At present, in the pharmaceutical production, silicone hoses are more commonly used for liquid transport, peristaltic pumps and irrigation operations. This article will discuss the advantages and limitations of silicone hoses and the variables that need to be considered by comparing the properties of various hose materials.
Silicones are the commercial name for many products, but most are made from polydimethylsiloxane (PDMS). These polymers are characterized by high covalent bond strength, resistance to cleavage and breakage (silicone has UV (UV) stability; it is also thermally and chemically stable, so it is easy to sterilize). Its polar backbone is prone to heterogeneous chain scission, but the methyl group on the chain provides protection.
Therefore, the silicone has hydrophobicity and the contact angle of water on the surface of the polydimethylsiloxane (PDMS) model is relatively high at 108°. Due to this hydrophobicity, in the absence of a surfactant, the silicone does not react with the aqueous medium and only reacts in a strong base or strong acid environment.
The hose is supplied in an extruded package, typically a 50-foot coil, housed separately in a double-sealed polyethylene bag. It is worth mentioning that because silicones are thermoset, they cannot be reprocessed like thermoplastics. For the same reason, they are not heat sealed; therefore, when connecting, the silicone tube is placed over the hose barbed fitting and secured with the two straps in the opposite direction to secure the hose. Common mold compression is feasible and is sometimes used in the field of medical devices.
Appearance and mechanical properties
The transparency of silicones is best described as "translucent" compared to some organic thermoplastics. This result is because the silicone elastomer from which the hose is made consists of a silicone polymer and amorphous silica. Since the two materials have different refractive indices and there is no specific mixing method to match them, all silicone tubes are translucent.
After curing, the silicone elastomer exhibits significant mechanical properties, including moderate hardness and high elongation at break, but lower tensile strength than polyurethane (PU). They have a tacky surface and a higher coefficient of friction than polytetrafluoroethylene (PTFE), but are much less rigid. They are attracted to dust due to their hydrophobic nature and excellent electrical insulation. They have a wider operating temperature range than polyvinyl chloride (PVC).