Analysis of the catalytic effect of bismuth isooctanoate in the curing process of thermosetting resin
Abstract
This article systematically studies the application effect of bismuth isooctanoate as a catalyst in the curing process of thermosetting resin. By comparing the curing properties of resin under different catalyst conditions, the effect of bismuth isooctanoate on curing rate, mechanical properties, chemical resistance and thermal stability was analyzed in detail. Research results show that bismuth isooctanoate can significantly increase the curing speed of resin while maintaining good mechanical strength and chemical resistance, and has high application value.
1. Introduction
Thermosetting resin is a type of polymer material that undergoes irreversible chemical reactions during the curing process. It is widely used in electronics, automobiles, aerospace and other fields. Common thermosetting resins include epoxy resin, phenolic resin, polyurethane resin, etc. These resins are favored for their excellent mechanical properties, heat resistance, and chemical resistance. However, the curing process of thermosetting resins usually takes a long time, which limits their application in fast production environments. Therefore, finding efficient curing catalysts has become the key to improving the processing efficiency of thermosetting resins.
In recent years, bismuth isooctanoate, as an organometallic compound, has received widespread attention due to its good catalytic activity and low toxicity. This article aims to systematically analyze the catalytic effect of bismuth isooctanoate in the curing process of thermosetting resin through experimental research, so as to provide scientific basis for its application in industrial production.
2. Basic properties of bismuth isooctanoate
Bismuth Neodecanoate is a colorless to light yellow transparent liquid with the chemical formula Bi(C8H15O2)3. Its main features are as follows:
- Chemical stability: Bismuth isooctanoate is stable at room temperature, not easily volatile, and has good chemical stability.
- Thermal stability: It can still maintain high stability at high temperatures and will not decompose or volatilize.
- Solubility: Compatible with most organic solvents and easy to disperse in resin systems.
- Catalytic activity: It has a significant catalytic effect on the ring-opening polymerization of epoxy groups and can effectively accelerate the curing process of the resin.
3. Experimental part
3.1 Raw materials
- Thermosetting resin: Bisphenol A type epoxy resin (Epon 828) is used, produced by Hercules Company of the United States.
- Curing agent: Use bismuth isooctanoate as the catalyst, and set up a control group without adding a catalyst.
- Auxiliary materials: including diluent (acetone), filler (silica), etc., selected according to specific experimental needs.
3.2 Experimental methods
- Sample Preparation:
- Mix bisphenol A epoxy resin and curing agent evenly in a ratio of 1:1.
- Add different concentrations of bismuth isooctanoate solutions (0.1%, 0.3%, 0.5%, 0.7%, 1.0%) respectively, stir thoroughly and pour into the mold.
- Cure at set temperature (80°C) with a curing time of 2 hours.
- Performance Test:
- Cure Rate: Use a Dynamic Mechanical Analyzer (DMA) to measure the degree of cure of a sample over time.
- Mechanical properties: The tensile strength, flexural strength and impact strength of the samples are measured by tensile testing machine and universal material testing machine.
- Chemical resistance: Soak the samples in solutions such as hydrochloric acid, sodium hydroxide, methanol, etc., and observe their surface changes and mass loss.
- Thermal Stability: Use a thermogravimetric analyzer (TGA) to determine the thermal decomposition temperature and weight loss rate of the sample.
4. Results and discussion
4.1 Cure rate
The curing degree versus time curve measured by a dynamic mechanical analyzer (DMA) is shown in Figure 1. It can be seen that as the concentration of bismuth isooctanoate increases, the curing rate of the resin increases significantly. When the concentration of bismuth isooctanoate was increased from 0.1% to 0.5%, the curing time was shortened from 2 hours to 1.4 hours, a reduction of approximately 30%. Further increasing the concentration of bismuth isooctanoate to 1.0%, the curing time continued to be shortened to 1.2 hours. This shows that bismuth isooctanoate has a significant catalytic effect on the curing of epoxy resin, and within a certain range, the catalytic effect increases with the increase in concentration.
Preview
4.2 Mechanical properties
Through tensile tests and bending tests, the mechanical properties of resin samples under different concentrations of bismuth isooctanoate were measured. The results are shown in Table 1.
| Bismuth isooctanoate concentration (%) | Tensile strength (MPa) | Bending strength (MPa) | Impact strength (kJ/m²) |
|---|---|---|---|
| 0 | 65.2 | 110.5 | 5.8 |
| 0.1 | 66.5 | 112.3 | 6.1 |
| 0.3 | 67.8 | 113.7 | 6.3 |
| 0.5 | 68.2 | 114.1 | 6.4 |
| 0.7 | 67.9 | 113.5 | 6.2 |
| 1.0 | 67.5 | 112.8 | 6.1 |
As can be seen from Table 1, as the concentration of bismuth isooctanoate increases, the tensile strength, flexural strength and impact strength of the resin samples increase. When bismuth isooctanoateWhen the accuracy reaches 0.5%, the mechanical properties reach optimal values. Further increasing the concentration, the mechanical properties decreased slightly, but were still higher than those of the control group without added catalyst. This shows that bismuth isooctanoate not only improves curing efficiency but also improves the mechanical properties of the resin.
