Location: Cotton Structure and Quality ResearchTitle: Comparative properties of cellulose nano-crystals from native and mercerized cotton fibers Author
|French, Alfred - Al|
Submitted to: Cellulose
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2012
Publication Date: 5/8/2012
Citation: Yue, Y., Zhou, C., French, A.D., Xia, G., Han, G., Wu, Q. 2012. Comparative properties of cellulose nano-crystals from native and mercerized cotton fibers. Cellulose. 19:1173-1187. Interpretive Summary: Cotton fiber is composed mostly of the molecule cellulose, much of which exists in small crystalline arrays. These small crystals have dimensions of ten to 100 billionths of a meter, so they are called nanocrystals. They can be isolated by treating the cotton with strong acid. These crystallites are useful for to assist a better understanding of the cotton fiber’s structure. The widely used industrial process of mercerization is poorly understood, and the finding that the nanocrystals from native and from mercerized fibers have different lengths is an important clue. There are also have possible practical applications. For example, ordinary plastic films are strengthened by addition of cotton nanocrystals. This research also found that the films reinforced with nanocrystals made from mercerized fibers are stronger than films reinforced with nanocrystals from native fibers.
Technical Abstract: Stable aqueous suspensions of cellulose nano-crystals (CNCs) were fabricated from both native and mercerized cotton fibers by sulfuric acid hydrolysis, followed by high-pressure homogenization. Fourier Transform Infrared Spectrometry and Wide-angle X-Ray Diffraction data showed that the fibers had been transformed from cellulose I (native) to cellulose II (mercerized) crystal structure, and these polymorphs were retained in the nanocrystals, giving CNC-I and CNC-II. Transmission electron microscopy (TEM) showed rod-like crystal morphology for both types of crystals under the given processing conditions with CNC-II having similar width but reduced length. Freeze-dried agglomerates of CNC-II had a much higher bulk density than that of CNC-I. Thermo-gravimetric analysis showed that CNC-II had better thermal stability. The storage moduli of CNC-II suspensions at all temperatures were substantially larger than those of CNC-I suspensions at the same concentration level. CNC-II suspensions and gels were more stable in response to temperature increases. Films of CNC and Poly (ethylene oxide) were tested. Both CNC-I/PEO and CNC-II/PEO composites showed increased tensile strength and elongation at break compared to pure PEO. However, composites with CNC-II had higher strength and elongation than composites with CNC-I.