POLYURETHANE ANIONOMERS .1. STRUCTURE-PROPERTY RELATIONSHIPS

Polyether polyurethane anionomers are prepared using poly(tetramethyle ne oxide) of molecular weight 2000 as soft segments, 4,4'-diphenylmeth ane diisocyanate (MDI) as diisocyanate, dimethylolpropionic acid (DMPA ) as chain extender, and two ionization agents, triethylamine (TEA) an d N-ethyl diethanolamine (EDEA). Properties of the films cast from sol ution are studied by infra-red spectroscopy, dynamic mechanical analys is, thermogravimetric analysis, differential scanning calorimetry, wid e-angle X-ray diffraction, tensile-elongation testing, transmission el ectron microscopy and gel-permeation chromatography. In the unionized film, soft segment crystallites are not present. Ionization creates so ft segment crystallites and produces increased cohesion in the hard do mains, which leads to an increase in both tensile strength and elongat ion at break. The tensile strength of the two systems studied increase s with increasing the ionic potential. The morphology of the films sho ws that the hard domains are dispersed in the soft domains and that th e size of the hard domains increases greatly after ionization. The TEA system has larger hard domains than the EDEA system. After annealing, the unionized film has improved ordering in the soft domains and enha nced tensile strength, but annealing provides no appreciable effect on the ordering of soft and hard domains and mechanical properties for t he ionized films.