Structure and Properties of Segmented Polyurethane-Urea Elastomers with Binary Hard Segment Component Which is Exhibited by Chain Extender

Abstract

Segmented polyurethane-urea (SPUU) is a block copolymer which consists of hard and soft segments. SPUU films with different ratios of ethylenediamine (EDA) and propylenediamine (PDA) as chain extenders were prepared. The values of two parameters of C₁ and higher order term Δh obtained by Mooney-Rivlin plots in the stress-strain relationship were estimated. It was clarified that these parameters had good relation with the aggregate structure of hard segments which were formed through hydrogen bonding. The higher order term Δh and hydrogen bond concentration of urea group measured by FT-IR decreased with increasing PDA content in hard segment. Infrared dichroism measurements revealed that hard segments showed peculiar orientation behaviors. Transverse orientations of hard segments occurred at initial state of elongation process, which were caused by orientation of long axis of the hard segment aggregate structures. The orientation of soft segments, however, was not affected by hard segment structures.