhao Jian1,2, Yang Po1, Yue Chunyu1
(1.College of Mechanical and Transportation Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China; 2.Shanxi Provincial Key Laboratory of Precision Machining, Taiyuan 030024, Shanxi, China)
【Abstract】In order to monitor the viscosity of epoxy resin system in the curing process in real time, a dynamic viscosity prediction model based on similarity theory and immersed body (plummet) method was established. First, combined with the main factors affecting viscosity, the dimensionless viscosity equation was derived by using dimensional analysis method. Secondly, by analyzing the real measured viscosity data, the viscosity prediction equation of aggregates with different particle sizes under different reaction time conditions was obtained. Finally, the predicted results of the equation were compared with the measured viscosity. The research results showed that this method could predict the actual viscosity of resin system in the curing process under different particle sizes of aggregate conditions. The confidence level of predicted viscosity in the early and late stage of curing reaction of resin system was higher than that in the middle stage of curing reaction. When the aggregate particle size was 4.75-6.00 mm, the consistency between the measured viscosity and the predicted viscosity was relatively the highest.
【Keywords】resin system; curing process; prediction model; similarity theory; immersed body (plummet) method
Study on synthesis and properties of double-crosslinked monomer modified PVAc emulsion adhesive
Ren Jie1,2, Xu Gang1,2, Chen Changzhu2
[1.SKSHU New Materials (Shanghai) Co., Ltd., Shanghai 201100, China; 2.SKSHU Paint Co., Ltd., Putian 351100, Fujian, China]
【Abstract】The double-crosslinked monomer modified polyvinyl acetate (PVAc) emulsion was prepared by semi-continuous seed emulsion polymerization using diallyl phthalate (DAP) as the pre-crosslinked monomer and vinyltriethoxysilane (VTES) as the post-crosslinked monomer. The effects of the using amount of two monomers on the stability of emulsion polymerization were studied, and the properties of the obtained emulsion were characterized by various means. The research results showed that the polymerization reaction could proceed stably when the mass fraction of VTES and DAP was 4% and 2.5%, respectively. The water absorption of modified emulsion film was as low as 8.3%, the maximum static contact angle was 80.2°, the maximum wet shear strength with wood could reach 2.53 MPa, the Tg of emulsion film reached 28.76 ℃, and the initial decomposition temperature reached 307.78 ℃, indicating that the water resistance and thermal stability of PVAc emulsion modified by these double-crosslinked monomers had been greatly improved.
【Keywords】polyvinyl acetate; double-crosslinked monomer; silicone modification; water resistance
Preparation and properties of electrically conductive adhesive with high thermal conductivity
Zuo Xing
(Shanghai Plastics Research Institute Co., Ltd., Shanghai 201702, China)
【Abstract】Different kinds of conductive adhesive was prepared by using a series of silver powder. Through different formulations to allocate the viscosity of conductive adhesive, and combined with the relevant properties of conductive adhesive, three kinds of conductive adhesive A, B and C were finally obtained through debugging. The viscosity, thermal stability, curing properties, electrical and thermal conductivity and mechanical properties were then studied. The research results showed that the thixotropy of three kinds of conductive adhesive was all good, the thermal decomposition temperature was about 390 ℃, the temperature resistance was excellent, and the curing temperature was all about 220 ℃. The thermal conductivity of three kinds of conductive adhesive was 27.31, 31.93 and 29.23 W/(m·K), respectively, which were far beyond the enterprise standard requirements [>2 W/(m·K)]. The tensile shear strength of prepared three kinds of conductive adhesive at high temperatures was 50% higher than that of traditional conductive adhesive, which could fully meet the high temperature use conditions of conductive adhesive. In summary, the conventional performance of three kinds of conductive adhesive could meet the enterprise standard with stable performance, and they could be applied to the high-precision semiconductor packaging field with high requirements for thermal conductivity.
【Keywords】high-filled silver powder; micronano silver powder; conductive adhesive; high thermal conductivity
Special Topics and Review
Research status and prospect of conductive adhesive for electronic packaging
Zhang Weiwei1, Liu Hao1, Liu Jiahao2, Li Mingyu 1, Chen Hongtao1
[1. Harbin Institute of Technology (Shenzhen) School of Materials Science and Engineering, Shenzhen 518055, Guangdong, China; 2. The Fifth Electronics Research Institute of Ministry of Industry and Information Technology, Guangzhou 511370, Guangdong, China]
【Abstract】Although conductive adhesive has received extensive attention in the field of electronic packaging, it can not completely replace solder with conductive adhesive because of some limitations of its performance. This is mainly related to the reliability of conductive adhesive, such as unstable contact resistance, limited impact resistance, low adhesion and electrical conductivity. In this paper, the classification of conductive adhesive, various conductive fillers and the research status of the reliability of conductive adhesive were introduced, aiming at revealing the comprehensive performance of conductive adhesive and prospecting the future development trend of conductive adhesive.
【Keywords】conductive adhesive; conductive filler; reliability; electronic packaging
Overview of durability of precast concrete segmental adhesive joint
Yao Shufang1,2, Zeng Bing1,2, Wang Xianqian3, An Shaodu1,2
(1.China Academy of Building Research, Beijing 100013, China; 2. CABR Testing Center Co., Ltd., Beijing 100013, China; 3.Shenzhen Municipal Design & Research Institute Co., Ltd., Shenzhen 518037, Guangdong, China)
【Abstract】The development history of precast segmental bonding technology and the basic characteristics of precast concrete segmental adhesive joint were summarized. The aging mechanism of this kind of epoxy resin adhesive and the research methods and achievements of the durability of adhesive joint were emphatically described, which mainly included the durability of precast segmental splicing adhesive and the durability of adhesive joint. On this basis, the shortcomings of current research were pointed out, and some suggestions for research direction were put forward.
【Keywords】precast segment; adhesive joint; epoxy resin; splicing adhesive; durability
Application of reactive polyurethane hot melt adhesive in electronic assembly
Xu Yuwen, Yan Mingfa
(Dongguan U-Bond Material Technology Co., Ltd., Dongguan 523837, Guangdong, China)
【Abstract】The research progress of reactive polyurethane (PUR) hot melt adhesive in recent years was reviewed. The curing mechanism, material design and performance optimization of different kinds of PUR hot melt adhesive were systematically discussed. In addition, the application of PUR hot melt adhesive in electronic assembly was described. Finally, the application and challenge of PUR hot melt adhesive in electronic assembly were prospected.
【Keywords】reactive polyurethane hot melt adhesive; electronic assembly; silane-modification; light-moisture dual-curing