Annealing Effects on Phase 1 Poly(vinylidene Fluoride)
Technical rept. Apr-Dec 1988
RUTGERS - THE STATE UNIV NEW BRUNSWICK NJ DEPT OF MECHANICS AND MATERIALS SCIENCE
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The effects of annealing temperatures on stretched poly vinylidene fluoride films were systematically studied from the as received condition up to the melting range 180 C. X ray diffraction studies indicate that the annealing process brings about better chain packing and increased crystallite perfection. The elastic modulus and piezoelectric strain and stress constants, d31, decrease as the annealing temperature, Ta, increases up to 160 C, while the remnant polarization, Pr, remains almost constant. Some of these characteristics may be interpreted in terms of a morphological transformation of microfibrils. The values of Pr, d31 and e31 increase dramatically as Ta increases form 160 to 180 C Pr goes from 56 to 85 mCsq. m,d31 from 20.2 to 27.7 pcn and e31 from 51.4 to 65.2 mCsq.m. As a result, Pr and d31 recorded the largest values obtained from any of the samples used in the present study. E31 showed a value close to the largest one this usually occurs in unannealed samples. Samples annealed in the melting range also exhibit significantly improved aging characteristics. The large value of Pr and the small relaxation strength of both the dielectric constant and elastic modulus indicates that the largest crystallinity obtained is approximately 70.
- Organic Chemistry
- Polymer Chemistry