Aromatic Diamines as Chain Extenders in Rim Urethane Elastomers

Crosslinking reaction and properties of two‐component waterborne polyurethane from terpene‐maleic ester type epoxy resin

“…Latest study shows that this crosslinking reaction follows an autocatalytic mechanism 17. The resultant of reaction (urethane NHCOO) can catalyze itself reacting with the NCO group and form allophanate 18. The motion of OH group and NCO group is easy at the beginning of the reaction when the viscosity is low, and the reaction fits a second order reaction kinetics.…”

Polymer research and synchrotron radiation perspectives

“…Reaction injection molding (RIM) [59] is a widely employed operating method in the industry of a wide broad of segmented block copolymers such as copolyurethanes [60], copoly(urethane-urea)s [61,62], copolyureas [63][64][65] and copoly (ether-amide)s to generate complex polymer elements in a fast and malleable processing routine. The polymer reaction by RIM comprises concomitantly phase separation, crystallization and cross-linking of the copolymer obtained as a kinetic competition that defined the development of the final structure [66].…”

Polyureas

“…The copolyureas were based on reactants (24) and (77)to (80),and were produced by the RIM process 77 using a stoichiometric ratio of isocyanate to amine groups of 1.03. (77) OCN--Q-eH 2 -0-NCO (24) (80) The properties of the copolyureas are dominated by the essentially two-phase structure comprising urea end-linked poly(oxypropylene) soft segments and amorphous, rigid and extensively hydrogen-bonded hard segments. Initial reactant and mould temperatures were 35 and 117°C, respectively, and mould filling was achieved within 1 s. Gelation and vitrification times of < 2 s were typical for the systems, which again exemplify the extremely fast rates of polymerization encountered in bulk copolyurea synthesis.…”