Biodegradability of Thermally Aged PHB, PHB-V, and PCL in Soil Compostage

Rosa, Derval dos Santos; Calil, M.R.; Guedes, Cristina das Graças Fassina; Rodrigues, Túlio César

doi:10.1007/s10924-004-8151-3

Cited by 38 publications

(10 citation statements)

References 18 publications

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“…Of the microbial biosynthesied PHA bioplastic family, poly (3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are the two most common types produced as bacterial intracellular granules [6,12]. Furthermore, PHA can also be biodegraded readily by microbial hydrolytic enzymes and therefore will not accumulate in the environment [13][14][15]. The ester bonds (-COO-) of these above mentioned bioplastics are very susceptible to hydrolysis during exposure to various natural environments such as marine and waste environment [6,15,16].…”

Section: Introductionmentioning

confidence: 99%

Accelerated weathering studies on the bioplastic, poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Wei

McDonald

2016

Polymer Degradation and Stability

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The effect of accelerated weathering exposure time on the bioplastic, poly(3-hydroxybutyrateco-3-hydroxyvalerate) (PHBV) was studied. The chemical structure and thermophysical property changes of solvent cast PHBV films were examined by a combination of optical microscopy, size exclusion chromatography, FTIR and 1 H-NMR spectroscopies, tensile testing, and differential scanning calorimetry (DSC). The exposed PHBV surfaces experienced surface crazing upon weathering. The molar mass of weathered PHBV was shown to decrease due to chain scission which was dominant over the crosslinking reaction mechanism, and compositional analysis showed the polymer degradation was non-random between the hydroxybutyratehydroxyvalerate units. The degree of crystallinity for PHBV was shown to increase significantly (by 20%) upon weathering. Tensile tests showed that the weathered PHBV exhibited reduced ultimate strength and elongation to break, while the Young's modulus increased ascribing to an increase in crystallinity. Different degradation mechanisms (Norrish I/II, radical initiation, crosslinking, and hydrolysis) of PHBV are proposed and confirmed based on the experimental

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Section: Introductionmentioning

confidence: 99%

Accelerated weathering studies on the bioplastic, poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Wei

McDonald

2016

Polymer Degradation and Stability

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“…In PHBV, an increased HV content is associated with faster degradation (Renard et al, 2004). Degradation mechanisms under aerobic conditions are different from those in anaerobic situations and reports indicate that PHBV degrades more rapidly than PHB under aerobic conditions (Mergaert et al, 1993;Yue et al, 1996;dos Santos Rosa et al, 2004;Li et al, 2007); however, the opposite effect has been reported by Abou-Zeid et al (2001.…”

Section: Degradabilitymentioning

confidence: 90%

“…The rate of PHA biodegradation is influenced by (1) molar mass, copolymer composition, crystallinity, stereochemistry, hydrophilic/hydrophobic balance, and chain mobility; and (2) environmental factors including the microbial population, temperature, moisture, pH and nutrient supply (Khanna and Srivastava, 2005). Numerous studies have explored the factors determining the biodegradability of PHA materials in soil (Savenkova et al, 2000;dos Santos Rosa et al, 2004;Corre Ãa et al, 2008), fresh water (Kasuya et al, 1998;Kusaka et al, 1999), marine environments (Tsuji and Suzuyoshi, 2002aThellen et al, 2008), sewage environments (Briese et al, 1994;Bucci et al, 2007) and compost media (Yue et al, 1996;Maiti et al, 2007). In general, the higher the polymer crystallinity and melting point, the lower the degradation rate.…”

Section: Degradabilitymentioning

confidence: 99%

Polyhydroxyalkanoates (PHAs) for food packaging

Plackett

Siró

2011

Multifunctional and Nanoreinforced Polymers for Food Packaging

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“…Three samples were analysed for each temperature to assess repeatability. A heat of fusion (∆H 0 f ) of 146.0 Jg −1 has been reported for PHB [30], and since no enthalpy of fusion has been published for the copolymer containing 3 wt.% 3-hydroxyvalerate, this value has been adopted by others in analysing copolymers of PHB with low concentrations of HV [31][32][33].…”

Section: Methodsmentioning

confidence: 99%

The Effect of a Secondary Process on the Analysis of Isothermal Crystallisation Kinetics by Differential Scanning Calorimetry

et al. 2019

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This paper demonstrates the application of a modified Avrami equation in the analysis of crystallisation curves obtained using differential scanning calorimetry (DSC). The model incorporates a square root of time dependence of the secondary process into the conventional Avrami equation and, although previously validated using laser flash analysis and infrared spectroscopy, is not currently transferable to DSC. Application of the model to calorimetric data required long-duration isotherms and a series of data treatments. Once implemented, the square root of time dependence of the secondary process was once again observed. After separation of the secondary process from the primary, a mechanistic n value of 3 was obtained for the primary process. Kinetic parameters obtained from the analysis were used in the model to regenerate the fractional crystallinity curves. Comparison of the model with experimental data generated R 2 values in excess of 0.995. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was used as model polymer due to the prominent secondary crystallisation behaviour that this polymer is known to display.The crystallisation kinetics of a polymer are generally described by the following Avrami equation [15]:where X p,t is the fractional primary crystallinity; X p,∞ is the final primary crystallinity; Z p is the Avrami primary crystallisation rate constant; t is time and n an integer combining values attributed to both the geometry and mechanism of nucleation. Although this equation is widely used, it often generates non-integer n values. In addition, it does not take into account the secondary crystallisation process, which has been proven to occur during polymer crystallisation [16][17][18][19]. Numerous authors have proposed modifications to the Avrami equation to account for these issues, with the most notable being Hillier [20,21], Velisaris [17] and Hay [22].The method developed by Hillier [20] assumes an initial constant radial growth of spherulites, followed by a first-order increase in crystallinity at time θ. This leads to the standard Avrami equation for the primary process (Equation (1)) and a modified version for the secondary process (Equation (2)) in which the n exponent is taken as 1:where X s,t−θ is the fractional crystallinity formed after time θ; X s,∞ is the final fractional crystallinity; and z s is the secondary rate constant. These two equations can then be combined to give an expression for the total crystallinity at time t. X t = X p,t + t 0

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Biodegradability of Thermally Aged PHB, PHB-V, and PCL in Soil Compostage

Cited by 38 publications

References 18 publications

Accelerated weathering studies on the bioplastic, poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Accelerated weathering studies on the bioplastic, poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

Polyhydroxyalkanoates (PHAs) for food packaging

The Effect of a Secondary Process on the Analysis of Isothermal Crystallisation Kinetics by Differential Scanning Calorimetry

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