Crystallization, Micro- and Nano-structure, and Melting Behavior of Polymer Blends

Groeninckx, Gabriël; Harrats, Charef; Vanneste, Myriam; Everaert, V.

doi:10.1007/978-94-007-6064-6_5

Cited by 13 publications

(19 citation statements)

References 253 publications

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“…Two separate crystallization peaks in different crystallization ranges can be observed, which proves that crystallization of the two components of the blends occurs sequentially. The crystallization of PHB, with a peak at 102 °C, shifts to slightly lower temperatures with increasing PBS and PBSA amount, likely due to the presence of melted domains of PBS or PBSA in proximity to the crystallization growth front, which can interfere with the crystal growth 40,41 . Conversely, crystallization of PBS and PBSA turned out to be favored by the presence of PHB, because of being shifted to slightly higher temperatures with respect to the plain polymers.…”

Section: Resultsmentioning

confidence: 99%

Immiscible PHB/PBS and PHB/PBSA blends: morphology, phase composition and modelling of elastic modulus

Righetti

Cinelli

Aliotta

et al. 2021

Polymer International

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This paper reports the thermal, morphological and mechanical properties of environmentally friendly poly(3-hydroxybutyrate) (PHB)/poly(butylene succinate) (PBS) and PHB/poly[(butylene succinate)-co-(butylene adipate)] (PBSA) blends, prepared by melt mixing. The blends are known to be immiscible, as also confirmed by the thermodynamic analysis here presented. A detailed quantification of the crystalline and amorphous fractions was performed, in order to interpret the mechanical properties of the blends. As expected, the ductility increased with increasing PBS or PBSA amount, but in parallel the decrease in the elastic modulus appeared limited. Surprisingly, the elastic modulus was found properly described by the rule of mixtures in the whole composition range, thus attesting mechanical compatibility between the two blend components. This unusual behavior has been explained as due to co-continuous morphology, present in a wide composition range, but also at the same time as the result of shrinkage occurring during sequential crystallization of the two components, which can lead to physical adhesion between matrix and dispersed phase. For the first time, the elastic moduli of the crystalline and mobile amorphous fractions of PBS and PBSA and of the mobile amorphous fraction of PHB at ambient temperature have been estimated through a mechanical modelling approach.

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Section: Resultsmentioning

confidence: 99%

Immiscible PHB/PBS and PHB/PBSA blends: morphology, phase composition and modelling of elastic modulus

Righetti

Cinelli

Aliotta

et al. 2021

Polymer International

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“…At the beginning of PBAT melting, PHB chains and crystals are still solid. Possibly, this hinders the heat transfer and free movement of macromolecular chains contributing to the increase in energy required to melt PBAT [ 12 ]. Therefore, in order to melt PBAT/PHB blends more heat should be provided to the blend systems.…”

Section: Resultsmentioning

confidence: 99%

“…Hence, their solid state is kept at higher temperatures which could be interesting for their mechanical performance, particularly when projecting products to support high temperatures. A detailed description of the mechanisms of heat transfer in blends was reported by Groeninckx et al [ 12 ].…”

Section: Resultsmentioning

confidence: 99%

Effect of Babassu Natural Filler on PBAT/PHB Biodegradable Blends: An Investigation of Thermal, Mechanical, and Morphological Behavior

