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Among the natural macromolecules potentially used as the scaffold material in hydrogels, xylan has aroused great interest in many fields because of its biocompatibility, low toxicity, and biodegradability. In this work, new pH and thermoresponsive hydrogels were prepared by the cross-linking polymerization of maleic anhydride-modified xylan (MAHX) with N-isopropylacrylamide (NIPAm) and acrylic acid (AA) under UV irradiation to form MAHX-g-P(NIPAm-co-AA) hydrogels. The pore volume, the mechanical properties, and the release rate for drugs of hydrogels could be controlled by the degree of substitution of MAHX. These hydrogels were characterized by swelling ability, lower critical solution temperature (LCST), Fourier-transform infrared (FTIR), and SEM. Furthermore, the cumulative release rate was investigated for acetylsalicylic acid and theophylline, as well as the cytocompatibility MAHX-based hydrogels. Results showed that MAHX-based hydrogels exhibited excellent swelling–deswelling properties, uniform porous structure, and the temperature/pH dual sensitivity. In vitro, the cumulative release rate of acetylsalicylic acid for MAHX-based hydrogels was higher than that for theophylline, and in the gastrointestinal sustained drug release study, the acetylsalicylic acid release rate was extremely slow during the initial 3 h in the gastric fluid (24.26%), and then the cumulative release rate reached to 90.5% after sustained release for 5 h in simulated intestinal fluid. The cytotoxicity experiment demonstrated that MAHX-based hydrogels could promote cell proliferation and had satisfactory biocompatibility with NIH3T3 cells. These results indicated that MAHX-based hydrogels, as new drug carriers, had favorable behavior for intestinal-targeted drug delivery.

An efficient homogeneous catalytic process was developed for the dehydration of xylose to furfural using inorganic salts as catalysts in a water/dimethyl sulfoxide (DMSO) system under mild condition. The effects of the types of inorganic salts were compared. The results showed that chlorides had higher catalytic performance than other salts, and SnCl4 was the most effective chloride. The catalytic activity of paired SnCl4/LiCl catalysts was much higher than that of the single salt, and when the distribution coefficient (χSnCl4) was 0.8, the maximum furfural yield was 56.9%. The effects of the reaction conditions on the furfural yield were also investigated. The highest furfural yield, 63.0%, was achieved at 130 °C for 6 h under the optimized reaction conditions.

Hemicelluloses were extracted from holocellulose of bamboo by alkaline treatment. The phosphorylated poly(vinyl alcohol) (P-PVA) samples with various substitution degrees were prepared through the esterification of PVA and phosphoric acid. A series of hydrogels of semi-interpenetrating polymeric networks (semi-IPN) composed of hemicelluloses-g-poly(acrylic acid) (HM-g-PAA) and the phosphorylated poly(vinyl alcohol) (P-PVA) were prepared by radical polymerization using potassium persulphate (KPS) as initiator. The HM-g-PAA networks were crosslinked by N,N-methylenebisacrylamide (MBA) as a crosslinking agent in the presence of linear P-PVA. FT-IR results confirmed that the hydrogels comprised a porous crosslink structure of P-PVA and HM with side chains that carried carboxylate and phosphorylate groups. SEM observations indicated that the incorporation of P-PVA induced highly porous structure, and P-PVA was uniformly dispersed in the polymeric network. The interior network structures of the semi-IPN matrix became more porous with increasing P-PVA. The TGA results showed that the thermo-decomposing temperature and thermal stability were increased effectively for intruding the chain of P-PVA. The maximum equilibrium swelling ratio of hydrogels in distilled water and 0.9 wt% sodium chloride solutions was up to 1085 g g(-1) and 87 g g(-1), respectively. The compressive strength increased with increasing the MBA/HM and P-PVA/HM ratios, and decreased with the increment of AA/HM ratio.

