Special Topics Review
Molecular design and application of easily processable bismaleimide resin
Zhang Dandan, Liu Caizhao, Xing Wenxu, Yu Hongxin, Zhang Bin, Sun Mingming
(Institute of Petrochemistry, Heilongjiang Academy of Sciences, Harbin 150040, Heilongjiang, China)
【Abstract】The latest research progress on easily processable bismaleimide (BMI) resin was systematically reviewed in this article, with a focus on molecular design and composite modification strategies to improve its processing performance. To address the issues of traditional BMI resin, such as high melting point, poor solubility, high melt viscosity, and insufficient toughness, novel BMI monomers were designed by introducing flexible aliphatic segments, bulky side groups (such as fluorenyl groups, phenolphthalein structures), or functional groups (such as DOPO) into the main chain, as well as designing new BMI monomer, which could effectively reduce the crystallinity, broaden the processing window, and enhance the solubility and toughness. Meanwhile, the use of blending and copolymerization modification methods, including compounding with allyl compounds, diamine chain extension, and other high-performance resins such as epoxy resin (EP), cyanate ester (CE), and benzoxazine (BOZ), could significantly optimize the melt flowability, curing behavior, and comprehensive performance of BMI resin. Finally, the development prospects of easily processable BMI resin were discussed, aiming to provide theoretical reference and technical guidance for the development of advanced resin-based composites with high performance and high process adaptability.
【Keywords】bismaleimide resin; processability; molecular design; modification; progress
Research progress and prospects of bismaleimide modification from the perspective of molecular structure
Bi Rui1, Lu Jiaying1, Wang Xian2, Zhang Xueping1,2, Fan Heping1,2
[1. Jianghan University, Wuhan 430056, Hubei, China; 2. Haiso Electronic Materials (Wuhan) Ltd., Ezhou 436032, Hubei, China]
【Abstract】Bismaleimide (BMI), as a key high-performance resin, has significant applications in fields such as electronic information, aerospace, and others. However, most BMI resins can only dissolve in toxic, strongly polar solvents, and have drawbacks such as high curing temperature and high brittleness after curing, which greatly limit their application. Therefore, the modification of BMI has become a major focus of current research. From the perspective of molecular structure design, four main modification approaches were systematically elaborated in this paper. Diamine chain-extension modification achieved a synergistic improvement in toughness and heat resistance by reducing crosslinking density and introducing rigid groups. Bridge-bond internal chain-extension modification significantly improved the solubility and comprehensive properties of BMI through different bridge-bond structures (such as aliphatic, alicyclic, fluorenyl-based Cardo, etc.). Introduction of functional groups, such as N-substitution, aromatic ring substitution, or terminal introduction of allyl, phosphorus-oxygen, silicon-oxygen groups, imparted targeted properties to BMI such as flame retardancy, low dielectric constant, and high toughness. Copolymerization/blending modification utilized multi-component synergistic effect, constructing multi-component crosslinked networks by compounding with epoxy resins, polyimides, to achieve integrated optimization of performance. Finally, in the summary, it was pointed out that current modification research faced challenges such as balancing properties, process compatibility, and environmental friendliness. It was also expressed that through multiple synergistic strategies, the development of bio-based modifiers, and the construction of green solvent systems, BMI could be promoted towards high performance, multifunctionality, and sustainability in high-end fields.
