Introduction to Room Temperature Vulcanized Silicon Rubber

Room Temperature Vulcanized Silicon Rubber (RTV) is widely used in industries such as electronics, light industry, machinery, construction, and chemical engineering. This article briefly introduces the research background and theoretical basis of RTV.

Background of Room Temperature Vulcanized Silicon Rubber

Silicon rubber is one of the most important organosilicon products. The raw materials for preparing silicon rubber usually consist of linear polysiloxane (raw rubber), reinforcing fillers, crosslinking agents, catalysts, modifying additives, etc. All the raw materials can be processed into mixed rubber through compounding (or mixing). The mixed rubber can be transformed from a highly viscous plastic state to an elastic state by vulcanization (also known as hardening, curing, or crosslinking) under certain conditions - vulcanized rubber. Silicon rubber raw rubber is a linear semi-inorganic polymer composed of Si-O alternate main chains and organic side chains. After vulcanization, silicon rubber has advantages such as high and low-temperature resistance, UV resistance, radiation resistance, weather resistance, electrical insulation, physiological inertness, etc. Therefore, silicon rubber has been widely used in aviation, aerospace, electronics, light industry, machinery, construction, chemical engineering, medicine, daily necessities, etc.

Theoretical Knowledge of Room Temperature Vulcanized Silicon Rubber

According to the different vulcanization methods and vulcanization temperatures, silicon rubber can be divided into two categories: high-temperature vulcanizing (HTV) silicon rubber and room-temperature vulcanizing (RTV) Silicon rubber. Room temperature vulcanizing silicon rubber (RTV silicone rubber) refers to a type of silicon rubber that can undergo curing crosslinking reaction at room temperature. According to the storage packaging form, it can be divided into one-component room temperature vulcanizing silicon rubber (referred to as one-component RTV rubber) and two-component room temperature vulcanizing silicon rubber (referred to as two-component RTV rubber); according to the crosslinking reaction mechanism, it can be divided into addition type and condensation type. Usually, one-component RTV rubber is a condensation type, and two-component RTV rubber has both condensation and addition types. Currently, condensation-type RTV rubber is the main type, and one-component RTV rubber dominates in the condensation-type RTV rubber.

One-component RTV rubber is based on hydroxyl-terminated poly-dialkyl siloxane with low molar mass (molecular weight usually ranges from 10,000 to 100,000) as the base rubber and is combined with fillers (silica, calcium carbonate, titanium dioxide, zinc oxide, quartz sand, etc.), crosslinking agents, catalysts, and other additives. Under anhydrous conditions, all the ingredients are uniformly mixed, packaged in a sealed container, and when used, it is taken out from the container and the condensation reaction occurs with the help of the moisture in the air, the low molecular weight components are removed, and a three-dimensional network structure is formed to crosslink into rubber elastic body. Currently, according to different crosslinking systems, one-component room temperature vulcanized silicone rubber is classified according to the types of low molecular weight substances removed by the crosslinking agent, such as carboxylic acid type, oxime type, alcohol type, acylamide type, amine type, acetone type, hydroxylamine type, etc.