Kinetics of the II-III phase transformation of polytetrafluoroethylene at high pressure
Journal Article
·
· J. Polym. Sci., Polym. Phys. Ed.; (United States)
The rate of transformation from helical to all-trans-planar polytetrafluoroethylene (PTFE) at high pressures has been determined by monitoring the Raman spectra of PTFE following pressure jumps from the stability field of PTFE II to pressures between 9 and 14 kbar at temperatures between 0 and -30/sup 0/C. The transformation kinetics can be described by Avrami's equation for nucleation and growth kinetics with an exponent of 0.5, although observations at lower temperatures suggest that even smaller values of the exponent may be appropriate. At 10 kbar and 0/sup 0/C, the specific rate constant is 0.51 min/sup -1/2. The energy and volume of activation are 11 kcal mole/sup -1/ and-7 cm/sup 3/ mole/sup -1/ respectively. The values of these parameters suggest that the transformation mechanism involves propagation of helix reversal planes along the several adjacent chains leaving all-trans material in their wakes. 10 figures, 2 tables.
- Research Organization:
- Univ. of California, Los Angeles
- DOE Contract Number:
- E(04-3)-34
- OSTI ID:
- 5347347
- Journal Information:
- J. Polym. Sci., Polym. Phys. Ed.; (United States), Journal Name: J. Polym. Sci., Polym. Phys. Ed.; (United States) Vol. 18:5; ISSN JPLPA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360402* -- Polymers & Plastics-- Structure & Phase Studies-- (-1987)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACTIVATION ENERGY
ENERGY
FLUORINATED ALIPHATIC HYDROCARBONS
HALOGENATED ALIPHATIC HYDROCARBONS
KINETICS
LOW TEMPERATURE
MEDIUM TEMPERATURE
NUCLEATION
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC POLYMERS
PHASE TRANSFORMATIONS
POLYETHYLENES
POLYMERS
POLYOLEFINS
POLYTETRAFLUOROETHYLENE
RAMAN SPECTRA
SPECTRA
VERY HIGH PRESSURE
360402* -- Polymers & Plastics-- Structure & Phase Studies-- (-1987)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACTIVATION ENERGY
ENERGY
FLUORINATED ALIPHATIC HYDROCARBONS
HALOGENATED ALIPHATIC HYDROCARBONS
KINETICS
LOW TEMPERATURE
MEDIUM TEMPERATURE
NUCLEATION
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC POLYMERS
PHASE TRANSFORMATIONS
POLYETHYLENES
POLYMERS
POLYOLEFINS
POLYTETRAFLUOROETHYLENE
RAMAN SPECTRA
SPECTRA
VERY HIGH PRESSURE