ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The thermal transition behavior of a series of hydroxy terminated polybutadiene (HTPBD) containing segmented polyurethanes has been studied by differential scanning calorimetry (DSC) and thermal mechanical analysis (TMA). Four transition regions are observed; the soft segment Tg, at -74°C, two hard segment transitions T1, at 40°C and T2 at 103°C and a softening region by TMA at 180°C, presumed to arise from the dissociation of allophonate bonding, The low Tg, only 7°C higher than the Tg of free HTPBD, indicates nearly complete phase segregation despite the amorphous nature of the hard segment structure. The dependence of T1, on hard segment length and thermal cycling suggests that it represents domains consisting primarily of shorter hard segments units. Factors contributing to the rather low mechanical properties of HTPBD polyurethanes are also discussed.
Additional Material:
11 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760191510
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