Development of Low-Smoke Epoxy Resin Carbon Fiber Prepreg
Abstract
1. Introduction
2. Experiment
2.1. Materials
2.2. Synthesis of Modified Resins
2.2.1. Synthesis of PPPS-Modified E51
2.2.2. Synthesis of PPPS-Modified EOCN
2.3. Sample Preparation
2.3.1. Preparation of Resin Castings
2.3.2. Cone-and-Plate Viscometry
2.3.3. Preparation of Prepreg
2.3.4. Preparation of Composite Material
2.4. Characterization
- (1)
- Infrared testing: Infrared spectroscopy of EOCN, PPPS, and EZ was carried out by KBr compression method using a Nicolet 6700 FTIR spectrometer (Waltham, MA, USA) with a scanning wave number range of 4000–5000 cm−1;
- (2)
- Thermogravimetric analysis was performed using a STA449F3 simultaneous thermal analyzer (Selb, Germany). The resin sample was heated from 40 to 1000 °C at a constant heating rate of 10 °C/min under a dynamic air atmosphere.
- (3)
- Cone Calorimetry Test: According to ISO 5660 standard, FTT 0007 Cone Calorimeter is used to conduct cone calorimetry test on resin and composite materials.
- (4)
- The microscopic morphology of char residues of the resin and the composites was observed, and spot elemental analysis was performed using an FEI Scios 2 scanning electron microscope (SEM, Hillsboro, OR, USA) equipped with energy-dispersive X-ray spectroscopy (EDS, Hillsboro, OR, USA) at an accelerating voltage of 20 kV. Prior to analysis, the sample surfaces were sputter-coated with platinum to enhance conductivity.
- (5)
- Smoke Density Testing: In accordance with ISO 5659-2 [15], a single-chamber smoke density test was performed on the composite material to determine the specific optical density of smoke (abbreviated as smoke density). This test was performed to assess compliance with the smoke toxicity requirements of the International Maritime Organization’s FTP Code.
3. Results and Discussion
3.1. Structure and Properties of the Matrix Resin
3.1.1. Structural Characterization
3.1.2. Heat Resistance Analysis
3.1.3. Cone Calorimetric Analysis
3.1.4. Char Residue Analysis of Resin Matrix Combustion
3.1.5. Rheological Analysis
3.2. Smoke Production Analysis of Composite Materials
3.2.1. Cone Calorimetry Analysis
3.2.2. Char Residue Analysis of Composite Materials
3.2.3. Smoke Density Test
4. Conclusions
- PPPS was chemically grafted into the molecular structures of E51 and EOCN resins, significantly improving their thermal stability and char residue yield. During combustion, silicon is uniformly distributed within the char residue as silicon oxides, forming a dense and homogeneous char layer that suppresses resin combustion, smoke transport, and reduces heat release and smoke generation. Compared to unmodified resins, the TSP of EB and EZ decreased by 54.8% and 48.3%, respectively. Compared with additive modification, the main reason for the significant smoke suppression effect is that the distribution of silicon elements introduced by grafting is more uniform, resulting in a more uniform distribution of silicon oxides after the resin pyrolysis.
- The significant reduction in TSP of modified resin-based composites is primarily attributed to the structural characteristics of the silicon-containing char residue. Microstructural analysis reveals that the silicon-rich char residue generated from the pyrolysis of modified resins uniformly accumulates on the fiber surface, forming a continuous protective layer. Notably, the char residue of LJF-CF exhibits a dual-layer architecture: a dense inner layer acts as an effective smoke barrier, drastically reducing the diffusion of smoke particles; a thickened outer layer effectively insulated heat, and delays the pyrolysis kinetics of the underlying resin matrix. This “dual-layer protection” mechanism achieves smoke suppression through a synergistic effect.
- LJF-CF composites meet the smoke density requirements for ship deck materials under the FTP Code. The LJF-CF composite material is a unidirectional carbon fiber laminatd unidirectionally structure, which only modify the resin matrix without adding any flame retardant/smoke suppressant. It is expected that through further smoke suppression measures, LJF-CF composites can be applied to the interior structural components of ships and other composite material fields with higher requirements for smoke toxicity.
