Information AboutKynar |
| CATEGORIES ABOUT POLYVINYLIDENE FLUORIDE | |
| fluoropolymers | |
| piezoelectric materials | |
| plastics | |
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PolyVinylidine DiFluoride, or '''PVDF''' is a highly non-reactive and pure Thermoplastic Fluoropolymer . It is also known as '''KYNAR'''®. PVDF is very expensive; its use generally reserved for applications requiring the highest purity, strength, and resistance to solvents, acids, bases and heat. It is available as piping products, sheet, plate and an insulator for Premium Wire . It can be injection molded and welded and is commonly used in the chemical, semiconductor, medical and defense industries. When poled, PVDF is a Ferroelectric polymer, exhibiting efficient Piezoelectric and Pyroelectric properties. These characteristics make it useful in Sensor and Battery applications. PVDF has a glass transition temperature (Tg) of about -35oC and is typically 50-60% crystalline. To give the material its piezoelectric properties, it is mechanically stretched to orient the molecular chains and then poled under tension. PVDF exists several forms: alpha (TGTG'), beta (TTTT), and gamma (TTTGTTTG') phases, depending on the chain conformations as trans (T) or gauche (G) linkages. COPOLYMERS Copolymers of PVDF are also used in piezoelectric and electrostrictive applications. One of the most commonly-used copolymers is P(VDF-TrFE), usually available in ratios of about 50-50 wt% and 65-35 wt% (equivalent to about 56-44 mol% and 70-30 mol%). HISTORY In 1969, the strong piezoelectricity of PVDF was observed by Kawai et al. The piezoelectric coefficient of poled thin films of the material were reported to be as large as 6-7 pCN-1, 10 times larger than that observed in any other polymer. SEE ALSO References: # Kawai, H., (1969). ''Jpn. J. Appl. Phys'', 8, p975. # Zhang, Q. M., Bharti, V., Kavarnos, G., Schwartz, M. (Ed.), (2002). "Poly(Vinylidene Fluoride) (PVDF) and its Copolymers", ''Encyclopedia of Smart Materials, Volumes 1-2'', John Wiley & Sons, 807-825. # Vinogradov, A., Schwartz, M. (Ed.), (2002). "Piezoelectricity in Polymers", ''Encyclopedia of Smart Materials, Volumes 1-2'', John Wiley & Sons, 780-792. # Tasaka, S., Miyata, S., (1981). ''Ferroelectrics'', 32 (1), 17-23. EXTERNAL LINKS |
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