The subject of this study was urethane elastomers synthetized from oligo (ethylene adipate) and diphenyl-methane-4,4′-di-isocyanate extended by means of 3,3′-dichloro-4,4′-diamine-diphenyl-methane with 1,4-butylene glycol. It has been demonstrated, with the aid of the method used by Weisfeld and co-workers that the changes in the NCO:OH molar relation from 2.75 to 5 at the prepolymer synthesis stage are the cause of an increase in the total crosslinking density as well as those derived from the primary and secondary valence crosslinks. The application of diamine as a chain extender, in comparsion with glycol, causes an increase of the crosslinking densities under investigation. The observed changes in the crosslinking stage of the elastomers obtained have been explained on the basis of the segment structure of the normal chains. The apparent differences in the crosslinking density by primary valence crosslinks, as determined chemically and by the method of Weisfeld et al., have been explained on the basis of IR measurements of the changes in the hydrogen bonding contents as functions of temperature.
No takes yet. Share an insight, caveat, or question.
Rutkowska et al. (1980) studied this question.