Synthesis and thermal stability of polyurethane using L-ascorbic acid

The purpose of this study is the improvement of thermal stability of the polyurethane elastmers (PUEs) by introduction of L-Ascorbic acid (L-As). The PUEs were prepared from poly(oxytetramethylene) glycol (PTMG: M̄_n=2017), and 4,4'-diphenylmethane diisocyanate (MDI), ethylene glycol (EG) or mixture of L-As and EG (0:100 25:75 33:66 50:50 wt%) as a curing agent by a prepolymer method. Density, hardness, aggregation structure, molecular mobility and thermal stability were investigated by measuring FT-IR, ¹H-pulsed NMR, thermal and dynamic viscoelastic properties. After thermal deterioration, density, hardness and dynamic storage modulus of rubbery plateau region of the PUEs decreased. With increasing L-As content, those magnitudes for the PUEs did not show large differences before and after thermal deterioration. These results clearly suggest that the L-As act as an oxidation inhibitor in the PUEs.