Low-density, microcellular polystyrene foams

Aubert, J.; Clough, R.L.

doi:10.1016/0032-3861(85)90186-7

Cited by 159 publications

(98 citation statements)

References 6 publications

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“…No liquid-liquid phase separation is observed when solutions of polylactides in 1,4-dioxane are cooled, at least until a solid-liquid phase separation occurs due to solvent crystallization. A similar observation has been reported by Aubert and Clough 25 for the polystyrene/ benzene system, which corresponds to the case where the critical solution temperature (T c ) is largely lower than the freezing point (T f ). The freezing temperature of 1,4-dioxane has been measured in the whole composition range, as shown in Figure 1.…”

Section: Results and Discutionsupporting

confidence: 87%

“…Therefore, the cooling mode and the phase-separation mechanism are expected to have a critical effect on the porous morphology of the final material. It is well known 25 that two types of liquid-liquid phase separation can occur when a homogeneous polymer solution is cooled. Between the binodal and spinodal curves of the phase diagram, the liquid-liquid phase separation proceeds through a nucleation and growth mechanism and gives rise to a generally dispersed structure.…”

Section: Results and Discutionmentioning

confidence: 99%

“…Several authors have reported that the porosity of foams prepared by freeze-drying depends on the quenching rate of the original homogeneous polymer solution 20,22,25 . A faster quenching usually results in a decrease of the average pore size.…”

Section: Preparation Of Polylactide Foams By Freeze-dryingmentioning

confidence: 99%

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Biodegradable and macroporous polylactide implants for cell transplantation: 1. Preparation of macroporous polylactide supports by solid-liquid phase separation

Schugens

Maquet

Grandfils

et al. 1996

Polymer

252

149

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Freeze-drying of polylactide solutions in 1,4-dioxane has been studied as a way to produce microcellular foams. The thermally induced phase separation has been studied in relation to several processing and formulation parameters. The effects of polymer concentration, chain stereoregularity, polymer molecular weight and cooling rate have been investigated in connection with the porous morphology and the physico-mechanical characteristics of the final foams. As a rule, bundles of channels are formed with a diameter of ~100 µ.m. They have a preferential orientation that fits the cooling direction. A porous substructure (~10 µm) is observed in the internal walls of the tubular macropores. Variations in this general porous morphology-and particularly in the porosity, density, solvent residue, mechanical resistance and degree of regularity in the spatial organization of pores-have been observed when polymer concentration in 1,4-dioxane and polylactide stereoregularity are changed. As expected, cooling rate has a strong effect on the foam morphology, which is essentially controlled by the solvent crystallization. Pores are nothing but the fingerprints of 1,4-dioxane crystallites.

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Section: Results and Discutionsupporting

confidence: 87%

Section: Results and Discutionmentioning

confidence: 99%

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Biodegradable and macroporous polylactide implants for cell transplantation: 1. Preparation of macroporous polylactide supports by solid-liquid phase separation

Schugens

Maquet

Grandfils

et al. 1996

Polymer

252

149

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“…As a general technique, TIPS has been widely used to fabricate a variety of polymer foams such as poly(4-methyl-1pentene) [5], polystyrene [6], and polyethylene. To obtain a better foam structure, the type of phase separation should be liquid-liquid phase separation with the co-solvent.…”

mentioning

confidence: 99%

Development of Perdeuterated Polymer Foams for Inertial Confinement Fusion Targets in China

