Preparation and properties of rigid polyurethane foam based on modified castor oil

Abstract

Castor oil polyol (COP) having a hydroxyl number of 400 mg KOH/g was prepared through the transesterification reaction of castor oil with glycerol. The effect of reaction temperature on the composition, hydroxyl number and viscosity of the COP products was studied. A series of rigid polyurethane foams were synthesised using the mixtures comprising COP and a petroleumbased polyol with various proportions as polyol component. It was found that the foaming rate, compressive strength and dimensional stability and morphology of resulting foams were dominated by the foam formulation, in a more accurate way, COP content in the polyol mixtures. The combination of expandable graphite and dimethyl methyl phosphonate exhibited stronger flame retardant function which was ascribed to the synergistic effect associated with the simultaneous presence of the two additives. An improvement in thermal stability was observed due to the inclusion of the flame retardants.

Polyurethane Foams for Thermal Insulation Uses Produced from Castor Oil and Crude Glycerol Biopolyols

“…These properties results presented similar values to those reported in the literature of foams produced from castor oil polyols [16,19,26,27]. A significant decrease in the compressive strength and Young modulus of the foams were observed with the addition of the higher blowing agent amounts, which can be related with the density decreases and the cell size increase.…”

“…The bands around 1112 -1000 cm -1 indicate the presence of primary and secondary hydroxyl groups. These bands are very pronounced in crude glycerol spectrum, due to the three hydroxyl groups present in its structure [16,18]. All the foams spectra produced from GCo polyols are very similar and one of these foams spectra is showed in Figure 3, which presented the typical polyurethane bands.…”

“…A band related to stretching asymmetric links OCONH was revealed in 1380 cm -1 . The bands between 1100 and 1000 cm -1 were attributed to primary and secondary hydroxyl groups [16,17].…”

“…In the last years, the uses of bio based polyols have being investigated to produce sustainable and eco-friendly rigid polyurethane foams, like lignin [5,6], biopitch [7,8], glycerol [9][10][11], and vegetable oils as castor [3,[12][13][14][15][16][17][18][19], palm [20,21], soybean [22,23], starch [24,25], etc. Castor oil (CO) is a mixture of triglycerides, mainly ricinoleic acid, which is produced from the seed of Ricinus communis plant.…”

“…These properties limited the use of castor oil as a raw material polyol, especially to prepare rigid polyurethane foams, and the pre-treatment reaction seems to be efficient to minimize these disadvantages. Transesterification [16,18,19,26], thio-ene [27] and amidization [28] reactions have been employed to introduce reactive OH groups in castor oil in order to produce suitable polyols to synthesize rigid polyurethane foams. .…”