The Role of the Rigid Amorphous Fraction on Cold Crystallization of Poly(3-hydroxybutyrate)

Lorenzo, Maria Laura Di; Gazzano, Massimo; Righetti, Maria Cristina

doi:10.1021/ma3010907

Cited by 109 publications

(100 citation statements)

References 45 publications

(93 reference statements)

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“…The appearance of at least two radical correlation times for the PHB matrix amorphous region indicated that the polymer intercrystalline regions were heterophasic. This agreed with the current biphasic model of the amorphous state of a crystallizing polymer that is applicable to partially crystallizing polyesters such as PHB, polylactide, and polyethyleneterephthalate [32].…”

supporting

confidence: 88%

Structure-Formation Features in Ultrathin Fibers of Poly(3-Hydroxybutyrate) Modified with Nanoparticles

et al. 2016

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Supramolecular structure formation of poly(3-hydroxybutyrate) ultrathin fibers prepared by electrospinning and the influence of low concentrations of silicon andTiO 2 nanoparticles on the structure, physicomechanical and sorption properties, and resistance to thermal destruction and thermoand photo-oxidative destruction of non-woven fibrous material based on these fibers were studied. It was found that nanoparticles promoted the formation of thinner fibers with enhanced physicomechanical parameters and a structure that was more resistant to thermal and thermo-and photo-oxidative destruction and had a positive effect on the growth dynamics of mesenchymal stem cells.Tissue engineering utilizes various polymeric constructs prepared by one of the most promising methods, i.e., electrospinning (ES) of fibrous nanocomposites from biopolymers [1-3]. The method allows fibrous scaffolds with large surface-to-volume ratios to be produced. This enables free migration and proliferation of cells into the three-dimensional matrix and; therefore, excellent integration of the material into living tissues [4].Polyoxyalkanoates (POA), the most scrutinized of which is poly(3-hydroxybutyrate) (PHB), are special biopolymers [5,6]. PHB is prepared by a biotechnology route, possesses promising properties such as a high level of biocompatibility [7][8][9], and can undergo biodegradation in living tissues without forming toxic substances [10][11][12]. Therefore, PHB is used in the development of medical implements for surgery, dentistry, cardiac surgery, orthopedics, and other areas [13,14].The diameter of a monofilament and its molecular and supramolecular structure affect its physicomechanical and diffusion properties, the kinetics of oxidative and photo-oxidative reactions, and the biodegradation of fibrous non-woven materials [7]. The diameter of fibers produced by ES depends on parameters such as the concentration of the substance in the starting solution, solvent evaporation rate, potential, distance from the needle to the spun layer, electrical conductivity, viscosity, temperature, etc.[4]. Therefore, the production of a finished fiber with a definite morphology continues to be a critical problem.However, the diameter of PHB ultrathin fibers is practically unaffected by changing the ES parameters (electrical conductivity, throughput, spinning solution viscosity) [15,16]. Therefore, the structure and properties of non-woven PHB materials remain practically unchanged.The creation of modern bioresorbable fibrous materials for use as matrices for targeted drug delivery, scaffolds for growing living cells, artificial ligaments, etc. requires a method for varying the PHB fiber structural parameters in order to construct materials with the desired array of properties.

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confidence: 88%

Structure-Formation Features in Ultrathin Fibers of Poly(3-Hydroxybutyrate) Modified with Nanoparticles

et al. 2016

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“…Molecule segments in the amorphous phase exhibit a reduced mobility if they are covalently connected with the crystalline phase. This part of the amorphous phase is commonly named rigid amorphous fraction (RAF) that was reported to be around 20-30% of the overall sample mass ( [17][18][19]), The kinetics of vitrification of the RAF of PHB was quantified upon quasi-isothermal cold crystallization at 22.8°C, and it was found that the whole RAF of PHB is established during crystallization [20] In a recent study, it was proven that the physical state of the amorphous layer in contact with the growing crystals influences the mechanism of crystallization of PHB. During heating of an initially amorphous PHB, the rigid amorphous fraction, which is established simultaneously with formation of the crystals during the first stage of cold crystallization, slows down further crystal growth, which can proceed only upon further increase of the temperature, when complete mobilization of the RAF is achieved [19].…”

Section: General Properties Of Polyhydroxyalkanoatesmentioning

confidence: 99%

Polyhydroxyalkanoate (PHA): Review of synthesis, characteristics, processing and potential applications in packaging

Bugnicourt¹,

Cinelli²,

Lazzeri³

et al. 2014

Express Polym. Lett.

753

463

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Abstract. Polyhydroxyalkanoates (PHAs) are gaining increasing attention in the biodegradable polymer market due to their promising properties such as high biodegradability in different environments, not just in composting plants, and processing versatility. Indeed among biopolymers, these biogenic polyesters represent a potential sustainable replacement for fossil fuel-based thermoplastics. Most commercially available PHAs are obtained with pure microbial cultures grown on renewable feedstocks (i.e. glucose) under sterile conditions but recent research studies focus on the use of wastes as growth media. PHA can be extracted from the bacteria cell and then formulated and processed by extrusion for production of rigid and flexible plastic suitable not just for the most assessed medical applications but also considered for applications including packaging, moulded goods, paper coatings, non-woven fabrics, adhesives, films and performance additives. The present paper reviews the different classes of PHAs, their main properties, processing aspects, commercially available ones, as well as limitations and related improvements being researched, with specific focus on potential applications of PHAs in packaging.

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“…The extrapolation fails and leads to erroneous values in the case of the presence of a rigid amorphous fraction (RAF) [24], which recently has been identified also in PLLA [25,26]. The RAF is located at the interface between the crystalline and the amorphous regions and includes amorphous chain segments whose mobility is reduced due to their covalent coupling to crystals [27][28][29]. If the presence of RAF is not taken into account, the extrapolated Dh m°v alue is underestimated [24].…”

Section: Introductionmentioning

confidence: 99%

Enthalpy of melting of α′- and α-crystals of poly(l-lactic acid)

Righetti

Gazzano

Lorenzo

et al. 2015

European Polymer Journal

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158

127

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The Role of the Rigid Amorphous Fraction on Cold Crystallization of Poly(3-hydroxybutyrate)

Cited by 109 publications

References 45 publications

Structure-Formation Features in Ultrathin Fibers of Poly(3-Hydroxybutyrate) Modified with Nanoparticles

Structure-Formation Features in Ultrathin Fibers of Poly(3-Hydroxybutyrate) Modified with Nanoparticles

Polyhydroxyalkanoate (PHA): Review of synthesis, characteristics, processing and potential applications in packaging

Enthalpy of melting of α′- and α-crystals of poly(l-lactic acid)

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