Selectively catalytic hydrothermal pretreatment of corncob into xylose and furfural has been developed in this work using solid acid catalyst ( SO 4 2 - /TiO2–ZrO2/La3+). The effects of corncob-to-water ratio, reaction temperature and residence time on the performance of catalytic hydrothermal pretreatment were investigated. Results showed that the solid residues contained mainly lignin and cellulose, which was indicative of the efficient removal of hemicelluloses from corncob by hydrothermal method. The prepared catalyst with high thermal stability and strong acid sites originated from the acid functional groups was confirmed to contribute to the hydrolysis of polysaccharides into monosaccharides followed by dehydration into furfural. Highest furfural yield (6.18 g/100 g) could be obtained at 180 °C for 120 min with 6.80 g/100 g xylose yield when the corncob/water ratio of was 10:100. Therefore, selectively catalytic hydrothermal pretreatment of lignocellulosic biomass into important platform chemicals by solid acids is considered to be a potential treatment for biodiesel and chemical production.

Recently, more and more attention has been centered on developing cheaper, highly efficient, environmentally friendly adsorbents for the removal of metal ions from industrial effluents. The present work deals with the removal of metal ions from an aqueous solution using a highly efficient, biodegradable adsorbent from hydrogel prepared by the free radical graft polymerization of sugarcane bagasse with acrylic acid and acrylamide using N, N-methylene-bis-acrylamide as a crosslinker. FTIR and SEM/EDX spectroscopies were used to characterize the structure and the morphology of adsorbent before and after the metal ions adsorption. The effects of pH, contact time, and initial concentration of metal ion on the adsorption capacity were studied. The adsorption equilibrium time of Pb2+, Cd2+, and Cu2+ were 60, 90, and 180 min, respectively. The maximum adsorption capacities of Cu2+, Pb2+, and Cd2+ were 268, 700, and 320 mg/g, respectively. The adsorption data were fit to often-used models for adsorption kinetics and isotherms. It was determined that the experimental results were well fitted to the pseudo-second-order equation and Langmuir adsorption isotherms.

The objective of this work was to prepare a series of composite films (polysaccharides with LaFe0.8Cu0.2O3) for the degradation of methyl orange under ultraviolet irradiation. LaFe0.8Cu0.2O3 was prepared by a sol-gel method, and the composite films were obtained by cross-linking reactions between polysaccharides (xylan and chitosan) and LaFe0.8Cu0.2O3. Physical and chemical properties of the composite films were investigated by XRD, FTIR, SEM, and BET. Moreover, the influence of the weight ratio of polysaccharide to LaFe0.8Cu0.2O3 on the methyl orange degradation reaction was also studied. Results showed that 67% of the degradation efficiency was achieved within 480 min using chitosan/LaFe0.8Cu0.2O3 (2:1) as photocatalysts, while 58% was for xylan/LaFe0.8Cu0.2O3 (1:1). The difference was due to the variety in the structure of chitosan and xylan.

Composite films of xylan and polyvinyl alcohol were produced with citric acid as a new plasticizer or a cross-linking agent. The effects of citric acid content and polyvinyl alcohol/xylan weight ratio on the mechanical properties, thermal stability, solubility, degree of swelling and water vapor permeability of the composite films were investigated. The intermolecular interactions and morphology of composite films were characterized by FTIR spectroscopy and SEM. The results indicated that polyvinyl alcohol/xylan composite films had good compatibility. With an increase in citric acid content from 10% to 50%, the tensile strength reduced from 35.1 to 11.6 MPa. However, the elongation at break increased sharply from 15.1% to 249.5%. The values of water vapor permeability ranged from 2.35 to 2.95 × 10−7 g/(mm2 h). Interactions between xylan and polyvinyl alcohol in the presence of citric acid become stronger, which were caused by hydrogen bond and ester bond formation among the components during film forming.

Two corncob-derived carbon electrode materials mainly composed of micropores (activated carbon, AC) and mesopores/macropores (corncob carbon, CC) were prepared and studied after the anodic electrodeposition of MnO2. The capacity of the MnO2/activated carbon composite (MnO2@AC) electrode did not noticeably increase after MnO2 electrodeposition, while that of the MnO2/corncob carbon composite (MnO2@CC) electrode increased up to 9 times reaching 4475 mF cm&minus, 2. An asymmetric all-solid-state supercapacitor (ASC) was fabricated using AC as the anode, MnO2@CC as the cathode, and polyvinyl alcohol (PVA)/LiCl gel as the electrolyte. An ultrahigh specific capacitance of 3455.6 mF cm&minus, 2 at 1 mA cm&minus, 2, a maximum energy density of 1.56 mW h cm&minus, 2, and a long lifetime of 10,000 cycles can be achieved. This work provides insights in understanding the function of MnO2 in biomass-derived electrode materials, and a green path to prepare an ASC from waste biomass with excellent electrochemical performance.

