Publications (6)14.66 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: A xylan nanocomposite film with improved strength and barrier properties was prepared by a solution casting using nanocellulose whiskers as a reinforcing agent. The 13C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR) analysis of the spectral data obtained for the NCW/xylan nanocomposite films indicated the signal intensity originating from xylan-cellulose interactions. Qualitatively, the spectral data obtained for the NCW/xylan nanocomposite films indicated that the amount of xylan adsorbed to cellulose increases with the addition of NCW. In an attempt to quantify this effect, non-linear least-squared spectral line fitting was used to deconvolute the adsorbed xylan peak at -82 ppm. The peak intensity ratio of adsorbed xylan peak and xylan C1 peak, which represents the total amount of xylan increases suggesting that upon the addition of NCW, the amount of adsorbed xylan increases. In an effort to further infer the structure-property relationships associated with the observed strength and barrier properties, 1H NMR T2 relaxation experiments were also conducted to investigate the change in the nature of carbohydrate-water interactions as a result of NCW incorporation. Water adsorbed into the 50% nanocomposite film had significantly shorter relaxation times with respect to the control xylan/sorbitol and all other NCW/xylan nanocomposite films. Additionally, X-ray diffraction of the nanocomposite films showed increased levels of crystalline material in the nanocomposites due to NCW addition.
- [Show abstract] [Hide abstract] ABSTRACT: Moisture barrier properties of films based on xylan reinforced with several cellulosic resources including nanocrystalline cellulose, acacia bleached kraft pulp fibers and softwood kraft fibers have been evaluated. Measurements of water vapor transmission rate (WVTR) were performed by a modification of the wet cup method described by ASTM E 96-95, indicating that membranes with 10% nanocrystalline cellulose, prepared using a sulfuric acid, exhibited the lowest permeability value of 174gmil/hm2 among the composite films studied. Both the acacia and the softwood kraft pulp fibers when used for xylan film formation exhibited higher water vapor transmission rates at addition levels of 50% and no improvement at lower levels of 5% and 10%, in comparison to control xylan films. Reinforcement of xylan with hydrochloric acid made nanocrystalline cellulose yielded films that showed a reduction in water transmission but the reduction was not as significant as with the reinforcement of xylan with sulfuric nanocrystalline cellulose. The results showed that xylan films reinforced with 10% sulfuric nanocrystalline cellulose exhibited reductions in water transmission rates of 362%, 62% and 61% over films prepared with 10% softwood kraft fibers, 10% acacia fiber and 10% hydrochloric acid prepared nanocrystalline cellulose, respectively. The morphology of the resulting nanocomposite films was examined by SEM and AFM which showed that control films containing xylan and sorbitol had a more open structure as compared to xylan–sorbitol films containing sulfuric nanocrystalline cellulose. The results from FT-IR suggested strong interactions occurred between the nanocrystalline cellulose and the matrix.
- [Show abstract] [Hide abstract] ABSTRACT: The goal of this work is to produce nanocomposite film with low oxygen permeability by casting an aqueous solution containing xylan, sorbitol and nanocrystalline cellulose. The morphology of the resulting nanocomposite films was examined by scanning electron microscopy and atomic force microscopy which showed that control films containing xylan and sorbitol had a more open structure as compared to xylan-sorbitol films containing sulfonated nanocrystalline cellulose. The average pore diameter, bulk density, porosity and tortuosity factor measurements of control xylan films and nanocomposite xylan films were examined by mercury intrusion porosimetry techniques. Xylan films reinforced with nanocrystalline cellulose were denser and exhibited higher tortuosity factor than the control xylan films. Control xylan films had average pore diameter, bulk density, porosity and tortuosity factor of 0.1730 mu m, 0.6165 g/ml, 53.0161% and 1.258, respectively as compared to xylan films reinforced with 50% nanocrystalline cellulose with average pore diameter of 0.0581 mu m, bulk density of 1.1513 g/ml, porosity of 22.8906% and tortuosity factor of 2.005. Oxygen transmission rate tests demonstrated that films prepared with xylan, sorbitol and 5%, 10%, 25% and 50% sulfonated nanocrystalline cellulose exhibited a significantly reduced oxygen permeability of 1.1387, 1.0933, 0.8986 and 0.1799 cm(3).mu m/m(2).d.kPa respectively with respect to films prepared solely from xylan and sorbitol with a oxygen permeability of 189.1665 cm(3).mu m/m(2).d.kPa. These properties suggested these nanocomposite films have promising barrier properties.
- [Show abstract] [Hide abstract] ABSTRACT: Nanocellulosic-xylan films were prepared employing oat spelt xylan, cellulose whiskers and a plasticizer. The mechanical properties of the films were evaluated using tensile testing under controlled temperature and humidity conditions. The tensile data showed that the addition of sulfonated cellulose whiskers lead to a substantial improvement in strength properties. Addition of 7wt% of sulfonated whiskers increased the tensile energy absorption of xylan films by 445% and the tensile strength of the film by 141%. Furthermore, films to which 7% cellulose whiskers were added showed that nanocellulose whiskers produced with sulfuric acid (sulfonated whiskers) were significantly better at increasing film strength than cellulose whiskers produced by hydrochloric acid hydrolysis of cellulosic fibers.
- [Show abstract] [Hide abstract] ABSTRACT: The reinforcement of natural biopolymers with cellulosic whiskers has been shown to be beneficial for physical strength properties including xylan films. This study examines the water transmission properties of xylan films reinforced with cellulosic whiskers prepared from kraft pulp hydrolyzed with sulfuric acid. Measurements of water transmission rate (WVTR) were accomplished by a modification of wet cup method described by ASTM E 96-95. The results showed that films prepared by xylan reinforced by 10% sulfonated whiskers exhibited a 74% reduction in specific water transmission properties with respect to xylan film and a 362% improvement with respect to xylan films reinforced with 10% softwood kraft fibers.
Georgia Institute of Technology
Atlanta, Georgia, United States
- School of Chemistry and Biochemistry