Liquefaction Of Bagasse And Preparation Of Polyurethane Foam From Liquefaction Products

The liquefaction of bagasse in the polyhydric alcohol and the preparation of rigid polyurethane foam from the liquefaction products as well as the modification of the liquefaction products were studied.Bagasse was liquefied in the mixture of polyethylene glycol (PEG 400) and glycerin as the liquefying reagent in the presence of sulfuric acid as the catalyst under atmospheric pressure. The impacts of the liquid-solid ratio, the reaction time, the type and content of catalyst and the composition of liquefy reagents on the liquefaction were studied. The liquefaction was accelerated by the addition of surfactant into the liquefaction mixture. The liquefaction products were esterified to increase the reactivity in the preparation of polyurethane. Experimental data showed that the surfactant could promote the penetration of liquefying reagents into the fibrous raw materials, resulting in accelerated liquefaction rate. In addition, the addition of surfactant favored the reduced dosage of relatively expensive polyethylene glycol (PEG 400), and the cost of liquefaction could thus be reduced.Rigid polyurethane foams were prepared from the liquefaction products, isocyanate (MDI) and other additives. The strength of foams was improved when the liquefaction products replaced a part of traditional polyether polyol. However, the compressive strength of foams decreased when excessive liquefaction product was used. The maximal compressive strength of polyurethane foam reached 238 kPa when the substitution of liquefaction products up to 60% based on the total polyol. In addition, polyurethane foam decomposed at temperature between 220 and 440°C, and the thermal stability of foams based on liquefaction products was improved. It was found that flame retardants can damage the cell structure, resulting in the decreased compressive strength of foams. Foaming agents can accelerate the foaming procedure and promote the bubble growth. However, excessive foaming agents can make the compressive strength of foams decreased. In addition, the thermal aging of polyurethane foams showed that the compressive strength of foams was improved with prolonged aging time.The compressive strength of foams manufactured from modified liquefaction products was higher than that of foams from liquefaction products. Modified liquefaction product was found to lead to rather uniform cell structure. The results indicated that the liquefaction products became rather reactive. The compressive strength and elastic modulus of foams from modified liquefaction products with caprolactone achieved the maximum, 226 kPa and 2.65MPa, respectivity. The thermal stability of the polyurethane foam was also improved by the introduction of modified liquefaction products.