Special Topics Review
Research progress of polyimide adhesive for aerospace application:
from molecular design to space application
Li Zhenjiang, Chen Juan
（AECC Aero Science and Technology Co., Ltd., Chengdu 610503, Sichuan, China）
【Abstract】Polyimide (PI) adhesive is a key material for ensuring the reliability of aerospace equipment under extreme environments. To meet the demands of hypersonic flight and deep space exploration, the research progress of PI adhesive from molecular design to space application was systematically reviewed in this paper, aiming to provide theoretical references for the independent innovation and development of next-generation high-performance, multifunctional PI adhesive. The full text focused on the synergistic enhancement mechanisms of dynamic covalent chemistry, alkynyl termination, and main chain structure regulation on heat resistance and processability. The synergistic enhancement effects of carbon nanotube/silver nanowire multicomponent systems and phytic acid/boron nitride nanosheet (PA/BNNS) flame-retardant networks were analyzed, and their current application status in on-orbit manufacturing, thermal protection, and electronic packaging was summarized. It was pointed out that current challenges included the disconnection between idealized molecular design and engineering preparation, unclear failure mechanisms under multi-field coupling, and low functional integration. Future research would focus more on challenges such as artificial intelligence-driven high-throughput design, green and sustainable manufacturing processes, and long-term durability in deep space environments, which would provide a material basis for the intelligent and lightweight development of next-generation aerospace crafts.
【Keywords】polyimide; adhesive; performance enhancement; aerospace; molecular design; space application
Research on key technologies of aerospace structural energy storage composites
Cao Xin, Lu Pengpeng, Wang Xinnian, Liang Fengfei, Yang Pu
(AVIC XAC Commercial Aircraft Co., Ltd., Xi'an 710089, Shaanxi, China)
【Abstract】In response to the urgent demand for the deep integration of aircraft lightweight design and energy systems, structural power composites (SPCs), by integrating energy storage and mechanical load-bearing functions, provide a disruptive research approach for the innovative integration of aircraft lightweight design and energy systems. The latest research progress of aviation SPCs, including the composition materials, working principles, and multifunctional performance characterization of structural batteries and structural capacitors was reviewed in this paper. The key fields and technical issues involved in the development of aviation SPCs were summarized, and key technical challenges such as material system development, structural design and manufacturing, advanced simulation and testing, and safety and reliability assurance technologies were discussed. Finally, suggestions and prospects for the development of aviation SPCs were proposed in conjunction with relevant technical issues.
【Keywords】composite material; structural energy storage; structural-functional integration; structural battery; structural capacitor
Research progress of Fourier transform infrared spectroscopy in asphalt materials
Wu Cai, Fan Siyuan, Wang Zhaocheng
[SINOPEC Dalian Research Institute of Petroleum and Petrochemical Co., Ltd., Dalian 116045, Liaoning, China]
【Abstract】Fourier transform infrared spectroscopy (FT-IR) is the core technique for analyzing the microstructure of asphalt and revealing the evolution laws of its properties. To address the bottleneck that traditional methods failed to elucidate the “structure-property” relationship of asphalt, the application progress of FT-IR in modification mechanism, aging behavior, fingerprint identification, and performance prediction was systematically reviewed in this paper. The principles of distinguishing physical blending and chemical modification by FT-IR were summarized, the evolution rules of key indices such as carbonyl and sulphoxide during thermo-oxidation, ultraviolet, and water aging were elucidated, and the asphalt source identification and rapid performance prediction models were summarized based on chemometrics and machine learning. Finally, challenges such as difficulty in spectral overlap resolution and lack of standardization system were pointed out, and the development directions of artificial intelligence-assisted spectral analysis, multimodal data integration, and in-situ characterization technology were discussed, which were aimed to provide theoretical references for asphalt materials from molecular design to engineering application, and promote the industry's transformation towards data-driven development.
