Impact of Nano – scale Flame – Retardant Fillers on the Flame Retardancy, Fluidity and Long – term Stability of Fireproof Adhesives and Optimization Strategies

This paper systematically discusses the application of nano – scale flame – retardant fillers such as montmorillonite and magnesium hydroxide nanoparticles in fireproof adhesives. It analyzes their influence mechanisms on the flame retardancy, fluidity and long – term stability of fireproof adhesives, and expounds scientific methods for determining the optimal addition ratio and dispersion process. This provides theoretical guidance and practical reference for the performance optimization and industrial production of fireproof adhesives.

 

As an important fireproof material, fireproof adhesives are widely used in construction, electronics, automotive and other fields. Nano – scale flame – retardant fillers can significantly improve the comprehensive performance of fireproof adhesives due to their unique size effect and surface effect. However, the addition of fillers may also have complex effects on the fluidity and long – term stability of fireproof adhesives. In – depth research on the relationship between nano – scale flame – retardant fillers and the performance of fireproof adhesives is of great significance for the development of high – performance fireproof adhesives.

Impact of Nano – scale Flame – Retardant Fillers on the Flame Retardancy of Fireproof Adhesives

Impact of Montmorillonite on Flame Retardancy

Montmorillonite is a kind of layered silicate nano – material. In fireproof adhesives, montmorillonite will form a continuous and dense char layer on the surface of the adhesive layer when heated. This char layer can effectively isolate heat and oxygen and prevent the release of combustible gases, thereby improving the flame retardancy of fireproof adhesives. When montmorillonite is uniformly dispersed in the fireproof adhesive system, its nano – scale lamellar structure can play a physical barrier role during the combustion process and slow down the spread speed of the flame. Studies have shown that the limiting oxygen index (LOI) of fireproof adhesives with an appropriate amount of montmorillonite added is significantly increased, and the self – extinguishing time in the vertical combustion test is shortened.

Impact of Magnesium Hydroxide Nanoparticles on Flame Retardancy

Magnesium hydroxide nanoparticles belong to inorganic hydroxide flame retardants. When heated, they will absorb a large amount of heat during decomposition, playing a cooling role and reducing the temperature of the adhesive layer. At the same time, the water vapor generated by decomposition dilutes the concentration of combustible gases and inhibits the progress of the combustion reaction. In addition, the magnesium oxide generated after the decomposition of magnesium hydroxide has good heat insulation and flame retardancy, and can form a protective layer on the surface of the adhesive layer. Compared with micron – scale magnesium hydroxide, nano – scale particles have a larger specific surface area, more sufficient contact with the fireproof adhesive matrix, and higher flame retardancy efficiency.

 

Impact of Nano – scale Flame – Retardant Fillers on the Fluidity of Fireproof Adhesives

Impact of Filler Addition Amount on Fluidity

With the increase of the addition amount of nano – scale flame – retardant fillers, the viscosity of fireproof adhesives gradually increases, and the fluidity becomes worse. This is because nano – particles have high surface energy and are easy to agglomerate with each other, forming a network structure in the fireproof adhesive system, which hinders the flow of the adhesive liquid. When the addition amount of montmorillonite or magnesium hydroxide nanoparticles exceeds a certain value, the fireproof adhesive may become too viscous to be applied and constructed.

Impact of Filler Dispersion State on Fluidity

The dispersion state of fillers directly affects the fluidity of fireproof adhesives. If the nano – particles are uniformly dispersed and exist in a single – dispersed state in the fireproof adhesive system, the negative impact on the fluidity of the adhesive liquid is small; on the contrary, if the particles are seriously agglomerated and form large agglomerates, it will significantly increase the internal friction of the adhesive liquid and reduce the fluidity. Therefore, optimizing the dispersion process of fillers is crucial to maintain the good fluidity of fireproof adhesives.

 

Impact of Nano – scale Flame – Retardant Fillers on the Long – term Stability of Fireproof Adhesives

Impact of Compatibility between Fillers and Matrix on Long – term Stability

The compatibility between nano – scale flame – retardant fillers and the fireproof adhesive matrix has an important impact on their long – term stability. If the compatibility between them is poor, the fillers may precipitate from the matrix during long – term use, leading to a decline in the performance of fireproof adhesives. After the surface of montmorillonite is organically modified, its compatibility with the organic fireproof adhesive matrix can be improved, the agglomeration and precipitation of fillers can be reduced, and the long – term stability can be improved. The surface modification treatment of magnesium hydroxide nanoparticles can also enhance the binding force with the matrix and improve the aging resistance of fireproof adhesives.

