Preparation of cardanol-based curing agent for underwater drainage pipeline repairs

• Published in: e-Polymers Vol. 24; no. 1; pp. 105511 - 11
• Main Authors: Li, Yu, Wang, Guoqing, Guo, Yali, Fang, Ning, Li, Jingxiang, Li, Zheng, Li, Junhan
• Format: Journal Article
• Language: English
• Published: De Gruyter 29.06.2024
• Subjects: cardanol; concrete; drainage pipeline repairs; epoxy resin; underwater curing agent
• ISSN: 1618-7229; 1618-7229
• DOI: 10.1515/epoly-2023-0190

The underwater curing agents have demonstrated promising potential in various applications, especially in underwater repair engineering, yet have proven considerable challenging. Here, we report a cardanol-based curing agent for epoxy resin that achieves robust adhesion to steel and concrete substrates both in air and underwater. Cardanol, paraformaldehyde, and -phenyldimethylamine are selected as the polymeric monomers to synthesize curing agent by Mannich reaction in the absence of chemical cross-linker agents. The coating is completely cured within 46 ± 1 min in air and 54 ± 2 min under water with an adhesion of 0 or 1 and a hardness of 5H. The impact strength, shear strength, and tensile strength of coating on underwater concrete were 9.58 ± 0.41 kJ·m , 13.1 ± 0.3, and 10.5 ± 0.2 MPa, respectively, demonstrating exceptional flexibility and mechanical strength as well as favorable hydrophobicity. This work paves the way for the rehabilitation of underwater drainage network for urban infrastructure and water conservancy projects.