Thermogravimetric analysis of carbon fiber reinforced epoxy resin using a thermogravimetric analyzer

Carbon fiber reinforced epoxy resin composite (CFRP) has become a key structural material in manufacturing fields such as aerospace, wind power, and automotive lightweighting due to its high specific strength, excellent fatigue resistance, and designability. During long-term service, composite materials may face harsh environments such as high temperature, humidity, and radiation. The thermal degradation of their resin matrix can directly lead to interfacial debonding, decreased mechanical properties, and structural failure. Thermogravimetric analysis (TGA), as a core technology for quantifying the thermal properties of materials, has advantages such as high sensitivity, dynamic monitoring, and objective data. It can capture the quality changes of composite materials in real-time during the programmed heating process, accurately obtain thermal degradation characteristic parameters, and provide scientific basis for material formulation optimization, molding process improvement, and service life evaluation.

1、 Operation steps of the experiment

1. Measuring equipment:DZ-TGA201 Thermogravimetric Analyzer

2. Measured samples: In this experiment, the laminated board prepared by compression molding of industrial grade carbon fiber reinforced epoxy resin prepreg was used as the test object, focusing on optimizing TGA testing conditions and analyzing thermal degradation behavior.

2.1 Preparation: Cut the composite material sample into small pieces and dry them in an 80 ℃ vacuum drying oven for 4 hours to remove surface adsorbed moisture and residual solvents, avoiding interference with the test results.

2.2 Preparation method: The sample is frozen and ground using liquid nitrogen, then sieved (200 mesh) to ensure uniform particle size and avoid the influence of fiber orientation on heat transfer.

2.3 Sample dosage: Use an alumina ceramic crucible, weigh 10-15mg of the sample and place it in the crucible. The sample size is moderate, ensuring signal strength while avoiding internal temperature gradients.

3. Experimental parameter setting: Temperature setting, heating rate, and atmosphere environment can be achieved through device operation software. End temperature: 900 ° C, heating rate of 20 ° C/min, full nitrogen atmosphere throughout the process.

4. Measured spectra: In this experiment, the spectra were tested to enhance the thermogravimetric (TG) and (DTG) curves of epoxy resin

5. Data analysis: From the data in the above figure, we can see that the thermal degradation of epoxy resin under nitrogen atmosphere exhibits a typical three-stage characteristic.

5.1 Stage I (room temperature -300 ℃): During this stage, the mass loss accounts for 0-1% of the total mass, mainly due to the volatilization process of residual trace adsorbed water, unreacted epoxy monomers, and small molecule additives in the sample, accompanied by the pyrolysis of a small amount of resin oligomers. The DTG curve has no obvious characteristic peak in this interval, and the trend of the curve is gentle, indicating that this stage is a mixed process of physical volatilization and slight pyrolysis, with a slow reaction rate and no significant impact on the main properties of the composite material.

5.2 Stage 2 (300-600 ℃): This stage is the main thermal degradation stage of the composite material, with a mass loss of 15-25% of the total mass, corresponding to the strong and sharp characteristic peak of the DTG curve. The maximum degradation rate temperature (Tmax) is 419.87 ℃. This stage is mainly characterized by a large number of molecular chain breaks in the epoxy resin matrix, decomposition of functional groups such as ether bonds and ester bonds, and release of small molecule degradation products such as phenol and formaldehyde. At the same time, the interfacial bonding between the resin and glass fiber gradually breaks down, which is the core range for evaluating the thermal stability of composite materials. The degree of degradation in this stage directly determines the structural retention ability of the material at high temperatures.

5.3di three-stage (600-900 ℃): The mass loss in this stage accounts for 3-5% of the total mass. This stage mainly involves the further cracking of resin carbides formed by the degradation of the previous stage, releasing low-carbon hydrocarbon compounds. The inorganic glass fiber reinforcement phase remains thermally stable in this temperature range without significant mass loss. The final residue is a mixture of glass fiber and stable carbonaceous residue.

The key thermal performance parameters of the epoxy anti-corrosion material can be obtained through curve analysis: the initial decomposition temperature (Tonset) is 393.39, the maximum decomposition rate temperature is 419.87 ℃ (main degradation stage), and the residual amount is 75% at 900 ℃. Among them, Tonset and Tmax in the main degradation stage directly reflect the material's tolerance to high temperature environments, while the residual amount is related to the material's carbon forming flame retardant performance and long-term anti-corrosion potential.

2、 Experimental conclusion

With the continuous upgrading of testing technology and the widespread application of combined technology, thermogravimetric analyzers will play a more important role in predicting the long-term service life of composite materials, evaluating the adaptability to high temperature environments, and developing customized special functional composite materials. This will promote the development of the composite materials industry towards high performance, high heat resistance, and high reliability, and better adapt to the strict requirements for the use of composite materials in aerospace, new energy, and other fields. More product inquiries:400-885-2060.