Biopolyol And Polyurethane Foam Preparation From Liquefaction Of Grape Seeds

Grape seed is an important raw material resources, the current application of grape seed is focuse on the extraction of single component or be simply used as feed or fertilizer. However, there is little research on the high-value conversion and utilization of lignin, cellulose and hemicellulose in grape seed. Liquefaction technology is an effective way to the high-value utilization of lignocellulosic biomass, the liquefied products can be used for the preparation of polyurethane. Therefore, this paper used grape seeds as raw material and carried out the following studies:First, the grape seeds were successfully liquefied in the blended solvents of PEG-400 and glycerol in the presence of concentrated sulfurie acid as catalyst. Different liquefaction conditions have great influences on the liquefaction of GS. The influences of the liquefaction condition such as temperature, time, catalyst percentage and liquid-solid ratio on the liquefaction reaction were discussed. The optimal conditions obtained were 180?,120 mins, catalyst percentage (percentage of solvent mass) of 3.5% and liquid-solid ratio of 4. The characteristic parameters of the biopolyol under the optimal conditions are as follows:conversion ratio of 85.7%, hydroxyl number of 397.46 mg KOH/g, acid number of 1.85 mg KOH/g, viscosity of 2960 mPa.s, weight-average molecular weight of 5.18×103 g mol-1 and polydispersity of 3.64. The FT-IR showed that the lignin, cellulose and hemicellulose in the grape seeds were effectively decomposed in the liquefaction process.Then the influences of different pretreatment including the extraction of grape seed oil, the alkaline hydrogen peroxide pretreatment and the extraction of high boiling solvent lignin on the structure and composition of grape seeds were studied. All the lignins and residues were then liquefied under the optimal condition. Properties of different liquefied products were compared, we found that the extraction of grape seed oil had no obvious influence on the liquefaction and polyols. The alkaline hydrogen peroxide pretreatment was more conducive to liquefaction reaction than the pretreatment of high boiling solvent lignin extraction. The FT-IR showed that the grape seed-based polyols had similar structure with polyether polyol 4110.Finally, different kinds ofpolyurethane foam were prepared by replace part of 4110 with grape seed-based polyols. The FT-IR showed that the main structure of the polyurethane does not change significantly and two kinds of lignin polyols introduced more benzene ring structure into the polyurethane,but the isocyanate would be excess after the introduction of grape seed based polyols, indicating that the reactivity of grape seed based polyols are lower than 4110. With the substitution rate increases, the compressive properties of the foam will gradually deteriorate, the foam exhibited the highest compressive strength of 356.21 kPa when the substitution rate of alkali lignin polyol was 20%. In addition, the introduction of grape seed-based polyol can improve the thermal stability of the foam, but the foam cells were generally larger, and the cell distribution would become uneven.This paper studied the feasibility of using liquefaction of grape seeds to prepare polyols and polyurethanes, and effects of different pretreatment methods on grape seed component, polyol properties and polyurethane foam performance were also studied. This would provide both practical experience and technical basis to the high-value utilization of grape seeds.