Special Topics Review

Research progress and prospects on organic dispersion of entangled polymer prepared by phase inversion component method

Cao Wenkai¹, Wang Lipeng¹, Su Siqi¹, Gu Jie², Bai Yongping^1,2

(1.School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin  150001, Heilongjiang, China; 2.Wuxi HIT New Material Research Institute Co., Ltd., Wuxi  214100, Jiangsu, China)

【Abstract】The technical principles of high and low energy emulsification methods were summarized respectively, and the technical characteristics and application status of different emulsification methods were analyzed. Inspired by the preparation method of nano emulsions, combining the structural characteristics of entangled polymer and the low molecular weight and easy deformation characteristics of organic phase in nano emulsion system, the defects of preparing entangled polymer dispersion by high-energy emulsification method were analyzed, and the phase transformation in the low energy emulsification method could be used to prepare entangled polymer dispersion. The technical feasibility of preparing organic dispersion of entangled polymer by PIC method was determined by combining the effects of phase inversion temperature (PIT) method and phase inversion component (PIC) method on the curvature change of emulsifiers, and the expansion of the application field of entangled polymer was prospected.

【Keywords】high energy emulsification; low energy emulsification; phase inversion temperature method; phase inversion component method

Research progress in acrylate-based conductive pressure sensitive adhesive

Xu Dan¹, Zhang Junying²,Niu Donghua¹, Song Jiayun¹, Liu Tong¹,Cheng Jue²

(1.BeijingTianyu Aerospace New Material Technology Co., Ltd., Beijing  101407, China; 2.College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing  100020, China)

【Abstract】The research progress of three types of fillers for acrylate-based conductive pressure sensitive adhesive, including metal fillers, inorganic non-metallic fillers, and hybrid fillers were reviewed. The structural design of acrylate-based conductive pressure sensitive adhesive, which includes accessing to urethane bond and epoxy group on the basis of acrylate-based conductive pressure sensitive adhesive was summarized. Finally, the future development of acrylate-based conductive pressure sensitive adhesive was prospected.

【Keywords】conductive pressure sensitive adhesive; acrylate; conductive filler

Research Report 

Preparation of temperature resistant epoxy resin with rapid curing at room temperature and properties of modified sealant

Liu Tantan¹, Wei Min¹, Cheng Zhenshuo², Zhu Xinbao^1,2

（1.College of Chemical Engineering, Nanjing Forestry University, Nanjing  210037, Jiangsu, China; 2.Anhui Xinyuan Technology Co., Ltd., Huangshan  245900, Anhui, China）

【Abstract】Phthalic acid diglycidyl ester (PADE) was synthesized by using phthalic anhydride and epichlorohydrin as raw materials, and then it was used as matrix resin to prepare two-component sealant. The structure of PADE and the surface drying time, hardness, mechanical properties, thermal properties, thermal stability, and microstructure of two-component sealant were measured or characterized. The research results showed that, ⑴ The product was structurally characterized by FT-IR and ¹H-NMR. The epoxy value of the product was 0.58 mol/100 g, and the viscosity at room temperature (25 ℃) was 2 245 mPa·s. ⑵ The surface drying time of PADE-10% sealant was shortened by 30 minutes compared to the sealant without PADE added. ⑶As the amount of PADE added increased, the tensile strength, elongation at break, flexural strength and impact strength of epoxy sealant first increased and then decreased. When the amount of PADE added was 10%, the comprehensive mechanical properties were excellent. The tensile shear strength of PADE-10% sealant at different aging time was higher than that of PADE-0 sealant, indicating that this adhesive had certain aging resistance. ⑷ It was found that PADE had a catalytic effect, reducing the activation energy and increasing the reaction speed. With the addition of PADE, the T_g of the system continued to decrease, from 93.1 ℃ to 81.6 ℃. ⑸ The T_10% and T_max of PADE-0 (pure E-51) sealant were lower than those of PADE-10% sealant, indicating that the addition of PADE formed a highly crosslinked network, making the cured product structure denser. Adding an appropriate amount of PADE could improve the heat resistance of the sealant and made the sealant have better mechanical properties. ⑹ By studying the effect of adding PADE on the bonding mechanism of modified E-51 epoxy sealant, it was found that the fracture surface of E-51 cured product exhibited brittle fracture characteristics, while the epoxy sealant added with 10% PADE showed an ordered band structure on the fracture surface, accompanied by a large number of small silver lines, exhibiting ductile fracture characteristics, indicating that PADE had the enhancing and toughening effect.

