Isothermal Crystallisation Kinetics of Microbial Poly(3-hydroxybutyrate- Co-3-hydroxyhexanoate)
نویسندگان
چکیده
Polyhydroxyalkanoates (PHA), a class of microbial polyesters produced from fermentation, is of interest for scientists and environmentalists due to its wide-ranged combinations of monomers, biodegradability and biocompatibility properties. In this study, efforts were made to understand the kinetics of isothermal crystallisation of PHA containing 3 mol% of 3-hydroxyhexanoate (3HHx) co-monomer [P(3HB-co-3 mol% 3HHx)]. Avrami model is used to describe the kinetics of the isothermal crystallisation. Besides, we discuss crystallinity, equilibrium melting temperature, kinetics of isothermal crystallisation and activation energy of isothermal crystallisation of P(3HB-co-3 mol% 3HHx). The average crystallinity of P(3HB-co-3 mol% 3HHx) is found to be 42.5% when it is isothermally crystallised from 121-127 °C. Meanwhile, the equilibrium melting temperature of P(3HBco-3 mol% 3HHx) ( 0 m T ) is 183 °C, which is in good agreement to the 0 m T s of various PHA reported in the literature. Half-time of crystallisation (t0.5) increases exponentially with temperature. Correspondingly, overall rate of isothermal crystallisation (K1/n) decreases with temperature. The isotherms of crystallisation exhibit sigmoid dependence on time, and they gradually shift toward longer crystallisation times with increasing crystallisation temperature. Kinetic data are compared with data for other alkanoates and copolymers with them.
منابع مشابه
Microbial Degradation Behavior in Seawater of Polyester Blends Containing Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx)
The microbial degradation behavior of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and its compound with several polyesters such as poly(butylene adipate-co-telephtharate) (PBAT), poly(butylene succinate) (PBS), and polylactic acid (PLA) in seawater was tested by a biological oxygen demand (BOD) method. PHBHHx showed excellent biodegradation in seawater in this study. In addition, the...
متن کاملSynthesis of Diblock copolymer poly-3-hydroxybutyrate -block-poly-3-hydroxyhexanoate [PHB-b-PHHx] by a β-oxidation weakened Pseudomonas putida KT2442
BACKGROUND Block polyhydroxyalkanoates (PHA) were reported to be resistant against polymer aging that negatively affects polymer properties. Recently, more and more attempts have been directed to make PHA block copolymers. Diblock copolymers PHB-b-PHHx consisting of poly-3-hydroxybutyrate (PHB) block covalently bonded with poly-3-hydroxyhexanoate (PHHx) block were for the first time produced su...
متن کاملFormation of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) by PHA synthase from Ralstonia eutropha.
The acetoacetyl-CoA reductase and the polyhydroxyalkanoate (PHA) synthase from Ralstonia eutropha (formerly Alcaligenes eutrophus) were expressed in Escherichia coli, Klebsiella aerogenes, and PHA-negative mutants of R. eutropha and Pseudomonas putida. While expression in E. coli strains resulted in the accumulation of poly(3-hydroxybutyrate) [PHB], strains of R. eutropha, P. putida and K. aero...
متن کاملPoly(3-hydroxybutyrate-co-3-hydroxyhexanoate)-based scaffolds for tissue engineering
Development and selection of an ideal scaffold is of importance for tissue engineering. Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is a biocompatible bioresorbable copolymer that belongs to the polyhydroxyalkanoate family. Because of its good biocompatibility, PHBHHx has been widely used as a cell scaffold for tissue engineering. This review focuses on the utilization of PHBHHx-base...
متن کاملEngineered Aeromonas hydrophila for enhanced production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) with alterable monomers composition.
Aeromonas hydrophila 4AK4 produces poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) containing 3-hydroxybutyrate (3HB) and about 15 mol% 3-hydroxyhexanoate (3HHx) from dodecanoate. To study the factors affecting the monomer composition and PHBHHx content, genes encoding phasin (phaP), PHA synthase (phaC) and (R)-specific enoyl-CoA hydratase (phaJ) from Aeromonas punctata (formerly named A...
متن کامل