Zhang

Luo

et al. 2009

Plasma and Fusion Research

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In this paper, we report the progress made in fabrication of perdeuterated polymer foam materials such as deuterated polystyrene (d-PS), deuterated polyethene (d-PE), and deuterated divinylbenzene (d-DVB) based on the inertial confinement fusion (ICF) research in China. Perdeuterated DVB foams were fabricated using the high internal phase emulsion (HIPE) technique, and perdeuterated PS and PE foams were prepared via the thermally-induced phase separation (TIPS) of polymer solution and freeze-drying. As a result, foams with a deuterium/hydrogen (D/H) ratio of more than 95%, density of 10-200 mg/cm 3 , and average porous sizes of 1-20 µm were obtained. Deuterated polymer foams as a type of target material can be widely used in high-gain, high-density compression fusion targets, for example, as supporting materials in multilayer targets, as holders of liquid or solid DT layers in cryogenic targets, and so on. They are more essential than other protonated polymer foams because of the following advantages [1]: they are more chemically and physically stable, are nonradioactive, and have a very high proportion of D/H (more than 98%). Therefore, not only can they increase the fusion fuel density of fusion targets but can also improve the wettability of liquid deuterium-tritium (DT).It is well known that in mild conditions the exchange of deuterium and hydrogen is very difficult. Therefore, the method of fabrication of deuterated polymer foams is similar to that for protonated polymers such as HIPE, TIPS, and Sol-Gel. However, there are few deuterated polymers for the fabrication of low-density foams at present.Steckle et al.[2] first reported a method to synthesize deuterated DVB (d-DVB). Moreover, they prepared perdeuterated polymer foams with d-DVB by means of the HIPE technique. The synthesis method is quite complex and includes a D/H exchange reaction using the high temperature and dilute acid (HTDA) technique. In our work, partially replaced deuterium foams were prepared from deuterated styrene (d-St) and protonated divinylbenzene (DVB) [3] using the HIPE technique. However, the deuterated ratio values of those foams were less than 90%.As an alterative technique, TIPS could be a competent method for fabricating perdeuterated polymer foams. Combined with freeze-drying, it can be used to prepare many low-density polymer foams such as polystyrene, PE, poly(4-methyl-1-pentene) (PMP), and cellulose. The author's e-mail: zhlmy@sina.com structure and density of the fabricated foams can be controlled by controlling the concentration of the polymer solution and the freezing rate of the solution. Using these two techniques, PMP, PS, and PE foams were prepared in our laboratory. They had a density of 10-200 mg/cm 3 and an average porous size of 1-10 µm. Meanwhile, d-PS and d-PE were also prepared; they had D/H ratios and purities of more than 98%.Because of different demands of ICF experiments in terms of density, porous size, deuterium content, etc, different foams need to be developed. In this paper, the fabrication methods...

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“…Therefore, the cellular polymers can be used as structural components for heat insulation and packaging in many engineering sectors [1]. Currently, the preparation of cellular polymers can be conducted by four methods: they are (i) thermo-induced phase separation [2], (ii) monomer polymerization [3], (iii) compression fluid anti-solvent precipitation [4] and (iv) ultra gas saturating [5]. In this study, a novel cellular PET fiber (hereafter called "CPET fiber") was prepared by using the ultra saturating gas method.…”

Section: Introductionmentioning

confidence: 99%

Preparation of a Novel Cellular Fiber: Control of Cell Density of the Fiber

et al. 2006

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Abstract:A new cellular fiber was obtained by a post-treatment of spun fibers. Cellular polymers such as poly(ethylene terephthalate) show great promise for different engineering applications due to their high density property. Recent study has shown that some high density cellular polymers possess long fatigue life and/or equivalent strengths as compared with commercial-type neat polymers. However, only few studies have focused on the process of cellular polymer fibers to date. In this paper, the effect on a cellular structure of cellular PET fibers (hereafter called "CPET fibers") subjected to different forming processes is discussed. An ultra saturating gas method was used to fabricate the CPET fibers with different cell densities. Inert gas nitrogen (N 2 ) was saturated in PET fiber at high pressure to form a polymer/gas system. A pressure vessel was then discharged and polymer/gas solutions were foamed at a temperature controlled medium. The effect on the fiber's cellular structure, particularly on the fiber cell density with different processing parameters such as pressure, saturation time, foaming temperature and time was investigated in detail. Experimental results showed that the cell density of the CPET fibers increased with increasing the pressure, saturation time, foaming temperature and time. The saturation time and pressure are key factors that affect the density of cells formed inside the CPET fibers. The foaming time however showed no substantial influence on the cell density of the fibers when held longer than 10s.

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Low-density, microcellular polystyrene foams

Cited by 159 publications

References 6 publications

Biodegradable and macroporous polylactide implants for cell transplantation: 1. Preparation of macroporous polylactide supports by solid-liquid phase separation

Biodegradable and macroporous polylactide implants for cell transplantation: 1. Preparation of macroporous polylactide supports by solid-liquid phase separation

Development of Perdeuterated Polymer Foams for Inertial Confinement Fusion Targets in China

Preparation of a Novel Cellular Fiber: Control of Cell Density of the Fiber

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