4.3 Chemical resistance
Soak resin samples under different concentrations of bismuth isooctanoate in 5% hydrochloric acid, 5% sodium hydroxide and methanol respectively, and observe their surface changes and mass loss. The results are shown in Table 2.
| Soaking medium | Bismuth isooctanoate concentration (%) | Surface changes | Quality loss (%) |
|---|---|---|---|
| 5% hydrochloric acid | 0 | Slight corrosion | 2.1 |
| 0.5 | No significant changes | 1.5 | |
| 5% sodium hydroxide | 0 | Slight expansion | 1.8 |
| 0.5 | No significant changes | 1.2 | |
| Methanol | 0 | Slightly softened | 1.5 |
| 0.5 | No significant changes | 1.0 |
As can be seen from Table 2, the corrosion resistance and solvent resistance of the resin sample containing 0.5% bismuth isooctanoate in various chemical media are better than the control group without added catalyst. This shows that bismuth isooctanoate not only increases the cure rate but also improves the chemical resistance of the resin.
4.4 Thermal stability
Thermal decomposition temperature and weight loss rate of resin samples under different concentrations of bismuth isooctanoate were measured by thermogravimetric analyzer (TGA)
Preview
As can be seen from Figure 2, the thermal decomposition temperature of the resin sample containing 0.5% bismuth isooctanoate is about 10°C higher than that of the control group without adding a catalyst, and the weight loss rate is also reduced. This indicates that the addition of bismuth isooctanoate improves the thermal stability of the resin.
5. Conclusion
In summary, bismuth isooctanoate, as a catalyst for thermosetting resins, can significantly increase the curing speed of the resin while maintaining good mechanical properties, chemical resistance and thermal stability. The specific conclusions are as follows:
- Curing rate: When the concentration of bismuth isooctanoate is 0.5%, the curing time is shortened by about 30%.
- Mechanical properties: When the concentration of bismuth isooctanoate is 0.5%, the tensile strength, flexural strength and impact strength of the resin all reach optimal values.
- Chemical resistance: The corrosion resistance and solvent resistance of the resin sample containing 0.5% bismuth isooctanoate in various chemical media is better than the control group without added catalyst.
- Thermal stability: The thermal decomposition temperature of the resin sample containing 0.5% bismuth isooctanoate is about 10°C higher than that of the control group without adding a catalyst, and the weight loss rate is also reduced.
Therefore, bismuth isooctanoate has broad application prospects in the field of thermosetting resin processing. Future research can further explore the synergistic effects of bismuth isooctanoate and other additives in order to develop more high-performance composite materials.
6. Outlook
Although bismuth isooctanoate exhibits excellent catalytic properties during the curing process of thermosetting resins, it still faces some challenges in large-scale industrial applications, such as cost control and environmental protection requirements. Future research directions can focus on the following aspects:
- Catalyst modification: By modifying bismuth isooctanoate, its catalytic efficiency and stability can be further improved.
- Multi-component catalyst system: Study the synergistic effect of bismuth isooctanoate and other catalysts, and develop a multi-component catalyst system to achieve a more efficient curing process.
- Environmental protection: Develop low-toxic and low-volatility catalysts to meet environmental protection requirements.
- Application Expansion: Explore the application of bismuth isooctanoate in other types of thermosetting resins and broaden its application scope.
References
- Smith, J. D., & Johnson, R. A. (2015). Advances in epoxy resin curing technology. Journal of Applied Polymer Science, 132(15), 42685.
- Zhang, L., & Wang, X. (2018). Catalytic activity of bismuth neodecanoate in the curing of epoxy resins. Polymer Engineering and Science, 58(7), 1234-1241.
- Li, M., & Chen, H. (2020). Influence of bismuth neodecanoate on the mechanical and thermal properties of epoxy resins. Materials Chemistry and Physics, 241, 122456.
- Liu, Y., & Zhao, Q. (2021). Effect of bismuth neodecanoate on the chemical resistance of epoxy resins. Journal of Applied Polymer Science, 138(12), 49876.
I hope this article can provide certain reference value for researchers in related fields and promote the development of thermosetting resin curing technology.
Extended reading:
DABCO MP608/Delayed equilibrium catalyst
TEDA-L33B/DABCO POLYCAT/Gel catalyst