Moisture absorption behavior of epoxy resin cured products and its influence on the dielectric properties

doi:10.19936/j.cnki.2096-8000.20250828.008

Abstract

Abstract: To investigate the moisture absorption behavior of epoxy resin and the changes in its dielectric properties post-absorption, the study developed epoxy resins with various structures by varying the type of curing agent. The moisture absorption rate of the cured materials was monitored under 70 ℃ water immersion conditions, and the dielectric properties were tracked. The results indicated that the moisture absorption process followed the Fick diffusion model, the type of curing agent affects the polarity and free volume of the cured material, the polarity determines the equilibrium moisture absorption rate of the resin, and the polarity and free volume jointly determine the diffusion coefficient of water molecules. The greater the polarity, the higher the moisture absorption rate of the resin equilibrium, and the easier it is for the polar groups to form hydrogen bonds with water molecules and hinder the movement of water molecules. The larger the free volume, the more diffusion channels the water molecule has, and the faster the diffusion. The dielectric properties of the cured matter are different with different curing agents, and the dielectric constant and loss tangent change linearly with the moisture absorption rate and are independent of the type of curing agent. Based on this research, a model was developed to predict the dielectric properties of epoxy resins as a function of their moisture absorption rates, with a deviation of no more than 10% between model predictions and actual measurements.

Key words: epoxy resin, curing agent, moisture absorption rate, dielectric constant, loss tangent, composites

CLC Number:

TB332

ZHANG Dujuan, LI Yafeng, LI Songming, LU Haijun. Moisture absorption behavior of epoxy resin cured products and its influence on the dielectric properties[J]. COMPOSITES SCIENCE AND ENGINEERING, 2025, 0(8): 66-73.

References

[1] AZIZ T, HAQ F, FARID A, et al. The epoxy resin system: function and role of curing agents[J]. Carbon Letters, 2024, 34(1): 477-494.
[2] 邢丽英, 李亚锋, 陈祥宝. 先进复合材料在航空装备发展中的地位与作用[J]. 复合材料学报, 2022, 39(9): 4179-4186.
[3] MI X, LIANG N, XU H, et al. Toughness and its mechanisms in epoxy resins[J]. Progress in Materials Science, 2022, 130: 100977.
[4] 余春秀, 王云凯, 贺子娟, 等. 环氧胶粘剂改性研究进展[J]. 材料导报, 2023, 37(15): 237-246.
[5] CARTER H G, KIBLER K G. Langmuir-type model for anomalous moisture diffusion in composite resins[J]. Journal of Composite Materials, 1978, 12(2): 118-131.
[6] GRACE L R, ALTAN M C. Non-fickian three-dimensional hindered moisture absorption in polymeric composites: model development and validation[J]. Polymer Composites, 2013, 34(7): 1144-1157.
[7] GRAVE C, MCEWAN I, PETHRICK R A. Influence of stoichiometric ratio on water absorption in epoxy resins[J]. Journal of Applied Polymer Science, 1998, 69(12): 2369-2376.
[8] LI L, YU Y, WU Q, et al. Effect of chemical structure on the water sorption of amine-cured epoxy resins[J]. Corrosion Science, 2009, 51(12): 3000-3006.
[9] BONE J E, SIMS G D, MAXWELL A S, et al. On the relationship between moisture uptake and mechanical property changes in a carbon fibre/epoxy composite[J]. Journal of Composite Materials, 2022, 56(14): 2189-2199.
[10] MOHANTY S C, SINGH B P, MAHATO K K, et al. Water absorption behavior and residual strength assessment of glass/epoxy and glass-carbon/epoxy hybrid composite[J]. IOP Conference Series: Materials Science and Engineering, 2016, 115(1): 012029.
[11] 欧阳俊杰, 王付胜, 孔繁淇, 等. 湿/热环境对环氧树脂复合材料冲击后压缩剩余强度的影响[J]. 复合材料科学与工程, 2021(9): 31-37.
[12] ALAM P, ROBERT C, Ó BRÁDAIGH C M. Tidal turbine blade composites-a review on the effects of hygrothermal aging on the properties of CFRP[J]. Composites Part B: Engineering, 2018, 149: 248-259.
[13] 孙健明, 温磊, 李斌太, 等. 湿热对石英纤维增强双马树脂基复合材料力学及电性能影响的研究[J]. 复合材料科学与工程, 2023(4): 41-44, 50.
[14] 李洪峰. 结构-功能一体化耐高温氰酸酯树脂改性及胶膜的研究[D]. 哈尔滨: 东北林业大学, 2017.
[15] PISTOR V, ORNAGHI F G, ORNAGHI H L, et al. Dynamic mechanical characterization of epoxy/epoxycyclohexyl-POSS nanocomposites[J]. Materials Science and Engineering: A, 2012, 532: 339-345.
[16] ZHANG H J, SELLAIYAN S, KAKIZAKI T, et al. Effect of free-volume holes on dynamic mechanical properties of epoxy resins for carbon-fiber-reinforced polymers[J]. Macromolecules, 2017, 50(10): 3933-3942.
[17] ABDELMOLA F, CARLSSON L. Water uptake in epoxy matrix with voids: experiments and modeling[J]. Journal of Composite Materials, 2019, 53(8): 1049-1065.
[18] LEI Y, XU M, JIANG M, et al. Curing behaviors of cyanate ester/epoxy copolymers and their dielectric properties[J]. High Performance Polymers, 2017, 29(10): 1175-1184.
[19] 张杜鹃, 李亚锋, 鹿海军, 等. 环氧树脂/双氰胺固化物吸湿和介电性能变化规律探究[J]. 中国胶粘剂, 2021, 30(5): 8-13, 20.
[20] LI Y, CORDOVEZ M, KARBHARI V M. Dielectric and mechanical characterization of processing and moisture uptake effects in E-glass/epoxy composites[J]. Composites Part B: Engineering, 2003, 34(4): 383-390.
[21] NAGELLA S R, HA C-S. Structural designs of transparent polyimide films with low dielectric properties and low water absorption: a review[J]. Nanomaterials, 2023, 13(14): 2090.