When prefabricated rubber track membranes operate in high-temperature environments, excessive softening can lead to a decrease in structural strength, diminished frictional performance, and even failures such as delamination or fracture. To address this challenge, it's crucial to focus on the core aspects of formulation design. By optimizing key components such as the rubber matrix, vulcanization system, filler composition, and functional additives, a high-temperature-resistant molecular network structure can be constructed, thereby enhancing the stability of the prefabricated rubber track membrane under extreme operating conditions.
The selection of the rubber matrix is fundamental to improving the heat resistance of prefabricated rubber track membranes. While traditional nitrile rubber offers excellent oil resistance, the double bonds in its molecular chain are susceptible to oxidation and cleavage at high temperatures, resulting in performance degradation. Hydrogenated nitrile rubber can be used as an alternative, reducing the double bond content through hydrogenation and significantly improving thermal stability. Alternatively, fluororubber can be used, as its backbone C-F bond energy is extremely high, allowing it to withstand temperatures exceeding 250°C for extended periods without softening. If cost and performance are to be balanced, a blend of silicone rubber and nitrile rubber can be used. The wide temperature range of silicone rubber can offset the heat resistance shortcomings of nitrile rubber, creating a composite matrix with complementary advantages.
Optimizing the vulcanization system is crucial to the high-temperature performance of prefabricated rubber track membranes. The polysulfide bonds formed by traditional sulfur vulcanization systems are prone to rearrangement or cleavage at high temperatures, resulting in a decrease in crosslink density. Alternatively, a peroxide vulcanization system, such as DCP, can be used. Its crosslinks are C-C single bonds, which have high bond energy and excellent thermal stability, effectively resisting high-temperature softening. Furthermore, by employing an effective vulcanization system and controlling the type and amount of accelerators to reduce polysulfide bond formation and increase the proportion of single sulfur bonds, the heat resistance of the vulcanized rubber can be further improved. For example, adding a small amount of thiuram accelerator to the formulation can promote the formation of single sulfur bonds, significantly enhancing the deformation resistance of the prefabricated rubber track membrane at high temperatures.
Improving the filler combination is a key approach to improving the heat resistance of prefabricated rubber track membranes. While traditional carbon black can enhance rubber strength, it is susceptible to thermal oxidation reactions with the rubber matrix at high temperatures, leading to performance degradation. It can be replaced with inorganic fillers such as silica or alumina. Silica contains numerous hydroxyl groups on its surface, which can form hydrogen bonds with rubber molecules, enhancing interfacial adhesion and offering superior thermal stability compared to carbon black. Alumina, with its high melting point and high thermal conductivity, effectively disperses high-temperature stresses and prevents localized overheating. Furthermore, adding a small amount of carbon nanotubes can form a three-dimensional thermally conductive network, increasing the thermal diffusivity of the prefabricated rubber track membrane and preventing softening caused by heat accumulation.
The introduction of functional additives can significantly slow the high-temperature aging process of prefabricated rubber track membranes. Traditional antioxidants, such as RD, tend to volatilize and become ineffective at 120°C and should be replaced with more heat-resistant varieties, such as hindered amine light stabilizer 944. Its molecular structure contains multiple nitroxide radicals, which can continuously capture free radicals generated at high temperatures and inhibit oxidative chain reactions. Furthermore, adding a small amount of phenolic antioxidants, such as BHT, can create a synergistic effect with antioxidants, extending the rubber's heat aging life several times. For prefabricated rubber track membranes exposed to high temperatures for extended periods, metal oxides such as zinc oxide can be added as heat stabilizers to absorb the acidic substances produced by decomposition and prevent catalytic degradation of the rubber.
Optimizing the plasticizing system requires balancing the flexibility and heat resistance of the prefabricated rubber track membrane. Traditional plasticizers, such as DOP, have low molecular weight and are prone to volatilization and exudation at high temperatures, causing the rubber to become hard and brittle. These can be replaced with high-flash-point petroleum oils or polyurethane plasticizers, which have high molecular weights and high softening points and are stable at 200°C. Furthermore, reactive plasticizers, such as coumarone resin, can polymerize with rubber molecules during the vulcanization process, forming chemical bonds. This fundamentally addresses the issue of plasticizer migration and ensures that the prefabricated rubber track membrane maintains its long-term flexibility at high temperatures.
By systematically optimizing the rubber matrix, vulcanization system, filler composition, functional additives, and plasticizer system, the softening resistance of prefabricated rubber track membranes in high-temperature environments can be significantly enhanced. This formulation improvement strategy is not only applicable to high-temperature operating environments such as construction machinery and agricultural machinery, but also provides a theoretical reference for the development of other heat-resistant rubber products, driving the rubber industry towards higher performance and functionalization.
