# Development of Low-Smoke Epoxy Resin Carbon Fiber Prepreg

## TL;DR

A new low-smoke epoxy resin was developed for carbon fiber composites, suitable for marine interiors due to reduced smoke toxicity.

## Contribution

A novel epoxy resin (EZ) was synthesized by grafting PPPS onto EOCN, resulting in a low-smoke composite without flame retardants.

## Key findings

- LJF-CF composites achieved a maximum smoke density of 276.9, meeting marine safety standards.
- The bilayer char structure in LJF-CF reduced smoke transport and provided thermal insulation.
- Silicon oxides in the char residue improved stability and compactness without additives.

## Abstract

The smoke toxicity of epoxy resin limits the application of its carbon fiber composites in marine interior structures. To address this issue, a novel epoxy resin (EZ) was synthesized by grafting phenyl propyl polysiloxane (PPPS) onto ortho-cresol novolac epoxy resin (EOCN), building upon the group’s earlier work on polysiloxane-modified epoxy resin (EB). The results confirmed successful grafting of PPPS onto EOCN, which significantly enhanced the thermal stability and char residue of EZ. Specifically, the peak heat release rate (PHRR), total heat release (THR), peak smoke production rate (PSPR), and total smoke production (TSP) of EZ were reduced by 68.5%, 35%, 73.1%, and 48.3%, respectively, attributable to the formation of a stable and compact char layer that suppressed smoke generation. By blending EZ with EB resin, a low-smoke epoxy system (LJF-2) was developed for prepreg applications. Carbon fiber composites (LJF-CF) prepared from LJF-2 exhibited minimal smoke emission and a unique bilayer char structure: a dense inner layer that hindered smoke transport and a thick outer layer that provided thermal insulation, delaying further resin decomposition. Silicon was uniformly distributed in the char residue as silicon oxides, improving its stability and compactness. Without adding any flame retardants or smoke suppressants, LJF-CF achieved a maximum smoke density (Ds,max) of 276.9, meeting the requirements of the FTP Code for ship deck materials (Ds,max < 400). These findings indicate that LJF-CF holds great promise for use in marine interior components where low smoke toxicity is critical.