Microencapsulation Process Factors Which Influence the Sphericity of 1 mm o.d. Poly(α-Methylstyrene) Shells for ICF

McQuillan, B.W.; Greenwood, A.

doi:10.13182/fst99-a11963921

Cited by 25 publications

(16 citation statements)

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“…All physical properties of the microcapsules will be established at that time (e.g. size distribution, 110 morphology, shape, …) [13][14]. Indeed, the dispersion of the organic phase in the continuous phase is prepared by a fragmentation process where wide areas of oil are broken up by shear or elongation.…”

Section: Preparation Of Microcapsules 80mentioning

confidence: 99%

Polymer nanoparticles to decrease thermal conductivity of phase change materials

et al. 2008

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Microparticles including paraffin are currently used for textiles coating in order to 15 deaden thermal shocks. We will show that polymer nanoparticles embedded in those microsized capsules allow for decreasing the thermal conductivity of the coating and enhance the protection in the stationary regime. A reasonable volume fraction of polymer nanoparticles reduces the conductivity more than predicted by Maxwell mixing rules. Besides, measurements prove that the polymer nanoparticles do not 20 affect the latent heat and even improve the phase change behaviour as well as the mechanical properties.

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Section: Preparation Of Microcapsules 80mentioning

confidence: 99%

Polymer nanoparticles to decrease thermal conductivity of phase change materials

et al. 2008

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“…It was also demonstrated that an increasing interfacial tension as well as density matching would improve the sphericity of polymer shells. [15][16][17][18][19][20] Liu increased the interfacial tension between the O-W2 boundary by adopting n-hexadecane as a third component in the O phase to improve the sphericity of polymer shells. 21 The effects of molecules of poly(vinyl alcohol) (PVA), which is used as stabilizer on the formation, stability and deformation of W1/O/W2 double droplets, has also been investigated.…”

Section: Introductionmentioning

confidence: 99%

Influence of fluorobenzene mass transfer on the qualities of poly-α-methylstyrene shells

Chen

Liu

et al. 2018

RSC Adv.

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Polymer shells prepared by the microencapsulation technique with perfect sphericity and defect-free surface finish are demanded in inertial confinement fusion (ICF) experiments. The sphericity and surface finish are some of the hardest specifications to fulfill. Driven by the need to improve qualities of the polymer shells to meet the critical specifications, the effects of fluorobenzene (FB) mass transfer rate on sphericity and surface finish were investigated and the mechanisms of the effects of FB mass transfer on sphericity and surface finish of poly-a-methylstyrene (PAMS) were also discussed. The sphericity and surface finish of the PAMS shells are greatly improved by decreasing the FB mass transfer rate. The calculative frequency of the final shells with an out-of-round (d OOR ) of less than 2 mm increases from 30% to 80%, while the power spectra density (PSD) plot gets closer to the specification of the national ignition facility (NIF). The tracking experiments show that the curing process is extended and the percolation transition is also postponed by decreasing the FB mass transfer rate. Therefore, the interfacial tension can work sufficiently, helping make double droplets become spherical, since the double droplets' stay in the liquid state is effectively extended. Moreover, the Marangoni instabilities at the O-W2 boundary are also restrained by controlling the mass transfer, due to the diffusivity of FB being slowed down. Both the results and methods presented in this work provide a more in-depth understanding of the curing process and the mass transfer, to the benefit of fabricating polymer shells with high sphericity and defect-free surface finish used in ICF experiments.

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“…These issues led to the widely-adopted conclusion, that such polymer shells should be cured slowly by a mild process (low polymerisation stress generation, and long relaxation time), to attain a spherical and concentric form. In addition, it has been assumed that, the component liquid phases of DE droplets must be density matched 32 . This is generally achieved by using a non-reactive solvent 23 , so that the inner droplet could be more readily centralised within the DE droplet, by hydrodynamic (buoyancy) forces during polymerisation.…”

Section: Introductionmentioning

confidence: 99%

Continuous and scalable polymer capsule processing for inertial fusion energy target shell fabrication using droplet microfluidics

Lindley-Start

Porch

et al. 2017

Sci Rep

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High specification, polymer capsules, to produce inertial fusion energy targets, were continuously fabricated using surfactant-free, inertial centralisation, and ultrafast polymerisation, in a scalable flow reactor. Laser-driven, inertial confinement fusion depends upon the interaction of high-energy lasers and hydrogen isotopes, contained within small, spherical and concentric target shells, causing a nuclear fusion reaction at ~150 M°C. Potentially, targets will be consumed at ~1 M per day per reactor, demanding a 5000x unit cost reduction to ~$0.20, and is a critical, key challenge. Experimentally, double emulsions were used as templates for capsule-shells, and were formed at 20 Hz, on a fluidic chip. Droplets were centralised in a dynamic flow, and their shapes both evaluated, and mathematically modeled, before subsequent shell solidification. The shells were photo-cured individually, on-the-fly, with precisely-actuated, millisecond-length (70 ms), uniform-intensity UV pulses, delivered through eight, radially orchestrated light-pipes. The near 100% yield rate of uniform shells had a minimum 99.0% concentricity and sphericity, and the solidification processing period was significantly reduced, over conventional batch methods. The data suggest the new possibility of a continuous, on-the-fly, IFE target fabrication process, employing sequential processing operations within a continuous enclosed duct system, which may include cryogenic fuel-filling, and shell curing, to produce ready-to-use IFE targets.

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Microencapsulation Process Factors Which Influence the Sphericity of 1 mm o.d. Poly(α-Methylstyrene) Shells for ICF

Cited by 25 publications

References 1 publication

Polymer nanoparticles to decrease thermal conductivity of phase change materials

Polymer nanoparticles to decrease thermal conductivity of phase change materials

Influence of fluorobenzene mass transfer on the qualities of poly-α-methylstyrene shells

Continuous and scalable polymer capsule processing for inertial fusion energy target shell fabrication using droplet microfluidics

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