Piezoelectric copolymers of vinylidene fluoride and trifluoroethylene
US4946913A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 1, 1988 |
| Grant date | Aug 7, 1990 |
| Priority date | — |
| Expiry date | Dec 1, 2008 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08F259/08
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A copolymer of vinylidene fluoride and trifluoroethylene having piezoelectric properties useful at elevated temperatures. The total molar content of trifluoroethylene is less than 30% characterized in that it has a heterogeneous structure with a distribution of accumulated molar composition comprised between two straight lines: PA0 Y=-3.18 X +140 and PA0 Y=-3.12 X +109 X is the molar percentage of trifluoroethylene in the macromolecular chains and Y is the percentage by weight of the total of macromolecular chains in which the content of trifluoroethylene is above or equal to X. This copolymer is obtained by copolymerization in an aqueous suspension by a two step process wherein, in a first step, a mixture of vinylidene fluoride and trifluoroethylene in molar proportions of vinylidene fluoride between about 67 and 54% per 33 to 46% trifluoroethylene and in a second step by progressive addition to the polymerization mixture of vinylidene fluoride in proportions such that the molar quantity of vinylidene fluoride added represents from 145 to 180% of the initial moles of vinylidene fluoride.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.