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Thermal and mechanical properties of linear segmented polyurethanes with butadiene soft segments
Author(s) -
Brunette C. M.,
Hsu S. L.,
Rossman M.,
MacKnight W. J.,
Schneider N. S.
Publication year - 1981
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760211108
Subject(s) - materials science , polybutadiene , glass transition , elastomer , amorphous solid , polyester , composite material , dynamic mechanical analysis , thermal , phase (matter) , phase transition , polymer , thermodynamics , crystallography , copolymer , organic chemistry , chemistry , physics
A series of segmented polyurethanes based on a hydroxyl terminated polybutadiene soft segment (HTPBD) have been prepared with varying hard segment content between 20 and 60 weight percent. These materials are linear and amorphous and have no potential for hydrogen bonding between the “hard” and “soft” segments. The existence of two‐phase morphology was deduced from dynamic mechanical behavior and thermal analysis. Both techniques showed a soft segment glass transition temperature, T gs , at −56°C and hard segment transitions between 20 and 100°C, depending on the urethane content. The low value of T g , only 8° higher than the T g of free HTPBD and independent of hard segment concentration indicated nearly complete phase segregation. Depending on the nature of the continuous and dispersed phases, the urethanes behaved as elastomers below 40 weight percent hard segment or as glasslike materials at higher hard segment contents. The effect of thermal history on transitions of the HTPBDurethanes was also investigated and the results suggest that the absence of hydrogen bonding to the soft segment must account for the extraordinary insensitivity to thermal history in dynamic mechanical, thermal and stress‐strain behavior. Comparisons are made to the more common polyurethanes containing polyether and polyester soft segments.