Enhanced crystallization of bisphenol-A polycarbonate by nano-scale clays in the presence of supercritical carbon dioxide

Hu, Xiangming; Lesser, Alan J.

doi:10.1016/j.polymer.2003.12.079

Cited by 45 publications

(24 citation statements)

References 37 publications

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“…It is noted that the low-temperature twin peaks are almost identical to those reported by Hu and Lesser 12 for PC clay nanocomposites treated with ScCO 2 at 95…”

Section: 22supporting

confidence: 82%

“…There are implications, however, arising from the susceptibility of polycarbonate to undergo solventassisted crystallization during the treatment, 12,13 which have not yet been addressed in the literature.…”

Section: −10mentioning

confidence: 99%

“…• C. 12 From the foregoing discussion, it is evident that there is a lack of understanding of the effect of crystallization on the foaming of polycarbonate with the use of supercritical CO 2 . 13 The purpose of the present investigation is, therefore, to address this issue in order to determine the way in which crystallinity induced by supercritical CO 2 may affect the foaming process and the microstructure of the resulting products.…”

Section: −10mentioning

confidence: 99%

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Crystallization effects on autoclave foaming of polycarbonate using supercritical carbon dioxide

Mascia

Ponti

et al. 2006

Adv Polym Technol

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In this study, the conditions leading to the formation of cells and to the onset of crystallization of polycarbonate were examined with the use of supercritical carbon dioxide for the production of foams from preforms. Small plaques cut from extruded sheets were treated with supercritical carbon dioxide in an autoclave at temperatures varying from 60 to 200°C and from 4.5 to 30 MPa pressure. Visual observations and stereoscan electron microscopy examination revealed that penetration of supercritical carbon dioxide takes place via the advancing layer mechanism and that, for the particular grade of polycarbonate used in this study, the nucleation of the cells can take place at temperatures as low as 60°C. It requires, however, long treatment times and high pressures, and the growth of foam cells is severely restricted. Nucleation and growth of cells occurred much more readily at somewhat higher temperatures. With treatments at around 80°C, the onset of crystallization started to impose considerable hindrance to the formation of uniform and evenly distributed cells. This becomes increasingly evident at higher temperatures, between 100 and 180°C, owing to the formation of large spherulitic crystalline domains. A very effective nucleation and growth mechanism for the formation of cells was obtained, on the other hand, with treatments at 200°C due to the absence of crystallization phenomena. The degree of crystallinity increased with increasing treatment temperature, and the resulting morphology gave rise to two broad melting peaks. These are displaced to higher temperatures and become closer, merging into one peak with a low‐temperature shoulder. These events were monitored by thermal analysis and wide‐angle X‐ray diffraction examinations. © 2007 Wiley Periodicals, Inc. Adv Polym Techn 25:225–235, 2006; Published online in Wiley InterScience (http://www.interscience.wiley.com). DOI 10.1002/adv.20075

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“…It is noted that the low-temperature twin peaks are almost identical to those reported by Hu and Lesser 12 for PC clay nanocomposites treated with ScCO 2 at 95…”

Section: 22supporting

confidence: 82%

Section: −10mentioning

confidence: 99%

Section: −10mentioning

confidence: 99%

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Crystallization effects on autoclave foaming of polycarbonate using supercritical carbon dioxide

Mascia

Ponti

et al. 2006

Adv Polym Technol

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“…The melt crystallization of PC is a nucleation process nucleated by the nanometersize ionic aggregated species of SPS ionomer in the PC matrix. Hu et al 12 have shown that, in the presence of CO 2 , nanoscale clay is an efficient nucleating agent that enhances the crystallization of PC. Previous research has shown that the addition of clay into semicrystalline polymers such as syndiotactic polystyrene ionomer, 21 poly(ethylene terephthalate) ionomer 13 and nylon 6 14 can enhance the overall crystallization of the matrix polymer due to the nucleation effect of molecularly dispersed clay layers.…”

Section: Introductionmentioning

confidence: 99%

Enhanced crystallization of bisphenol-A polycarbonate by organoclay in the presence of sulfonated polystyrene ionomers

Govindaiah

Lee

et al. 2009

Macromol. Res.

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Polycarbonate (PC)/sulfonated polystyrene (SPS) ionomer/organoclay nanocomposites were prepared by a solution intercalation process using the SPS ionomer as a compatibilizer. The effect of an organoclay on the melt crystallization behavior of the ionomer compatibilized PC were examined by differential scanning calorimetry (DSC). The melt crystallization behavior of PC was dependent on the extent of organoclay dispersion. The effect of the ionomer loading and cation size on intercalation/exfoliation efficiency of the organoclay in PC/SPS ionomer matrix was also studied using wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). Dispersion of the organically modified clay in the polymer matrix improved with increasing ionomer compatibilizer loadings and cation size. The SPS ionomer compatibilized PC/organoclay nanocomposite showed enhanced melt crystallization compared to the SPS ionomer/PC blend. Well dispersed organoclay nanocomposites showed better crystallization than the poorly dispersed clay nanocomposites. These nanocomposites also showed better thermal stability than the SPS ionomer/PC blend.

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“…The other important advantage of SCF extraction is rapid separation of solutes that can be easily achieved by a reduction of pressure. Examples of large-scale commercial applications of the supercritical fluid extraction technology include crystallization, Hu and Lesser (2004), extraction of vitamins, natural flavors, perfumes, and essential oils from fruits and plants, Mansoori et al (1988) and Martinelli et al (1991), removal of unwanted materials, such as caffeine and cholesterol from food products, Mohamad and Mansoori (2002), and pollution remediation using environmentally friendly supercritical fluids Ekhtera et al (1997).…”

Section: Introductionmentioning

confidence: 99%

Supercritical Fluids: Nanotechnology and Select Emerging Applications

Chehroudi

2006

Combustion Science and Technology

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2. REPORT TYPE 3. DATES COVERED (From -To) ABSTRACTIn this paper, a selected list of emerging applications of supercritical fluids (SCFs) is presented. In particular, demonstrated facts for the promise of the nanoscale science and technology and its overlap or interface with the SCFs technology are presented. It is argued that nanoengineered materials at the nanoscale have mechanical, optical, chemical, and electrical properties quite different from the bulk material. Examples of enhanced performance of many such materials when they are used in practical applications are given. SCFs, in particular carbon dioxide, on account of their special properties such as zero surface tension, low viscosity, and high solubility, enable them to play a critical role in many advanced technology applications. For example, as miniaturization efforts approach the nanoscale, surface tension forces become an important factor in many nanotechnology processes such as lithography in the electronic industry. In particular, the zero-surface-tension property of the SCFs presents them as a natural choice for nanotechnology. This article maybe used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden.The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. In this paper, a selected list of emerging applications of supercritical fluids (SCFs) are presented. In particular, demonstrated facts for the promise of the nanoscale science and technology and its overlap or interface with the SCFs technology are presented. It is ...

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Enhanced crystallization of bisphenol-A polycarbonate by nano-scale clays in the presence of supercritical carbon dioxide

Cited by 45 publications

References 37 publications

Crystallization effects on autoclave foaming of polycarbonate using supercritical carbon dioxide

Crystallization effects on autoclave foaming of polycarbonate using supercritical carbon dioxide

Enhanced crystallization of bisphenol-A polycarbonate by organoclay in the presence of sulfonated polystyrene ionomers

Supercritical Fluids: Nanotechnology and Select Emerging Applications

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