Thermal Degradation of Poly(3-hydroxyalkanoates):  Preparation of Well-Defined Oligomers

Nguyen, Sophie; Yu, Ga-Er; Marchessault, R. H.

doi:10.1021/bm0156274

Cited by 147 publications

(139 citation statements)

References 22 publications

Supporting

Mentioning

130

Contrasting

Unclassified

Order By: Relevance

“…Pyrolysis is an easy method to produce the functionalized PHA macromonomers. At the moderately low temperature (170~200°C), PHB degraded into a well-defined oligomer containing one unsaturated end group, predominantly a trans-alkenyl end group, as well as a carboxylic end group [50]. The dominant thermal degradation occurred via a random chain scission (cis-elimination) with a six-membered ring ester intermediate [51][52][53][54].…”

Section: Phas Copolymer Via An Oligomer-first Methodsmentioning

confidence: 99%

Synthetic routes to degradable copolymers deriving from the biosynthesized polyhydroxyalkanoates: A mini review

Ke¹,

Zhang²,

Ramakrishna³

et al. 2016

Express Polym. Lett.

View full text Add to dashboard Cite

Abstract.Polyhydroxyalkanoates are a family of natural polyesters being produced as intracellular carbon and energy reserves by a wide variety of microorganisms. They have developed rapidly in both research and development efforts globally in the last 15 years. Till now, over 100 different types of PHAs have been successfully biosynthesized using both genetic engineering and fermentation techniques. Their unique biodegradable, biocompatible and thermoplastic characteristics make PHAs promising candidates for the commodity and biomedical applications. This review focused on the chemical synthesis of the derivatives of the biosynthesized PHAs.

show abstract

Section: Phas Copolymer Via An Oligomer-first Methodsmentioning

confidence: 99%

Synthetic routes to degradable copolymers deriving from the biosynthesized polyhydroxyalkanoates: A mini review

Ke¹,

Zhang²,

Ramakrishna³

et al. 2016

Express Polym. Lett.

View full text Add to dashboard Cite

show abstract

“…Dependendo da escolha do outro componente do bloco, os copolímeros podem adquirir diversas propriedades, por exemplo, propriedades anfifílicas e biocompatíveis para aplicações na área biomédica [15] . Oliveira et al [16] sintetizaram copolímeros em blocos via reação de acoplamento entre o PHBHV e PNIPAAm (poliisopropilamida).…”

Section: Solventes E Reagentesunclassified

Estudo cinético da redução da massa molar do poli(3-hidroxibutirato-co-3-hidroxivalerato) (PHBHV)

et al. 2010

View full text Add to dashboard Cite

Resumo: Neste trabalho foi realizado um estudo cinético da redução da massa molar do poli(3-hidroxibutirato-co-3-hidroxivalerato) (PHBHV) em três diferentes metodologias: hidrólise ácida com ácido clorídrico, transesterificação com hexilenoglicol ou etilenoglicol e redução na presença do borohidreto de sódio (NaBH 4 ). Foram investigados os parâmetros de processo: tempo, temperatura, tipo e concentração de catalisadores. Os resultados de redução de massa molar foram analisados pelo modelo cinético de ordem n. A redução com NaBH 4 foi mais eficiente do ponto de vista cinético, tendo em vista os parâmetros: constante de reação k e energia de ativação (E a ), uma vez que os valores observados foram significativamente maiores em comparação com os calculados para os demais métodos. Palavras-chave: Polihidroxialcanoatos, PHBHV, redução da massa molar, análise cinética. Kinetic Study of the Molecular Weight Reduction of Poly (3-Hydroxybutirate-co-3-Hydroxyvalerate) (PHBHV)Abstract: In this work a kinetic study was carried out of the molecular weight reduction of poly(3-hydroxybutirate-co-3-hydroxyvalerate) (PHBHV) in three different methodologies: acid hydrolysis using hydrochloric acid, transesterification with ethylene glycol or hexylene glycol and reduction in the presence of sodium borohydride (NaBH 4 ). The following process parameters were investigated: time, temperature, type and concentration of catalysts. The results of molecular weight reduction were fitted with a n-order kinetic model. The kinetics analysis has shown that the NaBH 4 reduction was the most efficient in terms of reaction rate in comparison with the other methods.

show abstract

“…This band matched with the CH 3 stretching and CH deformation and this shift could be explained by the formation of oligomers with unsaturated propenyl endings (Nguyen et al 2002). There was a distinct peak appearing at 4347 cm -1 whose band assignment corresponded to CH 2 stretching and CH deformation and it is a characteristic peak in crotonic and 2-pentenoic acids (Holman and Edmondson 1956).…”