Impact of Environmental Factors on Long – term Stability

In practical applications, fireproof adhesives will be affected by environmental factors such as temperature, humidity and light. The addition of nano – scale flame – retardant fillers may change the response of fireproof adhesives to environmental factors. For example, in a humid environment, magnesium hydroxide nanoparticles that have not been well treated may undergo hydrolysis, affecting the structure and performance of fireproof adhesives. The layered structure of montmorillonite can, to a certain extent, block the intrusion of moisture and play a protective role on fireproof adhesives.

 

Methods for Determining the Optimal Addition Ratio

Experimental Design

A series of comparative experiments are designed to study the influence of different addition ratios of nano – scale flame – retardant fillers on the flame retardancy, fluidity and long – term stability of fireproof adhesives. The orthogonal experimental design method is adopted, and multiple key performance indicators are selected as evaluation parameters, such as the limiting oxygen index, vertical combustion grade, viscosity, storage stability, etc. During the experiment, other conditions are kept unchanged, and only the addition ratio of fillers is changed to systematically test and analyze all performances of fireproof adhesives.

Comprehensive Performance Evaluation

A comprehensive evaluation model is established to quantitatively evaluate the performances of fireproof adhesives under different addition ratios. For example, corresponding weights can be assigned according to the importance of each performance index, and a comprehensive score can be calculated. By comparing the comprehensive scores under different addition ratios, the addition ratio that can make the comprehensive performance of fireproof adhesives reach the optimal is determined. Generally speaking, the optimal addition ratio of montmorillonite in fireproof adhesives is usually between 3% and 8%; the optimal addition ratio of magnesium hydroxide nanoparticles is between 10% and 20%, but the specific values still need to be adjusted according to the matrix material and application requirements of fireproof adhesives.

 

Methods for Optimizing the Dispersion Process

Physical Dispersion Methods

Physical dispersion methods mainly include mechanical stirring and ultrasonic dispersion. Mechanical stirring breaks up the agglomerates of nano – particles through the shear force generated by the high – speed rotating stirring paddle; ultrasonic dispersion uses the cavitation effect of ultrasonic waves to generate local high temperature, high pressure and strong shock waves in the liquid, so that the nano – particles are uniformly dispersed in the fireproof adhesive system. Using the two methods in combination, first carrying out mechanical stirring for pre – dispersion, and then further refining the dispersion through ultrasonic, can obtain a better dispersion effect.

Chemical Dispersion Methods

Chemical dispersion methods mainly involve surface modification of nano – particles. For example, silane coupling agents, titanate coupling agents, etc. are used to treat the surface of montmorillonite or magnesium hydroxide nanoparticles, change the surface properties of the particles, reduce the surface energy, and enhance the compatibility with the fireproof adhesive matrix, thereby improving the dispersibility. In addition, by adding dispersants, they can be adsorbed on the surface of nano – particles to produce electrostatic repulsion or steric hindrance effects, preventing particle agglomeration.

Conclusion

The addition of nano – scale flame – retardant fillers (such as montmorillonite and magnesium hydroxide nanoparticles) can significantly improve the flame retardancy of fireproof adhesives, but it will also have a certain impact on their fluidity and long – term stability. By scientifically designing experiments to determine the optimal addition ratio and using appropriate physical and chemical dispersion methods to optimize the dispersion process, the relationship between all performances of fireproof adhesives can be effectively balanced, and fireproof adhesive products with excellent comprehensive performance can be prepared. In the future, with the continuous in – depth research on nano – materials, nano – scale flame – retardant fillers will have a broader application prospect and development space in the field of fireproof adhesives.

In actual production and application, it is also necessary to further explore and optimize the compounding process of nano – scale flame – retardant fillers and fireproof adhesives according to specific use scenarios and performance requirements to meet the increasing high – performance needs of fireproof adhesives in different industries.

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