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The influence of thermal history on the properties of poly(3‐hydroxybutyrate‐ co ‐12%‐3‐hydroxyvalerate)
Author(s) -
Verhoogt Henk,
Ramsay Bruce A.,
Favis Basil D.,
Ramsay Juliana A.
Publication year - 1996
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19960705)61:1<87::aid-app10>3.0.co;2-x
Subject(s) - plasticizer , differential scanning calorimetry , materials science , thermogravimetric analysis , polymer , dynamic mechanical analysis , composite material , polymer chemistry , chemical engineering , thermodynamics , physics , engineering
The influence of thermal history on the properties of commercial P(3HB‐ co ‐12%‐3HV) was studied. Thermogravimetric analysis and differential scanning calorimetry revealed that the plasticizer evaporated at 140°C or higher. The loss of plasticizer during thermal treatment at 170 and 180°C resulted in a slight increase of the melting temperature of the polymer. The processing time and temperature, as well as the cooling procedure influenced the thermal behaviour of the material. A decrease in molecular weight with time was found at the temperatures investigated and this significantly affected the mechanical properties of the polymer prepared at 180 and 200°C. The rate constant k d of thermal degradation was slightly higher for samples during a shape‐forming process in a Minimax apparatus than during a quiescent heating process (DSC) and its value increased with temperature. Limiting the processing at 170°C to 2 min gave a material with useful properties but increasing the residence time resulted in a decrease in strength, elongation at break, molecular weight and viscosity although it did not significantly influence the modulus of elasticity. Materials prepared at 180 or 200°C were more brittle and longer residence times resulted in a deterioration of the mechanical properties. © 1996 John Wiley & Sons, Inc.