PTFE vs PCTFE
The difference between PTFE and PCTFE is mainly in the chemical structure. The addition of one Chlorine atom in place of one Fluorine atom leads to a massive change in its properties and application.
PTFE is a versatile and cost effective material of average tensile strength. It has very good thermal properties and excellent chemical inertness, especially to strong acids. The coefficient of friction is unusually low and believed to be lower than any other solids. PTFE is an outstanding electrical insulator over a wide range of temperatures and frequency.
At the molecular level, PTFE is a linear polymer with high molecular weight (Length of Polymer Chains) and Crystallinity level of 50-70% depending on the processing conditions.
Due to its high viscosity, PTFE cannot be processed using conventional polymer processing techniques. Hence, PTFE is processed by cold forming operation followed by heat treatment (sintering) during which polymer particles fuse to form a solid moulding.
PCTFE has a higher tensile strength than PTFE and good thermal characteristics. It is non-flammable and heat resistant up to 180°C. PCTFE is resistant to the attack of most chemicals and oxidizing agents, due to the presence of high fluorine content. However, it swells slightly in halogenated compounds, ethers, esters and aromatic solvents.
PCTFE has one of the highest limiting oxygen index. It has good chemical resistance and also exhibits properties like zero moisture absorption and non-wetting.
PCTFE has a low coefficient of thermal expansion and its dimensional stability makes it attractive for use as a component of a structural part where the high temperature and chemical resistance of fluoropolymers is required.
PCTFE is melt processable by conventional process techniques such as Injection moulding, Extrusion and Compression moulding.
PCTFE is a homopolymer of chlorotrifluoroethylene (CTFE), whereas PTFE is a homopolymer of tetrafluoroethylene. PCTFE is a harder and stronger polymer, with better mechanical properties than PTFE. Though PCTFE has excellent chemical resistance, it is still less than that of PTFE. PCTFE has lower viscosity, higher tensile strength and creep resistance than PTFE.