Heats of mixing of atactic polybutene-1 and of a model molecule with normal alkanes-order in long alkanes
✍ Scribed by G. Delmas; P. Tancrède
- Publisher
- Elsevier Science
- Year
- 1973
- Tongue
- English
- Weight
- 674 KB
- Volume
- 9
- Category
- Article
- ISSN
- 0014-3057
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✦ Synopsis
Heats of mixing at infinite dilution of atactic polybutene-1 in the alkanes have been measured at 25 ° with a Calvet microcalorimeter. Heats for a model molecule, the 3,5-dimethylheptane, in the same alkanes were obtained also. The enthalpy parameter Xn was found to be very close for the two sets of systems. Fitting the experimental data with the calculated free volume term of the heats, the parameter X~ 2 (as expressed in the Flory theory) is found to go through a minimum with chain length. This feature is explained thus: for longer alkanes, the large heat is thought to be due to loss of order in the chain solvent. For the short alkanes, X~2 is found large to compensate an overestimation of the free volume term.