【Keywords】bismaleimide; molecular structure; modification; diamine; copolymerization
A review on the multi-factor coupled aging mechanism of modified asphalt and its characterization evaluation
Xu Bo1, Xiao Feng2,3, Zhang Haoming1, Wang Zhixiang2,3
(1. Jiangluo Branch of Guangdong Provincial Highway Construction Co., Ltd., Guangzhou 527423, Guangdong, China; 2. Guangdong Transportation Science and Technology R&D Co., Ltd., Guangzhou 510550, Guangdong, China; 3. Guangdong Hualu Transport Technology Co., Ltd., Guangzhou 510420, Guangdong, China)
【Abstract】The aging behavior of modified asphalt under the coupled effects of multiple factors such as heat, oxygen, ultraviolet radiation, and moisture is crucial for determining the durability of asphalt pavement. Its aging mechanism was systematically reviewed in this article, and the interactions among processes such as thermal-oxidative synergism, photochemical degradation, and water erosion were elucidated. In terms of characterization methods, the application and limitations of four component analysis, spectroscopy, chromatography, and microscopy techniques in revealing chemical composition, molecular structure, and microstructural evolution were analyzed. Research indicated that existing evaluations were mostly based on macroscopic properties such as high temperature, low temperature, and fatigue, and were gradually combined with microscopic characterization. However, current research still showed deficiencies in simulating the authenticity of conditions, quantitatively analyzing the multi-factor synergistic mechanisms, and establishing micro-macro cross-scale correlations. In the future, it was necessary to establish a coupled aging test method that was more closely aligned with actual service environments, deepened mechanistic understanding at the molecular scale, and established a unified multi-scale performance evaluation system, in order to provide theoretical basis and technical support for enhancing the service life of pavements.
【Keywords】road engineering; modified asphalt; multi-factor coupled aging; aging mechanism; aging evaluation
Research Report
Study on preparation and properties of curable acrylate pressure sensitive adhesive
Gong Fei, Xue Gang, Zhang Xugang, Sun Mingming, Liu Caizhao, Wang Lei, Li Jianhui, Zhang Bin
(Institute of Petrochemistry, Heilongjiang Academy of Sciences, Harbin 150040, Heilongjiang, China )
【Abstract】In response to the limited bonding strength of traditional pressure sensitive adhesive and the complex construction of high-strength structural adhesive, acrylate pressure sensitive adhesive solution was synthesized in this study through solution polymerization using acrylic soft and hard monomers and carboxyl functional monomers. A curable acrylate pressure sensitive adhesive was developed using aluminum acetylacetonate (AlACA) as the crosslinking agent and incorporating epoxy resin and latent curing agent. The effects of various components and processes on pressure sensitive properties before curing (initial tack, 180° peel strength, holding power) and high-strength properties after curing (shear strength, 90° peel strength) were systematically studied. The research results showed that the optimal mass ratio was determined as follows, m(acrylate pressure sensitive adhesive solution)∶m(AlACA solution)∶m(F-44 epoxy resin)∶m(latent curing agent)=100∶1.5∶30∶1.5. Under this ratio, the curable acrylate pressure sensitive adhesive exhibited excellent bonding properties before and after curing. This adhesive film achieved a combination of simple construction without external pressure and high-strength curing, suitable for fields that required both construction convenience and bonding strength.
【Keywords】acrylate; pressure sensitive adhesive; thermal curing
Development of electrolyte resistance high-performance acrylate pressure sensitive adhesive
Li Mingjie, Li Jianxiong
（Crown New Materials Technology Co., Ltd., Zhongshan 528478, Guangdong, China）
【Abstract】To address the issue of adhesive tape for lithium-ion battery easily failing in electrolyte environments, a solvent-based high-performance acrylate pressure sensitive adhesive with excellent high temperature resistance and electrolyte resistance was prepared in this study through single-factor experiments. The formulation included isooctyl acrylate (2-EHA) and lauryl methacrylate (LMA) as long-chain soft monomers, methyl methacrylate (MMA) as hard monomer, methacrylic acid (MAA) and hydroxyethyl acrylate (HEA) as functional monomers, glycidyl methacrylate (GMA) as self-crosslinking monomer, azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO) as initiators, and ethyl acetate as solvent. The effects of the dosage of long-chain soft monomers, functional monomers, initiators, self-crosslinking monomer, and curing agents on the viscosity, 180° peel force, high temperature resistance, and electrolyte resistance of pressure sensitive adhesive were explored systematically. The research results showed that for electrolyte resistance high-performance acrylate pressure sensitive adhesive, the amount of long-chain soft monomers and functional monomers had a significant impact on the 180° peel force performance of pressure sensitive adhesive. Self-crosslinking monomer could significantly improve the cohesive strength, high temperature resistance, and electrolyte resistance of pressure sensitive adhesive. When the proportion of long-chain soft monomers was 79.5%, the proportion of functional monomers was 4%, the initiators was 0.6%, the self-crosslinking monomer was 1.5%, and the curing agent was 0.8% of the adhesive solution mass, the comprehensive performance of the prepared pressure sensitive adhesive was excellent. Its viscosity was moderate, the 180° peel force was 14.1 N/25 mm, and it also had good high temperature resistance and electrolyte resistance. The electrolyte resistance adhesive tape product prepared from the high-performance acrylate pressure sensitive adhesive mentioned above could be applied to power batteries, energy storage batteries, consumer electronics batteries, and other products, meeting the performance requirements of battery products in terms of electrolyte resistance.
