In the frontier research of modern materials science, silicone rubber-based composites have become the focus of attention in many fields due to their strong designability and excellent comprehensive properties. By compounding different types of reinforcing agents with the silicone rubber matrix, not only can the mechanical properties of the materials be significantly improved, but also various unique functions can be imparted to them, meeting the increasingly complex practical application requirements. In-depth exploration of the synergistic reinforcement mechanisms of silicone rubber-based composites is of great significance for promoting their multifunctional development.
Synergistic Reinforcement Mechanisms
Synergistic Effect of Particle Reinforcement
In silicone rubber-based composites, nanoparticles such as nano-silica and nano-calcium carbonate are often used as reinforcing agents. These nanoparticles have an extremely high specific surface area and can generate a strong interaction with the silicone rubber molecular chains. When subjected to external forces, the nanoparticles can act as stress concentration points, triggering the generation of micro-cracks in the surrounding silicone rubber matrix. During the propagation process of these micro-cracks, they will encounter other nanoparticles, leading to crack branching or termination, thus consuming a large amount of energy and improving the strength and toughness of the material. For example, in the silicone rubber composite added with nano-silica, the nano-silica particles are uniformly dispersed in the silicone rubber matrix and form physical or chemical cross-linking points with the molecular chains. Studies have shown that the addition of an appropriate amount of nano-silica can increase the tensile strength of the silicone rubber several times, and the elongation at break can also be maintained at a good level, which benefits from the synergistic reinforcement effect between the nanoparticles and the silicone rubber matrix.
Synergistic Effect of Fiber Reinforcement
Fiber-like reinforcing agents such as carbon fibers and glass fibers play a unique reinforcing role in silicone rubber-based composites. Fibers have high strength and modulus and can bear most of the external load. Take the carbon fiber-reinforced silicone rubber composite as an example. The high strength of carbon fibers enables them to play a skeleton support role in the composite. When the material is stressed, the silicone rubber matrix transfers the stress to the carbon fibers, and the carbon fibers effectively resist the external force with their own high strength, while limiting the deformation of the silicone rubber matrix. In addition, the interfacial bonding strength between the fibers and the silicone rubber matrix is also crucial. By pre-treating the fiber surface, such as chemical grafting, plasma treatment, etc., the interfacial bonding force between the fibers and the matrix can be enhanced, enabling the stress to be transferred more effectively between the two, further improving the mechanical properties of the composite. The excellent mechanical properties and sealing performance of the carbon fiber-reinforced silicone rubber sealing material applied in the aerospace field are precisely based on the good synergistic reinforcement mechanism between the fibers and the matrix.
Synergistic Reinforcement of Multilayer Structures
Constructing a multilayer structure is also an effective way to achieve synergistic reinforcement of silicone rubber-based composites. For example, particles with a core-shell structure are prepared and added to the silicone rubber. The core layer can be made of materials with high strength, such as ceramic particles, and the shell layer can be made of a polymer with good compatibility with the silicone rubber. This structure makes the core layer less likely to deform when subjected to external forces, while the shell layer can be closely combined with the silicone rubber matrix to enhance the interfacial interaction. When subjected to external impact, the core layer bears the main load, and the shell layer coordinates the stress transfer, working together with the silicone rubber matrix to achieve synergistic reinforcement. In addition, through the method of layered compounding, material layers with different properties can be alternately compounded in the silicone rubber matrix. Each material layer cooperates with each other during the stress process, giving full play to their respective advantages, thus improving the comprehensive performance of the entire composite.
Multifunctional Exploration
Conductive Functionalization
By introducing conductive fillers such as carbon nanotubes and graphene into the silicone rubber, silicone rubber-based composites with conductive functions can be prepared. Carbon nanotubes have excellent electrical properties and a high aspect ratio, forming a conductive network in the silicone rubber matrix. When the content of carbon nanotubes reaches a certain threshold, the electrical conductivity of the composite is significantly improved, and it can be used to manufacture electromagnetic shielding materials, conductive seals, etc. For example, in the shell sealing of electronic devices, the conductive silicone rubber composite can effectively shield electromagnetic interference and ensure the normal operation of the devices. At the same time, by controlling the content and distribution of the conductive fillers, the electrical conductivity of the composite can also be adjusted to meet the requirements of different application scenarios for conductive performance.
Thermal Conductive Functionalization
To meet the requirements of thermal conductivity of materials in fields such as heat dissipation of electronic devices, high thermal conductivity fillers such as boron nitride and aluminum oxide can be compounded with the silicone rubber. Boron nitride has good thermal conductivity and chemical stability. After being uniformly dispersed in the silicone rubber matrix, it can form an efficient heat conduction channel. Experimental data shows that the thermal conductivity of the silicone rubber composite added with an appropriate amount of boron nitride can be several times higher than that of pure silicone rubber. This thermally conductive silicone rubber-based composite has important application value in aspects such as heat dissipation of electronic chips and packaging of power devices, which can effectively reduce the operating temperature of the devices and improve their performance and reliability.
Intelligent Response Functionalization
By introducing materials with intelligent response characteristics into the silicone rubber-based composites, they can be endowed with intelligent response functions. For example, by compounding shape memory polymers with the silicone rubber, composites with shape memory functions can be prepared. Under the action of external stimuli (such as temperature, electric field, magnetic field, etc.), the shape memory polymer undergoes a phase transition, driving the silicone rubber matrix to undergo corresponding shape changes. This intelligent response silicone rubber-based composite can be applied to intelligent medical devices in the biomedical field, such as deformable vascular stents, which can restore to the preset shape in the body temperature environment and effectively support the blood vessels; it can also be used for adaptive structural components in the aerospace field, automatically adjusting the structural shape according to the changes in the flight environment and improving the performance of the aircraft.
The synergistic reinforcement mechanisms of silicone rubber-based composites provide a solid foundation for improving their mechanical properties, and the multifunctional exploration enables them to show great application potential in many emerging fields. With the continuous in-depth research, it is expected to develop more high-performance and multifunctional silicone rubber-based composites, providing strong material support for the development of various industries.
Temperature resistant and flame retardant coated liquid silicone rubber
