Stirrer Shafts consist of a PTFE-jacketed stainless steel shaft and a stirrer blade made of solid PTFE. The stainless steel core provides high mechanical stability and allows safe fixing in the agitator. Due to the thick PTFE-jacket, the product which is stirred is only exposed to PTFE. This assures an almost universal chemical resistance. PTFE-jacketed stirrer shafts can be used whenever stirrer shafts made of PP (polypropylene), glass or stainless steel are not sufficient. All PTFE jacketed stirrer shafts can be used at temperatures of up to +250°C without any negative effects on their chemical resistance. The surfaces of glass and stainless steel stirrer shafts allow adhesion of products (in particular such as dyes and glues). PTFE Stirrer Shafts, however, are non-adhesive and therefore eliminate adhesion of dyes and glues.
The stirrer blade is fixed tightly to the stirrer shaft and cannot be loosened by the product which is still turning after switching off the agitator. The stirrer shafts are suitable for clockwise and counter clockwise rotation.
PTFE was discovered in 1938 by research-chemists of Du Pont (USA), but was not introduced or marketed until 1946. It is a partly crystalline fluoroplastic and belongs to the thermoplastic group. The rare combination of its exceptional properties is essentially due to its molecular structure. The remarkable chemical and thermal resistance results from the linkage between carbon atoms and flourine atoms and from the nearly complete shielding of the carbon chain by fluorine atoms. PTFE has a thermal resistance of -260°C to +300°C (there is for example no brittleness of boiling helium at -269°C). This temperature range is reached by no other commercial plastic material.
But the permanent temperature resistance depends on the load. This means that PTFE can be used from -200°C to +260°C at moderate mechanical load. Labware made of PTFE has a white appearance, its surface is non-adhesive and has excellent slip characteristics.
