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Master's Dissertation
DOI
Document
Author
Full name
Manoel Gregorio de Miranda Filho
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1999
Supervisor
Committee
Giacometti, José Alberto (President)
Eiras, José Antonio
Malmonge, José Antonio
Title in Portuguese
Determinação do coeficiente piroelétrico de polímeros utilizando a técnica de temperatura oscilante no tempo
Keywords in Portuguese
Ferroeletricidade
Piroeletricidade
Polarização elétrica
Abstract in Portuguese
O objetivo deste trabalho foi implementar um sistema para a determinação do coeficiente piroelétrico em materiais poliméricos. O método consiste em variar a temperatura da amostra de forma senoidal e medir a corrente em função do tempo. Através do sinal da corrente elétrica e da sua diferença de fase com a temperatura, separa-se a corrente elétrica de origem piroelétrica, a partir da qual se determina o coeficiente piroelétrico. Apresenta-se a caracterização do sistema abrangendo aspectos como o intervalo de temperatura das medidas e amplitude e freqüência da oscilação da temperatura. O método foi empregado para realizar medidas exploratórias com o polímero ferroelétrico poli(fluoreto de vinilideno), PVDF, polarizado pela aplicação de uma rampa de tensão, e com o polímero poli(metacrilato de metila), PMMA, com corante polar, polarizado com o triodo de corona. Nas medidas foram variados os parâmetros do processo de polarização elétrica tais como o campo elétrico máximo e a temperatura
Title in English
Pyroelectric coefficient determination of polymers using sinusoidal temperature variation technique
Keywords in English
Electric polarization
Ferroelectricity
Pyroelectricity
Abstract in English
An experimental setup to measure the pyroelectric coefficient of polymers was implemented. The method is based on the measurement of the electric current generated by the sample when its temperature was set to oscillate sinusoidally. Using the measured current and its phase difference related with the temperature thepyroelectric current was obtained, from that the pyroelectric coefficient was determined. It is shown the characterization of the experimental system such as the temperature amplitude and frequency interval of operation. The method was applied in exploratory measurements employing the ferroelectric polymer poly(vynilidene fIuoride), PVDF, poled by a ramp voltage, and the poly(methyl metacrylate), PMMA, having a polar dye, poled with the carona triode. Measurements were performed far different poling conditions such as the maximum applied field and temperature
 
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Publishing Date
2014-12-08
 
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