Extraction and characterization of cellulose whiskers from commercial cotton fibers

During the past few years, there has been a growing interest in incorporating cellulose whiskers from different sources as nanoreinforcement in polymer matrixes. The purpose of this study is to evaluate the performance of the cellulose whiskers obtained from Brazilian commercial cotton. In this sense, cellulose whiskers were prepared by acid hydrolysis which was carried out with a sulfuric acid solution 6.5 M at 45 and 60 °C for 75 and 20 min, respectively, and dried using different methods—an oven, a freeze dryer, and an air circulation oven. Cellulose whiskers were investigated in respect of crystallinity, thermal stability, and morphologically by scanning transmission electron microscopy. Cellulose cotton whiskers, independently of extraction conditions, provided an average length and a diameter of 150 ± 50 nm and of 14 ± 5 nm, respectively, and showed a rod-like shape. Whiskers extracted at 45 °C for 75 min have shown similar crystallinity and better thermal stability in oxidizing atmosphere. The use of the freezing dry process resulted in whiskers with better thermal stability and similar crystallinity than those obtained when dried in the air circulation oven process.