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Influence of diisocyanate, glycidol and polyol molar ratios on the mechanical and thermal properties of glycidyl‐terminated biobased polyurethanes
Author(s) -
Mathew Aiswarea,
Kurmvanshi Surendra,
Mohanty Smita,
Nayak Sanjay K
Publication year - 2017
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.5412
Subject(s) - glycidol , polyurethane , polyol , materials science , isocyanate , thermogravimetric analysis , epoxy , glass transition , differential scanning calorimetry , fourier transform infrared spectroscopy , thermal decomposition , polymer chemistry , composite material , chemical engineering , chemistry , organic chemistry , polymer , catalysis , physics , engineering , thermodynamics
A series of epoxy‐terminated polyurethanes (EPUs) were synthesized from castor oil, 4,4′‐methylenebis(cyclohexyl isocyanate) (H 12 MDI) and 2,3‐epoxy‐1‐propanol (glycidol) by changing the molar ratio of H 12 MDI to glycidol to polyol. Fourier transform infrared, 1 H NMR and solid‐state CP/MAS 13 C NMR spectroscopic analyses revealed the presence of epoxy linkages within the polyurethane backbone. Thermogravimetric analysis showed that EPU4 with a polyol:diisocyanate:glycidol molar ratio of 1:6:6 exhibited an initial decomposition temperature of 128 °C, which was 26 °C higher than that of EPU1 (1:3:3 molar ratio). Differential scanning calorimetry showed an upward shift in the glass transition temperature with increasing molar ratio. Mechanical analysis demonstrated that the tensile modulus of EPU4 was 7.8 times greater than that of EPU1. The crosslinking densities of EPUs were determined using swelling studies which revealed a gradual increase in crosslinking density with increasing epoxy content within the polyurethane. The morphologies of cryo‐fractured surfaces of EPUs were determined through scanning electron microscopy to analyse the phase dispersion of epoxy and polyurethane. © 2017 Society of Chemical Industry