N,N,N’,N”,N”-pentamethyldipropylene triamine: a highly efficient and environmentally friendly polyurethane foaming catalyst Introduction Polyurethane (PU) materials have become one of the indispensable materials in modern industry due to their excellent physical properties and wide application fields. Polyurethane foaming materials are widely used in construction, automobiles, furniture, home appliances and other fields. However, the impact of catalysts...