Nanocomposites Based on Cellulose, Hemicelluloses, and Lignin

121

Cellulose nanofibers (CNFs) were isolated from kenaf fibers and wheat straw by formic acid (FA)/acetic acid (AA), peroxyformic acid (PFA)/peroxyacetic acid (PAA), hydrogen peroxide (H 2 O 2 ) treatment; and subsequently through ball milling treatment. Characterization of extracted cellulose and cellulose nanofibers was carried out through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). TEM images showed that extracted cellulose nanofibers had diameter in the range of 8-100 nm. FTIR and XRD results implied that hemicellulose and lignin were mostly removed from lignocellulosic biomass with an increase in crystallinity, and isolation of cellulose nanofibers was successful. The TGA results showed that decomposition temperature of cellulose nanofibers increased by about 278C when compared with that of untreated lignocellulosic biomass. No significant change was observed in the decomposition temperature of bleached celluloses after ball milling.

Section: Ftir Spectroscopy Analysismentioning

confidence: 64%

A novel approach for extracting cellulose nanofibers from lignocellulosic biomass by ball milling combined with chemical treatment

Nuruddin¹,

Hosur²,

Uddin³

et al. 2015

121

“…Peaks at 897 and 1,165 cm 21 are assigned as CAOAC stretching vibrations of the characteristic b-(1-4)-glycosidic bond in glycogen. 36 Although all the characteristic peaks still presented in the spectrum of microcrystalline cellulose in Figure 1(b), a blue shift of the peaks to higher wavenumber values could be observed, confirming the formation of microcrystalline cellulose. 25 New peaks presented around 1758, 1374, and 1234 cm 21 in the spectra of acetylated cellulose are related to the stretching vibrations of C@O group, CAH bond in AO(C@O)ACH 3 group and ACOA in acetyl group, respectively, 6 confirming the hydroxyl groups were substituted for acetyl groups during the reaction.…”

Section: Acetylation Of Cellulosementioning

confidence: 73%

H₃PW₁₂O₄₀·4H₂O as an efficient catalyst for the conversion of cellulose into partially substituted cellulose acetate

Liao

Fang

Luo

et al. 2014

The preparation of partial acetylation of cellulose derived from rice straw was catalyzed by phosphotungstic acid with various numbers of crystal water, and H3PW12O40·4H2O was found to be as effective catalyst. The yield of the cellulose acetate was significantly enhanced by converting cellulose directly isolated from rice straw into microcrystalline cellulose before acetylation. The optimization of the acetylation was investigated by varying the amount of catalyst and acetic anhydride as well as reaction conditions including reaction time and medium, and a degree of substitution (DS) value of 2.29 and yield of 62.9% were obtained under the optimized conditions. The structure and the formation of the acetylated product were confirmed by Fourier transform infrared spectroscopy (FTIR) and powder X‐ray diffraction (XRD) technique, the thermal properties were determined by thermal analysis including thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC), and the morphology was observed by scanning electron microscope (SEM). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41212.

“…28 In addition, band at 1162 cm 21 is assigned to CAOAC stretching vibration of the characteristic b-(1-4)-glycosidic bond in glycogen. 31 The bands at 785 and 466 cm 21 are responsible for stretching vibration of SiAOASi in silica. 28 In the IR spectrum of crude cellulose [ Figure 1(b)], the bands around 785, 1734, and 1518 cm 21 are assigned to the vibrations in silica, hemicelluloses, and/or lignin almost disappear completely.…”

Section: Resultsmentioning

confidence: 99%

Preparation of microcrystalline cellulose from rice straw under microwave irradiation

Fan

Wang

Song

et al. 2017

Crude cellulose was isolated from rice straw and then converted into microcrystalline cellulose (MCC) via partial hydrolysis. Both the isolation and partial hydrolysis were carried out under microwave. Rice straw was successively pretreated with alkaline and acid solutions before hydrolysis. Lignin and silica were almost removed but partial removal of hemicellulose in dilute alkali solution, and the residual hemicellulose was further removed in dilute acid solution. The total removal rates of hemicellulose, lignin and silica reached up 92.0%, 98.5%, and 96.8%, respectively. The cellulose content of 93.6 wt % in MCC was given by partial hydrolysis of crude cellulose isolated from rice straw. The comparison between microwave irradiation and traditional heating method was also investigated. Compared to traditional heating method, similar results were obtained while milder conditions, including shorter time and lower temperature, were required. An effective microwave‐assisted and energy‐efficient methodology using rice straw as the alternative source of cellulose fiber was developed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44901.