【Keywords】acrylate; pressure sensitive adhesive; electrolyte resistance; high temperature resistance
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
Process and Application
Applicability of hot melt adhesive with different chemical systems in smooth aluminum-sheathed high-voltage cables
Chen Jiawei1, Zhou Hong1, Zhou Yunjie1, Shao Yue1, Li Yinyue2, Liu Ying2
(1. State Grid Shanghai Cable Company, Shanghai 200072, China; 2. School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China)
【Abstract】Smooth aluminum-sheathed high-voltage cross-linked polyethylene cables have advantages such as excellent electrical contact performance, large transmission capacity, small outer diameter, and light weight. However, they have deficiencies in mechanical properties, which need to be improved by firmly bonding the aluminum sheath to the outer protective layer (typically made of polyethylene or polyvinyl chloride) with hot melt adhesive. Therefore, there is an urgent need to conduct research on the key properties of hot melt adhesive tailored to the practical application requirements of cables. The preliminary screening of four different chemical systems of hot melt adhesive was focused in this paper. Firstly, infrared spectroscopy analysis and thermal performance testing were conducted to determine the basic components and melting temperature. Afterwards, four kinds of hot melt adhesive were applied to polyethylene (PE), polyvinyl chloride (PVC), and aluminum sheets to prepare adhesive samples. Finally, the T-peel strength and tensile shear strength of the samples were tested under normal temperature, steady-state temperature rise of 90 ℃, and short-term temperature rise of 180 ℃. Based on this, the applicability of four kinds of hot melt adhesive in smooth aluminum-sheathed high-voltage cables with PE and PVC outer protective layers was analyzed. The research results showed that, ⑴ PE hot melt adhesive had good compatibility with PE material, with the elastic modulus of about 316.0 MPa and the melting point of about 128 ℃. At room temperature, the T-peel strength and tensile shear strength were 3.39 N/mm and 5.91 MPa, respectively. Under steady-state temperature rise conditions at 90 ℃, they decreased to 2.63 N/mm and 2.31 MPa, respectively. After short-term heat treatment at 180 ℃, the parameter values slightly increased. All the above performance parameters met the application requirements of smooth aluminum-sheathed cables with PE outer protective layer. ⑵ When applied to PVC material, the bonding effects of all four kinds of hot melt adhesive were poor. Among them, PEVA hot melt adhesive had relatively the best bonding performance at room temperature, with the T-peel strength of 1.56 N/mm and the tensile shear strength of 3.05 MPa. However, its melting temperature was only 58.84 ℃, which still could not meet the temperature requirements for cable operation. ⑶ Based on the test results in this paper, the recommended selection of hot melt adhesive for smooth aluminum-sheathed high-voltage cross-linked polyethylene cables was: when using PE outer protective layer, high melting temperature PE hot melt adhesive should be preferred, which could maintain excellent bonding strength and stability at both room temperature and transient high temperature. When using PVC outer protective layer, it was necessary to further develop or search for a new type of hot melt adhesive system with higher melting temperature and matching PVC polarity.
