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Trifluoroethanol/chloroalkane mixtures: Excellent novel solvents for aliphatic polyamides
Author(s) -
Aharoni Shaul M.,
Cilurso Frank G.,
Hanrahan James M.
Publication year - 1985
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1985.070300618
Subject(s) - nylon 6 , solubility , polymer , nylon 66 , solvent , polymer chemistry , dissolution , solvation , phase diagram , molecule , materials science , polyamide , phase (matter) , hildebrand solubility parameter , chemistry , organic chemistry
Certain mixtures of TFE/CHCl 3 were found to be excellent solvents for aliphatic polyamides such as nylon‐6, nylon‐66, nylon‐11, nylon‐12, nylon‐69, nylon‐610, and nylon‐612. Intrinsic viscosities were measured and Mark–Houwink coefficients determined for nylon‐6/TFE/CHCl 3 , indicating TFE‐rich mixtures to be better solvents than TFE alone. Similar results were obtained for TFE/CH 2 Cl 2 . Four ternary phase diagrams were constructed for nylon‐6/TFE/chloroalkanes, of which the ones with CHCl 3 and CH 2 Cl 2 are the most interesting. In the nylon‐6/TFE/CHCl 3 diagram higher nylon‐6 solubility in TFE‐rich mixtures and a biphasic region in the CHCl 3 ‐rich compositions are evident. In the TFE/CH 2 Cl 2 system, the higher dissolution of nylon‐6 is observed, but no biphasic regions are detected. In certain solvent compositions and/or polymer concentrations the polymer is incompletely soluble, making the phase diagrams rather complicated. Observed thermodynamic excess properties appear to relate to the quality of TFE/chloroalkanes as solvents for nylon‐6. Studies on swelling of nylon‐6 networks immersed in TFE/CHCl 3 show a behaviour previously described by Krigbaum and Carpenter for a general case where the formation of contracts between molecules of the two solvents is discouraged and their preferential solvation of the polymer is, therefore, encouraged. The phenomena observed in this work can be qualitatively explained as arising from antagonistic interaction of TFE molecules with chloroalkane ones. The presence of the polyamides in solution reduces such contacts, enchancing the dissolution of the polymer in the (TFE‐rich) solvent mixtures.