In recent years, numerous studies have focused on biodegradable plastics for agricultural applications. To improve the mechanical and hydrophobic properties, biodegradable xylan composite films containing poly(vinyl alcohol) (PVA) were successfully prepared by casting method in this work. A series of composite films at a PVA/xylan weight ratio of 3:1 under the addition of glycerol and urea were investigated. Influences of the urea and glycerol amounts on the functional properties of composite films such as hydrophilicity/hydrophobicity, water vapor permeability (WVP), mechanical properties, solubility and degradability were comparatively investigated. Results showed that increasing the glycerol amount led to a decrease in tensile strength and an increase in elongation at break and WVP, while the addition of 1 % urea in composite films without glycerol had a positive impact on improving the water resistance of composite films; the contact angle and WVP values reached 114.68° and 4.11 × 10−11 g m−1 s−1 Pa−1. Moreover, thermogravimetric analysis, FTIR and a scanning electron microscope were used to confirm the compatibility of the PVA and xylan components. FTIR analysis displayed the intensity of hydroxyl groups of films became stronger with increasing amounts of glycerol, while the opposite results were obtained with an increase of the amount of urea. These indicated that glycerol could improve the miscibility between PVA and xylan, and the addition of urea could enhance the water resistance of composite films.

The present study was conducted to develop a simple and versatile method to prepare carboxylated bamboo fibers which can be applied as potential bio-adsorbent for metal ions removal due to the high content of carboxyl groups. The chemical modification of bamboo fibers with citric acid (CA) was carried out by friendly semi-dry oven method. The resulting products with carboxyl group content between 1.99 and 4.13 mmol/g were accessible by changing ultrasonic pretreatment time, reaction temperature, reaction time and the amounts of catalyst and citric acid in order to minimize cross-linking reaction and thereby maximize carboxyl groups content. The characterization of the resulting products confirmed that carboxyl groups were successfully grafted onto surface of bamboo fibers. Moreover, the carboxylated bamboo fibers could be applied as bio-adsorbent for the removal of lead(II) ions from aqueous solution. Results showed that the adsorption capacity of Pd2+ could reach 127.1 mg/g for carboxylated bamboo fibers with 4.13 mmol/g carboxyl group content prepared under the ultrasonic pretreatment for 20 min at the CA/bamboo fibers weight ratio of 4.0 in the catalyst amount of 30 wt% at 120 °C for 90 min and the carboxylated bamboo fibers exhibited highly efficient regeneration with no significant loss of adsorption capacity of lead ion after five repeated adsorption/desorption cycles.

Recently, homogeneous synthesis of functional carbohydrate polymers carried out in ionic liquids (ILs) has attracted extensive consideration because high reaction efficiency can be achieved. The objective of our work was to develop a new strategy to prepare acid anhydrides-modified xylan by the esterification of xylan with different types of acid anhydride such as acetic anhydride and succinic anhydride under the optimal dissolution condition of xylan in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid. Significantly, effect factors on the xylan dissolution in [BMIM]Cl ionic liquid such as the concentration of xylan and the temperature were comparatively investigated, and the dissolution mechanism of xylan in [BMIM]Cl ionic liquid was revealed The physical and chemical properties of regenerated xylan were characterized by with various techniques such as FT-IR and GPC as well as TGA. Under the optimal dissolution condition of xylan in [BMIM]Cl, different acid anhydrides-modified xylan was comparatively discussed in the presence and the absence of catalyst. It was found that catalyst has different role in the chemical modification of xylan with different types of acid anhydride due to the chemical structure of acid anhydride.

Acylated xylan-based magnetic Fe3O4 nanocomposite hydrogels (ACX-MNP-gels) were prepared by fabricating Fe3O4 nanoctahedra in situ within a hydrogel matrix which was synthesized by the copolymerization of acylated xylan (ACX) with acrylamide and N-isopropylacrylamide under ultraviolet irradiation. The size of the Fe3O4 fabricated within the hydrogel matrix could be adjusted through controlling the crosslinking concentrations (C). The magnetic hydrogels showed desirable magnetic and mechanical properties, which were confirmed by XRD, Raman spectroscopy, physical property measurement system, SEM, TGA, and compression test. Moreover, the catalytic performance of the magnetic hydrogels was explored. The magnetic hydrogels (C = 7.5 wt %) presented excellent catalytic activity and provided a sensitive response to H2O2 detection even at a concentration level of 5 × 10−6 mol·L−1. This approach to preparing magnetic hydrogels loaded with Fe3O4 nanoparticles endows xylan-based hydrogels with new promising applications in biotechnology and environmental chemistry.

