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Study of the influence of nanoparticles on the performance and the properties of polyamide 6

von Dr. Mohammad Reza Sarbandi

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[1.] Mrs/Fragment 049 01 - Diskussion
Zuletzt bearbeitet: 2015-03-30 11:55:09 SleepyHollow02
Fornes 2003, Fragment, Gesichtet, Mrs, SMWFragment, Schutzlevel sysop, Verschleierung

Typus
Verschleierung
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Hindemith
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Untersuchte Arbeit:
Seite: 49, Zeilen: 1 ff. (entire page)
Quelle: Fornes 2003
Seite(n): 254, 255, 256, 258, 259, Zeilen: 254: 3 ff.; 255: 1 ff.; 256: 1 ff.; 258: 1 ff.; 259: 1 ff.
The disappearance of the γ-form at ~190 °C has been commonly referred to as the Brill transition, a phenomenon first observed in polyamide 66 [195]. This transition corresponds to the merging of the two reflections of the α-form into a single peak in plots of X-ray diffraction intensity versus 2 [196-199] as the sample is heated. Kyotani and Mitsuhashi [194] also found that very short crystallization times at either 100 or 200 °C lead to both crystalline forms, while longer times produced predominantly γ- and α-form, respectively. In general, rapid cooling or quenching from the melt produces the γ-form [196, 200-202]. Annealing also affects the crystal structure. For example, annealing of quenched samples or those crystallized between 100 and 150 °C, at 200 °C for extended times leads to the conversion of the γ- into α-form [194]. Gogolewki et al. [186] and Gurato et al. [193] demonstrated similar annealing results. Based on the above, it is clear that, in general, rapid cooling and low temperature crystallization promotes the γ-form of polyamide 6, while higher crystallization temperatures or slow cooling leads to the α-form. Kyotani and Mitsuhashi [194] attribute the temperature dependence to the crystallization rates of the two forms; i.e. at temperatures below 130 °C the rate of formation of γ is faster, while above ~190 °C the crystallization rate of α-form is faster, while at intermediate temperatures, the rates are comparable. Interestingly, the maximum crystallization rate of polyamide 6 occurs at approximately 140 °C [203]. The temperature dependence of the crystallization rate above this maximum is dominated by the driving force for crystallization, i.e. the degree of undercooling, while below, the rate is dominated by the resistance to crystallization, i.e. polymer chain mobility. Therefore, it may be postulated that conditions of limited polymer chain mobility favor the crystallization of the γ-form for polyamide 6.

Studies of polyamide 6-based nanocomposites have caused renewed interest in the factors affecting the crystalline structure. As mentioned above, Kojima et al. [203] and Liu et al. [165] reported that when the one nanometer thick platelets of montmorillonite are dispersed in polyamide 6 the polymer crystallizes in the γ-form. Wu and coworkers [204-207] examined the influence of thermal treatment on the crystallization behavior of melt processed nanocomposites using FTIR, WAXD, and DSC. From FTIR measurements on thin film samples, it has been claimed that the hydrogen bonding in both crystalline forms of polyamide 6 is weakened by the presence of the clay. WAXD analysis revealed that nanocomposites films exhibit both crystalline forms when slowly cooled from the melt; whereas, pure polyamide 6 gave predominantly the α-form. Methods that permit higher cooling rates, e.g. air and water-cooling, have increased the content of the γ-phase especially for the nanocomposite. Further WAXD investigations conducted on samples that had been annealed at different temperatures showed the onset of [the γ- to α- transition, normally observed around 130 °C for p ure polyamide 6, in this case at 120 °C, occurred approximately 40 °C higher for the nan ocomposite.]


[165] L.M. Liu, Z.N. Qi, X.G. Zhu, J Applied Polymer Science 1999, 71, 1133.

[186] D.C. Vogelsong, J Polymer Science 1963; 1(Pt. A):1055–68.

[193] M. Kyotani, S. Mitsuhashi, J Polymer Science, Part A-2 1972; 10(8): 1497–508.

[194] R.J. Brill für Praktische Chemie 1942;161:49–64.

[195] N. Murthy, S.M. Aharoni, A. Szollosi, J Polymer Science, Polymer Physics Edition 1985; 23(12):2549–65.

[196] N.Murthy, S.A. Curran, S.M. Aharoni, H. Minor, Macromolecules 1991; 24(11):3215–20.

[197] C. Ramesh, E.B. Gowd, Macromolecules 2001; 34(10):3308–13.

[198] D.M. Lincoln, R.A. Vaia, Z.G. Wang, B.S. Hsiao, R. Krishnamoorti, Polymer 2001; 42(25):09975–85.

[199] D.R. Salem, R. Moore, H. Weigmann, J. Polymer Science, Part B: Polymer Physics 1987; 25(3):567–89.

[200] I. Campoy, M.A. Gomez, C. Marco, Polymer 1998; 39(25):6279–88.

[201] A. Okada, M. Kawasumi, I. Tajima, J Applied Polymer Science 1989;37(5):1363–71.

[202] J.H. Magill, Polymer 1962; 3:655–64.

[203] Y. Kojima, A. Usuki, M. Kawasumi, A. Okada, J Material Research 1993; 8(5):1185–9.

[204] Q. Wu, X. Liu, L. Berglund, Macromolecular Rapid Communications 2001;22(17): 1438– 40.

