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Crystallization of hydroxybutyrate oligomers. Part 2. Growth and thickening of solution grown crystals observed in situ using synchrotron radiation

Organ, S.J.; Li, J.; Terry, A.E.; Hobbs, J.K. and Barham, P.J. (2004). Crystallization of hydroxybutyrate oligomers. Part 2. Growth and thickening of solution grown crystals observed in situ using synchrotron radiation. Polymer, 45(26) pp. 8925–8936.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/j.polymer.2004.10.035
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Abstract

Synchrotron X-ray radiation has been used in situ to follow the crystallization of a hydroxybutyrate oligomer containing 32 repeat units from dilute solution in propylene carbonate, and to study chain unfolding during heating in oligomers with 24 and 32 repeat units. A discontinuity in growth rate occurs at 36-37˚C for the 32-mer: crystals grown below this temperature contain folded chains, which transform during heating through a process of partial dissolution and re-crystallization to form extended chain crystals. Crystals grown above the transition temperature contain extended chains that do not rearrange during heating. A similar change happens in the 24-mer between 35 and 40˚C. Thermal expansion in the (110) lattice direction (the fold direction) was in the range 5.3 +/- 0.3 x 10-5 nm degreesC<sup-1</sup>, with an additional discontinuous increase in 0.001 nm accompanying chain unfolding.

Item Type: Journal Article
Copyright Holders: 2004 Elsevier Ltd.
ISSN: 0032-3861
Keywords: hydroxybutyrate oligomers; WAXS; crystallization from solution
Academic Unit/Department: Mathematics, Computing and Technology > Engineering & Innovation
Item ID: 2443
Depositing User: Sally Organ
Date Deposited: 13 Jun 2006
Last Modified: 04 Jul 2011 11:41
URI: http://oro.open.ac.uk/id/eprint/2443
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