“…The mechanical properties of polyurethane depend mainly on the cell structure, including cell size [ 33 , 34 , 35 ], cell content, anisotropy of the cell structure [ 36 , 37 , 38 ], closed (cell content), and wall thickness of the cell [ 39 ]. The formation stages of polyurethane foams include four phases cell nucleation, cell growth, microphase separation, and polymerization [ 40 ]. In the process of foaming to molding, ambient temperature, raw material ratio, mold temperature, material temperature, and curing time affect the foaming rate and the final cell structure morphology of polyurethane foams.…”