Solubility parameter acid anhydrides

The Infrared spectrum of the SMA copolymer labeled SMA-2, is consistent with other SMA copolymer spectra published (33). However, the absorption peaks in the range of 1700 - 1820 cm indicate that this copolymer has been partially esterified to yield a half/acid ester of maleic anhydride which should exhibit peaks in the range of 1700 - 1725 cm"l and 1735 -1750 cm (Figure 3). The small absorption bands at 1780 and 1820 cm indicate the presence of a small amount of unreacted maleic anhydride. These data appear to be consistent for those of a styrene-maleic anhydride copolymer reported by Muskat (34). The carbon, hydrogen, oxygen analyses indicate that this polymer is a half/acid ester of a 90% styrene/10% maleic anhydride copolymer wherein theoretical values of C, H and 0 are 88.89%, 7.017. and 2.58% versus values of 89.14%, 7.68% and 2.81% found for C, H and 0, respectively. The solubility parameter was found to be equal to 9.47 H. 

The lyotropic behavior of ethyl cellulose in various solvents (methanol, ethanol, diox-ane, acetic acid, acetic anhydride, m-cresol, phenol, etc.) was studied as a function of the critical concentration of the liquid crystal phenomenon produced by refractometry, polarized light microscopy, and optical transmission [118, 119]. It has been observed that critical concentration increases with decreasing the solubility of the solvent, and also that the critical concentrations for alcohols were much higher than those of other solvents with similar solubility parameters. 

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