Durability assessment of PEN/PET FRP composites based on accelerated aging in alkaline solution/seawater with different temperatures

• Published in: Construction & building materials 2022-04, Vol.327, p.126992, Article 126992
• Main Authors: Zeng, Jun-Jie, Zhuge, Yan, Liang, Sheng-Da, Bai, Yu-Lei, Liao, JinJing, Zhang, Lihai
• Format: Article
• Language: English
• Subjects: Alkaline solution; Arrhenius equation; Durability; FRP; polyethylene naphthalate (PEN); Polyethylene terephthalate (PET); Seawater
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2022.126992

•A transition portion is seen in the tensile stress–strain curves of PET FRP sheets after accelerated aging.•The tensile strength of PEN FRP sheets in 25 °C alkaline solution decreases by only 5%.•The decrease in the tensile strength of PEN FRP sheets after aging in 40 °C alkaline solution and seawater are 13% and 4% respectively.•The alkaline resistance of PEN FRP composites is better than that of PET FRP composites.•The Arrhenius formula is adopted to predict the long-term tensile strength of LRS FRP sheets. Large rupture strain (LRS) fiber-reinforced polymer (FRP) composites, including polyethylene naphthalate (PEN) FRP and polyethylene terephthalate (PET) FRP composites, have become increasing popular in civil construction. PET FRP and PEN FRP can be recyclable and thus they are environmentally friendly. However, the durability of LRS FRP composites under extreme environmental conditions (e.g., marine environment and high temperature) has not been understood. To this end, durability tests on 282 LRS FRP sheets after aging in alkaline/seawater solution with different temperatures (25℃, 40℃, 60℃) were conducted in this study. The microstructure of PEN FRP sheets was also analyzed using scanning electron microscope (SEM). The results show that the changes of the elastic modulus of the first linear portion and the elastic modulus of the second linear portion of PEN FRP sheets after aging in different aging temperatures are slight. For PEN FRP sheets with an aging period of 365 days in 60 °C solutions, the degradation rate of the tensile strength is around 10% for both alkaline (pH = 13.2) and seawater solutions, and the degradation rate of the tensile rupture strain is around 12.5%. Additionally, under a higher exposure temperature, there is a significant decrease in the tensile strength of LRS FRP composites. Furthermore, it shows that the durability of PEN FRP sheets was significantly affected in the alkaline environment compared to that in the seawater environment, and the alkaline resistance of PEN FRP composites is better than that of PET FRP composites.