Scientific Research Report
Synthesis of branched polyacrylate and application of pressure sensitive adhesive
Xu Dezhe, Liu Chang, Qian Jun, Shi Yifeng
(School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237, China)
【Abstract】Using hexanediol diacrylate (HDDA) as the branched monomer and n-dodecanethiol (DDT) as the chain transfer agent, the branched poly(butyl acrylate) (BPBA) was prepared by free radical solution polymerization using free radical modulation-polyene monomer copolymerization method (Strathclyde method) at the mass ratio of 100∶10∶7.0 of butyl acrylate (BA), HDDA and DDT. The effects of initiator, theoretical solid content and branched monomers on the polymerization reaction were discussed, the formation process of branching was also analyzed, and the different properties of linear and branched polymers were compared. Based on the preparation of BPBA, a preliminary investigation was conducted on the preparation of pressure sensitive adhesives with butyl acrylate as the main monomer. The branched acrylate pressure sensitive adhesives (BPSA) with different degrees of branching were prepared, and the mechanical properties of BPSA were analyzed. The research results showed that, (1) under the same ratio of chain transfer agents to branched monomers, the degree of polymer branching increased with the increase of branched monomer concentration. As the reaction progressed, the degree of polymer branching gradually increased, and the final reaction product consisted of polymers with different molecular weights and degrees of branching. (2) Compared to linear polymers, branched polyacrylate had lower viscosity and more compact molecular chain structure at high content. The differences in structure and composition made BPBA polymers have characteristics such as low glass transition temperature and unclear high elastic state regions. (3) The presence of low molecular weight polymers and branched structures in branched acrylic pressure sensitive adhesives resulted in a gradual decrease in the tack strength and peel strength of BPSA as the concentration of branched monomers increased. (4) Both crosslinking agent aluminum acetylacetone (ALAA) and HDDA monomers could cause coupling between polymer molecular chains, but ALAA caused the formation of a three-dimensional cross-linked structure in the polymer. The pressure sensitive adhesive prepared with HDDA as a branched monomer had good organic solvent solubility, strong processability, and high tack strength.
【Keywords】solution polymerization; branched polymer; pressure sensitive adhesive
Study on low mole ratio urea-formaldehyde resin adhesive modified by melamine for moisture-proof fiberboard
Jiang Qian1, Lu Li1, Qing Yan1, Yang Shoulu2, Li Tianhua3, Liu Ming3
(1. Central South University of Forestry and Technology, Changsha 410004, Hunan, China; 2.Guizhou Academy of Forestry, Guiyang 550005, Guizhou, China; 3.Guangxi Fenglin Wood Industry Group Co., Ltd., Nanning 530221, Guangxi, China)
【Abstract】The mechanical and moisture-proof properties of fiberboard prepared with low mole ratio urea-formaldehyde resin adhesive are low, therefore it is of great significance to improve the performance of fiberboard by modifying urea-formaldehyde resin. Using melamine as the modifier, the low mole ratio urea-formaldehyde resin modified with melamine was prepared by one-time addition method. The effects of different contents of melamine on the physical and chemical properties of urea-formaldehyde resin and its prepared fiberboard were investigated. The research results showed that when the mass fraction of melamine increased from 0 to 25%, the storage stability of the modified urea-formaldehyde resin was good, the curing time was first extended and then shortened, and the release of free formaldehyde was first reduced and then increased, but all were below E1 level. The addition of melamine significantly improved the bonding performance and water resistance of urea-formaldehyde resin. When the content of melamine reached 25%, the thickness swelling rate of the fiberboard could be reduced from 12.73% to 3.69%. The addition of melamine blocked the hydrophilic groups, reduced the crystallinity of the cured urea-formaldehyde resin, and improved the mechanical and moisture resistance of the fiberboard.
