Polyurethanes are prepared by the polyaddition processes between poly isocyanates and polyols to form urethane linkages. Rigid polyurethane foam is one of the most important insulating materials used in the construction industry, refrigerators and freezers [
1]. Polyurethane foams have unique characteristics the consist of adherence to materials such as steel, wood, thermosetting resins and fibers, varied density ranging 20 to 3000 kg/m
3, resistance to petroleum, oils, and other nonpolar solvents [
2]. PU foams were considered as structural-thermal material in the appliance and construction industry due to both their thermal insulation and mechanical properties. Polyurethane foam properties are different from foams such as polystyrene, polyolefin and phenolic foams. Today, these foams are produced from polymeric methylene diphenyl diisocyanate (polymeric MDI) and either polyether or polyester polyols that are petro-chemical derived chemicals. Increasing cost of petrochemical feed stocks, concern of future shortage in petroleum supplies and public desire for environmentally friendly green products have encouraged many research projects to explore the polymers from sustainable and renewable resources [
3]. Interest in the use of lignocellulosic biomass for preparing PU foams is increasing now. The most popular methods of biomass liquefaction for production of PUF are based on the incorporation of organic solvents with suitable molecular weight and acidic or basic catalysts [
4]. Although these methods take advantage of the renewable biomass, the major weakness of these processes is the use of more solvents and chemicals, as well as energy inputs to make the bio polyols [
5,
6]. To reduce the production cost of polyols and thus the prevention of future commercialization efforts, the researchers have applied crude glycerol as the liquefaction solvent of lignocellulosic biomass [
7,
8]. Vegetable oils or animal fats and methanol reacted with each other via trans-esterification under alkalis such as NaOH and KOH that mainly produced biodiesel as renewable fuel. The byproduct of the biodiesel production process is the unrefined crude glycerol. The produced crude glycerol consists mainly of a mixture of methanol, fatty acids/soap, salts, and alkaline catalyst residues that due to the presence of these impurities have little economic value. Recently researchers applied refined crude glycerol for liquefaction of cellulose that was successfully used to produce polyols and polyurethane foam [
9]. In another study, Hu et al. [
8] reported the production of bio polyol and PU foams from crude glycerol based liquefaction of soybean straw. In this research maximum liquefaction efficiency was obtained at 360 min, whereas studies on liquefaction by PEG 400/glycerol showed higher liquefaction efficiency for a lower liquefaction time [
10]. The relatively lower liquefaction efficiency in the former might be explained by the use of crude glycerol versus PEG 400/glycerol chemical solvent. To combine the advantages of both the solvent in liquefaction process, the present research investigated the PUF properties produced from polyols of binary solvent (CG/PEG) based liquefaction of sawdust. The CG used in this study was based on waste vegetable oils. The recent researches applied the CG derived from a kind of waste vegetable oil for liquefaction and production of polyols. The composition of crude glycerol depends on feedstocks, processes, and post-treatments at biodiesel plants. The varying compositions of crude glycerol let to the change of the produced polyols and PU foams properties. It was hypothesized that adding chemical solvent to crude glycerol as liquefaction solvent could improve the properties of foams in comparison to foams obtained from polyols of CG based liquefaction. The use of waste vegetable oils based CG and its combination with PEG as a liquefaction solvent of biomass has not been reported so far.