Second virial coefficients, critical temperatures, and the molecular shapes of long n-alkanes
The second virial coefficient for a molecular model of n-alkanes with up to 200 carbon atoms has been computed for temperatures in the range of 1000 K<T<2000 K. The model used in the calculations is based on one which reproduces the experimental values of the second virial coefficient for short n-alkanes. The Boyle temperature of n-alkanes is not much affected by the length of the chain for n-alkanes with more than 100 carbon atoms. According to the Flory theory, for infinitely long chains the Boyle temperature and the critical temperature, denoted as the θ temperature are the same. On this basis using the present model we find θ=1620 K as the critical temperature of polymethylene. Scaling laws for the square of the end-to-end distance and for the radius of gyration at several temperatures are analyzed. For high temperatures, the scaling laws correspond to good solvent conditions whereas at the θ temperature the scaling laws are those of an ideal chain. The shape of long n-alkanes at several temperatures is also analyzed. We find that the polymethylene chains present an anisotropy similar to that of a parallelepiped with a ratio of sizes of 1:1.7:3.6. © 1996 American Institute of Physics..
| Medienart: |
E-Artikel |
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| Erscheinungsjahr: |
1996 |
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| Erschienen: |
1996 |
| Reproduktion: |
AIP Digital Archive |
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| Enthalten in: |
Zur Gesamtaufnahme - volume:105 |
| Enthalten in: |
The Journal of Chemical Physics - 105(1996), 10, Seite 4223-4233 |
| Sprache: |
Englisch |
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| Beteiligte Personen: |
Vega, Carlos [Sonstige Person] |
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| Links: |
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| Themen: |
ALKANES |
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| Umfang: |
11 |
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| doi: |
10.1063/1.472291 |
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| funding: |
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| Förderinstitution / Projekttitel: |
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NLEJ219119112 |
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| 245 | 1 | 0 | |a Second virial coefficients, critical temperatures, and the molecular shapes of long n-alkanes |
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| 520 | |a The second virial coefficient for a molecular model of n-alkanes with up to 200 carbon atoms has been computed for temperatures in the range of 1000 K<T<2000 K. The model used in the calculations is based on one which reproduces the experimental values of the second virial coefficient for short n-alkanes. The Boyle temperature of n-alkanes is not much affected by the length of the chain for n-alkanes with more than 100 carbon atoms. According to the Flory theory, for infinitely long chains the Boyle temperature and the critical temperature, denoted as the θ temperature are the same. On this basis using the present model we find θ=1620 K as the critical temperature of polymethylene. Scaling laws for the square of the end-to-end distance and for the radius of gyration at several temperatures are analyzed. For high temperatures, the scaling laws correspond to good solvent conditions whereas at the θ temperature the scaling laws are those of an ideal chain. The shape of long n-alkanes at several temperatures is also analyzed. We find that the polymethylene chains present an anisotropy similar to that of a parallelepiped with a ratio of sizes of 1:1.7:3.6. © 1996 American Institute of Physics. | ||
| 533 | |f AIP Digital Archive | ||
| 650 | 4 | |a MOLECULAR MODELS | |
| 650 | 4 | |a ALKANES | |
| 650 | 4 | |a VIRIAL EQUATION | |
| 650 | 4 | |a CRITICAL TEMPERATURE | |
| 650 | 4 | |a SCALING LAWS | |
| 700 | 1 | |a Vega, Carlos |4 oth | |
| 700 | 1 | |a López Rodríguez, Antonio |4 oth | |
| 773 | 0 | 8 | |i In |t The Journal of Chemical Physics |d College Park, Md. : Inst., 1933 |g 105(1996), 10, Seite 4223-4233 |h Online-Ressource |w (DE-627)NLEJ217994202 |w (DE-600)1473050-9 |x 1089-7690 |7 nnns |
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