Scientific Research Report
Preparation and properties of high performance two-component conductive adhesive cured at room temperature
Yang Xiaoyang, Li Zheng, Zhang Fan, Liu Mengnan, Wang Zekai, Wang Tao, Wang Tong, Guo Jiping, Zhou Yingchun
(Shenzhen Academy of Metrology and Quality Inspection, Shenzhen 518055, Guangdong, China)
【Abstract】The component A of silver conductive adhesive was prepared with epoxy resin matrix and micron flake silver powder as raw materials, and two-component conductive adhesive was prepared with self-made curing agent, which was solvent-free, could be cured at room temperature for 24 h and heated at 100 ℃ for fast curing. The effects of silver powder type, filler content and curing agent type on the electrical and mechanical properties of conductive adhesive cured at room temperature or heated at 100 ℃ were studied, and the conductive mechanism of the influence of curing agent on conductivity of two-component conductive adhesive by surface coating of silver powder was proposed, the relationship between the curing agent on surface coating state of silver powder and the conductivity of conductive adhesive was analyzed. The research results showed that the optimal filler loading amount of conductive adhesive was 81% after the micron flake silver powder was properly treated. Self-made curing agent (ECA-lab) was used as component B of conductive adhesive, the resistivity was as low as 1.60×10-3 W·cm after curing at room temperature, the shear strength was up to 11.05 MPa, which was comparable with commercially available imported conductive adhesive.
【Keywords】epoxy resin; shear strength; volume resistivity; isotropy; curing agent
Design and self-healing properties of urethane/hydrogen bond double responsive high-performance polyurethane networks
Chen Meng, Hao Xudong, Qin Yu, Liu Gandong, Guo Yongchun, Wang Jinliang
（Institute of Chemistry Co., Ltd. Henan Academy of Sciences, High Performance Bonding and Sealing Materials Innovation Research Center of Henan Academy of Sciences, Zhengzhou 450002, Henan, China）
【Abstract】Elastomers with self-healing function could improve the service life of materials, which has attracted the continuous attention of relevant scholars and industry. However, the problems of high response temperature and long repair efficiency time of self-healing elastomers based on single-response thermal reversible bonds such as D-A bond, ester bond and disulfide bond still needed to be solved. In this paper, urethane monomer (EUHDI) was synthesized by addition reaction, and the structure and deblocking properties of urethane monomer were characterized by infrared and nuclear magnetic resonance test. The research results showed that the urethane monomer was successfully synthesized, and the urethane monomer did have a certain degree of deblocking performance. The degree of deblocking increased with the increase of temperature, and finally tended to balance. The optimal deblocking temperature of urethane monomer was 150 ℃.Subsequently, the elastomer based on urethane bond and hydrogen bond double responsive thermal reversible self-healing was prepared, and the self-healing performance of elastomer was characterized. The research results showed that the hydrogen bond single response at room temperature had the self-healing effect, after the cut-off spline was placed at room temperature for 30 min, it could bear the weight of 500 g. After heat treatment, the urethane bond and hydrogen bond double response self-healing effect was ideal, the surface scratches of EUHDI/3SH and EUHDI/4SH elastomer could basically achieve 100% repair, and the mechanical properties of EUHDI/3SH elastomer could be restored to 90.5% of the original sample, the mechanical properties of EUHDI/4SH elastomer could be restored to 75.7% of the original sample. The double response solved the problems of high response temperature and long repair efficiency time of self-healing elastomer with single response thermal reversible bond, which was of great significance for the development of self-healing materials with short repair response time and relatively mild response conditions.
【Keywords】elastomer; self-healing; urethane bond; hydrogen bond; thermal reversible; double response
Study on bonding properties and crosslinking mechanism of soybean oil-based pressure sensitive adhesive
Kuang Yongyan1, Chen Yao2, Tan Jing1, Liu Xingyu1, Bi Yanlan1, Li Jun1, Peng Dan1
(1. School of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, Henan, China; 2. Shandong Xiangchi Cereals & Oils Co., Ltd., Binzhou 256500, Shandong, China)
【Abstract】With epoxidized soybean oil as raw material, the optimal preparation process of soybean oil-based pressure sensitive adhesive was determined by studying the effects of phosphoric acid addition amount, rosin ester addition amount, coating thickness, reaction temperature and reaction time on bonding properties of soybean oil-based pressure sensitive adhesive. On this basis, Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectrometry (NMR) were used to analyze the structure of pressure sensitive adhesive, revealing its crosslinking polymerization mechanism and structural changes before and after aging. The research results showed that the optimal preparation process of soybean oil-based pressure sensitive adhesive was, w(phosphoric acid)=6%, w(rosin ester)=70% (all relative to the mass of epoxidized soybean oil), the coating thickness was 80 μm, the reaction temperature was 50 ℃, and the reaction time was 5 min. At this time, the adhesive film was in a continuous state, the molecular chains were effectively entangled, the reaction of polyether and polyester proceeded gradually, the polar functional groups were relatively more, the adhesion to the steel plate was stronger, the degree of crosslinking was larger, and the cohesive strength was increased. The soybean oil-based pressure sensitive adhesive prepared had no residual, the 180° peel strength was (1.866±0.18) N/cm, and the loop tack was (3.88±0.44) N. The structure of pressure sensitive adhesive was analyzed by FT-IR and 1H-NMR, which showed that phosphoric acid could catalyze the ring opening of epoxy bond to generate hydroxy polyether on the one hand, and could generate phosphate ester with epoxidized soybean oil on the other hand, and some of them existed in the free state. Rosin ester in soybean oil-based pressure sensitive adhesive was in the form of covalent or physical blocks, partly fully embedded in the network structure and partly in a semi-embedded or free state in the polymer structure.
