Original Articles
Lais C Machado, Diana M da Cos
Abstract
In the present study, cellulose ether films containing two kinds of sorbitan based surfactants, namely, polyoxyethylenesorbitan monolaurate (Tween 20) and polyoxyethylenesorbitan monopalmitate (Tween 40) were prepared by casting from aqueous solutions. Three cellulose ethers were used hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), and carboxymethylcellulose (CMC). The obtained films were characterized by means of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), optical properties, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). ATR-FTIR spectra of cellulose ether/tween films showed that OH band shifted towards higher wavenumber values when compared to pristidine cellulose ethers. The transparency of cellulose ether films was reduced after the addition of Tween 20 and 40. The thermal stability of CMC and HPC films increased in the presence of Tween 20 and 40. For HEC film, the thermal stability depends on the Tween used. DSC measurements indicated that Tween 20 and 40 act as plasticizers for CMC, HEC and HPC.