ISSN:
1435-1536
Keywords:
Polyurethane
;
hard segments
;
crystal structure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract Polyurethane elastomers extended with aliphatic glycols or diamines, show a characteristic fluctuation in their thermal and hydrothermal properties which is dependent on the number of CH2 groups in the chain extender (“even” or “odd”). The causes of this behavior are examined in the following report using X-ray crystallographic analyses of single crystals of model urethanes. These model compounds were prepared by reaction between diphenylmethane -4-mono-isocyanate and glycoles of the HO-(CH2)n-OH structure withn=2 to 6. Whilst strain-free hydrogen bonds can form between neighboring molecules in urethanes with “even” chain extenders, significant strains occur in urethanes containing “odd” chain extenders which result in reduced stability of the physical crosslinking system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01419091
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