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Mechanical Properties at High Temperatures and Thermal Properties of Polyurethane Elastomers With Different Amide Segments
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DOI:10.1002/pen.70704.png)
Abstract
En 中文
A series of amino-terminated oligomers containing amide units were synthesized by the polycondensation reaction of aliphatic diesters with different chain lengths and amino-terminated poly (propylene oxide) of 400 g/mol. The obtained oligomers were used to prepare polyurethane elastomers with different amide segments in soft segments (PU-A, PU-G, PU-M, and PU-E), in which the lengths of methylene groups between amide units were varied systematically. The influences of the discrepancies in methylene groups lengths between amide units on the mechanical properties at high temperatures and thermal properties of polyurethane elastomers were investigated. The results revealed that the mechanical properties at elevated temperatures of all polyurethane elastomers with amide units in soft segments were significantly improved compared with polypropylene glycol based polyurethane elastomer (PU-PPG2000). Especially, the tear strength of PU-M at 80°C, 100°C, and 120°C was 48.5%, 43.7%, and 45.4% higher than that of PU-PPG2000 respectively. Different lengths of methylene groups between amide units induced different hydrogen bonding between amide units, thus leading to different glass transition temperature of amide segments (Tamide). Polyurethane elastomers with the lower Tamide value possessed the higher mechanical properties retention rates at high temperatures, whereas the higher Tamide value led to the lower retention rates of tear and tensile strength at 80°C, 100°C, and 120°C. Moreover, the DSC and SEM results demonstrated that the discrepancies in the lengths of methylene groups between amide units in soft segments could also make influences on the hard segments structures.
Keywords:
amide units
mechanical properties at high temperatures
methylene groups lengths between amide units
thermal properties
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