【Keywords】sealant; glycidyl ester; fast curing; mechanical property; thermal stability

Study on curing kinetics of allyl etherified phenolic imine resin

Hu Liangkai¹,Yu Xinhai¹,Li Zhifang²

(1. College of Chemistry and Chemical Engineering, Donghua University, Shanghai  201620, China;2. Special Resin Research Institute, Shandong Shengquan New Materials Co., Ltd., Ji’nan  250200, Shandong, China)

【Abstract】The DSC curves of allyl etherified phenolic imine resin (APMI-F resin) were measured at different heating rates by using differential scanning calorimeter. The curing reaction kinetics of APMI-F resin were studied by using non isothermal thermodynamic research method. Using T-β extrapolation method, the starting temperature T_i, peak temperature T_p, and termination temperature T_f of the curing reaction of APMI-F resin were determined, and it was used as the basis for exploring the curing process of APMI-F resin. The apparent activation energy of APMI-F resin was obtained by Kissinger method and Starink method. The apparent activation energy at different curing degrees was obtained by Starink method and compared with experimental data to verify the accuracy of the curing kinetics model. The research results showed that, ⑴ The T_i, T_p and T_f of the curing reaction of APMI-F resin were determined by extrapolation method to be 161.09, 226.81 and 263.42 ℃, respectively. ⑵ The average activation energy obtained by Starink method was higher than that obtained by Kissinger method. ⑶ During the curing reaction, as the degree of curing increased, the apparent activation energy of APMI-F resin showed a trend of first decreasing and then increasing. In the initial stage of curing, the activation energy decreased due to the decrease in viscosity. As the degree of crosslinking increased, the movement of chain segments was limited, leading to a gradual increase in activation energy. ⑷ The curing kinetics model of APMI-F resin was successfully established through the Málek method, and compared with experimental data, it was found that the model could well describe the curing process of APMI-F.

【Keywords】phenolic imine resin; allyl group phenolic; curing reaction kinetics; addition curing reaction; apparent activation energy

Preparation and properties of PEG-CL-LA copolymer for polyurethane bandage

Yu Yuanzhong, Xia Zhean, Chen Lingli, Ye Wei

(School of Materials Science and Engineering, East China University of Science and Technology, Shanghai  200237, China)

【Abstract】Using stannous octoate as the catalyst, polyethylene glycol (PEG) as the starting agent, ε-caprolactone (CL) and lactic acid (LA) as raw materials, the binary alcohol copolymers (PLCA) with different quantities of CL unit and LA unit were directly condensed and synthesized under the condition of 170 ℃ and high vacuum. PLCA was mixed with an excess of 4,4'-diphenylmethane diisocyanate (MDI-100) and a small amount of tertiary amine catalyst, reacted at 70 ℃ to obtain a copolymer mixed colloid (PLCA-PU) with isocyanate end terminated, which was then coated on polyester porous woven belt to prepare polyurethane bandage. By maintaining the amount of PEG, changing the ratio of CL and LA and the amount of isocyanate, a series of PLCA and PLCA-PU were obtained. Their structures were analyzed, and the curing time and radial compressive force of polyurethane bandage were tested. The research results showed that PLCA and PLCA-PU had been successfully prepared. When R=5, and n(PEG)∶n(CL)∶n(LA)=1∶6∶7, the curing time of the bandage prepared by PLCA-PU was 383 s, the maximum compressive force could reach 19.4 N. Choosing the appropriate material ratio could meet the requirements of rapid curing and having appropriate rigidity and strength of bandage.

【Keywords】polyethylene glycol; polyurethane bandage; ε-caprolactone; lactic acid

Process and Application

Preparation and performance characterization of EPI wood adhesive with high wet strength and long opening period

Yu Guixun, Huang He

(College of Chemistry, Chemical Engineering and Materials Science of Soochow University, State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Suzhou    215123, Jiangsu, China)

【Abstract】First, two emulsions (SAEP3 and SAEP4) for EPI wood adhesive, i.e. one with excellent wet strength (6.4 MPa) but short opening period (40 min) , the other with long opening period (145 min) but low wet strength (3.8 MPa), were prepared respectively. Then the effect of the ratio of two emulsions on the properties of composite emulsion adhesive was explored. The research results showed that, when the amount of two emulsions was the same, the synergistic effect was achieved. The opening period of the prepared emulsion (SAEP5) adhesive was 100-120 min, and the wet strength reached 6.4 MPa. Compared with the commercially available SL6517 adhesive tested under the same conditions, its opening period was equivalent, and its wet strength was about 25% higher than that of SL6517 adhesive (average 5.1 MPa). As a result, EPI wood adhesive with high wet strength and long opening period was successfully prepared.

