Glass transition temperature measured at high frequencies by piezoelectric excitation

As the temperature of a polymer melt or rubber is lowered, a point known as the glass transition temperature, Tg, is reached where polymeric materials undergo a marked change in properties associated with the virtual cessation of local molecular motion. In fact, as the thermal energy reduces, the di...

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Autores principales:	Povolo, Francisco, Jorge, Guillermo Antonio, Hermida, Elida Beatriz
Publicado:	2000
Materias:	Glass transition Piezoelectricity Ultrasonics Viscoelasticity Piezoelectric excitation Polymers
Acceso en línea:	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09258388_v310_n1-2_p388_Povolo http://hdl.handle.net/20.500.12110/paper_09258388_v310_n1-2_p388_Povolo
Aporte de:	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires

id	paper:paper_09258388_v310_n1-2_p388_Povolo
record_format	dspace
spelling	paper:paper_09258388_v310_n1-2_p388_Povolo2023-06-08T15:51:25Z Glass transition temperature measured at high frequencies by piezoelectric excitation Povolo, Francisco Jorge, Guillermo Antonio Hermida, Elida Beatriz Glass transition Piezoelectricity Ultrasonics Viscoelasticity Piezoelectric excitation Polymers As the temperature of a polymer melt or rubber is lowered, a point known as the glass transition temperature, Tg, is reached where polymeric materials undergo a marked change in properties associated with the virtual cessation of local molecular motion. In fact, as the thermal energy reduces, the distance between macromolecules, and consequently the specific volume of the sample, diminishes. However, this change is not abrupt, that is, the glass transition is not a rigorous phase transition from the thermodynamical point of view. Effectively, it depends not only on the polymeric structure but also on the heating rate, the measuring method, etc. Since there is a copious literature referring to traditional methods employed to measure Tg, this work will only present them as a frame to compare them with the experimental procedure we used. The determination of Tg is based on the change of the real component of the dynamic modulus with temperature. This modulus is measured at high frequencies on exciting the sample with a piezoelectric crystal attached to it. Glass transition temperatures of several glassy polymers are determined. These results are compared with values measured through other methods. Finally, the advantages of our procedure are discussed. Fil:Povolo, F. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Jorge, G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Hermida, E.B. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2000 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09258388_v310_n1-2_p388_Povolo http://hdl.handle.net/20.500.12110/paper_09258388_v310_n1-2_p388_Povolo
institution	Universidad de Buenos Aires
institution_str	I-28
repository_str	R-134
collection	Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic	Glass transition Piezoelectricity Ultrasonics Viscoelasticity Piezoelectric excitation Polymers
spellingShingle	Glass transition Piezoelectricity Ultrasonics Viscoelasticity Piezoelectric excitation Polymers Povolo, Francisco Jorge, Guillermo Antonio Hermida, Elida Beatriz Glass transition temperature measured at high frequencies by piezoelectric excitation
topic_facet	Glass transition Piezoelectricity Ultrasonics Viscoelasticity Piezoelectric excitation Polymers
description	As the temperature of a polymer melt or rubber is lowered, a point known as the glass transition temperature, Tg, is reached where polymeric materials undergo a marked change in properties associated with the virtual cessation of local molecular motion. In fact, as the thermal energy reduces, the distance between macromolecules, and consequently the specific volume of the sample, diminishes. However, this change is not abrupt, that is, the glass transition is not a rigorous phase transition from the thermodynamical point of view. Effectively, it depends not only on the polymeric structure but also on the heating rate, the measuring method, etc. Since there is a copious literature referring to traditional methods employed to measure Tg, this work will only present them as a frame to compare them with the experimental procedure we used. The determination of Tg is based on the change of the real component of the dynamic modulus with temperature. This modulus is measured at high frequencies on exciting the sample with a piezoelectric crystal attached to it. Glass transition temperatures of several glassy polymers are determined. These results are compared with values measured through other methods. Finally, the advantages of our procedure are discussed.
author	Povolo, Francisco Jorge, Guillermo Antonio Hermida, Elida Beatriz
author_facet	Povolo, Francisco Jorge, Guillermo Antonio Hermida, Elida Beatriz
author_sort	Povolo, Francisco
title	Glass transition temperature measured at high frequencies by piezoelectric excitation
title_short	Glass transition temperature measured at high frequencies by piezoelectric excitation
title_full	Glass transition temperature measured at high frequencies by piezoelectric excitation
title_fullStr	Glass transition temperature measured at high frequencies by piezoelectric excitation
title_full_unstemmed	Glass transition temperature measured at high frequencies by piezoelectric excitation
title_sort	glass transition temperature measured at high frequencies by piezoelectric excitation
publishDate	2000
url	https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_09258388_v310_n1-2_p388_Povolo http://hdl.handle.net/20.500.12110/paper_09258388_v310_n1-2_p388_Povolo
work_keys_str_mv	AT povolofrancisco glasstransitiontemperaturemeasuredathighfrequenciesbypiezoelectricexcitation AT jorgeguillermoantonio glasstransitiontemperaturemeasuredathighfrequenciesbypiezoelectricexcitation AT hermidaelidabeatriz glasstransitiontemperaturemeasuredathighfrequenciesbypiezoelectricexcitation
_version_	1768546075541504000

Glass transition temperature measured at high frequencies by piezoelectric excitation

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