【Keywords】asphalt; Fourier transform infrared spectroscopy (FT-IR); polymer modification; aging; prediction
Research Report
Development of novel high-toughness colorless transparent epoxy adhesive
Qing Zhihui, Yu Xinhai
(College of Chemistry and Chemical Engineering, Donghua University, Shanghai 201620, China)
【Abstract】To address the insufficient toughness and susceptibility to yellowing and aging of traditional epoxy resin adhesive, which made it difficult to meet the stringent requirements for high reliability, long service life, and low dielectric loss in fields such as optical devices, aerospace, and high-frequency electronic packaging, an innovative strategy based on the synergistic modification of hydrogenated bisphenol A epoxy resin (HBPAE) and silicone epoxy resin modifier (SE362) was proposed in this study. By adjusting the ratio of silicone modifier and the structure of normal-temperature amine curing agent, the structure-activity relationship among gelation behavior, dielectric properties, mechanical properties, optical transmittance and weather resistance was systematically investigated. The research results showed that, ⑴ The molecular structure of curing agents significantly affected the crosslinking density and network regularity of adhesive systems. Among them, 1,3-cyclohexanedimethylamine (1,3-BAC) endowed the system with superior impact toughness due to the absence of side group substitution. ⑵ The series of high-toughness colorless transparent epoxy adhesive exhibited excellent capacitance stability, meeting the application requirements of low dielectric loss in high-frequency electronic packaging. ⑶ The dosage of modifier SE362 exhibited a "volcano curve" effect on mechanical properties. When its mass fraction was 20% (CTEA-2 formula), the system formed an ideal "sea-island" microphase separation structure, achieving efficient synergy between "rigid skeleton" and "flexible toughening". At this point, the impact strength reached 56.0 kJ/m², the shear strength was 10.0 MPa, the tensile strength was 26.9 MPa, and the bending strength was 56.0 MPa, indicating that the comprehensive mechanical properties were relatively optimal. ⑷ After 120 minutes of intense ultraviolet irradiation (3.25 kW/m², 60 ℃), the yellowing index change (△b) of CTEA-2 formula sample remained less than 0.2, far superior to the industrial standard (△b<1.0 was considered no significant yellowing). This work successfully developed novel epoxy adhesive that combined high-toughness, excellent weather resistance, and good electrical insulation, providing theoretical basis and technical support for the molecular design and engineering application of high-end adhesive.
【Keywords】hydrogenated bisphenol A epoxy resin; silicone epoxy resin modifier; high-toughness; weather resistance
Preparation and properties of reactive polyurethane hot melt adhesive for underwear
Qiu Weijun1,2, Chen Jinghua1, Zhang Jianzhen1, Gan Haibo1, Chen Jianjun1,2, Huang Hengchao1
(1.Guangzhou Baiyun Technology Co., Ltd., Guangzhou 510440, Guangdong, China;
2.Guangdong Baiyun Technology Co., Ltd., Foshan 528143, Guangdong, China)
【Abstract】To address the problem that current reactive polyurethane (PUR) hot melt adhesive for underwear is difficult to balance low hardness, high bonding strength, and appropriate application viscosity, leading to poor wearing comfort and poor adaptability to automated production, the PUR adhesive for underwear with both softness and high strength was prepared in this study by polyol compounding and formulation synergistic optimization. The effects of the isocyanate index (R value), type and ratio of polyester polyols, acrylic resin dosage, and catalyst dosage on the melting viscosity, surface drying time, peel strength, and hardness of the adhesive film were systematically investigated. The research results showed that the PUR exhibited the best comprehensive performance when the R value was 2.1, the mass ratio of crystalline polyester polyols (Dynacoll® 7380/Dynacoll® 7360 at a mass ratio of 2∶1) to liquid polyester polyol was 1∶1, the acrylic resin dosage was 20%, and the catalyst DMDEE dosage was 0.08%. This formulation utilized the synergistic effect of crystalline and liquid polyester polyols to optimize the soft-segment microphase structure, achieving low melting viscosity (5 880 mPa·s, 130 ℃) and appropriate surface drying time (23 s), together with high peel strength (48 N/25 mm) and moderate Shore A hardness (71), effectively solving the industry bottleneck of “hardness-strength-application property” coordination difficulty. It provided a reliable material solution for the automated bonding of high-end seamless underwear and had significant application value.
