Macro, Micro and Nanostructured Morphologies of Multiphase Polymer Systems

Huang, Han‐Xiong

doi:10.1002/9781119972020.ch6

Cited by 14 publications

(26 citation statements)

References 359 publications

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“…Shear flow induced breakup of the droplets is controlled by the value of capillary number, Ca [2,3].…”

Section: Resultsmentioning

confidence: 99%

“…On the other hand, generally accepted dependence of F on R does not exist and strongly differing expressions were used in various theories describing competitions between the breakup and coalescence [2,5]. Various breakup mechanisms are operative in dependence of R/R c ratio and other system parameters [2,3]. Theoretical calculations of the breakup time must be done numerically, which complicates determination of its dependence on system parameters.…”

Section: Introductionmentioning

confidence: 99%

“…Generally, F is zero for R smaller than its critical value R c , related to critical capillary number, Ca c [1][2][3]. Dependence of Ca c on system parameters is well-known, at least for blends of Newtonian liquids in simple shear and extensional flows.…”

Section: Introductionmentioning

confidence: 99%

“…Most available theories describe systems, where dynamic equilibrium between the droplet breakup and coalescence is established [1][2][3]. It relates to the situation in a batch mixer if mixing continues for a long enough time and degradation of the blend components is avoided.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, control of the blend phase structure evolution during their mixing and processing is an object of intensive scientific and industrial interest, especially for blends of biodegradable polymers, where conditions of mixing and processing are less established than for blends of synthetic polymers. It is generally accepted that the size of droplets in flowing blends with the droplets-in-matrix morphology is determined by the competition between the droplet breakup and coalescence [1][2][3]. The phase structure formed during blend mixing is affected by a number of parameters as mixing rate and time, mixer type, temperature, and the blend composition.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Phase structure evolution during mixing and processing of poly(lactic acid)/polycaprolactone (PLA/PCL) blends

et al. 2015

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The morphology of quenched and compression molded samples of poly(lactic acid)/polycaprolactone (PLA/PCL) blend prepared by melt mixing was carefully characterized by the method reflecting eventual nonuniformity of the blend structure and/or broad particle size distribution. Determined number and volume average droplet radii for quenched samples were compared with theory, assuming that flow field in a mixing chamber can be substituted by the shear flow with effective shear rate. An increase in droplet radii during compression molding was compared with theory of the coalescence in quiescent state. Using the concept of effective shear flow to describe mixing leads to a strong disagreement between theory and experiment for the critical droplet radius of its breakup, and for the coalescence efficiency. The theory of coalescence in quiescent state provides fair description of an increase in the number average droplet radius during compression molding, but totally fails at prediction of an increase in the volume average droplet radius.

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“…Shear flow induced breakup of the droplets is controlled by the value of capillary number, Ca [2,3].…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Phase structure evolution during mixing and processing of poly(lactic acid)/polycaprolactone (PLA/PCL) blends

et al. 2015

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Prediction of average droplet size in flowing immiscible polymer blends

Fortelný

Jůza

2017

J of Applied Polymer Sci

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The paper is focused on calculation of the average droplet size in immiscible blends during their steady flow. Available theoretical and experimental results of studies of the droplet breakup and coalescence are utilized to derive the equations describing dynamic equilibrium between the droplet breakup and coalescence. New expression for the coalescence efficiency, reliably reflecting recent theoretical results, is proposed. The equation for the average steady droplet size, controlled by the stepwise breakup mechanism and coalescence of droplets with not very different sizes, is derived for blends containing up to 10-20 vol % of the droplets. For blends with above approximate 20 vol % of the droplets, the breakup by the Tomotika mechanism and coalescence in highly polydisperse system is modeled. Results of the derived equations are compared with experimental data; qualitative agreement is found for the dependence of the droplet size on the amount of the dispersed phase.

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Prediction of the Phase Structure Evolution during Processing of Polymer Blends. Results and Problems

Fortelný¹,

Jůza²

2016

Macromolecular Symposia

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Summary: The paper summarizes state of art in the description of the droplet breakup, coalescence, and competition between them in flowing immiscible polymer blends. It has been shown that, in contrast to the conditions for the start of droplet breakup, knowledge of the dependence of the droplet breakup frequency on system parameters is quite limited. It has been demonstrated that the switch between expressions for the matrix drainage between spherical and highly deformed droplets leads to a reasonable description of the flow induced coalescence. This method makes it possible to include the effect of the matrix elasticity into the calculation of the probability of coalescence. The analysis of the competition between the droplet breakup and coalescence leads to the conclusion that knowledge of the mechanism and frequency of the droplet breakup is essential for at least qualitative prediction of the droplet size dependence on system parameters.

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Macro, Micro and Nanostructured Morphologies of Multiphase Polymer Systems

Cited by 14 publications

References 359 publications

Phase structure evolution during mixing and processing of poly(lactic acid)/polycaprolactone (PLA/PCL) blends

Phase structure evolution during mixing and processing of poly(lactic acid)/polycaprolactone (PLA/PCL) blends

Prediction of average droplet size in flowing immiscible polymer blends

Prediction of the Phase Structure Evolution during Processing of Polymer Blends. Results and Problems

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