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Vaughan, Canada

Nerkar M.,Queens University | Ramsay B.,Polyferm Canada Inc.
Annual Technical Conference - ANTEC, Conference Proceedings

Poly(lactic acid) (PLA) was reactively modified by using a multifunctional co-agent (triallyl trimesate) in the presence of dicumyl peroxide. The viscosity, elasticity and melt strength of PLA increased substantially following reactive compounding. Furthermore, the rate of crystallization of co-agent in modified PLA was significantly higher than that of the pristine PLA and a distinct crystallization peak appeared. Reactively modified blends of PLA with an elastomeric polyhydroxyoctanoate exhibited similar features, and significant improvements in blend morphology. Copyright © (2014) by the Society of Plastics Engineers. Source

Poly(lactic acid) (PLA) is chemically modified by radical mediated solvent-free, peroxide-initiated grafting of triallyl trimesate (TAM) coagent in the melt state. When compared with the parent material and with PLA samples treated with peroxide alone, coagent-modified materials demonstrate higher molar mass and improved melt rheological properties, including substantial improvements in melt elasticity and strain hardening under uniaxial extension. Although similar rheological modifications are obtained by PLA chain extension using a multi-functional epoxide oligomeric chain extender, the coagent-modified material demonstrates significantly enhanced crystallinity and crystallization rates. The appearance of a distinct crystallization exothermic peak and the disappearance of the cold crystallization temperature point to a nucleation effect in the coagent modified PLA, which together with the rheological enhancements can promote the processability of this material in conventional thermoplastics operations. © 2014 WILEY-VCH Verlag GmbH & Co. Source

Rathinasabapathy A.,Queens University | Rathinasabapathy A.,CINVESTAV | Ramsay B.A.,Polyferm Canada Inc. | Ramsay J.A.,Queens University | Perez-Guevara F.,CINVESTAV
World Journal of Microbiology and Biotechnology

The aim of this study was to increase the density of wild type Cupriavidus necator H16 biomass grown on fructose in order to produce sufficient copolymer of short-chain-length (scl) and medium-chain-length (mcl) polyhydroxyalkanoate (PHA) from canola oil for mechanical testing of the PHA. Initial batch cultivation on fructose was followed by exponential feeding of fructose at a predetermined μ to achieve 44.4 g biomass/l containing only 20 % w/w of polyhydroxybutyrate (PHB) with a Yx/fructose of 0.44 g/g. In a third stage, canola oil was added under N-limited conditions to produce 92 g/l of biomass with 48 % w/w scl-mcl PHA. Using known standards, the PHA composition was confirmed by GC-MS analysis as 99.81 % 3-hydroxybutyrate, 0.06 % 3-hydroxyvalerate, 0.09 % 3-hydroxyhexanoate and 0.04 % 3-hydroxyoctanoate. The melting temperature (179 °C), crystallinity (54 %), tensile stress (25.1 Mpa) and Young's modulus (698 Mpa) for a PHB standard decreased to 176 °C, 52 %, 19.1 and 443 Mpa respectively for C. necator PHA produced in the 3-stage process. © 2013 Springer Science+Business Media Dordrecht. Source

Nerkar M.,Queens University | Ramsay J.A.,Queens University | Ramsay B.A.,Polyferm Canada Inc. | Kontopoulou M.,Queens University
Journal of Polymers and the Environment

Blends of poly-3-hydroxybutyrate with an elastomeric medium-chain-length poly-3-hydroxyalkanoate (MCL-PHA), containing 98 mol% 3-hydroxyoctanoate and 2 mol% 3-hydroxyhexanoate (referred to as PHO), were prepared by melt compounding. Coarsening of the droplet-matrix morphology of the blends was noted as the PHO content increased beyond 5 wt%; this was attributed to the significant viscosity mismatch between the components. Addition of PHO improved the thermal stability of the blends, reduced their crystallinity and resulted in shifts in their melting and crystallization temperatures. The blends had improved tensile strain at break. The unnotched impact strength showed a threefold increase at 30 wt% PHO content. Cross-linking of PHO using a peroxide initiator increased its viscosity, thus improving the morphology and mechanical properties of the blends. © 2013 Springer Science+Business Media New York. Source

Gao J.,Queens University | Ramsay J.A.,Queens University | Ramsay B.A.,Queens University | Ramsay B.A.,Polyferm Canada Inc.
Journal of Biotechnology

Decanoic acid is an ideal substrate for the synthesis of medium-chain-length poly-3-hydroxyalkanoate (MCL-PHA), but its use for this purpose has only previously been studied in shake-flasks likely due to its surfactant properties, low aqueous solubility and high melting temperature. A fed-batch fermentation process was developed for the production of MCL-PHA from decanoic acid using Pseudomonas putida KT2440. Decanoic acid was kept in liquid form by heating or by mixing with acetic acid to prevent crystallization. Different ratios of decanoic acid:acetic acid:glucose (DA:AA:G) were fed to produce a specific growth rate of 0.15h-1. This method produced a maximum of 39gL-1 dry biomass containing 67% MCL-PHA when the DA:AA:G ratio was 5:1:4. However, a declining growth rate occurred in the late stage of fermentation, resulting in decanoic acid accumulation in the bioreactor leading to foaming. The duration of MCL-PHA production was extended by shifting from exponential to linear feeding before accumulation of decanoic acid. This resulted in 75gL-1 biomass containing 74% PHA and an overall PHA productivity of 1.16gL-1h-1 with the production of each gram of PHA requiring only 1.16g of decanoic acid. The final PHA composition (on a molar basis) was 78% 3-hydroxydecanoate, 11% 3-hydroxyoctanoate and 11% 3-hydroxyhexanoate. © 2015 Elsevier B.V. Source

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