Deformation of melts of mixtures of incompatible polymers in a uniform shear field and the process of their fibrillation

Dreval, V. E.; Vinogradov, G. V.; Plotnikova, E. P.; Zabugina, M.P.; Krasnikova, N. P.; Kotova, E. V.; Pelzbauer, Z.

doi:10.1007/bf01679834

Cited by 32 publications

(12 citation statements)

References 15 publications

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“…The resul ts of Han et al [25] and CrevaI et al [26] are in agreement with observations Î .... [20]), and show that a uniform shear field can be effective in orienting the dispersed phase in the matrix phase.…”

Section: Theorysupporting

confidence: 80%

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Morphology and permeability in extruded polypropylene/ethylene vinyl‐alcohol copolymer blends

Lohfink

Kamal

1993

Polymer Engineering & Sci

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ABSTRACTstudies of ~he morphology of extruded polyrner blend syst~ms have shawn that it is feasible to produce a laminar structure of an ethylene vinyl-alcohr-l copolymer (EVOH) dispersed phase in a po1yprapylene (PP) m~trix phase. The laminar structure forms in the core of the extrudate when a 5lit die 1s incorporated into the extrusion process.Morphological studies, including a study of morphology d~vel opment inside the die and studies of the effect of processing conditions on the morphology of the final product, :evealed that the laminar structure is a resul t of die design. Processing conditions influence main1y the shape and dimensions of the laminnr core region of the extrudate.Oxygen permeation tests have shown that the blend e:,hibits lower oxygen permeability than pure PP, when EVOH is incorporated as a dispersed phase into the system. Oxygen transmission rates obtained with a blend system can be as low as those obtained with a mUlti-layer coextrusion product, although only at h~gh EVOH concentrations. Comparison of experimental data with theoretical permeation predictions shows that, up to 20wt% EVOH, the reduction in oxygen transmission rate is on1y minor, and follows the prediction for a homogeneous system. At 25wt%, a considerable decrease in oxygen transmission rate is noticeable, and the tr'end for higher EVOH contents is towards the behavior of a multi-layer system .

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Section: Theorysupporting

confidence: 80%

“…Dreval et al [26] have studied the deformation of melts of mixtures of linear low density polyethylene (LOPE) and PS. The polymers had different viscosities, but similar elasticity moduli.…”

Section: Theorymentioning

confidence: 99%

Morphology and permeability in extruded polypropylene/ethylene vinyl‐alcohol copolymer blends

Lohfink

Kamal

1993

Polymer Engineering & Sci

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“…Since the experimental measurements of the normal force N 1 are delicate, most studies devoted to the brillar morphology have focused on the effect of viscosity ratio neglecting the importance of the elasticity ratio between the dispersed and continuous phase, leading to contradictions and ambiguity to draw a clear correlation between the viscosity ratio and the optimal conditions of ber formation and its temporal stability in the case of viscoelastic immiscible polymer blends. [19][20][21][22] According to several literature reports, 1,[23][24][25][26] in the particular case of berlike morphology, the droplet-bril transition could be controlled by the viscosity ratio (k) between the dispersed phase and matrix (a more viscous matrix promotes the breakdown of droplets [27][28][29][30][31] ), the elasticity ratio (k 0 ) between the dispersed phase and matrix (a more elastic matrix promotes deformation and extension of the nodules into brils 14,17,23,[32][33][34][35][36][37][38][39] ) and a compromise between deformation (shear or elongation) and relaxation should be achieved in order to have a stable lamentous morphology.…”

Section: -12mentioning

confidence: 99%

Development of nanofibrillar morphologies in poly(l-lactide)/poly(amide) blends: role of the matrix elasticity and identification of the critical shear rate for the nodular/fibrillar transition

et al. 2018

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Bio-based poly(L-lactide)/poly(amide-11) blends (PLA/PA11, 80/20 w/w) and poly(L-lactide)/poly(amide-6) blends (PLA/PA6, 80/20 w/w) are processed by twin-screw extrusion followed by injection-moulding and key rheological parameters controlling their morphologie are investigated. The same work is done using the same PLA modified by a multi-step reactive extrusion route with an epoxy-based chain extender to obtain modified poly(lactide)/poly(amide-11) (PLA-j/PA11 80/20 w/w) blends. The morphologies of the extruded materials and of the injection moulded parts are characterized by SEM and their formation is deeply discussed via rheological investigation to highlight the contribution of viscosity, elasticity and interfacial tension. The existence of a critical shear rate related to the transition from nodular to fibrillar morphology is highlighted and the results are in good agreement with the condition of fibrillation Ca/Ca (crit) $ 4. Interestingly, with the exception of PLA/PA6 specimens, all blends obviously display uniform thin-thread fibrillar morphologies after injection-moulding. Compared with pure PLA, a drastic increase of the ductility was observed in the blends exhibiting a fiberlike structure without meanwhile sacrificing the stiffness. This study confirms that, through the appropriate choice of blend components (viscosity and elasticity ratio, flow conditions, interfacial tensions) the in situ fibrillation concept provides access, at a reasonable cost, to new materials with improved thermomechanical performances, without sacrificing weight and ability to be recycled.

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“…The fiber formation was observed at the entrance of the capillary where the contraction generates an elongational flow. The role of viscosity on the droplet deformation was also explained . Gonzalez‐Nunez et al concluded that the elongation flow formed during melt drawing is very effective for the formation of dispersed fibers.…”

Section: Resultsmentioning

confidence: 99%

Melt Spinning of Biodegradable Nanofibrillary Structures from Poly(lactic acid) and Poly(vinyl alcohol) Blends

Tran

Brünig

Hinüber

et al. 2013

Macro Materials & Eng

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A novel fabrication process for preparing continuous thermoplastic nanofibrillary structures by using the conventional melt spinning method of thermoplastic polymer fibers is developed. Poly(lactic acid) nanofibrils with average diameter of 60 nm are obtained by processing water soluble poly(vinyl alcohol) (PVA) and poly(lactic acid) (PLA) blends at weight ratio of 70/30 and subsequent removal of the PVA matrix. The textile physical properties (tensile and elongation properties) of the PVA/PLA filaments are investigated and interpreted. Produced 2D and 3D PLA textile structures are promising candidates as scaffolds for tissue engineering. Using the conventional melt spinning method and selecting PVA with the properties of ''green polymer'' as a matrix component, this fabrication process therefore provides an optimal solution to handle important scientific challenges at the present time: the economic and environmental friendly fabrication of highly specialized products for medical purposes.

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Deformation of melts of mixtures of incompatible polymers in a uniform shear field and the process of their fibrillation

Cited by 32 publications

References 15 publications

Morphology and permeability in extruded polypropylene/ethylene vinyl‐alcohol copolymer blends

Morphology and permeability in extruded polypropylene/ethylene vinyl‐alcohol copolymer blends

Development of nanofibrillar morphologies in poly(l-lactide)/poly(amide) blends: role of the matrix elasticity and identification of the critical shear rate for the nodular/fibrillar transition

Melt Spinning of Biodegradable Nanofibrillary Structures from Poly(lactic acid) and Poly(vinyl alcohol) Blends

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