R. F. Harris, Jason E. Kinney, M. Savina
1995
Citations
0
Influential Citations
7
Citations
Journal
Polymer
Abstract
The reactions of urea with 1,6-hexanediamine at 150°C in a polyol continuous phase in the presence of a stabilizer for the resultant particles, produce low-molecular-weight oligomers of urea-terminated poly(1,6- hexamethyleneurea) having a Mn in the range of 500–700 gmol−1. This is thought to involve a polymerization/precipitation mechanism in which the molecular units are held together by hydrogen bonding into a macrostructure which separates as a stable dispersed phase. This macrostructure has a spiral fibre bundle morphology, a particle size distribution of about 1 to 10 μm, and aspect ratios from about 6 to 20. The urea-terminated poly(1,6-hexamethyleneurea) particles are highly crystalline thermoplastics with a melting point of ∼ 270°C and are only soluble in strong acids, where the macroparticles dissociate into their molecular units. High-molecular-weight poly(1,6-hexamethyleneurea) has been synthesized in bulk by other methods and is reported to have a melting point in the range 270–300°C. Urea-terminated poly(1,6- hexamethyleneurea) oligomers having a spiral fibre bundle morphology have not been previously reported. These materials are useful as filled polyols for polyurethanes.