A feasible approach was developed to produce furfural from the pre-hydrolysis liquor of corncob via biochar catalysts as the solid acid catalyst in a new biphasic system with dichloromethane (DCM) as the organic phase and the concentrated pre-hydrolysis liquor (CPHL) containing NaCl as the aqueous phase. The biochar catalyst possessing many acidity groups (SO3H, COOH and phenolic OH groups) was prepared by the carbonization and sulfonation process of the corncob hydrolyzed residue. The influence of the catalytic condition on furfural yield and selectivity was comparatively studied. It was found that 81.14% furfural yield and 83.0% furfural selectivity were obtained from CPHL containing 5wt% xylose using this biochar catalyst in the CPHL-NaCl/DCM biphasic system at 170°C for 60min. In addition, with the regeneration process, this catalyst displayed the high performance and excellent recyclability.

The expensive production of bioethanol is because it has not yet reached the 'THREE-HIGH' (High-titer, high-conversion and high-productivity) technical levels of starchy ethanol production. To cope with it, it is necessary to implement a high-gravity mash bioethanol production (HMBP), in which sugar hydrolysates are thick and fermentation-inhibitive compounds are negligible. In this work, HMBP from an atmospheric glycerol autocatalytic organosolv pretreated wheat straw was carried out with different fermentation strategies. Under an optimized condition (15% substrate concentration, 10 g/L (NH4)2SO4, 30 FPU/g dry matter, 10% (V/V) inoculum ratio), HMBP was at 31.2 g/L with a shaking simultaneous saccharification and fermentation (SSF) at 37 degrees C for 72 h, and achieved with a conversion of 73% and a productivity of 0.43 g/(L x h). Further by a semi-SFF with pre-hydrolysis time of 24 h, HMBP reached 33.7 g/L, the conversion and productivity of which was 79% and 0.47 g/(L x h), respectively. During the SSF and semi-SSF, more than 90% of the cellulose in both substrates were hydrolyzed into fermentable sugars. Finally, a fed-batch semi-SFF was developed with an initial substrate concentration of 15%, in which dried substrate (= the weight of the initial substrate) was divided into three portions and added into the conical flask once each 8 h during the first 24 h. HMBP achieved at 51.2 g/L for 72 h with a high productivity of 0.71 g/(L x h) while a low cellulose conversion of 62%. Interestingly, the fermentation inhibitive compound was mainly acetic acid, less than 3.0 g/L, and there were no other inhibitors detected, commonly furfural and hydroxymethyl furfural existing in the slurry. The data indicate that the lignocellulosic substrate subjected to the atmospheric glycerol autocatalytic organosolv pretreatment is very applicable for HMBP. The fed-batch semi-SFF is effective and desirable to realize an HMBP.

Xylan-based temperature/pH sensitive hydrogels were prepared by the crosslinking copolymerization of xylan with N-isopropylacrylamide (NIPAm) and acrylic acid (AA) using N,Ń-methylenebis-acrylamide (MBA) as a cross-linker and 2,2-dimethoxy-2-phenylacetophenone as a photoinitiator via ultraviolet irradiation. The influence of the NIPAm, AA and MBA amount on properties of xylan-based hydrogels was discussed. The morphology and interactions of hydrogels were characterized by SEM and FTIR. The lower critical solution temperature (LCST) of hydrogels was investigated by DSC. The results indicated that the LCST of hydrogels emerged at around 34°C and increased with increasing the AA content. The drug encapsulation efficiency of as-prepared hydrogels reached to 97.60% and the cumulative release rate of acetylsalicylic acid was 90.12% and 26.35% in the intestinal and gastric fluid, respectively. Xylan-based hydrogels were proved to be biocompatible with NIH3T3 cell by MTT assay and showed the promising application as drug carriers for the intestinal-targeted oral drug delivery.