et al. 2018

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Blending of biodegradable polymers in combination with low-price organic fillers has proven to be a suitable approach to produce cost-effective composites in order to address pollution issues and develop products with superior mechanical properties. In the present research work PBAT/PHB/Babassu composites with 25, 50, and 75% of each polymer and 20% of Babassu were produced by melting extrusion. Their thermal, mechanical, and morphological behavior was investigated by differential scanning calorimetry (DSC), tensile testing, and scanning electron microscopy (SEM). Blending PBAT with PHB inhibited the crystallization of both polymers whereas adding Babassu did not significantly change their melting behaviour. Incorporation of Babassu reduced the tensile strength of its respective blends between 4.8 and 32.3%, and elongation at break between 26.0 and 66.3%. PBAT as highly ductile and low crystalline polymer may be seen as a crystallization tool control for PHB as well as a plasticizer to PBAT/PHB blends and PBAT/PHB/Babassu composites. As PBAT content increases: (i) elongation at break increases and (ii) surface fracture becomes more refined indicating the presence of more energy dissipation mechanisms. As PBAT/PHB/Babassu composites are biodegradable, environmental friendly, and cost effective, products based on these compounds have a great potential since their mechanical properties such as ductility, stiffness, and tensile strength are still suitable for several applications even at lower temperatures (−40 °C).

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“…Some of the works reporting fractionated crystallization are summarized in Table 1, along with information on the obtained morphology, composition and crystallization peak temperatures, when available. For a comprehensive discussion of all the literature, the reader is referred to the recent chapter from Groeninckx et al [6], while hereby we will mainly highlight the most important observations for these systems, discussing them in the light of the general concepts outlined above. Two paradigmatic examples of fractionated crystallization encountered in immiscible blends by varying concentration are shown in Figure 3 for polystyrene/polypropylene (PS/iPP) and polystyrene/linear low-density polyethylene (PS/LLDPE) blends.…”

Section: Immiscible Blendsmentioning

confidence: 99%

“…When the number density of MDs is several orders of magnitude (i.e., [6][7][8][9][10] higher than the number density of type A heterogeneities available in the bulk polymer, only clean MDs are formed on average. Hence, fractionated crystallization disappears and is replaced by a single exotherm located at very large undercoolings due to crystallization initiated by surface or homogeneous nucleation.…”

Section: Conclusion and Perspectivementioning

confidence: 99%

Fractionated crystallization in semicrystalline polymers

Sangroniz

Wang

et al. 2021

Progress in Polymer Science

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The crystallization of heterogeneously nucleated bulk polymers typically occurs in a single exothermic process, within a narrow temperature range, i.e., a single exothermic peak is detected by Differential Scanning Calorimetry when the material is cooled from the melt. However, when a bulk semicrystalline polymer is subdivided or dispersed into a multitude of totally (or partially) isolated microdomains (e.g., droplets or cylinders), in number comparable to that of commonly available nucleating heterogeneities, several separated crystallization events are typically observed, i.e., fractionated crystallization. This situation is often found for the minor crystallizable component in immiscible blends.When the bulk polymer is dispersed into a number of microdomains that is several orders of magnitude higher than the available number of heterogeneities within it, most microdomains will be heterogeneity-free. In these clean microdomains the nucleation can occur by contact with the interfaces (i.e., surface nucleation) or by homogeneous nucleation inside the microdomain volume. These cases can be easily encountered in cylinders or spheres within strongly segregated block copolymers, or in infiltrated polymers within nanopores of alumina templates.In this work, a comprehensive review of the known cases of fractionated crystallization is provided. The changes upon decreasing microdomain sizes from a dominant single heterogeneous nucleation, through fractionated crystallization, to surface or homogeneous nucleation are critically reviewed. Emphasis is placed on the common features of the phenomenon across the different systems, and thus on the general conclusions that can be drawn from the analysis of representative semicrystalline polymers. The origin of the fractionated crystallization effects and their dramatic consequences on the nucleation and crystallization kinetics of semicrystalline polymers are also discussed.

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Crystallization, Micro- and Nano-structure, and Melting Behavior of Polymer Blends

Cited by 13 publications

References 253 publications

Immiscible PHB/PBS and PHB/PBSA blends: morphology, phase composition and modelling of elastic modulus

Immiscible PHB/PBS and PHB/PBSA blends: morphology, phase composition and modelling of elastic modulus

Effect of Babassu Natural Filler on PBAT/PHB Biodegradable Blends: An Investigation of Thermal, Mechanical, and Morphological Behavior

Fractionated crystallization in semicrystalline polymers

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