【Keywords】epoxidized soybean oil; pressure sensitive adhesive; 180° peel strength; loop tack; polymer structure; crosslinking mechanism
Preparation of polyurethane/polyacrylate emulsion interpenetrating polymer network
Tao Xiange1, Wang Yu2, Zhai Yufu1
(1. Guangzhou Vocational and Technical University of Science and Technology, Guangzhou 510550, Guangdong, China; 2. Guangdong University of Technology, Guangzhou 510006, Guangdong, China)
【Abstract】Waterborne polyurethane (WPU) was synthesized by using polypropylene carbonate diol as soft segment, and the emulsion interpenetrating polymer network (PU/PA LIPN) of polyurethane (PU) and polyacrylate (PA) was prepared by interpenetrating network technology. The properties of polyurethane and polyacrylate emulsion interpenetrating polymer network were studied, the effects of different initiators on the synthesis of PU/PA LIPN were investigated. The effects of different components of polyacrylate on the properties of PU/PA LIPN and the effects of different proportions of polyacrylate/polyurethane on the properties of PU/PA LIPN were also studied. The research results showed that PA and PU had good interpenetration, the glass transition temperature (Tg) was close to each other, and polymethyl methacrylate (PMMA) had been synthesized in PU. Different initiators were used to initiate PA, comparatively ammonium persulfate (APS) had better effect, which could synthesize PU/PA LIPN with stable emulsion and good film formation. When the components of PA were changed, with the increase of the content of BA in the soft segment of PA, the mechanical properties of the prepared polyurethane emulsion decreased, but the water resistance increased. When the proportion of PA/PU was changed, with the increase of the proportion of PA, the water resistance and mechanical properties of emulsion first increased and then decreased, and the proportion of 30% PA was excellent.
【Keywords】polypropylene carbonate diol (PPCD); interpenetrating polymer network; waterborne polyurethane
Development and Application
Study on effects of screw combination on properties of polyethylene grafted maleic anhydride
Li Xutian, Wang Jiasheng, Tang Fangcheng, Wen Haijun, He Chuang
(Guangzhou Lushan New Material Co., Ltd., Guangzhou 510530, Guangdong, China)
【Abstract】A series of polyethylene grafted maleic anhydride (PE-g-MAH) with different relative grafting ratios (range from 0.17% to 0.39%) and melt indices (0.5 to 3.6 g/10 min) were prepared by melt grafting using twin-screw extruder with different screw combinations. The bonding resin with the same content of PE-g-MAH was prepared by mixing PE-g-MAH with unmodified polyethylene and antioxidant. The grafted products of different screw combinations were characterized and measured by means of infrared spectroscopy, number of crystal points, grafting ratio, thermal and mechanical properties, and their properties were also measured by preparing multilayer composite sheets. The research results showed that the smaller the dislocation angle was, the stronger the conveying capacity of kneading block screw element was, and the shorter the residence time of the material was. Maleic anhydride could be grafted onto polyethylene by four groups of different screw combinations. With the increase of shear strength and dispersion ability, the retention time increased, the number of crystal points of the grafted products decreased, the grafting ratio increased from 0.17% to 0.39%, and the melt index increased from 0.5 g/10 min to 3.6 g/10 min. With the increase of shear strength, the oxidation induction period of the grafted products shortened, the mechanical strength decreased, the elongation at break increased, and the color turned yellow. The increase of grafting ratio could enhance the adhesion of the grafted products to ethylene-vinyl alcohol copolymer (EVOH) and PE in the bonding resin. Under the same grafting ratio, the more serious the structural damage of the grafted products was, the weaker the adhesion of the bonding resin was.
