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Thermal properties of a tough, new semicrystalline polyimide
Author(s) -
Chalmers Tammy M.,
Zhang Anqiu,
Shen Dexing,
Lien Shawn HsunShan,
Tso Chung C.,
Gabori Patricia A.,
Harris Frank W.,
Cheng Stephen Z. D.
Publication year - 1993
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.4990310308
Subject(s) - crystallinity , differential scanning calorimetry , amorphous solid , glass transition , materials science , polyimide , polymer chemistry , crystal (programming language) , chemical engineering , polymer , composite material , chemistry , crystallography , thermodynamics , physics , layer (electronics) , computer science , programming language , engineering
Abstract Thermal properties of a new semicrystalline polyimide synthesized from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride ( BTDA ) and 2,2‐dimethyl‐1,3‐(4‐aminophenoxy)propane ( DMDA ) have been studied. Heat capacities in the solid and liquid states of BTDA ‐ DMDA have been measured. The heat capacity increase at the glass transition temperature ( T g = 230°C) is 145 J/°Cmol for amorphous BTDA ‐ DMDA . The equilibrium heat of fusion of the BTDA ‐ DMDA crystals has been obtained using wide‐angle X‐ray diffraction and differential scanning calorimetry measurements, and is 75.8 kj/mol. Based on the information on crystallinity and the heat capacity increase at T g , a rigid amorphous fraction is identified in semicrystalline BTDA ‐ DMDA samples, which represents an interfacial region between the crystalline and amorphous states. In particular, this fraction increases with the crystallinity of the sample, which should be associated with crystal sizes, and therefore with crystal morphology. It has also been found that this polymer has a high‐temperature crystal phase upon annealing above its original melting temperature. The thermal degradation activation energies of BTDA ‐ DMDA in nitrogen and air are determined to be 154 and 150kJ/mol, respectively.