Mechanism of fibrillation in the flow of molten polymer mixtures

Цебренко, М. В.; Yudin, A. V.; Ablazova, T.I.; Vinogradov, G. V.

doi:10.1016/0032-3861(76)90040-9

Cited by 114 publications

(42 citation statements)

References 3 publications

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“…One could also predict that the smaller droplets in the die entry region collide and can coalesce into larger droplets, and then they further extend into brils. 80 Other authors have examined bril formation in the converging die entrance and found droplet coalescence to occur there. 30,80,81 In brief, in the case of the present study, the combined effect of deformation and coalescence leads to brillation of the PA11 dispersed phase droplets in viscoelastic PLA matrix modied by the ( CE [.…”

Section: Morphology Of the Blends In The Extrudatementioning

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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Section: Morphology Of the Blends In The Extrudatementioning

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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“…Melt flow properties and the influence of flow behavior on morphology were deterroined using a capillary rheometer. Based on the analysis l':\ade by Han and Funatsu [21], and Vinogradov et al (32], the authors analyzed two poss ible cases (Figure 2.9). In two-phase f low through a capillary, the average velocity of the high viscosity polymer phase is smaller than that of the low viscosity polymer phase.…”

Section: B) Capillary Flowmentioning

confidence: 99%

“…Han [29] PS/PP Danesi [30] PP/EP Vinogradov POM/CPA [31][32][33] Krasnikova PP/PS [34] Tsebrenko POM/CEVAc [35] Lyngaae-PE/PP Jorgensen À<l,""l À""l Table 2.6). Micrographs of samples produced under controlled processing conditions (blow-molded container and extruded sheet) showed that the nylon material was not distributed as a homogeneous, unifcrm blend, ~ut rather as multiple layers, or platelets, along the wall thickness.…”

Section: B) Capillary Flowmentioning

confidence: 99%

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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“…4, with or without n B . Figure 9 gives a speculative schematic, showing that spherical drops entering the upstream end of the reservoir section (region A) are elongated as they approach the die entrance (region B) and undergo recoil after the elongated drops pass through the entrance region (region C) [22]. The long threadlike liquid cylinders would, if they were stable, then move down to the straight flow channel (region D).…”

Section: Critique Of Experimental Methods Used For Determining the Melmentioning

confidence: 99%

Untitled

2009

Polymer Engineering & Sci

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The purpose of this article is to clear the confusion in the literature on the following two issues: (1) determination of the bulk viscosity of immiscible polymer blends using a plunger-type capillary viscometer and (2) modeling the composition dependence of the bulk viscosity of immiscible polymer blends. Related to the first issue, it is pointed out that measurement of the total pressure drop across the entire length of a capillary die, while using a plunger-type viscometer, to determine the bulk viscosity of an immiscible polymer blend is not justified. This is because the morphology (the state of dispersion) of an immiscible polymer blend varies along the axis of a capillary die. Related to the second issue, it is pointed out that the use of such empirical expressions as inverse additivity or logarithmic additivity relationships is of no rheological significance to determine the composition dependence of the bulk viscosity of immiscible polymer blends. This is because such empirical expressions do not contain terms describing the state of dispersion of an immiscible polymer blend. A computational approach is suggested, though formidable but not insurmountable, which will lead to establishing rheology-morphology-processing relationships in immiscible polymer blends.

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Mechanism of fibrillation in the flow of molten polymer mixtures

Cited by 114 publications

References 3 publications

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

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

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

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