[205] X.Liu, Q. Wu, European Polymer Journal 2002;38(7):1383–9.

[206] Q. Wu, X. Liu, Berglund LA. Polymer 2002;43(8):2445–9.

[207] X. Liu, Q. Wu, Polymer 2002;43(6):1933–6.

The disappearance of the γ−form at ~190°C has been commonly referred to as the Brill transition, a phenomenon first observed in nylon 6,6 [29]. This transition corresponds to the merging of the two reflections of the α-form into a single peak in plots of X-ray diffraction intensity versus 2θ [30-33] as the sample is heated.

[page 255]

Kyotani and Mitsuhashi [28] found that very short crystallization times at either 100 and 200°C lead to both crystalline forms, while longer times produced predominantly γ and α , respectively. In general rapid cooling or quenching from the melt produces the γ-form [30, 34-36].

Annealing also affects the crystalline structure. For example, annealing of quenched samples, or those crystallized between 100 and 150 °C, at 200 °C for extended times leads to the conversion of the γ into α [28]. Similar annealing results were demonstrated by Gogolewki et al. [19] and Gurato et al. [27]. [...]

Based on the above, it is clear that, in general, rapid cooling and low temperature crystallization promotes the γ-form of nylon 6, while higher crystallization temperatures or slow cooling leads to the α-form. Kyotani and Mitsuhashi [28] attribute the temperature dependence of the α- and γ-form to their crystallization rates; i.e., at temperatures below 130°C the rate of formation of γ is faster, while above ~190°C the crystallization rate of α is faster, while at intermediate temperatures, the rates are comparable.

[page 256]

Interestingly, the maximization crystallization rate of nylon 6 occurs at approximately 140°C [37]. The temperature dependence of the crystallization rate above this maximum is dominated by the driving force for crystallization, i.e., the degree of undercooling, while below, the rate is dominated by the resistance to crystallization, i.e., polymer chain mobility. Therefore, it may be postulated that conditions of limited polymer chain mobility favor the crystallization of the γ-form for nylon 6.

[page 258]

Studies of nylon 6-based nanocomposites have caused renewed interest in the factors affecting the crystalline structure. As mentioned above, Kojima et al. [1] and Liu et al. [2] reported that when the one nanometer thick platelets of montmorillonite are dispersed in nylon 6 the polymer crystallizes in the γ-form. [...]

Wu and coworkers [49-52] examined the influence of thermal treatment on the crystallization behavior of melt processed nanocomposites using FTIR, WAXD, and DSC. From FTIR measurements on thin film samples, it has been claimed that the hydrogen bonding in both crystalline forms of nylon 6 are weakened by the presence of the clay. WAXD analysis revealed that nanocomposites films exhibit both crystalline forms when slowly cooled from the melt; whereas, pure nylon 6 gave predominantly the α form. Methods that permit higher cooling rates, e.g., air and water-cooling, increased the content of the γ- phase especially for the nanocomposite. Further WAXD investigations conducted on samples that had been annealed at different temperatures showed the onset of

[page 259]

the γ to α transition, normally observed around 130°C for pure nylon 6, in this case 120°C, occurred approximately 40°C higher for the nanocomposite.


1. Kojima, Y, Usuki, A, Kawasumi, M, Okada, A, Fukushima, Y, Kurauchi, T, Kamigaito, O. J Mater Res 1993;8(5): 1185-9.

2. Liu, L, Qi, Z, Zhu, X. J Appl Polym Sci 1999;71(7): 1133-8.

19. Gogolewski, S, Gasiorek, M, Czerniawska, K, Pennings, AJ. Colloid Polym Sci 1982;260(9): 859-63.

27. Gurato, G, Fichera, A, Grandi, FZ, Zannetti, R, Canal, P. Makromol Chem 1974;175(3): 953-75.

28. Kyotani, M, Mitsuhashi, S. J Polym Sci, Part A-2 1972;10(8): 1497-508.

29. Brill, R. J prakt Chem 1942;161: 49-64.

30. Murthy, NS, Aharoni, SM, Szollosi, AB. J Polym Sci, Part B 1985;23(12): 2549-65.

31. Murthy, NS, Curran, SA, Aharoni, SM, Minor, H. Macromolecules 1991;24(11): 3215-20.

32. Ramesh, C, Gowd, EB. Macromolecules 2001;34(10): 3308-13.

33. Lincoln, DM, Vaia, RA, Wang, ZG, Hsiao, BS, Krishnamoorti, R. Polymer 2001;42(25): 9975-85.

34. Salem, DR, Moore, RAF, Weigmann, HD. J Polym Sci, Part B 1987;25(3): 567-89.

35. Campoy, I, Gomez, MA, Marco, C. Polymer 1998;39(25): 6279-88.

36. Okada, A, Kawasumi, M, Tajima, I, Kurauchi, T, Kamigaito, O. J Appl Polym Sci 1989;37(5): 1363-71.

37. Magill, JH. Polymer 1962;3: 655-64.

49. Wu, Q, Liu, X, Berglund, LA. Macromolecular Rapid Comm 2001;22(17): 1438-40.

50. Liu, X, Wu, Q. European Polymer Journal 2002;38(7): 1383-9.

51. Wu, Q, Liu, X, Berglund, LA. Polymer 2002;43(8): 2445-9.

Anmerkungen

The source is not mentioned.

Sichter
(Hindemith), SleepyHollow02


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