Influence of hygrothermal aging on durability and interfacial performance of pultruded glass fiber-reinforced polymer composites

Significance 

Intensive engineering research has led to the development of high-performance fiber-reinforced polymer composites. Owing to their excellent physical and mechanical properties, their application has tremendously increased over the past few years. More specifically, pultruded glass fiber reinforced polymers composites are widely preferred for structural and civil applications. However, recent studies have shown that exposing these materials to extreme temperature and moisture conditions result in the degradation of mechanical properties and reduction of the glass transition temperature.

To this end, understanding the effects of the environmental conditions on the behaviors and performance of glass fiber reinforced polymer composites is highly desirable.

Generally, several studies have been conducted to investigate the mechanical properties of the composites under the influence of hygrothermal environments. Despite the remarkable achievements, the effects of hygrothermal conditions on the interfacial performance between the matrix and the fiber are still missing. Alternatively, the durability of fiber reinforced polymers composites has been significantly investigated while on the other hand, little have been reported about the degradation mechanisms based on the microstructural and spectroscopic analysis.

To this note, a group of researchers from College of Civil Engineering at Nanjing Tech University: Dr. Shulan Yang, Professor Weiqing Liu, A/Prof. Yuan Fang and A/Prof. Ruili Huo investigated the influence of the fiber-matrix interface of pultruded glass fiber-reinforced polymer composites under hygrothermal conditions. Specifically, they analyzed the effects of hygrothermal environments on the micro and macro mechanical properties of the polymer materials. Their work is currently published in Journal of Materials Science.

Their study involved immersing the composite in saltwater and deionized water at different temperatures. In particular, the moisture absorption kinetics of the pultruded fiber-reinforced polymer composites and its effects on the properties and interfacial strength was investigated. Next, the changes in the chemical structures and microstructures were examined through Fourier transform infrared spectroscopy and scanning electron microscope. Lastly, the Weibull distribution model was designed, taking into account the hygrothermal aging and eventually used to predict the durability and tensile performance of the pultruded fiber-reinforced polymer composites.

The authors observed that the moisture absorption increased nonlinearly with an increase in the temperature. Consequently, higher temperatures resulted in a corresponding high moisture absorption capacity and diffusion coefficient of the pultruded fiber-reinforced polymer composites immersed in both saltwater and distilled water. On the other hand, after approximately 180 days of aging, the tensile strength and modulus were recorded as 25.7% and 25% respectively for the samples immersed in distilled water and 2.15 and 18.2% for the specimen in saltwater. This was attributed to the increase in moisture absorption and tensile properties degradation.

In summary, Nanjing Tech University scientists are the first to successfully investigated the degradation mechanism of glass fiber-reinforced polymers composites in hygrothermal conditions based on the microstructural analysis. In general, the author singled out hydrolysis of resin and E-glass fibers as the main causes of the degradation of the tensile properties. The degradation trends of the composites in hygrothermal environments observed in the modeled Weibull distribution was noted to be an effective tool in describing the temperature effects. Therefore, the study will enhance the development of fiber-reinforced polymer composite suitable for numerous applications.

Influence of hygrothermal aging on the durability and interfacial performance of pultruded glass fiber-reinforced polymer composites - Advances in Engineering

About the author

Shulan Yang is a lecturer at the College of Civil and Architectural Engineering, Changzhou Institute of Technology, Jiangsu, China. She received her Ph.D. degree from Nanjing Tech University, Jiangsu, China, in 2018.

Her research focus on the degradation mechanism of glass fiber reinforced polymer profiles in marine environment and application of composite structures etc.

About the author

Weiqing Liu is an academic leader of civil engineering subject, Advanced Engineering Composites Research Center, Nanjing Tech University, Jiangsu, China. He received his Ph.D. degree in structural engineering from Southeast University, Jiangsu, China, in 1995. He was the vice president of Nanjing Tech University from 2004 to 2018. He is the director of The Key Laboratory of Civil Engineering and Disaster Prevention and Mitigation of Jiangsu province.

His research interests include: composite structures, modern timber structures, seismic design and structural control etc. He has published more than 500 scientific papers. Over forty invention patents were authorized on these topics.

About the author

Yuan Fang is an associate professor at the College of Civil Engineering, Nanjing Tech University, Jiangsu, China. She received her Ph.D. degree in chemical engineering from Nanjing Tech University, Jiangsu, China, in 2011. She did research at University of Cambridge as a Visiting Researcher from 13 February 2017 to 12 February 2018.

Her research interests include: life prediction and degradation mechanism of composite structures under marine environment, synthesis of nanocomposites with high properties, fire protection mechanism of microcapsules modified composite structures. She has published more than 30 scientific papers.

About the author

Ruili Huo is an associate professor at the College of Civil Engineering, Nanjing Tech University, Jiangsu, China. She received her Ph.D. degree in civil materials and engineering from Nanjing Tech University, Jiangsu, China, in 2017.

Her research interests include: fatigue properties, interfacial properties and failure mechanism of composite structures under different environment. She has published more than 20 scientific papers. And twelve invention patents were authorized.

Reference

Yang, S., Liu, W., Fang, Y., & Huo, R. (2018). Influence of hygrothermal aging on the durability and interfacial performance of pultruded glass fiber-reinforced polymer composites. Journal of Materials Science, 54(3), 2102-2121.

Go To Journal of Materials Science

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