ISSN:
1042-7147
Schlagwort(e):
Thermal analysis
;
Heat capacity
;
Rigid amorphous
;
Glass transition
;
Poly(pivalolactone)
;
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
Notizen:
Quantitative thermal analysis was carried out for poly-(pivalolactone) (PPVL), including heat capacity determinations from 140 to 550 K. The experimental Cp below the glass transition temperature was fitted to an approximate vibrational spectrum and the ATHAS computation scheme was used to compute the “vibration only” heat capacities from 0.1 to 1000 K. The liquid Cp was derived from an empirical addition scheme and found to agree with the experimental Cp with an RMS of ±2.8% from 240 K to 550 K. A glass transition, Tg, could be detected at 260 K, and the change in heat capacity for 100% amorphous PPVL was calculated to be 38.8 J/(K mol). Above Tg, semicrystalline samples seem to show a rigid amorphous fraction that does not contribute to the increase in heat capacity at Tg. Using the ATHAS recommended heat capacities, the various thermodynamic functions (enthalpy, entropy, and Gibbs function) were derived. The residual entropy at 0 K for the amorphous PPVL was calculated to be 5.2 J/(K mol) per mobile bead, and was comparable to that obtained for a series of linear, aliphatic polyesters analyzed earlier.
Zusätzliches Material:
5 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/pat.1992.220030202
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