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Carboxymethyl xylan- g -poly(propylene oxide) (CMX- g -PPO) was successfully synthesized by grafting poly(propylene oxide) chains onto xylan from bamboo using the Al(O i -Pr) 3 initiated ring-opening polymerization of propylene oxides, followed by carboxymethylation with sodium chloroacetate under microwave irradiation. The synthesized CMX- g -PPO was well characterized by FT-IR, 13 C NMR, and AFM. The AFM imaging showed that the average sizes of xylan were 422.1 × 67.4 × 1.2 nm, while the average sizes of grafting branches PPO were 128.0 × 38.5 × 5.1 nm, which firstly provided an irrefutable and visual evidence for the structure of grafted xylan at single molecular level. Subsequently, a serial of CMX- g -PPO/CS films were prepared without addition of any plasticizers. The surface morphologies, wettability, water vapor barrier properties, mechanical properties, and thermal stabilities of the obtained films were characterized and compared with those of the control films by AFM, contact angle, WVP, tensile testing, and TGA, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Water and alkali-soluble polysaccharides, isolated by sequential extractions with distilled water, 0.5% and 1% NaOH, 60% ethanol containing 1% NaOH, and 3%, 5% and 8% NaOH, were prepared at 60°C for 3h from dewaxed bamboo Phyllostachys incarnata Wen. The yields of the seven fractions together accounted for 80.1% of total available hemicellulosic polysaccharides. Sugar composition studies showed that the water-soluble polysaccharides consisted mainly of glucose units, while xylose, arabinose and glucuronic acid were the major sugars in alkali-soluble hemicelluloses. Moreover, the molecular weights of these polymers varied between 3760 and 36,000g/mol as revealed by GPC. Furthermore, the structure of the hemicellulosic fraction extracted with 3% NaOH was determined by 1H and 13C NMR spectroscopy along with 2D HSQC. It was found that the bamboo hemicelluloses were O-acetyl-(4-O-methylglucurono)-arabinoxylans, and the structural element could be identified as below: 1,4-β-D-[2-O-Ac][2,3-di-O-Ac][4-O-Me-α-D-GlcpA-(1→2)][α-L-Araf-(1→2)(1→3)]-xylp. [Copyright &y& Elsevier]

The nanocomposite films were prepared using Eucommia ulmoides gum (EUG) matrix reinforced with nanocrystalline cellulose (NCC) at different concentrations. Subsequently, the obtained films were characterized by Raman spectra, AFM, XRD, TGA, and DSC. Meanwhile, the wettability, mechanical, and water vapor barrier properties of these films were analyzed. AFM noticed that the average sizes of NCC were 81.95 × 50.17 × 13.06 nm, while the size of molecular chain for EUG was 2530 × 57.33 × 1.28 nm. In comparison with control film, a certain amount of NCC obviously improved elongation at break and enhanced their crystallinity and Δ H m . More importantly, NCC/EUG nanocomposite films presented lower thermal stability, glass transition temperature ( T g ), melting temperature ( T m ), and water vapor permeability (WVP) values, especially the WVP values of 4% NCC film were the lowest as 0.28 × 10 −9 , 0.30 × 10 −9 , and 0.58 × 10 −9 g/m/h/Pa at RH 34%, 55%, and 76%, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Effect of ionic liquid pretreatment on enzymatic hydrolysis of cellulose was investigated in terms of the changes in the chemical and physical structure of the preparation. In this case, original cellulose isolated from sugarcane bagasse was subjected to ionic liquid ([Emim]Ac) dissolution at a mild temperature (90°C) followed by regeneration in water and subsequently hydrolyzed by commercial cellulases. The original and regenerated cellulose were thoroughly characterized by XRD, FT-IR, CP/MAS 13C NMR, and SEM. It was found that the original cellulose experienced an increase in glucose content from 80.0–83.3% to 91.6–92.8%, a decrease in the degree of polymerization from 974–1039 to 511–521, a crystal transformation from cellulose I to cellulose II, as well as an increase of surface area during the pretreatment. The results suggested that pretreatment led to effective disruption of cellulose for subsequent enzyme hydrolysis as evidenced by a high glucose conversion yield of 95.2%. [Copyright &y& Elsevier]