Dendrimers/Hyperbranched/Star Polymers

摘要

Hyperbranched polyurethane elastomers were prepared from dimer fatty acid-ethylene glycol polyester diol, toluene diisocyanate and glycerol by a two step process in solvent-free conditions. The effect of glycerol on the phase separation was studied by FTIR and differential scanning calorimetry. The thermal and viscoelastic properties of the hyperbranched polyurethane were investigated by thermogravimetric analysis and dynamic mechanical analysis. The transparent hyperbranched polyurethane presented a single glass transition temperature at -25°C and an on set decomposition at temperature of 275°C. The increased glycerol quantity resulted in a lower decomposition temperature and the crosslinked hyperbranched polyurethane with glycerol had a high elasticity with best viscoelastic properties at a ratio n_(NCo)_(OH) of 0.95. The lowest water absorptivity was found for a ratio of 1.05.