Development of high-strength hydrogels has recently attracted ever-increasing attention. In this work, a new design strategy has been proposed to prepare graphene oxide (GO)/polyacrylamide (PAM)/aluminum ion (Al(3+) )-cross-linked carboxymethyl hemicellulose (Al-CMH) nanocomposite hydrogels with very tough and elastic properties. GO/PAM/Al-CMH hydrogels were synthesized by introducing graphene oxide (GO) into PAM/CMH hydrogel, followed by ionic cross-linking of Al(3+) . The nanocomposite hydrogels were characterized by means of FTIR, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray analysis (SEM-EDX) along with their swelling and mechanical properties. The maximum compressive strength and the Young's modulus of GO3.5 /PAM/Al-CMH0.45 hydrogel achieved values of up to 1.12 and 13.27 MPa, increased by approximately 6488 and 18330 % relative to the PAM hydrogel (0.017 and 0.072 MPa). The as-prepared GO/PAM/Al-CMH nanocomposite hydrogels possess high strength and great elasticity giving them potential in bioengineering and drug-delivery system applications.

In this study, hemicelluloses were isolated from the apical, middle and basal segments of N. cadamba using a 2N KOH extraction procedure. Chemical composition and structural characterization of the three hemicellulosic fractions obtained were comparatively investigated by a combination of HPLC, GPC, FTIR, 1H,13C, HSQC NMR and TGA techniques. According to the sugar analysis and spectral results, (4-O-methyl) glucuronoxylan was the primary hemicellulose identified in the samples with trace levels of mannan also present. All of the three samples showed spherical polymers in 0.005M sodium phosphate solution (containing 0.02N NaCl). Xylan in the middle and basal segment stems had higher molecular weights. Our findings show that during xylogenesis in N. cadamba, changes are observed in xylan content and molecular weight.

In this paper, a novel type of hemicellulosic derivative containing polymerizable double bonds (C=C) was synthesized by chemical reaction of xylan-rich hemicelluloses and glycidyl methacrylate (GMA) in dimethyl sulfoxide (DMSO) in presence of catalysts. The chemical structure, reaction mechanism, and rheological properties of the derivative were investigated by means of FT-IR, 1H and 13C-NMR, DEPT 135 NMR, GC–MS and rheometer. The influence of the reaction conditions including reaction time, temperature, catalysts, and the amount of reagents on the degree of substitution were investigated in detail. Results showed that the chemical reaction of xylan-rich hemicelluloses with GMA was transesterification, which resulted in direct attachment of methacrylate (MA) groups to xylan-rich hemicelluloses, instead of GMA. A maximum degree of substitution of 0.94 could be achieved under the optimum reaction condition (40 °C, 1.8 equiv of GMA to per xylose unit, 36 h, 20 % DMAP). Results from rheological analysis indicated that the aqueous solutions of the methacrylated xylan-rich hemicelluloses (MAXH; 0.5, 1.0 and 2.0 wt%) exhibited typical shear-thinning behavior in the range of shear rates tested. The viscoelasticity of MAXH solutions increased with the increasing concentration and DS.

Delignified Arundo donax was sequentially extracted with DMSO, saturated barium hydroxide, and 1.0 M aqueous NaOH solution. The yields of the soluble fractions were 10.2, 6.7, and 10.0% (w/w), respectively, of the dry Arundo donax materials. The DMSO-, Ba(OH)(2)- and NaOH-soluble hemicellulosic fractions were further fractionated into two subfractions by gradient 50% and 80% saturation ammonium sulfate precipitation, respectively. Monosaccharide, molecular weight, FT-IR, and 1D ((1)H and (13)C) and 2D (HSQC) NMR analysis revealed the differences in structural characteristics and physicochemical properties among the subfractions. The subfractions precipitated with 50% saturation ammonium sulfate had lower arabinose/xylose and glucuronic acid/xylose ratios but had higher molecular weight than those of the subfractions precipitated by 80% saturation ammonium sulfate. FT-IR and NMR analysis revealed that the highly acetylated DMSO-soluble hemicellulosic subfraction (H(D50)) could be precipitated with a relatively lower concentration of 50% saturated ammonium sulfate, and thus the gradient ammonium sulfate precipitation technique could discriminate acetyl and non-acetyl hemicelluloses. It was found that the DMSO-soluble subfraction H(D50) precipitated by 50% saturated ammonium sulfate mainly consisted of poorly substituted O-acetyl arabino-4-O-methylglucurono xylan with terminal units of arabinose linked on position 3 of xylose, 4-O-methylglucuronic acid residues linked on position 2 of the xylan bone, and the acetyl groups (degree of acetylation, 37%) linked on position 2 or 3. The DMSO-soluble subfraction H(D80) precipitated by 80% saturated ammonium sulfate was mainly composed of highly substituted arabino-4-O-methylglucurono xylan and β-d-glucan.

