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Comparative properties of cellulose nano-crystals from native and mercerized cotton fibers

Yue, Yiying, Zhou, Chengjun, French, Alfred D., Xia, Guan, Han, Guangping, Wang, Qingwen, Wu, Qinglin
Cellulose 2012 v.19 no.4 pp. 1173
Fourier transform infrared spectroscopy, X-ray diffraction, acid hydrolysis, bulk density, cellulose, crystal structure, crystals, ethylene oxide, gels, homogenization, lint cotton, mercerization, pressure treatment, storage modulus, sulfuric acid, temperature, tensile strength, thermal stability, transmission electron microscopy
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 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.