Morphology and rheology of ternary fluid–fluid–solid systems

Nagarkar, Shailesh; Velankar, Sachin

doi:10.1039/c2sm25758k

Cited by 66 publications

(49 citation statements)

References 62 publications

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“…) does not collapse even after 45 minutes under molten conditions although an increase in cell size is apparent. Addition of PTFE particles does not retard this increase in cell size, in fact it accelerates coalescence, an effect that has been noted previously in aqueous foams or in polymer blends . Similar results are seen for PP and polyolefin elastomer as well (Fig.…”

Section: Resultssupporting

confidence: 87%

Improving the stability of polylactic acid foams by interfacially adsorbed particles

Lobos

Iasella²,

Rodríguez‐Pérez

et al. 2015

Polymer Engineering & Sci

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Polymers such as poly(lactic acid) (PLA), which have poor melt strength, are difficult to foam due to severe cell coalescence during foaming. We show that addition of a few percent of polytetrafluoroethylene (PTFE) particles can stabilize PLA foams against bubble coalescence and collapse. The particles and a chemical blowing agent, were dispersed into the PLA by extrusion, and then foamed by heating. The PTFE‐containing foams remained stable even when the foams were held under molten conditions for extended periods. Foam stability is attributed to an interfacial mechanism: due to their low surface energy, the PTFE particles adsorb on the inner surface of the foam bubbles at a high surface coverage, and endow the bubbles with an interfacial “shell” that prevents coalescence. This mechanism resembles the particle‐stabilization of Pickering emulsions in oil/water systems. Particle adsorption at the interface is a necessary condition for using this approach, and hence this approach is most likely to be successful if the particles have a low surface energy and the polymer has a high surface tension. The approach of using interfacially adsorbed particles can be broadly generalized, and offers the opportunity of foaming various polymers with low melt strength, or for expanding the processing window within which foaming can be conducted. POLYM. ENG. SCI., 56:9–17, 2016. © 2015 Society of Plastics Engineers

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Section: Resultssupporting

confidence: 87%

Improving the stability of polylactic acid foams by interfacially adsorbed particles

Lobos

Iasella²,

Rodríguez‐Pérez

et al. 2015

Polymer Engineering & Sci

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“…2j). [36][37][38] This structure resembles the suspension in a capillary state, except that the drops are much bigger than the particles. This is not the favorable configuration as noted in Section 3.2 and in the ESI.…”

Section: Partially-wetted Particlesmentioning

confidence: 95%

A non-equilibrium state diagram for liquid/fluid/particle mixtures

Velankar

2015

Soft Matter

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The equilibrium structures of ternary oil/water/surfactant systems are often represented within a triangular composition diagram with various regions of the triangle corresponding to different equilibrium states. We transplant this idea to ternary liquid/fluid/particle systems that are far from equilibrium. Liquid/liquid/particle mixtures or liquid/gas/particle mixtures yield a wide diversity of morphologies including Pickering emulsions, bijels, pendular aggregates, spherical agglomerates, capillary suspensions, liquid marbles, powdered liquids, and particle-stabilized foams. This paper argues that such ternary liquid/fluid/particle mixtures can be unified into a non-equilibrium state diagram. What is common among all these systems is that the morphology results from an interplay between the preferential wettability of the particles, capillarity, and viscous forces encountered during mixing. Therefore all such systems share certain universal features, regardless of the details of the particles or fluids used. These features guide the construction of a non-equilibrium state diagram which takes the form of a triangular prism, where each triangular cross-section of the prism corresponds to a different relative affinity of the particles towards the two fluids. We classify the prism into regions in which the various morphologies appear and also emphasize the major difference between systems in which the particles are fully-wetted by one of the fluids vs. partially-wetted by both fluids. We also discuss how the state diagram may change with mixing intensity or with interparticle attractions.

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“…A small quantity of PIB and PEO were mixed together to make a concentrated "masterbatch" using a custom ball mixer [38]. PIB (80 wt.…”

Section: B Sample Preparationmentioning

confidence: 99%