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The thermosonimetry of polymers Soulsbury, Kevin Andrew
Abstract
Thermosonimetry is the measurement of sound (acoustic emission) emitted from a substance as a function of temperature, while the substance is heated in a controlled manner. In this work the thermo-oxidative decompositions of poly(vinyl chloride), polyethylene, polypropylene, poly(ethylene terephthalate) and ethylene-vinyl acetate have been studied using thermosonimetry. The amount of acoustic emission produced was dependent on the polymer, the heating rate and the sample mass but not the molecular mass of the polymer. Thermosonimetry was also used to obtain apparent activation energies and the reaction orders for the thermo-oxidative decomposition processes under a variety of experimental conditions. Typically, the activation energies obtained were higher than values reported in the literature obtained using thermal analysis methods such as thermogravimetry. An apparatus has been developed that permits simultaneous thermogravimetric analysis (TG) and thermosonimetry (TS). The acoustic emission commenced at the maximum rate of mass loss, and confirmed that thermosonimetry was not suitable for measuring the relative thermal stability of polymers. Extensive chemical analysis of the polymer residues was used to study the decomposition mechanisms but did not reveal any direct link between the chemical structure of the polymers and the acoustic emission. Microscopic analysis of the residues, using scanning electron microscopy, suggested that the physical nature of the residues and the physical processes occurring during thermo-oxidative decomposition determined whether acoustic emission was produced. For PVC and PET, gas evolution and fracture processes were linked to the production of acoustic emission. For PE and PP, which did not produce significant amounts of acoustic emission, these processes were not observed to the same degree. Further studies sought to investigate whether acoustic emission was produced during other polymer processes. Polymerization and phase transitions did not produce acoustic emission. The crystallization of isotactic polypropylene was found to produce acoustic emission. The acoustic emission had been linked to the formation of cavities between the polymer spherulites. Thermosonimetry was also used to measure the rates of crystallization from the isothermal crystallization of polypropylene.
Item Metadata
Title |
The thermosonimetry of polymers
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1994
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Description |
Thermosonimetry is the measurement of sound (acoustic emission) emitted from
a substance as a function of temperature, while the substance is heated in a controlled
manner. In this work the thermo-oxidative decompositions of poly(vinyl chloride),
polyethylene, polypropylene, poly(ethylene terephthalate) and ethylene-vinyl acetate
have been studied using thermosonimetry. The amount of acoustic emission produced
was dependent on the polymer, the heating rate and the sample mass but not the
molecular mass of the polymer. Thermosonimetry was also used to obtain apparent
activation energies and the reaction orders for the thermo-oxidative decomposition
processes under a variety of experimental conditions. Typically, the activation energies
obtained were higher than values reported in the literature obtained using thermal
analysis methods such as thermogravimetry.
An apparatus has been developed that permits simultaneous thermogravimetric
analysis (TG) and thermosonimetry (TS). The acoustic emission commenced at the
maximum rate of mass loss, and confirmed that thermosonimetry was not suitable for
measuring the relative thermal stability of polymers. Extensive chemical analysis of the
polymer residues was used to study the decomposition mechanisms but did not reveal
any direct link between the chemical structure of the polymers and the acoustic
emission. Microscopic analysis of the residues, using scanning electron microscopy,
suggested that the physical nature of the residues and the physical processes
occurring during thermo-oxidative decomposition determined whether acoustic
emission was produced. For PVC and PET, gas evolution and fracture processes were
linked to the production of acoustic emission. For PE and PP, which did not produce
significant amounts of acoustic emission, these processes were not observed to the
same degree.
Further studies sought to investigate whether acoustic emission was produced
during other polymer processes. Polymerization and phase transitions did not produce
acoustic emission. The crystallization of isotactic polypropylene was found to produce
acoustic emission. The acoustic emission had been linked to the formation of cavities
between the polymer spherulites. Thermosonimetry was also used to measure the
rates of crystallization from the isothermal crystallization of polypropylene.
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Extent |
6088084 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-04-14
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0061696
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.