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Crystallization and Properties of Novel Polyurethanes Based on the Chain Extender Ethylene Glycol and Aromatic Diisocyanates of Variable Flexibility
Author(s) -
Prisacariu Cristina,
Scortanu Elena
Publication year - 2007
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200750824
Subject(s) - differential scanning calorimetry , adipate , crystallinity , extender , ethylene glycol , materials science , isocyanate , polymer chemistry , crystallization , polyurethane , chemical engineering , composite material , physics , engineering , thermodynamics
Summary: Novel polyurethane elastomers (PUs) were synthesized with ethylene glycol (EG) as a chain extender. The macrodiol was poly(ethylene adipate) (PEA), MW = 2000 ± 50. Two isocyanates were employed: 4,4′‐methylene bis(phenyl isocyanate) (MDI) and 4,4′‐dibenzyl diisocyanate (DBDI). The conformational mobility of DBDI causes an unusually wide range of mechanical, physical and chemical properties, associated with the possibility of pronounced phase separation into a domain – matrix morphology, and with a higher tendency to crystallization and self‐association by hydrogen bonding. Materials were characterized by wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical analyses (DMA), and mechanical measurements. Results were discussed in terms of the effect of PUs crystallinity. In the case where the chain extender–diisocyanate couple was EG‐DBDI, the hard segments were observed to crystallize. The DBDI based PUs displayed higher flow stress in the hard phase caused by stronger phase segregation.