Accession Number : ADA289996
Title : Polyethylene-Based Polyurethane Copolymers and Block Copolymers.
Descriptive Note : Final rept.,
Corporate Author : ARMY RESEARCH LAB WATERTOWN MA MATERIALS DIRECTORATE
Personal Author(s) : Byme, C. A. ; Desper, C. R. ; Schneider, N. S. ; Chu, B. ; Li, Y. J.
PDF Url : ADA289996
Report Date : NOV 1994
Pagination or Media Count : 34
Abstract : Low molecular weight hydroxy terminated polyethylene (HTPE) containing on average an ethyl group every 16-18 carbon atoms, and a hydroxy functionality of 2.6, has been used to prepare polyurethane copolymers and block copolymers which have good solvent resistance. The polymers show somewhat complicated thermal behavior, including T sub g at around -40 deg C due to the HTPE and diffuse endotherms between 40 and 60 deg C. The simple copolymers, containing only the polyol and a diisocyanate, show infrared evidence for two phases in the case where CHDI (trans-1,4-diisocyanatocyclohexane), was used, and poorer phase separation where other diisocyanates were used. Dynamic mechanical spectra show very broad tan delta transitions for the copolymers in the range of -9 to -23 deg C. All the polymers exhibit another transition in the G" curve above room temperature. For the simple copolymers at 30 deg C, SAXS reveals a microphase separated structure which increases in spacing, then disappears in the 60-70 deg C range. With cooling, the microphase separated structure reappears readily for the CHDI-based copolymer, while its reappearance shows a hysteresis resulting from rate effects for the other copolymers. (jg)
Descriptors : *COPOLYMERS, *BLOCK COPOLYMERS, *POLYURETHANE RESINS, *POLYETHYLENE, THERMAL PROPERTIES, MECHANICAL PROPERTIES, DYNAMICS, POLYMERS, RESISTANCE, ELASTOMERS, RATES, CARBON, COOLING, PHASE, ROOM TEMPERATURE, SPECTRA, SOLVENTS, SEPARATION, DIFFUSION, INFRARED RADIATION, HYSTERESIS, ETHYL RADICALS, HYDROGENATION, ISOCYANATES, ENDOTHERMIC REACTIONS.
Subject Categories : Polymer Chemistry
Distribution Statement : APPROVED FOR PUBLIC RELEASE