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| [1.] Mrs/Fragment 014 01 - Diskussion Zuletzt bearbeitet: 2015-05-16 17:50:00 Hindemith | Bhattacharya et al. 2008, Fragment, Gesichtet, Mrs, SMWFragment, Schutzlevel sysop, Verschleierung |
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| Untersuchte Arbeit: Seite: 14, Zeilen: 1ff (entire page) |
Quelle: Bhattacharya et al. 2008 Seite(n): 27-29, Zeilen: 27: 19 ff.28: 9-12; 29: 10 ff. |
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| [Studies [30, 31] of both rubbery and glassy epoxy/clay nanocomposites using different type of amine curing agents were] conducted and the mechanisms leading to the mono-layer exfoliation of clay layers in thermoset epoxy systems were elucidated.
2.2.3. Elastomers Burnside and Giannelis [32] have described the two-step preparation of silicon rubber-based nanocomposites. First, silanol-terminated poly (dimethyl siloxane) (PDMS) was blended at room temperature with dimethyl-ditallow ammonium-exchanged montmorillonite, followed by crosslinking of the silanol end groups with tetra ethyl- orthosilicate (TEOS) in the presence of bis(2-ethylhexanoate) as catalyst at room temperature. Also Okada and co-worker [33] obtained a nitrile rubber (NBR) – based nanocomposite in a dual-step synthesis. 2.2.4. Natural and biodegradable polymers Natural and biodegradable polymers are a new generation of polymers that are relatively friendly to the environment with little or no impact when disposed. Such polymers include polylactide (PLA), starch, and cellulose among others. Although these polymers are considered to be environmentally-friendly, they have relatively weak mechanical properties, such as brittleness, low heat distortion, low tensile strength. And their use in packaging is limited due to high gas permeability [34]. Addition of nano-scale fillers has been shown to improve these properties significantly, allowing these polymers to be used in applications such as disposable food service items, food packaging, health care product, packing foams and agricultural mulch film. PLA polymers are linear aliphatic polyester, generally produced by ring-opening polymerization of lactide dimer. Sinha Ray and Okamoto [35] have shown that the addition of nanoscale modified montmorillonite increased both solid and melt state properties, such as flexural properties, rheological properties, reduced gas permeability and increased rate of biodegradability. Ogata et al. [36] also reported similar enhancement of properties. Another biodegradable polymer is polycaprolactone (PCL), linear polyester manufactured by ring-opening polymerization of ε-caprolactone. The PCL chain is flexible and exhibits high elongation at break and low modulus. Its physical properties make it very attractive, not only as a substitute material for nondegradable polymer but also as a plastic material for medical and agricultural applications. The main drawback of PCL is its low melting point (65°C ), which can be overcome by blending it with other polymers. Many attempts to prepare PCL nanocomposites with much improved mechanical and materials properties than that of neat PCL have been reported [34]. [30] P.B., Messersmith, E.P. Giannelies, Chemical Matterial 6, (1994), 1719-1725 [31] T. Lan, T.J. Pinnavaia, Chemical Materials, 6, 1994, 2216- 2219 [32] S.D., Burnside, E.P. Giannelis, Chemical Materials, 7, (1995), 1597-1600 [33] A. Okada, K. Fujumori, A. Usuki, Polymer Chemistry, 32,(2), 540-541, 1991 [34] S. Sinha Ray, M. Bousmina, Progress in Material Science, 50, 962-1079, 2005 [35] S. Sinha Ray, M. Okamoto, Macromolecule Rapid Communication,24 (14), 815- 840, 2003 [36] N. Ogata, G. jimentz, Journal of polymer science Part B, 35 (2), 389- 396, 1997 |
[S. 28]
Studies of both rubbery and glassy epoxy/clay nanocomposites using different types of amine curing agents were conducted and the mechanisms leading to the monolayer exfoliation of clay layers in thermoset epoxy systems were elucidated. [S.27] 2.3.2 Elastomers [Burnside and Giannelis (1995)] have described the two-step preparation of silicon rubber- based nanocomposites. First, silanol-terminated poly(dimethyl siloxane) (PDMS, Mw= 18000) was melt blended at room temperature with dimethyl-ditallow ammonium- exchanged montmorillonite, followed by cross-linking of the silanol end groups with tetraethyl-orthosilicate (TEOS) in the presence of bis(2-ethylhexanoate) as catalyst at room temperature. [...] [Okada and co-workers (1990), (1991)] obtained a nitrile rubber (NBR)-based nanocomposite in a dual-step synthesis. [S. 29]
Natural and biodegradable polymers are a new generation of polymers that are relatively friendly to the environment with little or no impact when disposed. Such polymers include polylactide (PLA), starch, and cellulose among others. Although these polymers are considered to be environmentally-friendly, they have relatively weak mechanical properties, such as brittleness, low heat distortion, low tensile strength, and their use in packaging is limited due to high gas permeability [Sinha Ray and Bousmina (2005)]. Addition of nanoscale fillers has been shown to improve these properties significantly, allowing these polymers to be used in applications such as disposable food service items, food packaging, health care products, packing foams and agricultural mulch film. PLA polymers are linear aliphatic polyesters, generally produced by ring-opening polymerization of lactide monomers. According to [Sinha Ray and Okamoto (2003)], their mechanical properties, thermal plasticity and biocompatibility are generally good and have much promise in many applications. They have, however, shown that the addition of nanoscale modified montmorillonite increased both solid and melt state properties, such as flexural properties, rheological properties, reduced gas permeability and increased rate of biodegradability. [...] Polycaprolactone (PCL) is a linear polyester manufactured by ring-opening polymerization of ε-caprolactone. [...] The PCL chain is flexible and exhibits high elongation at break and low modulus. Its physical properties and commercial availability make it very attractive, not only as a substitute material for nondegradable polymers for commodity applications, but also as a plastic material for medical and agricultural applications. The main drawback of PCL is its low melting point (65°C), which can be overcome by blending it with other polymers or by radiation cross-linking processes resulting in enhanced properties for a wide range of applications. Many attempts to prepare PCL nanocomposites with much improved mechanical and materials properties than that of neat PCL have been reported [Ray and Bousmina (2005)]. |
The source is not mentioned. All references to the literature except one have been taken from the source. |
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