【Keywords】melamine; urea-formaldehyde resin; fiberboard; thickness swelling rate
Preparation design and performance study of carbon nanotube modified coating composite materials
Ma Aili, He Xiaohong, Guo Ying, Chen Jiayu, Qi Tao, Ye Yiming, Wen Zhenxing
（Beijing Institute of Technology, Zhuhai, Zhuhai 519088, Guangdong, China）
【Abstract】In order to solve the problems of carbon nanotubes easy to agglomerate and poor dispersion in polymer matrix, carbon nanotubes were functionalized by coupling agent to make carbon nanotubes uniformly dispersed in water-based epoxy resin and form an ideal two-phase interface, which fully exerted the excellent performance of carbon nanotubes, then the anti-corrosion composite coating with excellent performance was prepared. The mechanical properties, hydrophobicity, and other aspects of the composite material were deeply explored. The research results showed that through Fourier transform infrared spectroscopy and X-ray diffraction spectroscopy analysis, it was confirmed that the chemical reaction occurred between the surface of carbon nanotubes and the coupling agent, resulting in successful grafting. Before modification, when the concentration of carbon nanotubes reached 5%, significant agglomeration began to occur, while after modification, the dispersion effect was significantly improved, and agglomeration only began to occur when the concentration was 9%. The adhesion of modified carbon nanotubes to composite materials was significantly improved, which was superior to unmodified carbon nanotube composite materials, but the addition amount should not be too large. The modification did not weaken the hardness of the composite coating, and the composite coating still maintained good mechanical properties. In summary, adding modified carbon nanotubes to the composite coating could effectively improve its comprehensive performance, but the addition amount should not exceed 9%.
【Keywords】carbon nanotube; anti-corrosion; composite material
Molecular dynamics simulation of the properties of epoxy resin composite material reinforced by surface chemical structure of carbon fiber
Ma Yuanyuan, Wang Jiangtao, Dang Jianrong, Liu Yaqing
（Key Laboratory of Functional Nanocomposites of Shanxi Province, North University of China, Taiyuan 030051, Shanxi, China）
【Abstract】A molecular dynamics simulation method was used to construct the model of carbon fiber oxidation surface and its reinforced epoxy resin composite material. The relationship between the evolution of oxygen-containing functional groups on the surface of carbon fiber and the surface tension of carbon fiber was systematically studied. The epoxy resin model reinforced with different oxidation surfaces of carbon fiber was constructed, and the final thermosetting composite material was obtained by further heating and curing. The effects of different surface chemical structures of carbon fiber on the shear, tensile and bending properties of composite material were revealed. The research results showed that the increase in the content of —C=O and —COOH was beneficial for the improvement of the surface energy of carbon fiber, which was mainly attributed to the fact that —C=O double bonds could compensate for the loss of surface covalent bond energy caused by —C=C— damage, and also increased the surface non-bonding interaction energy. In addition, the introduction of a certain amount of oxygen-containing functional groups improved the mechanical properties of composite material to varying degrees, but excessive oxygen-containing functional groups weakened the mechanical properties. When the current density was 0.69 A/m2, the corresponding shear stress, tensile strength and bending strength of carbon fiber reinforced epoxy resin composite material were all optimal. The further increase in current density gradually reduced the mechanical strength of composite material.
