Presentation on theme: "Polytetrafluorethylene (PTFE) Chandra Heller Michael Mallicote."— Presentation transcript:
Polytetrafluorethylene (PTFE) Chandra Heller Michael Mallicote
Discovery Accidentally discovered on April 6, 1938 by Roy Plunkett.
Uses By 1941, PTFE had been patented and had its first brand name Teflon®. By 1946, the resin product was being used to produce machine parts for military and industrial applications. In the 1960s it began its life in the arena of nonstick cookware.
Uses (continued) Today it has expanded into a whole family of polymers (resins, films, coatings, moldable forms, powders) and sold under various brand names, including Gore-Tex® and Zylon®. It is used in a wide range of industries from aerospace to pharmaceuticals and is sold in over 40 countries worldwide.
Emulsion Polymerization Initiation: Free radical formation ROOR + Heat → 2 RO Initiation: Formation of new free radicals by peroxide + TFE in aqueous phase RO + CF 2 =CF 2 → RO(CF 2 –CF 2 ) Propagation: Growth of free radicals by further addition of TFE RO(CF 2 –CF 2 ) + n CF 2 =CF 2 → RO(CF 2 –CF 2 )–(CF 2 –CF 2 ) Free radicals undergo hydrolysis where a hydroxyl group replaces the peroxide RO(CF 2 –CF 2 )–(CF 2 –CF 2 ) + H 2 O → HO(CF 2 –CF 2 ) n –(CF 2 –CF 2 ) + H + + HOR HO(CF 2 =CF 2 ) n –(CF 2 =CF 2 ) + H 2 O → COOHCF 2 –(CF 2 –CF 2 ) n + 2HF Termination: COOH– CF 2 –(CF 2 – CF 2 ) n + COOH– CF 2 –(CF 2 – CF 2 ) m → COOH– CF 2 –(CF 2 – CF 2 ) m+n COOH
Toxicity The monomer TFE is a confirmed animal carcinogen with unknown relevance to humans. The finished polymer in solid form is inert under ordinary conditions. There is some indication that the powdered forms of PTFE may be carcinogenic if inhaled.
Recycling of PTFE It is easy to recycle since no chemical reaction is necessary. Only the extruded forms are recycled (not the resin or powerdered forms). The uses of recycled PTFE are restricted. It is typically ground up into fine powders and used as additives in such products as inks, paints, and cosmetics.