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Investigating the structure–property relationship of bacterial PHA block copolymers

Paper ID Volume ID Publish Year Pages File Format Full-Text
24903 43544 2007 7 PDF Available
Title
Investigating the structure–property relationship of bacterial PHA block copolymers
Abstract

Mechanical testing of solvent cast films consisting of short-chain-length (SCL) polyhydroxyalkanoate (PHA) films suggested that films consisting of block copolymers retained more elasticity over time with respect to films of similar random copolymers of comparable composition. Two experimental techniques, wide angle X-ray scattering (WAXS) and uniaxial extension, were used to quantitatively investigate the structure–property relationship of bacterially synthesized PHA block copolymers of poly(3-hydroxybutyrate) (PHB) homopolymer and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) random copolymer (PHBV) segments. Uniaxial testing experiments yielded the Young's modulus, ultimate tensile strength, and the elongation until fracture of the films. Percent crystallinity was determined by deconvolution of amorphous and crystalline scattering peaks obtained from WAXS. Two PHBV films containing either 8% 3-hydroxyvalerate monomer (3HV) or 29% 3HV exhibited a quick transition to brittle behavior, decreasing to less than 20% percent elongation at fracture within a few days after annealing. Conversely, the block copolymer samples remained higher than 100% elongation at fracture a full 3 months after annealing. Because block copolymers covalently link polymers that would otherwise form thermodynamically separate phases, the rates and degrees of crystallization of the block copolymers are less than the random copolymer samples. These differences translate into materials that extend the property space of biologically synthesized SCL PHA.

Keywords
Polyhydroxyalkanoates (PHA); Block copolymers; Mechanical properties
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 132, Issue 3, 1 November 2007, Pages 296–302
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
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Price was $35.95
You save - $31
Price after discount Only $4.95
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Online Support
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