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4 results on '"A.A. Correa"'

3. Kinetics of crystallization in conducting polymers observed from electron spin resonance

Author

Ernesto C. Pereira, L. Walmsley, A.A. Correa, Agnieszka Pawlicka, Otaciro R. Nascimento, and L. O. S. Bulhões

Subjects
chemistry.chemical_classification, Materials science, Absorption spectroscopy, Doping, Analytical chemistry, General Physics and Astronomy, Polymer, Spectral line, Amorphous solid, law.invention, Differential scanning calorimetry, chemistry, law, Physical and Theoretical Chemistry, Crystallization, Electron paramagnetic resonance
Abstract

Electron spin resonance (ESR) spectra of pressed pellets of ClO4− doped poly(3-methylthiophene) (P3MT) were recorded as a function of time for samples quenched to 110 K and rapidly heated to 223 K. For a thin sample, fitting the ESR spectra with two Lorentzian absorption lines we were able to follow the decrease of the narrow line associated with the amorphous fraction of the polymer and the increase of the broad line, corresponding to the crystalline fraction. The crystallization process is discussed in terms of Avrami’s equation and confirmed from differential scanning calorimetry (DSC) data.

Published
1998
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4. Crystallization observed from the spin behavior in poly(3-methylthiophene)

Author

Agnieszka Pawlicka, W.A. Ortiz, A.A.J. Oliveira, L. Walmsley, Luis O.S. Bulhões, A.A. Correa, Otaciro R. Nascimento, and Ernesto C. Pereira

Subjects
chemistry.chemical_classification, Materials science, Mechanical Engineering, Doping, Metals and Alloys, Analytical chemistry, Polymer, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Amorphous solid, law.invention, SQUID, chemistry, Mechanics of Materials, law, Materials Chemistry, Crystallization, skin and connective tissue diseases, Spin (physics), Electron paramagnetic resonance, Line (formation)
Abstract

Electron Spin Resonance (ESR) data in pressed pellets of doped poly(3-methylthiophene) (P3MT) show a single ESR line that changes into a broad and a narrow superimposed lines below 225K. D.C. susceptibility measurements using a SQUID susceptometer didn't reveal any special feature at this temperature. Assuming crystallization of the polymer, we attribute the broad line to the crystalline fraction of the polymer and the narrow line to the amorphous one.

Published
1999
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