TY JOUR TI DEPENDENCE OF THE PERFORMANCE COEFFICIENT ON THE AVERAGE HARMONIC DIAMETER OF POLYURETHANE FOAM KW polyurethane foam KW filler KW mathematical modeling KW foaming coefficient KW mining waste KW harmonic diameter JO Bulletin of Belgorod State Technological University named after. V. G. Shukhov AU Suleymanova, L.A. AU Kocherzhenko, A.V. AU Ryabchevskiy, I.S. PY 2019 IS 4 PB Belgorod State Technological University named after V.G. Shukhov