Synthesis and properties of clay-modified polyurethane elastomers Using organifiers with two hydroxyl groups

Abstract

The aim of this dissertation was to prepare the organoclays by treatment with chain-extended organifiers and to add the organoclays to polyurethane/clay nanocomposites. The effect of the chemical structures of the organifiers on the properties of the organoclay such as d-spacing, ion-exchanged fraction was investigated to confirm proper organoclay for polyurethane/clay nanocomposites. The polyurethane/clay nanocomposites were synthesized with two types of organoclays. We changed the molecular weight of PTMG which was one of the reactant to make organifiers. We called them as CL-UT2K, CL-UT1K. Therefore, the molecular effect on organoclay such as d-spacing and IEF value would be changed. The procedure to make polyurethane nanocomposites was 2-shot(2 steps) process. Organoclay was dispersed and sonicated in PTMG 1K which was one of the reactant. And then, PTMG/clay suspension reacted with MDI until reaching theoretical isocyanate percent. IPDI was used to compare to MDI as well. 1,4-BD reacted with prepolymer made from $1^{st}$ step and air bubble was removed under vacuum. Then we casted them and keep in the oven at $110^\circ C$. The reaction proceeded until we observed the disappearance of intrinsic isocyanate peak by using FT-IR instrument. The effects of the organoclays on the properties of the PU nanocomposites were investigated. Moreover, we changed the ratio of reactant to make polyurethane nanocomposites. The morphology of polyurethane nanocomposites was observed by TEM and SEM. Polyurethane nanocomposites CL-UT2K used to make showed larger d-spacing than polyurethane nanocomposites CL-UT1K used. The molecular weights were detected by GPC. We also observed thermal properties such as glass transition temperature and thermal stability by using DMTA and TGA respectively. The glass transition temperature of polyurethane nanocomposites was increased by adding organoclay. For tensile properties modulus was increased with increasing clay contents. But tensile st...