Frequency dependence of the heat capacity of polystyrene in the glass transition region measured by multi-frequency light-modulated DSC

The reversing heat capacity of polystyrene has been measured in the glass transition region as a function of frequency by temperature-modulated DSC using infra-red light for the modulation. The mean temperature was controlled by the calorimeter operating in the standard DSC mode. The additional powe...

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Bibliographic Details
Published inThermochimica acta Vol. 396; no. 1; pp. 109 - 117
Main Authors Kamasa, P, Pyda, M, Buzin, A, Wunderlich, B
Format Journal Article Conference Proceeding
LanguageEnglish
Published Amsterdam Elsevier B.V 05.02.2003
Elsevier Science
Subjects
Applied sciences
DSC
Exact sciences and technology
Frequency-dependent heat capacity
Glass transition
LMDSC
Organic polymers
Physicochemistry of polymers
Polystyrene
Properties and characterization
Temperature modulation by infra-red light
Thermal and thermodynamic properties
TMDSC
LMDSC
Glass transition
DSC
TMDSC
Temperature modulation by infra-red light
Frequency-dependent heat capacity
Polystyrene
Differential scanning calorimetry
Frequency dependence
Heat capacity
Thermal properties
Styrene polymer
Thermal analysis
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Summary:The reversing heat capacity of polystyrene has been measured in the glass transition region as a function of frequency by temperature-modulated DSC using infra-red light for the modulation. The mean temperature was controlled by the calorimeter operating in the standard DSC mode. The additional power transferred to the specimens is obtained by infra-red diodes with their mean power controlled by a pulse-width modulation method. This method allows to synthesize sinusoidal temperature-profiles with negligible distortion with frequencies of up to 0.125 Hz. The experiments were carried out using multi-frequency temperature-profiles composed by superposition of four sinusoidal modulations of periods of 243, 81, 27, and 9 s, which cover the frequency range from the 1st to the 27th harmonic. To study the kinetics in the glass transition region, the thermal history was produced by cooling the samples at different rates. The results and the advantages of the new method are discussed and compared to a series of less-precise separate single-frequency analyses.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
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ISSN:0040-6031
1872-762X
DOI:10.1016/S0040-6031(02)00527-0