# AlOOH-Coated Glass Fiber-Reinforced Composites for Pipeline Rehabilitation: Enhancement of Interfacial Adhesion and Durability

## TL;DR

This paper introduces a new method to improve the durability and strength of glass fiber composites used in pipeline rehabilitation by coating them with a special aluminum oxide layer.

## Contribution

The novel use of a polyhydric boehmite (AlOOH) coating on glass fibers to enhance interfacial adhesion and mechanical properties in composites.

## Key findings

- AlOOH-coated glass fibers increased flexural strength by 41.21% and tensile strength by 21.05%.
- The enhancement is due to mechanical interlocking, covalent bonding, and hydrogen bonding at the interface.
- The method offers a durable and cost-effective solution for pipeline rehabilitation materials.

## Abstract

Glass fiber (GF) reinforced unsaturated polyester resin (UP) composites are used in cured-in-place pipe (CIPP) rehabilitation technology of drainage systems due to their low cost and excellent force chemical properties. However, the weak interfacial compatibility between GF and the polymer matrix limits the stress transfer efficiency. Herein, a strategy of a polyhydric boehmite (AlOOH) layer coated on GF (GF-AlOOH) was developed for improving the mechanical properties of UP composites, and the enhancement effects of the coating process were analyzed. The AlOOH-modified GFs significantly improved the flexural and tensile strengths of the modified composites by 41.21% and 21.05%, respectively. Moreover, the enhancement mechanism was explored by analyzing the surface chemical structure of GF-AlOOHs. The nano-AlOOH was grafted on the GF surface by O=Al–OH. Meanwhile, the increase in the mechanical properties of UP/GF-AlOOH was mainly attributed to the combined effect of mechanical interlocking interaction, covalent bonding and hydrogen bonding, which improved the interfacial adhesion between GF and UP. In summary, this work provides effective guidance for achieving high-quality interfaces in GF composites and offers important insights into designing durable and cost-effective materials for CIPP rehabilitation and broader infrastructure applications.