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Title: Heat Capacity Study of Solution Grown Crystals of Isotactic Polystyrene

Abstract

We have performed measurements of the specific heat capacity on isotactic polystyrene (iPS) crystals grown from dilute solution. Solution grown crystal (SGC) samples had larger crystal fractions and greatly reduced rigid amorphous fractions compared to their bulk cold-crystallized counterparts. Heat capacity studies were performed from below the glass transition temperature to above the melting temperature by using quasi-isothermal temperature modulated differential scanning calorimetry (TMDSC) and standard DSC. Two or three endotherms are observed, which represent the melting of crystals. The small rigid amorphous fraction relaxes in a wide temperature range from just above the glass transition temperature to just below the first crystal melting endotherm. As in bulk iPS, 1 multiple reversing melting was found in iPS SGCs, supporting the view that double melting in iPS may be due to dual thermal stability distribution existing along one single lamella.2 The impact of reorganization and annealing on the melt endotherms was also investigated. Annealing occurs as a result of the very slow effective heating rate of the quasi-isothermal measurements compared to standard DSC. The improvement of crystal perfection through annealing causes the reversing melting endotherms to occur at a temperature higher than the endotherms seen in the standard DSC scan.

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
913905
Report Number(s):
BNL-78473-2007-JA
TRN: US200804%%117
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 38
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; POLYSTYRENE; SPECIFIC HEAT; CRYSTAL STRUCTURE; MELTING; national synchrotron light source

Citation Formats

Xu, H, and Cebe, P. Heat Capacity Study of Solution Grown Crystals of Isotactic Polystyrene. United States: N. p., 2005. Web. doi:10.1021/ma048042l.
Xu, H, & Cebe, P. Heat Capacity Study of Solution Grown Crystals of Isotactic Polystyrene. United States. https://doi.org/10.1021/ma048042l
Xu, H, and Cebe, P. 2005. "Heat Capacity Study of Solution Grown Crystals of Isotactic Polystyrene". United States. https://doi.org/10.1021/ma048042l.
@article{osti_913905,
title = {Heat Capacity Study of Solution Grown Crystals of Isotactic Polystyrene},
author = {Xu, H and Cebe, P},
abstractNote = {We have performed measurements of the specific heat capacity on isotactic polystyrene (iPS) crystals grown from dilute solution. Solution grown crystal (SGC) samples had larger crystal fractions and greatly reduced rigid amorphous fractions compared to their bulk cold-crystallized counterparts. Heat capacity studies were performed from below the glass transition temperature to above the melting temperature by using quasi-isothermal temperature modulated differential scanning calorimetry (TMDSC) and standard DSC. Two or three endotherms are observed, which represent the melting of crystals. The small rigid amorphous fraction relaxes in a wide temperature range from just above the glass transition temperature to just below the first crystal melting endotherm. As in bulk iPS, 1 multiple reversing melting was found in iPS SGCs, supporting the view that double melting in iPS may be due to dual thermal stability distribution existing along one single lamella.2 The impact of reorganization and annealing on the melt endotherms was also investigated. Annealing occurs as a result of the very slow effective heating rate of the quasi-isothermal measurements compared to standard DSC. The improvement of crystal perfection through annealing causes the reversing melting endotherms to occur at a temperature higher than the endotherms seen in the standard DSC scan.},
doi = {10.1021/ma048042l},
url = {https://www.osti.gov/biblio/913905}, journal = {Macromolecules},
number = ,
volume = 38,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 2005},
month = {Sat Jan 01 00:00:00 EST 2005}
}