【Keywords】smooth aluminum-sheathed high-voltage cable; hot melt adhesive; bonding strength; thermal performance
Research on optimization of thixotropic system of epoxy adhesive for hybrid wind generator tower
Ding Xiaoxu, Xue Xuexue, Zhang Chao, Zhou Hongzhi, Wei Ying, Song Shaobo
(Carbon Technology Group Co., Ltd., Tianjin 300380, China)
【Abstract】The thixotropic system affects the compactness of epoxy adhesive after stirring, thereby indirectly influencing the final mechanical properties of the adhesive. In order to meet the high-strength requirements of structural adhesive for hybrid wind generator tower during low-temperature construction, the changes in the thixotropic and mechanical properties of epoxy adhesive with hydrophobic or hydrophilic fumed silica mixed with different additives were explored in this paper. It was found that both hydrophobic fumed silica/defoaming agent and hydrophilic fumed silica/rheological additive systems exhibited good thixotropy and adhesive compressive strength. In addition, the addition amounts of defoaming agent and rheological additive had been optimized. Finally, the stability of each thixotropic system after heat treatment was compared. The research results showed that, ⑴ Although hydrophobic fumed silica had excellent thixotropy, its high viscosity tended to cause bubble defects. Adding 0.5% (mass fraction, the same below) defoaming agent could significantly improve the compressive strength (>97 MPa). ⑵ The structure of hydrophilic fumed silica system was denser, but its thixotropy was weaker. Adding 0.7% rheological additive could improve its thixotropic performance to be comparable to that of the hydrophobic system. ⑶ Excessive additives could reduce performance, while rheological additives could improve thermal stability. ⑷ In summary, by selecting the composite system of hydrophobic fumed silica/defoaming agent or hydrophilic fumed silica/rheological additive, and controlling the amount of additives added, the workability, final strength, and high-temperature storage stability of structural adhesive for wind power could be effectively balanced.
【Keywords】epoxy adhesive; thixotropy; fumed silica; additive; thermal stability
Material Science
Preparation and performance characterization of multi-color low infrared emissivity coating
Zhang Weigang, Ma Xueping, Tang Ying, Gao Yi, Cao Tongtong
(Chuzhou University, Chuzhou 239000, Anhui, China)
【Abstract】Three types of low infrared emissivity coating with outstanding mechanical properties and low gloss properties, namely green, yellow, and blue systems, were prepared by using polyurethane (PU) as the adhesive, flake Al powder as the low emissivity filler, and yellow-green colorant, orange-yellow colorant, and blue-purple colorant as toners. The effects of yellow-green colorant ratio, orange-yellow colorant ratio, and blue-purple colorant ratio on the microstructure, color characteristics, reflectance spectra, optical properties, and mechanical properties of PU/Al composite coating were systematically studied. The research results showed that after adjusting the ratio of different colorants, the coating could produce strong reflection peaks in the green, yellow, and blue ranges, thereby endowing the coating with green, yellow, and blue color characteristics. The emissivity and glossiness of the green PU/Al composite coating after being controlled by yellow-green colorant were in the range of 0.617-0.640 and 9.9-12.1, respectively. The emissivity and glossiness of the yellow PU/Al composite coating after being controlled by orange-yellow colorant were in the range of 0.508-0.686 and 10.1-14.2, respectively. The emissivity and glossiness of the blue PU/Al composite coating after being controlled by blue-purple colorant were in the range of 0.507-0.605 and 6.6-9.3, respectively. The low infrared emissivity PU/Al composite coating of different color systems had excellent mechanical properties (adhesion level of grade 1, flexibility of 2 mm, impact strength of 50 kg·cm) and infrared stealth effect. The prepared coating had broad application prospects in the camouflage design field of various land equipment such as tanks, combat vehicles, communication vehicles, etc.
【Keywords】multi-color; coating; infrared emissivity; mechanical property; glossiness; infrared stealth