Relationship between conformation and enthalpy or volume relaxation in polycarbonate

• Published in: Polymer (Guilford) Vol. 42; no. 12; pp. 5337 - 5342
• Main Authors: Heymans, N., Dequenne, B.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-06-2001; Elsevier
• Subjects: Annealing; Applied sciences; Exact sciences and technology; FTIR; Organic polymers; Physicochemistry of polymers; Polycarbonate; Properties and characterization; Structure, morphology and analysis; Polycarbonate; Annealing; FTIR; Experimental study; Structure relaxation; Conformational transition
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/S0032-3861(01)00017-9

Conformational changes are observed during sub-
T
g annealing of solution-cast films of BPA–polycarbonate by following changes in the conformationally sensitive IR aromatic breathing band at 1600
cm
−1. The rate of conformational relaxation is compared with published data on enthalpy and volume relaxation on the same polymer. The relaxation rates and timescales converge in the immediate vicinity of
T
g, but diverge at temperatures below
T
g−15
K and conformational energy only accounts for a very small fraction of observed enthalpy relaxation. The results suggest that a single process is active in volume and conformational relaxation and that at least two processes contribute to enthalpy relaxation.