Preparation of rigid polyurethane foams using catalysts prepared from metal nitrates and tetraethylenepentamine/pentaethylenehexamine

Abstract

The scope of this research was to synthesize copper-tetraethylenepentamine and copper-pentaethylenehexamine complexes, namely Cu(NO₃)₂ (tetraen), Cu(NO₃)₂ (pentaen), Cu(Cl)₂(pentaen) and Cu(Cl)₂(tetraen) and used as catalysts in the preparation of rigid polyurethane foams. These copper complexes were synthesized from the reaction between inorganic compounds (copper nitrate/copper chloride) and amines (tetraethylenepentamine/pentaethylenehexamine). The copper complexes were characterizes by FTIR, UV-visible and elemental analysis. The copper complexes were used as catalysts to prepare rigid polyurethane foams. The reaction time, physical properties, and mechanical properties of rigid polyurethane foams were studied and compares with the foam catalyzed by dimethylcyclohexylamine (DMCHA), which is a reference commercial catalyst. The isocyante conversion was obtained by ATR-IR. It was found that Cu(NO₃)₂ (tetraen) could accelerate the reaction of polyurethane foam better than Cu(NO₃)₂(pentaen), Cu(Cl)₂(pentaen) and Cu(Cl)₂(tetraen). Foam density and compressive strength of polyurethane foams which were catalyzed by Cu(NO₃)₂(tetraen), Cu(NO₃)₂(pentaen), Cu(Cl)₂(pentaen) and Cu(Cl)₂(tetraen) showed higher values than the foam catalyzed by DMCHA at NCO index 100. The morphology of RPUR prepared from Cu(NO₃)₂(tetraen) showed good morphology and the cell size increased when increasing the amount of blowing agent.