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Influence of poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyvalerate) on miscibility and properties of atactic poly(methyl methacrylate)
Author(s) -
Cimmino Sossio,
D'Alma Edoardo,
Di Lorenzo Maria,
Silvestre Clara
Publication year - 2004
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.1464
Subject(s) - miscibility , upper critical solution temperature , materials science , differential scanning calorimetry , glass transition , annealing (glass) , ultimate tensile strength , dynamic mechanical analysis , polymer chemistry , methyl methacrylate , polymer blend , composite material , chemical engineering , copolymer , polymer , lower critical solution temperature , thermodynamics , physics , engineering
Abstract Miscibility and properties of two atactic poly(methyl methacrylate)‐based blends [containing 10 and 20% of poly(3‐hydroxybutyrate‐ co ‐3‐hydroxyvalerate)] have been investigated as a function of thermal treatments. Differential scanning calorimetry and dynamic mechanical thermal analysis of blends quenched in liquid nitrogen or ice/water, after annealing at T > 190 °C, showed a single glass transition temperature, indicating miscibility of the components for the time‐temperature history. Two glass transition temperatures, equal to those of the pure components, are instead found for blends after annealing at T < 190 °C. Scanning electron microscopy confirmed the homogeneity for the former quenched blends and phase separation for the latter. These results indicate the presence of an upper critical solution temperature (UCST). Tensile experiments, performed on two series of samples annealed at temperatures above and below the UCST, showed that the copolyester induces a decrease of Young's modulus and stresses at yielding and break points, and a marked increase of elongation at break. Differences in tensile properties between the two series of annealed blends are accounted for by the physical state of the components at room temperature after annealing above or below the UCST. Copyright © 2004 Society of Chemical Industry