Structure-Function Relationships of Highly Refined Cellulose

Highly Refined Cellulose (HRC) is made from fibrous agricultural residues through a patented proprietary process (Ruan, 2000). The structural properties of HRC are of great importance to its applications. Therefore, characterization of the structural properties of HRC would help in developing processes for making and using HRC products. The relationships between structural and functional properties were studied in this research. The content of lignin, hemicellulose, and cellulose of HRC was measured using thermogravity analysis. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to identify and characterize the chemical structure of HRC. A Micromeritics ASAP 2000 was used to analyze the morphology of HRC. Crystallinity ratio was obtained through X-ray diffraction. The raw material had hemicellulose content ranging from 25 to 35%, while HRC had less than 2% hemicellulose. Lignin content was reduced from 35% of raw materials to 22.3% of HRC. The DRIFTS of HRC indicated that the resultant HRC materials had a typical cellulose structure. The water retention capacity (WRC) and oil retention capacity (ORC) of HRC were 23.5-40.0 g water per gram sample and 13.7-20.8 g oil per g sample, respectively. These values were greater than those for the raw materials. The Langmuir surface area, BET surface area, and pore diameter of HRC were 7-11 times, 4-7 times, and 1.2-1.5 times values for the raw materials, respectively. The linear correlation coefficients between WRC and BET surface area, and between WRC and Langmuir surface area are 0.93 and 0.96, respectively. Crystallinity ratio (1.5-2.2) was negatively correlated with both BET surface area and Langmuir surface area. The linear correlation coefficient between Crystallinity ratio and pore diameter was 0.84. This study provides basic understanding of the properties of HRC and information that can be used to design and control the manufacturing of HRC products.