【Keywords】carbon fiber; epoxy resin composite material; surface chemical structure; molecular dynamics
Development and Application
Preparation and properties of heavy calcium carbonate/epoxy resin composite material
Xiong Zhimin1, Fang Jiahui1,2, Yang Zhe1,2, Gao Xue1, Hong Ying1, Hu Sheng1,2
(1.School of Chemistry and Environmental Engineering, Hubei Minzu University, Enshi 445000, Hubei, China; 2. Hubei Key Laboratory of Biological Resources Protection and Utilization, Hubei Minzu University, Enshi 445000, Hubei, China)
【Abstract】Using heavy calcium carbonate as raw material, stearic acid and titanate as modifiers, the modified heavy calcium carbonate was prepared. It was compounded with epoxy resin, and the modified heavy calcium carbonate/epoxy resin composite material was then prepared. The composite material was characterized by using thermogravimetric analysis, near-infrared spectroscopy, X-ray diffraction, and scanning electron microscopy, and the effect of modification conditions on the mechanical properties of composite material was explored. The research results showed that dry modification of heavy calcium carbonate was carried out by using stearic acid and titanate as compounding modifiers. When the amount of stearic acid was 1.5% of the mass of heavy calcium carbonate, the modification time of stearic acid was 20 minutes, the amount of titanate was 2.0% of the mass of heavy calcium carbonate, and the modification time of titanate was 10 minutes, the tensile performance of composite material was the best, as 10.2 MPa, and the oil absorption value was the lowest. After modification with stearic acid, titanate, and compounding with epoxy resin, the crystal form of heavy calcium carbonate was not changed, the compounding modifiers were successfully grafted onto the surface of heavy calcium carbonate. The modified heavy calcium carbonate particles had good dispersion and strong adhesion with epoxy resin.
【Keywords】heavy calcium carbonate; dry modification; epoxy resin; composite material; mechanical property
Study on the effect of curing temperature on the tensile strength of epoxy resin adhesive for road repair
Shi Xiaozhen, Zhu Lijing, Wu Kebao
(Wuhan Huazhong Science and Technology University Testing Technology Co., Ltd., Wuhan 430074, Hubei, China)
【Abstract】Epoxy resin adhesive samples for road repair were prepared by using materials such as E-51 epoxy resin, T31 curing agent, and three diluents. The effect of different curing temperatures on the tensile strength of epoxy resin adhesive was tested by using mechanical testing equipment. The research results showed that, ⑴ when the curing temperature exceeded the normal working temperature, the sample adhesive would generate a large number of bubbles, these bubbles would consume energy of adhesive, which increased the elongation at break of epoxy resin adhesive, and reduced the tensile strength of epoxy resin adhesive. When the curing temperature was 105 ℃, the bending strength and compressive strength of the adhesive sample were 90.6 MPa and 128.9 MPa respectively, indicating that the mechanical properties of the sample were good. ⑵ The higher the curing temperature, the better the bonding performance of the sample. However, an excessively high curing temperature could cause the adhesive to have excessive curing phenomenon, which resulted in a more fragile adhesive layer and reduced the T-peel strength of the sample. When the curing temperature was 85 ℃ and the curing time was 160 minutes, the bonding strength of the sample was the best, and the addition of CYD660 diluent could effectively improve the mechanical properties of epoxy resin adhesive.
【Keywords】road repair; epoxy resin adhesive; curing agent; diluent; curing temperature; tensile strength
Yu Binbin, Liu Bo, Zhang Aiping, Zhu Jun, Zhang Yao
(Zhejiang Keli Anaerobic Adhesive Co., Ltd., Hangzhou 311305, Zhejiang, China)
【Abstract】A two-component high-strength and high-toughness epoxy resin adhesive was developed by using bisphenol A epoxy resin, five toughening agents (dimeric acid modified epoxy resin toughening agent, polyurethane modified epoxy resin toughening agent, rubber CTBN modified epoxy resin toughening agent, polyethersulfone toughening agent and core-shell particle modified epoxy resin toughening agent), composite fillers, and composite curing agents as the main raw materials. The effects of the type and addition amount of toughening agent on the strength and toughness of epoxy adhesive were studied, and suitable toughening agents were selected to optimize the adhesive formula. The research results showed that when the ratio of rubber CTBN modifier and core-shell particle toughener was 5∶5, the two-component epoxy resin adhesive had good mechanical properties and toughness, the tensile strength was 64.4 MPa, the shear strength was 28.3 MPa, the elongation at break was 3.1%, and it also had good anti-aging performance.
