ISSN:
0025-116X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The dimer of ∊-caprolactam (1,8-diazacyclotetradecan-2,9-dione), an impurity always present in industrial nylon 6, was characterized by mass spectrometry and solution 13C NMR analysis. DSC and X-ray diffraction lead to the complete description of the behavior of two crystalline phases: the one stable at room temperature and showing a transition to the other form at 244°C; the second one, more symmetrical, melting at 347°C and slowly converting to the first one at temperatures below 200°C. Both structures are stabilized by intermolecular hydrogen bonds, and the transition is due to conformational changes (from G+TTG- to G+G+TG+ on the aliphatic sequence and from eclipsed to ≈90° on the N—CH2 bonds) which can be taken into account in the discussion about the tight chain folding of nylon 6.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/macp.1987.021881125
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