【Keywords】reactive polyurethane hot melt adhesive; moisture curing; underwear; polyester polyol; catalyst
Process and Application
Preparation of high-strength and high-toughness epoxy adhesive
and its performance research in prefabricated buildings
Xing Yongchang¹, Chen Xiaoyu¹, Dong Liancheng1, Wang Dongyang1, Liu Ju2, Wang Lingling1
[1.Kehui (Henan) New Materials Technology Co., Ltd., Nanyang 474650, Henan, China; 2.SINO-SINA Building Technology Co., Ltd., Zhengzhou 450001, China]
【Abstract】In response to the urgent demand for high-strength, high-toughness, and excellent durability of connection materials for prefabricated building components, a kind of high-strength and high-toughness epoxy adhesive was prepared in this study through systematic optimization of the matrix resin, curing agent, diluent system, filler compounding, and preparation process, and its performance was systematically evaluated. Bisphenol A-type (E-51) and bisphenol F-type (F-170) epoxy resins were compounded, and flexible (modified polyamide 615), rigid (modified aromatic amine D-134), and polar-group-containing (modified polyetheramine D230) curing agents were combined to achieve synergistic enhancement of strength and toughness. The diluent (693) and inorganic filler (quartz sand and white corundum) gradations were optimized. The two-component adhesive was prepared by high-speed dispersion, vacuum stirring, and vibratory compaction processes. The research results showed that the optimal formulation was m(E-51):m(F-170)=2:8, curing agents m(D230):m(D-134):m(615)=3:3:4, the filler proportion was 70%, and the porosity decreased to about 6%. The compressive strength after curing reached 192 MPa, the tensile strength was 45 MPa, the elongation at break was 1.33%, and the steel-steel tensile shear strength was 18.9 MPa, which far exceeded the requirements of GB/T 44543—2024 and T/CECS 10080—2020 standards. Meanwhile, the moisture-heat resistance, freeze-thaw resistance, and acid-alkali-salt aging resistance were outstanding. This study revealed the mechanisms of performance enhancement by resin functionality, rigid-flexible balance of curing agents, and filler synergy. The adhesive was applicable to key joint connections of prefabricated buildings, possessed high-strength, durability, and construction adaptability, and helped to improve the overall structural safety and long-term service performance of prefabricated buildings, providing an effective material solution for enhancing the overall performance and connection reliability of prefabricated buildings.
【Keywords】prefabricated component; epoxy resin; adhesive; amine curing agent; porosity; material property
Prediction of mechanical properties of silicone sealant after room-temperature curing based on machine learning
Yang Quan, Li Ziyang, Li Tao
(Guanzhou Baiyun Technology Co., Ltd., Guangzhou 510540, Guangdong, China)
【Abstract】To address the problems of the long standard curing cycle and lagging quality control of silicone sealant, a rapid prediction method for room-temperature mechanical properties was proposed based on thermal accelerated curing and machine learning algorithms. Using tensile strength, elongation, and modulus after accelerated curing at 55 °C as inputs, machine learning training and prediction were performed using linear regression (LR), support vector regression (SVR), random forest (RF), and extreme gradient boosting (XGBoost) models. The research results showed that the XGBoost model had the best accuracy, with R² values of 0.999 44, 0.999 97, and 1.000 00 for the prediction of the room-temperature modulus of weather-resistant sealant, the room-temperature tensile strength and room-temperature elongation at maximum strength of structural sealant, respectively. Shapley Additive Explanations (SHAP) characteristic analysis confirmed that the model accurately captured the characteristic differences of “low strength and high elasticity” for weather-resistant sealant and “high strength and low elasticity” for structural sealant, revealing the evolution pattern of the crosslinking network. This method effectively overcame the misjudgment risk of traditional accelerated tests, providing an efficient technical means for realizing pre-quality control at the production end.
