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Transition behavior and phase segregation in TDI polyurethanes
Author(s) -
Schneider N. S.,
Sung C. S. Paik
Publication year - 1977
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.760170203
Subject(s) - materials science , toluene diisocyanate , phase (matter) , polymer , polyester , phase transition , homologous series , glass transition , crystallization , butanediol , polyurethane , mixing (physics) , chemical engineering , polymer chemistry , crystallography , composite material , organic chemistry , thermodynamics , chemistry , physics , quantum mechanics , fermentation , engineering
Prior studies of two series of segmented polyurethanes based on 2, 4 toluene cliisocyanate (2, 4 TDI) or 2, 8 TDI, butanediol, and a 1000 molecular weight polytetramethyleneoxide (PTMO‐1000) soft segment revealed a rapid increase in soft segment glass transition temperature ( T g ) with increasing urethane content in the 2, 4 TDI series. The change in T g couldbe correlated with estimates of hard segment‐soft segment phase mixing obtained by infrared analysis of the urethane NH and carbonyl bands. In the present paper, the infrared data have been reevaluated using improved procedures for resolving the carbonyl band into H‐bonded and nonbonded components, and the relation between the estimated extent of phase mixing and T g has been reexamined. The transition behavior in an extensive series of related polymers has also been determined, including 2, 4 TDI arid 2, 6 TDI samples with PTMO2000 as well as polybutyleneadipate (PBA‐1000 and PBA‐2000) soft segments. The results indicate the effectiveness, of increased soft segment molecular weight in promoting phase segregation, imply that much greater phase mixing occurs in polyester than polyether samples, suggest that anchoring the ends of the soft segments has only a small effect on T g , and provide some evidence that H‐bonding not only increases T g but can also impede soft segment crystallization.