Synthesis and characterization of polyurethane/organo-montmorillonite nanocomposites

Polyurethane (PU)/organo-montmorillonite nanocomposites were prepared by in situ polymerization of toluene diisocyanate and butanediol in the presence of different contents of organo-montmorillonite (9–18 mass%). Organo-montmorillonite were prepared by an ion exchange process of sodium montmorillonite with –NH₃⁺ groups in polyoxyalkylene amine hydrochloride with two different molecular masses of 403 and 5000. To change the degree of surface modification, sodium montmorillonite was reacted with polyoxyalkylene amine hydrochloride in equivalent ratios (1:1 and 1:2). Dimethyl formamide (DMF) was used as a swelling agent for the prepared organo-montmorillonite. Different nanocomposite structures, depending on the molecular mass of the polyoxyalkylene and the degree of surface modification of montmorillonite were studied. The results of X-ray analysis and transmission electron microscopy showed that the organo-montmorillonite with polyoxyalkylene of higher molecular mass (T₅₀₀₀) produced the exfoliated PU nanocomposites; (T₄₀₃), led to an intercalated structure. Nanocomposites exhibited lower water adsorption values and higher thermal stability than that of pure PU₀. In addition, the hardness of the nanocomposites was measured.