- Although chemical modification achieves superior smoke suppression and flame retardancy, it is more complex and costly than additive blending. This study successfully tuned the hybrid resin’s viscosity via formulation optimization to meet the prepreg processing window (10–20 Pa·s), acknowledging that not all EB/EZ resin ratios yield suitable rheology. Future work will focus on industrial scale-up, cost–benefit analysis, and assessing long-term durability in marine environments (aging, water/salt spray resistance). Additionally, mechanical property evaluation (tensile strength, flexural modulus, fracture toughness) will be expanded to validate structural performance.
- The low-smoke prepreg developed in this study enriches the manufacturing techniques for low-smoke composites and significantly broadens their application scope.
Author Contributions
Funding
Institutional Review Board Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Sample | T5%/°C | Tmax1/°C | Tmax2/°C | MLRmax (%/°C) | R800/% |
---|---|---|---|---|---|
EOCN | 318.2 | 407.1 | 552.5 | 7.8 | 0 |
EZ | 342.8 | 390.1 | 617.5 | 6.8 | 20 |
Sample | E51 | EB | EOCN | EZ |
---|---|---|---|---|
PHRR (kW/m2) | 710.9 | 672.5 | 3121.4 | 981.87 |
THR (MJ/m2) | 80.8 | 83.3 | 85.46 | 55.56 |
PSPR (m2/s) | 0.24 | 0.10 | 0.67 | 0.18 |
TSP (m2/m2) | 30.5 | 13.8 | 20.08 | 10.39 |
Sample | Percentage of Residual Elements | |||
---|---|---|---|---|
C/wt% | O/wt% | Si/wt% | P/wt% | |
EOCN | 74.7 | 25.0 | 0.2 | 0.1 |
EZ | 56.6 | 22.3 | 21.0 | 0.1 |
Sample | E51-CF | EB-CF | EZ-CF | LJF-CF |
---|---|---|---|---|
PHRR (kW/m2) | 376.6 | 311.7 | 337.1 | 294.0 |
THR (MJ/m2) | 24.67 | 20.12 | 26.19 | 26.16 |
PSPR (m2/s) | 0.14 | 0.11 | 0.12 | 0.09 |
TSP (m2/m2) | 13.5 | 9.4 | 9.0 | 8.2 |
Sample | Percentage of Residual Carbon Elements (%) | ||
---|---|---|---|
C | O | Si | |
E51-CF | 100.00 | 0 | 0 |
EB-CF | 50.06 | 37.94 | 12.00 |
EZ-CF | 61.85 | 31.27 | 6.88 |
LJF-CF | 59.08 | 30.84 | 10.08 |
Sample | Ds max |
---|---|
E51-CF | 586.9 |
EB-CF | 371.3 |
EZ-CF | 358.5 |
LJF-CF | 276.9 |
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Zhao, Y.; Wu, L.; Xu, Y.; Cao, D.; Ji, Y. Development of Low-Smoke Epoxy Resin Carbon Fiber Prepreg. Polymers 2025, 17, 2710. https://doi.org/10.3390/polym17192710
Zhao Y, Wu L, Xu Y, Cao D, Ji Y. Development of Low-Smoke Epoxy Resin Carbon Fiber Prepreg. Polymers. 2025; 17(19):2710. https://doi.org/10.3390/polym17192710
Chicago/Turabian StyleZhao, Yu, Lili Wu, Yujiao Xu, Dongfeng Cao, and Yundong Ji. 2025. "Development of Low-Smoke Epoxy Resin Carbon Fiber Prepreg" Polymers 17, no. 19: 2710. https://doi.org/10.3390/polym17192710
APA StyleZhao, Y., Wu, L., Xu, Y., Cao, D., & Ji, Y. (2025). Development of Low-Smoke Epoxy Resin Carbon Fiber Prepreg. Polymers, 17(19), 2710. https://doi.org/10.3390/polym17192710