【Keywords】silicone weather-resistant sealant; silicone structural sealant; machine learning
Study on properties of hot melt pressure sensitive adhesive for pre-applied waterproof sheets
Wang Xiaoli, Wang Yufeng, Shen Peiliang
(CNBM Suzhou Waterproof Research Institute Co., Ltd., Suzhou 215008, Jiangsu, China)
【Abstract】In response to the issues of poor lap bonding, insufficient weather resistance, and performance degradation after long-term water immersion encountered by pre-applied waterproof sheets in practical engineering application, the comprehensive performance of seven kinds of hot melt pressure sensitive adhesive based on styrene-isoprene-styrene block copolymer (SIS) was systematically evaluated in this study. The structure-property relationship between the chemical structure of the adhesive and its performance was revealed through testing of basic physical properties, thermal treatment stability, thermal aging resistance, and long-term water immersion performance, combined with analysis of bonding performance with post-pouring concrete under different environmental conditions. The research results showed that the epoxidized-modified sample exhibited the most excellent comprehensive performance. Its softening point reached 110 ℃ and its low-temperature flexibility was -37.0 ℃. The retention rates of peel strength after thermal aging and long-term water immersion both exceeded 94%. The study also found that hot-melt coating process temperature exceeding 180 ℃ caused a significant decrease in the cohesive strength of the adhesive layer, and control below 170 ℃ was recommended. Ultraviolet radiation caused the most severe damage to the bonding performance of all samples. Long-term water immersion at the bonding interface was identified as a key risk affecting the durability of the waterproofing system. This study provided important experimental basis and theoretical guidance for the selection and application of high-performance hot melt pressure sensitive adhesive for pre-applied waterproof sheets.
【Keywords】pre-applied waterproof sheets; hot melt pressure sensitive adhesive; SIS; peel strength; durability
Material Science
Investigation of test method for tensile shear strength of adhesive joints between difficult-to-clamp materials and rigid materials — A case study of ceramic fiber insulation tiles
Shen Yan1, Zhang Chunhong2
(1.Shanghai Institute of Rubber Products Co., Ltd., Shanghai 201702, China; 2.Yantai Research Institute, Harbin Engineering University, Yantai 264006, Shandong, China)
【Abstract】Ceramic fiber insulation tiles are key components of aerospace thermal protection systems, and their adhesive bonding reliability with airframe structures directly affects flight safety. Such materials have high porosity, high brittleness, and low tensile strength. Traditional clamping tests easily cause substrate fracture, and the standard method of GB/T 7124—2008 cannot be used to directly test its adhesive bonding strength. Aiming at the above engineering problems, a three-specimen bridge-type symmetric lap tensile shear strength test method was proposed in this paper, which indirectly transmitted loads through rigid specimens and avoided direct clamping of brittle substrates. Epoxy, silicone, and inorganic high-temperature resistant adhesive were selected, and the method effectiveness, repeatability, time stability, and multi-laboratory validation were carried out within the range from room temperature to 1 000 ℃. The research results showed that this method had good consistency with the test results of GB/T 7124—2008. It had ideal repeatability at both room temperature and high temperature. Time stability was good under different storage time. Validations from multiple independent laboratories all achieved adhesive interfacial failure, and the method had strong universality. This method provided an effective technical means for the evaluation of adhesive bonding quality of thermal protection systems, as well as for the testing of adhesive bonding properties of difficult-to-clamp materials such as ceramic fiber insulation tiles and glass.
【Keywords】difficult-to-clamp materials; ceramic fiber insulation tiles; adhesive bonding strength; tensile shear strength; three-specimen bridge-type symmetric lap; test method