【Keywords】two-component epoxy resin; toughening; elongation at break
Rapid determination of maleic anhydride grafting rate in polyolefin by Py-GCMS combined with FT-IR
Hu Zhenlong, Tang Fangcheng, Du Zhuang, Wang Jiasheng, Li Mingliang
(Guangzhou Lushan New Material Co., Ltd., Guangzhou 510530, Guangdong, China)
【Abstract】Using dodecyl succinic anhydride (DDSA) as the standard substance for maleic anhydride (MA) in polyolefin, a series of polyolefin films with different DDSA contents could be obtained by mixing DDSA and polyolefin uniformly through internal mixing, controlling the temperature and hot pressing time of vulcanizing press machine. The content of DDSA in the film samples could be quickly quantified by using pyrolysis-gas chromatography and mass spectrometry (Py-GCMS), and the corresponding MA content could be converted. By combining infrared spectroscopy (FT-IR), the absorbance ratio A1791/A1167 of the film samples could be obtained. The standard curve of A1791/A1167 was fitted by using MA content, and the absolute intercept value of the linear equation was the MA grafting rate of the polypropylene sample. The research results showed that through Py-GCMS, FT-IR test and curve fitting, the grafting rates of sample PP-1# and PP-2# were 0.099% and 0.254%, respectively. Comparing the curve fitting method with the titration method, the relative deviations of PP-1# and PP-2# were 4.04% and 2.36%, respectively, indicating that the results were close to consistency. This method was used to test the MA grafting rate of polyethylene and ethylene-octene polymer. Compared with the titration method results, the relative deviation was all less than 10%, demonstrating that the curve fitting method had good accuracy. The repeatability test showed that the relative standard deviation was all less than 5%, and the curve fitting method had good repeatability. This curve fitting method could be further used for measuring the MA grafting rate of other polyolefin samples.
【Keywords】maleic anhydride; dodecyl succinic anhydride; grafting rate; Py-GCMS; FT-IR
Special Topics and Review
Research progress of polyurethane sealant for highway engineering
Liu Xiaosong, Zhang Zengping, Guo Yinxiao, Liu Hao, Yu Xinhe, Kan Shiyun
（Key Laboratory for Special Area Highway Engineering of Ministry of Education, Chang’an University, Xi’an 710064, Shaanxi, China）
【Abstract】In this paper, the research progress of polyurethane materials as road sealant, including the overview of polyurethane sealing materials and their reaction mechanisms, main components of materials (polyisocyanates, polyols, chain extenders, catalysts, and fillers, etc.), performance evaluation (macro, micro, molecular dynamics simulations, etc.), new types of polyurethane sealant (such as modified polyurethane sealant, bio-based polyurethane sealant, solvent-free polyurethane sealant, etc.) was mainly concluded, and the practical application of polyurethane sealant used in highway engineering was summarized. Finally, the problems existing in the research of polyurethane sealant were put forward, and the development trend was prospected.
【Keywords】polyurethane; sealant; road engineering; pavement maintenance
Modification of lignin and its application in the field of adhesive
Fang Zhao, Shi Liwang, Du Chao, Guo Min, Yi Zhuo, Wang Ying
(SINOPEC Key Laboratory of Research and Application of Medical and Hygienic Material, Beijing 100013, China)
【Abstract】Lignin serves as a natural polymer in plants, and its rigid structure provides a certain degree of support strength for plant fibers. In recent years, lignin is gradually replacing non-renewable petroleum-based raw materials in the manufacturing of adhesive due to its abundance content, non-toxic nature, harmless and biodegradable properties. Lignin can serve either as filler or as reactive component in the adhesive. With phenolic structure, it shows promising potential to replace phenol component in conventional phenolic resin. Meanwhile phenolic hydroxyl group can be grafted with epoxy group conveniently, replacing polyols to react with isocyanates. Lignin or modified lignin based phenolic, epoxy, and polyurethane adhesives have been used for the bonding of wood components such as fiberboard, particleboard, and plywood. In this article, the structural characteristics, curing performance, bonding strength, and potential application value of different types of lignin based adhesives were introduced from the perspectives of lignin and modified lignin, and their future development was prospected.
【Keywords】lignin; adhesive; phenolic; epoxy; polyurethane