Rheology of molten blends of polyoxymethylene and ethylene‐vinyl acetate copolymer and the microstructure of extrudates as a function of their melt viscosities

Цебренко, М. В.; Резанова, Н. М.; Vinogradov, G. V.

doi:10.1002/pen.760201507

Cited by 66 publications

(26 citation statements)

References 8 publications

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“…A commonly used approximation for the ratio of the permeability of the conducting, continuous phase as a function of the tortuosi ty and the volume fraction of matrix polymer, ~m' has been proposed by Michaels and Bixler [93] and Barrer et al [94] -~ (35) where Pe is the permeability of the composite, and Pm is the permeability of the matrix.…”

Section: Evaluation Of Barrier Performancementioning

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%

“…Tsebrenko et al [35] studied the microstructure of polymer blends of POM and ethylene vinyl-acetate copolymer (CEVAc) (20/80wt%). When the viscosity ratio, ;\'=T1Poe!T1cEVACI was 1.…”

Section: B) Capillary Flowmentioning

confidence: 99%

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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: Evaluation Of Barrier Performancementioning

confidence: 99%

Section: B) Capillary Flowmentioning

confidence: 99%

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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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“…The q values calculated using the model are in good agreement with the conclusions of [8], according to which the melt moves with acceleration in transition from a wide reservoir to a narrow one: the velocity grows as the entrance is approached and has its maximum values on the axial line. Different degrees of strain of POM droplets in the flow, in addition to aggregation, are one reason for the spread in the diameters of POM microfibers, which has been established experimentally [2,10].…”

mentioning

confidence: 99%

“…For this purpose we used the data of [10], where the influence of the composition of the blend and the relation of the viscosities of the components on the phenomenon of specific fiberization was investigated with the example of polyoxymethylene/ethylene-vinyl acetate copolymer (POM/EVAC) blends. Using the model, we calculated the strain and orientation of a POM droplet in the flow as it approached the entrance to the molding orifice.…”

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confidence: 99%

Mathematical model of strain of droplets of a dispersed-phase polymer in flow of molten polymer blends

Rezanova

Pridatchenko

Цебренко

2005

J Eng Phys Thermophys

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A mathematical model of strain of a dispersed-phase-polymer droplet in flow of a molten polymer blend from a wide reservoir to a narrow one has been created with the use of the structural-continuum approach. The system of differential equations obtained has numerically been solved by the Runge-Kutta method. The model satisfactorily describes the actual processes of flow of molten polymer blends in the entrance zone of a molding orifice: the values of the droplet strains are a function of the relation of the viscosities of the starting components and their absolute values, the volume concentration of the dispersed phase, the interphase tension, and the elasticity of the droplet. The adequacy of the model created has been confirmed by comparison of the droplet strains calculated using the equations obtained and the theoretical conclusions and experimental results.The use of polymer blends is one efficient method of creating materials with a prescribed set of properties. Polymer blends may be considered as specific colloidal systems whose properties are determined by the type of structure formation and the surface phenomena at the phase boundary [1]. Processing of molten blends offers a new method of molding of ultrafine synthetic fibers (microfibers) of diameter from several fractions to tenths of a fraction of a micrometer. This phenomenon has been called specific fiberization [2]. The empirical approach is dominant in investigating the processes of formation of a structure in polymer dispersions. Romankevich et al. have made an attempt to describe the process of formation of microfibers in the matrix of the other polymer in the case of flow of a molten binary mixture; the emphasis was on the strain of a polymer droplet in the channel of the molding orifice and after the exit from it or in subsequent thermoorientational stretching [3, 4]. The mechanism of the phenomenon of specific fiberization, whose essence is that the fiberization of one polymer in the mass of the other (matrix) polymer is carried out in the field of tensile forces arising in transition from a wide reservoir to a narrow one, has been formulated and experimentally confirmed in [2].The present work seeks to create a mathematical model of strain of a droplet of the dispersed-phase component in flow of a molten polymer blend in the entrance zone of a molding orifice.To describe the processes occurring in dispersion flow one must know of numerous characteristics of the dispersion: the viscoelastic properties of the components, the volume concentration of the dispersed phase, the shape, size, and interaction of particles, etc. It is possible to allow for these indices in detail within the framework of the structural (microscopic) approach which has widely been used in investigating comparatively simple media, such as diluted suspensions with simply shaped particles. The possibility of using the structural method in the rheology of dispersions is limited by their diversity and complex morphology. The structural-continuum method proposed in [5,6] combi...

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The development of phase morphology and polymer chain orientation in the processing of incompatible polymer blends

White

Min

1985

Adv Polym Technol

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Rheology of molten blends of polyoxymethylene and ethylene‐vinyl acetate copolymer and the microstructure of extrudates as a function of their melt viscosities

Cited by 66 publications

References 8 publications

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

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

Mathematical model of strain of droplets of a dispersed-phase polymer in flow of molten polymer blends

The development of phase morphology and polymer chain orientation in the processing of incompatible polymer blends

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