Miscibility and carbon dioxide transport properties of blends of bacterial poly(3-hydroxybutyrate) and a poly(vinylidene chloride- co-acrylonitrile) copolymer (original) (raw)
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Polymer, 2003
In this work the miscibility and the carbon dioxide transport properties of a bacterial, isotactic poly(3-hydroxybutyrate) (iPHB) and its blends with a copolymer of epichlorohydrin and ethylene oxide (ECH-co-EO) have been studied. Blends were prepared by solution/precipitation. The aim to obtain miscible blends of iPHB with a rubbery second component (such as the ECH-co-EO copolymer) is to have mixtures with glass transition temperatures below room temperature. In these conditions, the iPHB chains not involved in the crystalline regions retain its mobility. This mobility seems to be necessary for the attack of microorganisms and the corresponding biodegradability.Miscibility is the general rule of these mixtures, as shown by the existence of a single glass transition temperature for each blend and by the depression of the iPHB melting point. The interaction energy density stabilising the mixtures, calculated using the Nishi–Wang treatment, was similar to those of other polymer mixtures involving different polyesters and poly(epichlorohydrin) (PECH) and ECH-co-EO copolymers. The so-called binary interaction model has been used in order to simulate the evolution of the interaction energy density with the ECH-co-EO copolymer composition. Previously reported experimental data on blends of iPHB with PECH and poly(ethylene oxide) (PEO) have been used to quantify the required segmental interaction energy densities.In the determination of the CO2 transport properties of the mixtures, only iPHB rich blends containing up to 40% of copolymer were considered. The effect of the ECH-co-EO copolymer is to increase the sorption and the diffusion of the penetrant (and, consequently, the permeability) with respect to the values of the pure iPHB. This is primarily due to the reduction of the global crystallinity of the blends and to the low barrier character of the ECH-co-EO copolymer. Sorption data can be reasonably reproduced using an extension of the Henry's law to ternary systems.
Polymer, 2004
This work summarizes the miscibility and transport properties of different polymer blends obtained by mixing a bacterial, isotactic poly(3-hydroxybutyrate) (iPHB) with copolymers of styrene and vinyl phenol (Sty-co-VPh copolymers). Given that iPHB and pure commodity poly(styrene) (PS) form immiscible blends, PS has been modified by copolymerizing it with vinyl phenol (VPh) units, in an attempt to promote blend miscibility. VPh units have appropriate functional groups that interact with iPHB ester moieties. The potential miscibility was investigated by differential scanning calorimetry (DSC) measuring the glass transition temperatures of blends of different compositions. As an additional test, the interaction parameter between the two components, using the iPHB melting point depression caused by the second component, was also measured. Copolymers containing less than 90% styrene showed miscibility with iPHB.Given the remarkable barrier properties of iPHB to gases and vapours, the study has been completed by measuring transport properties of carbon dioxide through different iPHB/Sty-co-VPh copolymer blends, using gravimetric sorptions in a Cahn electrobalance. A clear difference was observed between the behaviour of rubbery blends and those that exhibit a glassy behaviour at the selected experimental temperature (303 K).
Journal of Molecular Liquids, 2010
The present paper focuses on the study of novel blends based on poly(3-hydroxybutyrate) (PHB) and polymers with different hydrophilicity (LDPE and PA). Polymer blends were produced from five ratios of PHB/LDPE in order to regulate the resistance to hydrolysis or (bio)degradation through the control of water permeability. The relation between the water transport and morphology (TEM data) shows the impact of polymer component ratio on the regulating water flux in a hydrophobic matrix. To elucidate the role of hydrophilicity of the second component presented in the PHB blends, we studied the PHB/PA blends where PA is the polyamide resin composed of statistical copolymer of hexamethyleneadipinate and ε-caprolactam in the ratio of 1:1. The complex of techniques including DCS and FTIRimaging (for T-scale) demonstrates the interaction between PHB and PA in the temperature ranges of crystallization and melting. The general approach based on Flory-Huggins equation is presented as the way for choosing the pairs of compatible or partly compatible polymers.
Journal of Materials Science, 2005
Poly(hydroxyalkanoates) (PHAs) are natural polyesters produced by microorganisms . In order to improve mechanical properties and reduce its cost, blending of natural PHBHV with synthetic polymers has been performed . PHBHV is a semi-crystalline, biodegradable, thermoplastic polymer synthesized by many different kinds of bacteria . Miscible and immiscible blends of PHBHV with synthetic polymers have been obtained . Blends of semi-crystalline and amorphous polymers can result in miscibility of both components. PHBHV has been blended with amorphous polymers to allow a decrease in its , translating it into a better processability. Surface and internal mechanical properties of polymeric solids might be closely related to the thermal molecular motion and the aggregation state on the surface, which are thought to be directly associated with the inherent properties of polymers such as the glass transition temperature, T g . In this study, the thermal and dynamic mechanical properties of bacterial poly(3-hydroxybutiric-3-hydroxyvaleric acid) (PHBHV, 21 mol% of 3 HV units), poly(2hydroxyethylmethacrylate) (PHEMA) and their blends prepared by slowly casting are presented.