Section: Nir Data Analysis 923mentioning

confidence: 71%

“…The NMR spectra were analysed in order to obtain the ratio of the areas of the proton associated with the tertiary carbon located in the PHA backbone (5.24-5.15 ppm) (Dai et al 2008); the CH groups present in the butenyl or propenyl endings (6.98-7.0 ppm) (Nguyen et al 2002, Hablot et al 2008; the trans-(7.1 ppm) and cis-(6.5 ppm) CH groups associated with crotonic acid (Ariffin et al 2008) and the CH groups of trans-2-pentenoic acid (7.14-7.15 ppm) (Nguyen et al 2002). Integration of these peaks was performed in PeakFitv4 ® in order to establish a relative ratio of the different species in the mix.…”

Section: 1mentioning

confidence: 99%

“…Increasing the length of the co-monomer side chains can improve the toughness and elongation properties of PHAs, but PHV has been found to reduce its molecular weight at a faster rate compared with PHB during thermal treatment at 190 °C (Nguyen et al 2002), since the ethyl group in 3HV monomers have a stronger electron-donating compared to the methyl one in 3HB. Figure 9.5 shows that material MC-PHA1 (36 % mol 3HV) degrades faster than material MC-PHA2 (7 % mol 3HV).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Composition of mixed culture PHA biopolymers and implications for downstream processing

Montano-Herrera¹

View full text Add to dashboard Cite

Polyhydroxyalkanoates (PHAs) are biopolymers synthesised and accumulated by most bacteria for carbon and energy storage. They have properties and applications comparable to petrochemical thermoplastics. Although PHAs are produced at high yields using pure biological cultures, the use of mixed cultures can significantly reduce the production costs and make use of waste streams to produce environmentally sustainable materials. In order to produce mixed culture PHAs of relevance for broader industry applications it is necessary to develop the ability to tailor polymers with diversified mechanical properties through understanding and controlling the monomer composition and compositional distribution.Diverse and complex PHA polymer structures have been achieved in mixed microbial cultures using time-based feeding strategies. However, PHA monomer composition and compositional distribution in PHA random and blocky copolymers are sensitive to substrate feeding history, making more complex the prediction of final PHA content and composition.In this sense, a better understanding of the changing cell physiologies that develop in response to different feeding strategies and substrates is necessary to design optimised feeding strategies and process control algorithms for PHA production.This thesis presents for the first time a comprehensive flux characterisation of monomer development during mixed culture PHA accumulation concurrent with biomass growth using Metabolic Flux Analysis (MFA). A dynamic trend in active biomass growth and in polymer composition was observed and was consistent over replicate accumulations. Monomer (3-hydroxybutyrate and 3-hydroxyvalerate) incorporation into poly(3-hydroxybutyate-co-3-hydroxyvalerate) copolymers in a pilot scale production system was evaluated based on published models that describe polymer production during PHA accumulation. However, it was found that these existing models could not describe the fluctuations in the proportion of Additionally, thermal degradation of mixed culture PHAs during melt processing was assessed by Near-Infrared (NIR) spectroscopy coupled to Multivariate Data Analysis. It was shown that, with correct pretreatment, a copolymeric product that was much more stable to extrusion processing than commercially available PHA was produced.Overall, this thesis explores both the fundamental and applied aspects of PHA production by mixed microbial cultures with concurrent active biomass growth. The use of computational iii tools to explore and help understand the underlying metabolic processes was explored.Polymer composition seems to follow a very complex regulation processes which can be described through the incorporation of more detailed reactions in current metabolic models.Furthermore, this thesis gives further insight into the fundamental properties of the materials produced and an assessment of their potential for degradation during processing.iv

show abstract

Thermal Degradation of Poly(3-hydroxyalkanoates): Preparation of Well-Defined Oligomers

Cited by 147 publications

References 22 publications

Synthetic routes to degradable copolymers deriving from the biosynthesized polyhydroxyalkanoates: A mini review

Synthetic routes to degradable copolymers deriving from the biosynthesized polyhydroxyalkanoates: A mini review

Estudo cinético da redução da massa molar do poli(3-hidroxibutirato-co-3-hidroxivalerato) (PHBHV)

Composition of mixed culture PHA biopolymers and implications for downstream processing

Contact Info

Product

Resources

About