The core reason silicone elastomers maintain stable performance over a wide temperature range of -60°C to 200°C stems from their unique molecular structure design and material modification technology. This can be explained from three perspectives:
First, the stability of the backbone molecular structure. The backbone is composed of alternating silicon-oxygen (Si-O) bonds, with a bond energy of 452 kJ/mol, far exceeding the 347 kJ/mol of carbon-carbon (C-C) bonds. At high temperatures, the Si-O bonds are resistant to cleavage, preventing molecular chain decomposition. Furthermore, the symmetrical distribution of the methyl groups (-CH₃) attached to the backbone reduces intermolecular forces, making it difficult to form rigid crystals at low temperatures. This allows for elasticity at low temperatures and prevents embrittlement.
Second, the optimized design of the crosslinking network. The crosslinking structure, formed through peroxide or hydrosilylation reactions, creates a uniform and stable three-dimensional network. This structure limits excessive molecular chain creep at high temperatures while retaining a certain amount of molecular movement, ensuring the material maintains flexibility at low temperatures and balancing performance stability at both high and low temperatures.
Finally, there's the synergistic effect of heat-resistant additives. Reinforcements and heat-resistant additives, such as silica and iron oxide, are often added during production to not only improve mechanical strength but also further enhance thermal stability. For example, silica particles disperse heat, reducing damage to molecular chains caused by localized high temperatures; special heat-resistant additives inhibit oxidation reactions at high temperatures, slowing material aging and further broadening the temperature resistance range.