Polymer Degradation and Stability, 2004
Biodegradation studies of binary blends of bacterial poly(hydroxybuyrate-co-hydroxyvalerate) (PHB-21%HV) with synthetic poly(2-hydroxyethylmetacrylate) (PHEMA) prepared by casting were performed. The compositions were explored in a range of 20-50% PHEMA on PHBHV. ASTM G21-90 including measurements of CO 2 were used to determine biodegradability. The time required for biodegradation increased as PHEMA content in the blend increased. Although all blends were biodegradable, as determined by ASTM G21-90 method, the CO 2 measurements could be indicative that the degradation of PHEMA, if it exists, is limited. Degradation of blends attained 90% (mass loss) in a period from 7 to 15 days, though after 30 days no degradation was detectable when PHEMA was tested as a single component. Penicillium funiculosum showed the highest degradation activity among five fungal species tested for biodegradation. Microscopic studies show that biodegradation of blends started at their surface.
Production and Characterization of Polymer Blends and Assessment of Biodegradation
Journal of Nanomaterials
Polyhydroxybutyrate (PHB), a microbial polyester well known for its high glass transition and melting temperatures, is found in the intracellular granule within microbes. Herein, we have attempted to synthesize PHB along with xyloglucan (XG) as a copolymer to lower glass transition and melting temperature. Fourier transform infrared spectroscopic (FTIR) and Scanning Electron Microscopic (SEM) analyses were used to investigate the characteristics of blend films. We found that the addition of XG resulted in increased moisture absorption of the blend films. XG-PHB blend of ratio 80 : 20 showed the highest tensile strength and was subjected to thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. The results revealed that the XG-PHB blend has a lower melting point (121.3°C) and lesser crystalline degree (17.26%) than PHB. TGA results showed that blend film was more thermally stable than PHB. An effort to understand and analyze microorganisms that can pro...
Cellulose, 2018
Biodegradable and biocompatible poly (3hydroxybutyrate) (PHB) is considered a good candidate for biomedical applications provided that its inherent brittleness and thermal stability are corrected. In this work, poly (3-hydroxyhexanoate-co-3-hydroxyoctanoate) (PHHO) and bacterial cellulose nanofibers (BC) were used as ''soft'' and ''stiff'' modifiers to improve PHB properties. PHHO (5-20 wt%) increased the thermal stability of PHB and PHB-BC composites. On the other hand, BC increased the glass transition and the crystallization temperature of PHB in the blends. The surface morphology of PHB was differently changed by the addition of PHHO and BC: a microporous surface morphology with many well spread pores was produced by the addition of PHHO (20-50 wt%) and a smoother surface by the addition of BC. Still, the surface morphology of PHB/PHHO blends, with homogenously spread submicronic pores, was not changed by BC. Thermal, structural and morphological investigations showed that BC nanofibers are mainly located in PHHO rich phase and at interface. PHB nanocomposite with 20 wt% PHHO showed balanced stiffness-toughness properties and excellent thermal stability, with the onset thermal Electronic supplementary material The online version of this article (
Miscibility of bacterial poly(3-hydroxybutyrate) with cellulose esters
Macromolecules, 1992
Blends of bacterial poly(3-hydroxybutyrate) (P(3HB)) with cellulose acetate butyrate (CAB) and cellulose acetate propionate (CAP) were prepared by melt compounding. P(3HB)/CAB blends containing 5 5 0 % P(3HB) and P(3HB)/CAP blendawith 5-60% P(3HB) are transparent,stable homogeneous amorphous glasses, while blends with higher P(3HB) content are partially crystalline. When in the amorphous state, both P(BHB)/CAB and P(3HB)/CAP blends show a glass transition which regularly decreases with increasing P(3HB) content, in excellent agreement with the behavior predicted for totally miscible blends. Bothdynamic mechanical (DMTA) and calorimetric (DSC) measurements show that P(3HB) and CAB can crystallize from the blends only at temperatures higher than the composition-dependent Tg. When crystallization is induced by thermal treatments, the melting temperature of the crystalline phase obtained depends on composition, as expected for miscible blends of crystallizable polymers. Besides the strongly composition dependent glass transition, another relaxation is observed, located in proximity to the Tg of P(3HB) and slightly shifting to higher temperature with increasing CAB or CAP content. DSC measurements on melt-quenched blends containing more than 60% P(3HB) indicate contribution of both blend components to this glass transition process, on the basis of the very large specific heat increment observed. It is suggested that the two glass transitions are the manifestation of two mobilization processes coexisting in blends which appear in all respects to be single-phase, homogeneous mixtures.
Miscibility in blends of poly(3-hydroxybutyrate) and poly(vinylidene chloride-co-acrylonitrile)
Journal of Polymer Science Part B: Polymer Physics, 1997
Miscibility behavior of poly(3-hydroxybutyrate) [PHB]/poly(vinylidene chloride-co-acrylonitrile) [P(VDC-AN)] blends have been investigated by differential scanning calorimetry and optical microscopy. Each blend showed a single T g , and a large melting point depression of PHB. All the blends containing more than 40% PHB showed linear spherulitic growth behavior and the growth rate decreased with P(VDC-AN) content. The interaction parameter x 12 , obtained from melting point depression analysis, gave the value of 00.267 for the PHB/P(VDC-AN) blends. All results presented in this article lead to the conclusion that PHB/P(VDC-AN) blends are completely miscible in all proportions from a thermodynamic viewpoint. The miscibility in these blends is ascribed to the specific molecular interaction involving the carbonyl groups of PHB.