Method for preparing biodegradable polyurethane rigid foam from bamboo waste liquefaction products

The invention discloses a method for preparing biodegradable rigid polyurethane foam with liquefaction products of bamboo waste, which comprises the following steps: 1 mass portion of crude glycerin/polyethylene glycol liquefying solvent and 0.02-0.04 mass portion of concentrated sulfuric acid are added into a reaction vessel, heated till the temperature reaches 120-180 DEG C after a reflux condensation tube is connected to the reaction vessel; 0.2-0.5 mass portion of crushed and dried bamboo waste is added, reacted for 90-180min with stirring, taken out and cooled and neutralized by MgO till being neutral; 1 mass portion of liquefaction products of bamboo waste, 0.02-0.08 portion of a dibutyl tin dilaurate/triethylene diamine mixed catalyst, 0.02-0.06 portion of silicone oil, 0.02-0.1 portion of water and 0.1-0.15 portion of fire retardant are added into a container, premixed for 20-30s when stirred at 2,000r/min, added with sufficient PAPI with the molar ratio between isocyanato-NCO in PAPI and hydroxyl gro