Prediction of Phase Separation During the Drying of Polymer Shells

Wilemski, Gerald; Boone, Travis; Cheung, L.Y.G.; Nelson, Donald S.; Cook, Robert

doi:10.13182/fst95-a30411

Cited by 10 publications

(3 citation statements)

References 11 publications

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“…Generally the beads were cloudy indicating the presence of many small (few micron) voids well known in microencapsulation work. 9 Measurements of size and mass indicated that the internal void volume was no more than a few percent.…”

Section: Methodsmentioning

confidence: 99%

Thermal decomposition of polystyrene in the high temperature fabrication technology of hollow microspheres. Revision 1

Dorogotovtsev

Akunets

Merkuliev

et al. 1997

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The degree and nature of polymer degradation that occurs in the high temperature microshell formation process developed at the Lebedev Physical Institute has been examined experimentally. We find that significant mass degradation occurs during the final stages of shell formation. This manifests itself both in terms of mass loss and molecular weight degradation as measured by gel permeation chromatography. This decrease in the molecular weight may be in part responsible for the relatively fragile nature of the shells produced by this high temperature process.

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Section: Methodsmentioning

confidence: 99%

Thermal decomposition of polystyrene in the high temperature fabrication technology of hollow microspheres. Revision 1

Dorogotovtsev

Akunets

Merkuliev

et al. 1997

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“…In the sorption description, the polymer membrane is treated either as a homogenous amorphous surrounding where solute molecules are dissolved, or as surrounding including amorphous and the crystalline phases, where molecules of solutes are dissolved only in the homogenous amorphous phase and crystalline phase behaves as an inert phase [28]. Examples of the models used to describe these systems include: (i) the Flory-Huggins equation [29][30][31][32]; the Flory-Rehner equation [28,[33][34][35][36][37], which is a modified form of the original Flory-Huggins equation; (iii) the UNIFAP model [28,[38][39][40][41][42], which is based on the UNIFAC model [43,44]. A different approach for highly concentrated polymer solutions and swelled membranes immersed into liquid solutions was given by van de Witte et al [45] and Young et al [46], in which the ternary interaction parameter in the Flory-Huggins equation was used.…”

Section: Introductionmentioning

confidence: 99%

Describing the sorption characteristics of a ternary system of benzene (1) and alcohol (2) in a nonporous polymer membrane (3) by theFlory–Huggins model

Hovorka

Randová

Sysel

et al. 2014

Polymer Engineering & Sci

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The Flory-Huggins equation was used to describe results of total and preferential sorption measurements for the binary liquid mixture of benzene (1) and alcohol (2) in one of two nonporous polymer membranes (3), low-density polyethylene (LDPE) and Nafion membrane. The concentration dependence of binary and ternary interaction parameters was determined. The interaction parameters for the benzene -methanol binary mixture were obtained from binary vapor-liquid equilibrium data in the literature to decrease the number of adjusted parameters. The results show that use of a ternary interaction parameter is necessary. Data treatment was performed assuming either no crystallinity or an average crystallinity typical for the studied membranes. Subsequently, the limiting activity coefficients of solutes in LDPE were calculated from the values of the interaction parameters and their values compared to values of the limiting activity coefficients of benzene and methanol in hypothetical liquid alkane with the same density as LDPE obtained by the UNIFAC method. POLYM. ENG. SCI., 55:1187-1195

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“…This is not explicitly true for the decomposable mandrel approach. Details of vacuole formation and the associated phase separation have been investigated previously (Wilemski, 1995;Boone, 1995). Because we are implementing a decomposable mandrel approach (Letts, 1995a;1995b;1996), vacuoles are not an issue for us (provided their formation does not affect the exterior shell surface), and they will not be discussed further in any great detail.…”

Section: Introductionmentioning

confidence: 99%

Science of NIF scale capsule development (activities for FY97)

Hamilton¹,

Buckley²,

Cook³

1997

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The focus of this work is the production of 2-mm PczMS mandrels by microencapsulation for use as National Ignition Facility (NH?) laser targets. It is our findings thus far that the processing techniques used previously for the 0.5mm and I.O-mm targets are no longer usefid for preparation of the larger targets for a few fundamental reasons. The driving force for sphericity (from the minimization of interracial energy) decreases as the radius of curvature increases. Simultaneously, the mechanical robustness /stability of the wateroil-water emulsion droplets decreases as the droplet size increases. The impact of these physical conditions and the possibilities of circumventing these limitations have been examined while attempting to meet the NIF shell power spectrum criteria. Identi&ing the key parameters in the transition (solidification) from a w-o-w droplet to a solid polymer shell has been understood implicitly to be the paramount goal. It is believed through the knowledge gained that it will be possible to minimize the deleterious forces and maximize shell sphericity. At this point it is believed that properties intrinsic to the polymer (i.e., PcxMS) such as its solution behavior and evolution of iilm stresses control the overall shell sphericity.

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Prediction of Phase Separation During the Drying of Polymer Shells

Cited by 10 publications

References 11 publications

Thermal decomposition of polystyrene in the high temperature fabrication technology of hollow microspheres. Revision 1

Thermal decomposition of polystyrene in the high temperature fabrication technology of hollow microspheres. Revision 1

Describing the sorption characteristics of a ternary system of benzene (1) and alcohol (2) in a nonporous polymer membrane (3) by theFlory–Huggins model

Science of NIF scale capsule development (activities for FY97)

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