【Keywords】wood adhesive; styrene-acrylate emulsion; wet strength; opening period; composite emulsion

Discussion on process verification of flooring cloth paving for rail vehicles

Zhao Min, Wang Hao

（CRRC Qingdao Sifang Co., Ltd., Qingdao  266111, Shandong, China）

【Abstract】 In response to the problem of bulging on the flooring cloth of rail vehicles, the first class carriage of a certain vehicle model was taken as the research object. The flooring cloth paving structure was "aluminum honeycomb floor + three layers of soundproofing material (undetermined material) + a certain type of rubber flooring cloth". The optimal welding construction process parameters were optimized through orthogonal experiment. The performance of different types of soundproofing materials and the matching between flooring cloth and soundproofing materials were judged through T-shaped peeling, surface wetting test, thermal expansion deformation rate, etc. The feasibility of the paving process was confirmed through simulation experiment of structural parts in harsh environment. Finally, the process verification of flooring cloth paving was completed based on the above experimental results. The research results showed that, ⑴ The optimal process parameters suitable for welded rubber flooring cloth were the welding machine temperature scale of 3.0, the speed scale of 2.5, and the air output scale of 2.0. At this time, the tensile strength of the welded joint was the highest and the fusion state was good. ⑵ Experimental analysis was conducted on the compatibility of soundproofing materials from three dimensions: T-shaped peel strength, surface wettability, and thermal expansion deformation. The results showed that "aluminum honeycomb floor + three layers of rubber soundproofing materials + rubber flooring cloth" basically met the production requirements. ⑶ The system of "aluminum honeycomb floor + DN341SA + the first layer of rubber soundproofing material + DU345D + the second layer of rubber soundproofing material + DU345D + the third layer of rubber soundproofing material + DN341SA + rubber flooring cloth" had undergone high and low temperature cycling test and continuous high temperature test without any surface bulging and weld cracking of the flooring cloth, indicating that the paving system had strong aging resistance and could meet the needs of rail production and operation.

【Keywords】rail vehicles; flooring cloth; process verification; aging test

Research on high reliability bonding technology for space-borne microwave dielectric resonator

Fan Tian¹, Zhang Le^1,2, Fan Kai¹, Diwu Dongchao¹

[1.China Academy of Space Technology (Xi’an), Xi’an  710100, Shaanxi, China；2.National Key Laboratory of Science and Technology on Space Microwave, Xi’an  710100, Shaanxi, China]

【Abstract】Dielectric resonator is the core component of the space-borne microwave dielectric multiplexer and is a key component of the payload of communications satellite. Dielectric resonator is generally made of cylindrical ceramic media with low loss, high dielectric constant, and stability to temperature changes. Usually, adhesive is used to bond onto specialized screws and adjust the position in the multiplexer chamber through quartz tubes or columns. In response to the key difficulties in the bonding technology of space-borne microwave dielectric ceramic resonator, a dedicated fixture was designed to control the entire process of adhesive selection, bonding, and experimental verification, ensuring process factors such as adhesive coaxiality, bonding pressure, and adhesive dosage. Simultaneously ensuring the reliability of bonding and the high Q value of the dielectric resonator, thermal, mechanical and radiation verifications were carried out according to the experimental level of space-borne products, achieving high reliability bonding of microwave dielectric ceramic materials and obtaining high-performance space-borne microwave passive products. The research results showed that the bonding process of space-borne microwave dielectric resonator was determined by the characteristics of the adhesive, the roughness of the bonding surface, and the control process of the adhesive usage. A resonator that met the requirements for aerospace use could only be qualified for aerospace flight after passing aerospace level testing verification under specific process parameters.

【Keywords】space-borne; dielectric resonator; high Q value; reliability

Material Science

Research on the influence of fillers and plasticizers on the performance of polysulfide road potting sealant

Tian Peijun¹, Liu Xiaosong², Chen Song³, Zhang Zengping², Yang Yang¹, Xia Jingjie¹, Qian Jianxing⁴

（1.Ningbo Dongxing Asphalt Products Co., Ltd., Ningbo  315000, Zhejiang, China;2.Key Laboratory for Special Area Highway Engineering of Ministry of Education, Chang’an University, Xi’an  710064, Shaanxi, China; 3.Jiangsu Expressway Engineering Maintenance Co., Ltd., Huaian  223000, Jiangsu, China; 4.Chang’an Dublin International College of Transportation at Chang’an University, Xi’an  710018,Shaanxi, China）

【Abstract】A comparison was made by using lightweight CaCO₃, heavy CaCO₃, kaolin, and nano ZnO as fillers for polysulfide road potting sealant. Fumed SiO₂ was added as the reinforcing filler to the sealant, and two kinds of plasticizers, dibutyl phthalate (DBP) and butyl benzyl phthalate (BBP) were selected for comparison. The influence of different types and dosages of fillers and plasticizers on the performance of polysulfide road potting sealant was studied, at the same time, the optimal dosage of filler and plasticizer for polysulfide potting sealant was determined. The research results showed that the polysulfide potting sealant prepared with lightweight CaCO₃ as filler had better mechanical properties and could be better dispersed in the system. Compared to DBP, BBP was more environmentally friendly and less prone to contaminating the substrate. Therefore, lightweight CaCO₃ and BBP were selected as filler and plasticizer, respectively. After studying their mechanical properties, microstructure, dispersion, and thermal stability, it was believed that the comprehensive performance of the prepared polysulfide potting sealant was relatively good when the optimal dosage of lightweight CaCO₃ was 200 parts and the optimal dosage of BBP was 80 parts.

【Keywords】polysulfide road potting sealant; filler; plasticizer; road maintenance