Effects of isothermal crystallization on the mechanical properties of a elastomeric medium chain length polyhydroxyalkanoate

Effects of isothermal crystallization on the mechanical properties of a elastomeric medium chain length polyhydroxyalkanoate

[Display omitted] •Relationship between molecular structure and mechanical properties for a mcl-PHA is elucidated.•Higher crystallization temperature results in more ordered crystalline domains and narrower crystal distributions.•Higher crystallinity results in higher secant moduli calculated at 2%...

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Bibliographic Details
Published in:European polymer journal Vol. 85; pp. 401 - 410
Main Authors: Larrañaga, A., Pompanon, F., Gruffat, N., Palomares, T., Alonso-Varona, A., Larrañaga Varga, A., Fernandez-Yague, M.A., Biggs, M.J.P., Sarasua, J.R.
Format: Journal Article
Language:English
Published: Oxford Elsevier Ltd 01-12-2016
Elsevier BV
Subjects:
Chains (polymeric)
Crystallinity
Crystallization
Degree of crystallinity
Differential scanning calorimetry
Diffraction
Dynamic mechanical analysis
Elastomers
Glass transition temperature
Heat measurement
Mathematical analysis
Mechanical analysis
Mechanical properties
Molecular structure
Polyhydroxyalkanoates
Structure-property relations
Thermal analysis
Yield strength
Yield stress
Mechanical properties
Structure-property relations
Polyhydroxyalkanoates
Crystallization
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Summary:[Display omitted] •Relationship between molecular structure and mechanical properties for a mcl-PHA is elucidated.•Higher crystallization temperature results in more ordered crystalline domains and narrower crystal distributions.•Higher crystallinity results in higher secant moduli calculated at 2% of deformation.•A positive correlation was found between crystallization temperature and secant moduli at 50, 100 and 200% In the present study, the relationship between molecular structure and mechanical properties for a medium chain length polyhydroxyalkanoate (mcl-PHA) composed of 3-hydroxyoctanoate and 3-hydroxyhexanoate was elucidated. The mcl-PHA was crystallized from the melt at four different temperatures between its glass transition and melting point (37, 21, 3 and −21°C) and its molecular structure was analysed by means of differential scanning calorimetry (DSC) and wide-angle X-ray diffractometry (WAXD). The mechanical properties, which were analysed via tensile-tests and dynamic mechanical analysis (DMA), were clearly affected by the selected crystallization temperature and corresponding molecular structure of the polymer. In this sense, samples crystallized at 37, 21 and 3°C displayed higher secant moduli calculated at 2% (E2%∼20MPa) than the sample crystallized at −21°C (E2%∼7MPa) due to their higher crystallinity. Even if samples crystallized at 37, 21 and 3°C had very similar degree of crystallinity, their secant moduli calculated at 50, 100 and 200% (E50%, E100% and E200%) and yield strength (σy) were clearly affected by the selected crystallization temperature, showing a positive correlation (i.e., higher crystallization temperatures and corresponding more ordered crystalline domains with narrower crystal distributions resulted in higher E50%, E100% and E200% values).
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ISSN:0014-3057
1873-1945
DOI:10.1016/j.eurpolymj.2016.10.050