【Keywords】polyethylene grafted maleic anhydride; EVOH; bonding property; composite film
Preparation and application of high performance acrylic resin dispersion
Du Peihua1, Dai Guoxu2, Zhang Linxiang2
(1.Changzhou Dubo Polymer Co., Ltd., Changzhou 213000, Jiangsu, China; 2. Chuzhou Dubo New Materials Technology Co., Ltd., Chuzhou 239400, Anhui, China)
【Abstract】Hydroxy acrylic resin with core-shell structure was prepared by subsection dropping method, and waterborne acrylic resin dispersion was obtained by phase inversion method. The hardness, thickness, viscosity and impact of the dispersion were tested by hardness tester, film thickness tester, viscometer and cylindrical mandrel bending tester. The research results showed that when the ratio of hard and soft monomers was 4∶3, m(benzoyl peroxide)∶m(tert-butyl peroxy-2-ethylhexanoate)=1∶1, m(hydroxyethyl methacrylate)∶m(hydroxypropyl methacrylate)=4∶5, the monomer titration time was controlled at 4.0 h, N, N-dimethylethanolamine was selected as the neutralizer and the neutralization degree was 100%, the synthesized hydroxy acrylic resin dispersion had relatively the best performance. The dispersion could be used to prepare both baked coatings and two-component self-drying coatings. Through testing, it was found that the coating layer had good hardness, dryness, gloss, water resistance performance and excellent chemical resistance, which could be applied to various industrial anti-corrosion fields.
【Keywords】acrylic resin; dispersion; waterborne coating
Development of a kind of conductive adhesive with high temperature resistance
Zhang Lingyun
(Shanghai Plastics Research Institute Co. Ltd., Shanghai 201702, China)
【Abstract】The conductive adhesive with high temperature resistance was prepared with phenolic cyanate resin as the conductive adhesive matrix and flake silver powder as the filler material. Imidazole curing agent and acetate diluent were used to adjust the curing process and viscosity of conductive adhesive, and its thermal mechanical properties, mechanical strength and electrical/thermal conductivity were studied. The research results showed that the glass transition temperature of conductive adhesive was 232 ℃, the dynamic modulus at 100 ℃ and 250 ℃ were 6 271 and 273 MPa respectively, the coefficient thermal expansion before the glass transition was 36.63 μm/(m·K), and the construction work could be stabilized at high temperature. The shear strength of conductive adhesive increased by 40% after kept at 320 ℃ for 10 min, indicating that high temperature treatment did not affect the shear strength of conductive adhesive. The volume resistivity of this conductive adhesive was extremely low (3.48×10-6 Ω·m), the electrical conductivity was excellent, which was superior to similar conductive adhesive on the market.
【Keywords】phenolic cyanate; flake silver powder; conductive adhesive; high temperature resistance
Influence of chemical oxidation on bonding properties of aluminum alloy
Li Yongliang, An Donglan, Duan Jianzhen, Huang Tao
(AVIC Xi’an Flight Automatic Control Research Institute, Xi’an 710065, Shaanxi, China)
【Abstract】The influence of chemical treatment temperature, chemical treatment time, the number of times of using chemical treatment solution and the storage mode of treated specimen in chemical oxidation surface treatment on test results of adhesive shear strength was analyzed. The research results showed that the bonding effect of aluminum alloy was relatively good when the chemical treatment temperature was around 70 ℃, the chemical treatment time was controlled between 10-30 min, the chemical treatment solution was used at most 2 times, and the bonding of the treated and dried specimens were completed within 4 h.
【Keywords】adhesive; surface treatment; shear strength
Special Topics and Review
Research progress on environmental-friendly polyurethane adhesive
Xu Xinxin, Sun Jian, Ji Shangchao, Shi Lei, Zhao Lei
（Provincial Enterprise Research Institute of Zhejiang Hexin Science & Technology Co., Ltd., Zhejiang Hexin Science & Technology Co., Ltd., Key Laboratory of Jiaxing, Jiaxing 314000, Zhejiang, China）
【Abstract】With the increasingly strict environmental protection policy in China and the strengthening of people's awareness of environmental protection, traditional polyurethane adhesive containing VOC is gradually eliminated by the market and consumers. Waterborne and solvent-free are the important technical routes for the transformation of traditional polyurethane adhesive into environmental-friendly one. Compared with foreign chemical giants, China's polyurethane adhesive manufacturers are still in the initial stage of development and research of environmental-friendly polyurethane adhesive products. In this paper, the research progress of environmental-friendly polyurethane adhesive in China in recent years was reviewed from the aspects of basic formulation research, key raw material performance, and application of special functional polyurethane adhesive.
【Keywords】polyurethane; adhesive; environmental-friendly; functionality
Study on bonding behavior of polysulfide sealant
Fang Yuanrong, Yu Meichao, Bao Chuanlei, Wu Songhua
（AECC Beijing Institute of Aeronautical Materials, Beijing 100095, China）
【Abstract】The good bonding properties, mechanical properties, medium resistance, low temperature resistance and heat aging resistance of polysulfide sealant were briefly described. The bonding theories, such as mechanical interlocking theory, electrostatic adsorption theory, diffusion theory, chemical reaction theory, acid-base theory and weak boundary layer theory were mainly described. The application of bonding thermodynamics and detection methods in the study of bonding behavior was also introduced. It could be seen that bonding behavior was a complex physical and chemical phenomenon, which needed to be studied and analyzed from different aspects in cooperation with each other.
【Keywords】polysulfide sealant; bonding theory; detection