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Experimental study of piezoelectric and dielectric responses in Poly-L-lactic acid / Siti Hannah Mat Zin

The piezoelectric d- and e-constants, as well as the elastic constant, c, and the dielectric constant, ε were determined as a function of frequency and temperature for oriented poly-L-lactic acid (PLLA) films with various elongation ratios and annealing temperatures using the dielectric resonance me...

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Main Author: Siti Hannah , Mat Zin
Format: Thesis
Published: 2022
Subjects:
Q Science (General)
QC Physics
Online Access:http://studentsrepo.um.edu.my/14706/1/Siti_Hannah.pdf
http://studentsrepo.um.edu.my/14706/2/Siti_Hannah.pdf
http://studentsrepo.um.edu.my/14706/
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spelling my.um.stud.147062023-08-23T23:08:35Z Experimental study of piezoelectric and dielectric responses in Poly-L-lactic acid / Siti Hannah Mat Zin Siti Hannah , Mat Zin Q Science (General) QC Physics The piezoelectric d- and e-constants, as well as the elastic constant, c, and the dielectric constant, ε were determined as a function of frequency and temperature for oriented poly-L-lactic acid (PLLA) films with various elongation ratios and annealing temperatures using the dielectric resonance method. The findings are discussed in terms of a general theory of piezoelectricity for inhomogeneous systems, more specifically a disperse two-phase system. Five observations demonstrate that the piezoelectricity of PLLA film originates from the piezoelectric and optically active symmetry of PLLA crystallites and their orientation distribution. d14 component of the piezoelectric matrix is observed. The e14 is proportional to the product of orientation factor, Fc and crystallization fraction, Xc (Fc*Xc) of PLLA crystallites as determined by x-ray diffraction. The piezoelectric constants for a perfect crystal of PLLA was determined as e14 ~27 mC/m2 from the three-spring model and extrapolation to perfect orientation using the correlation of Fc*Xc assuming the PLLA crystallites are rigid. At ~100°C, the piezoelectric relaxation of PLLA is due to segmental mode relaxation in the amorphous phase within the crystalline region. A significant decrease in e14 with increasing temperature is caused by the non-crystalline phase softening, which results in a decrease in strain in the crystalline phase. The retardation of d14 is due to softening in the non-crystalline region caused by a parallel crystalline phase's stress concentration. An equivalent model is proposed that incorporates the PLLA film's higher order structure. 2022-05 Thesis NonPeerReviewed application/pdf http://studentsrepo.um.edu.my/14706/1/Siti_Hannah.pdf application/pdf http://studentsrepo.um.edu.my/14706/2/Siti_Hannah.pdf Siti Hannah , Mat Zin (2022) Experimental study of piezoelectric and dielectric responses in Poly-L-lactic acid / Siti Hannah Mat Zin. Masters thesis, Universiti Malaya. http://studentsrepo.um.edu.my/14706/
institution Universiti Malaya
building UM Library
collection Institutional Repository
continent Asia
country Malaysia
content_provider Universiti Malaya
content_source UM Student Repository
url_provider http://studentsrepo.um.edu.my/
topic Q Science (General)
QC Physics
spellingShingle Q Science (General)
QC Physics
Siti Hannah , Mat Zin
Experimental study of piezoelectric and dielectric responses in Poly-L-lactic acid / Siti Hannah Mat Zin
description The piezoelectric d- and e-constants, as well as the elastic constant, c, and the dielectric constant, ε were determined as a function of frequency and temperature for oriented poly-L-lactic acid (PLLA) films with various elongation ratios and annealing temperatures using the dielectric resonance method. The findings are discussed in terms of a general theory of piezoelectricity for inhomogeneous systems, more specifically a disperse two-phase system. Five observations demonstrate that the piezoelectricity of PLLA film originates from the piezoelectric and optically active symmetry of PLLA crystallites and their orientation distribution. d14 component of the piezoelectric matrix is observed. The e14 is proportional to the product of orientation factor, Fc and crystallization fraction, Xc (Fc*Xc) of PLLA crystallites as determined by x-ray diffraction. The piezoelectric constants for a perfect crystal of PLLA was determined as e14 ~27 mC/m2 from the three-spring model and extrapolation to perfect orientation using the correlation of Fc*Xc assuming the PLLA crystallites are rigid. At ~100°C, the piezoelectric relaxation of PLLA is due to segmental mode relaxation in the amorphous phase within the crystalline region. A significant decrease in e14 with increasing temperature is caused by the non-crystalline phase softening, which results in a decrease in strain in the crystalline phase. The retardation of d14 is due to softening in the non-crystalline region caused by a parallel crystalline phase's stress concentration. An equivalent model is proposed that incorporates the PLLA film's higher order structure.
format Thesis
author Siti Hannah , Mat Zin
author_facet Siti Hannah , Mat Zin
author_sort Siti Hannah , Mat Zin
title Experimental study of piezoelectric and dielectric responses in Poly-L-lactic acid / Siti Hannah Mat Zin
title_short Experimental study of piezoelectric and dielectric responses in Poly-L-lactic acid / Siti Hannah Mat Zin
title_full Experimental study of piezoelectric and dielectric responses in Poly-L-lactic acid / Siti Hannah Mat Zin
title_fullStr Experimental study of piezoelectric and dielectric responses in Poly-L-lactic acid / Siti Hannah Mat Zin
title_full_unstemmed Experimental study of piezoelectric and dielectric responses in Poly-L-lactic acid / Siti Hannah Mat Zin
title_sort experimental study of piezoelectric and dielectric responses in poly-l-lactic acid / siti hannah mat zin
publishDate 2022
url http://studentsrepo.um.edu.my/14706/1/Siti_Hannah.pdf
http://studentsrepo.um.edu.my/14706/2/Siti_Hannah.pdf
http://studentsrepo.um.edu.my/14706/
_version_ 1781704985065553920
score 13.211869

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