Alkali-soluble hemicelluloses were extracted from delignified peashrub (Caragana korshinskii) by sequential treatments with 0.5, 1.0 and 2.0 mol L−1 KOH under a solid to liquid ratio of 1:25 (g mL−1) at 25 °C for 10 h. The successive treatments resulted in a total dissolution of 64.1, 15.6, and 12.5% of the original hemicelluloses, respectively. The released hemicelluloses were separated into linear and branched hemicellulosic subfractions by the iodine-complex precipitation technique. Their chemical and physical characteristics were determined by HPAEC, GPC, FT-IR and 1H and 13C NMR spectroscopy. It was found that the hemicelluloses precipitated by iodine-potassium iodide solution were more linear as shown they contained more xylose and less uronic acid than the hemicelluloses remaining in the solution, which were more branched and contained higher amounts of arabinose, galactose and glucose. In addition, the linear hemicellulosic subfractions with a low arabinose/xylose ratio had higher molecular weights than those of the branched hemicellulosic subfractions in solution.

In this study, a novel amphoteric macromolecule was synthesized by sequential incorporation of carboxymethyl and quaternary ammonium groups into the backbone of xylan-type hemicelluloses under microwave irradiation. The reaction parameters such as the molar ratio of reagent (NaOH or 3-epoxypropyltrimethylammonium chloride)/anhydroxylose unit in hemicelluloses, the temperature, and the reaction time were investigated to optimize the reaction condition. The maximum degrees of substitution (DS) of carboxymethyl and quaternary ammonium groups under the optimum reaction condition were 0.90 and 0.52, respectively, exhibiting a higher efficiency as compared to the conventional heating method. Moreover, the thermal stability and weight-average molecular weight of amphoteric hemicellulosic derivatives decreased as compared to the native hemicelluloses. The viscosity, elastic modulus, and loss modulus of the amphoteric biomacromolecules increased with the increasing DS of quaternary ammonium groups in aqueous solution due to stronger electrostatic attraction. This study provides an efficient and rapid method to prepare amphoteric biomacromolecules.

The objective of this work was to develop appropriate reaction pathways to explain the liquefaction behavior of cornstalk in sub- and super-critical ethanol. This reaction system was divided into gas lump, water-soluble oil lump, heavy oil lump, volatile organic compounds lump and residue lump based on the characteristics of cornstalk and liquefaction products, and the residue was further separated into carbon, hydrogen, oxygen and nitrogen. Results showed that the reversible reaction between heavy oil and volatile organic compounds occurred in the liquefaction process, and the decrease in the water-soluble oil yield was mainly attributed to the conversion of water-soluble oil to gas in the sub- and super-critical ethanol. The GC/MS analysis showed that the volatile organic compounds, water-soluble oil and heavy oil comprised a mixture of organic compounds of 6–10, 3–12 and 8–20 carbons, respectively, which mainly included esters, phenols, acids, furans and their derivatives.

A novel cationic gelatin graft copolymer was developed by the graft copolymerization reaction of gelatin with acrylamide (AM) and methacryloyloxyethyl trimethylammonium chloride (DMC) in this paper. The structure of graft copolymer was analyzed briefly by the analysis of infrared spectrum, and it was found that monomers (AM and DMC) actually were grafted onto the backbone of gelatin. The effect of reaction conditions such as the weight ratios of AM/gelatin or AM/DMC on grafting parameters and the application of the cationic graft copolymer as the dry strength agent in papermaking were investigated. Experiments showed that a graft copolymer with high the percent grafting and the grafting efficiency could be obtained by controlling the AM/gelatin weight ratio and AM/DMC weight ratio. The application test showed that the results obtained from the physical intensities of handsheets under the treatment of the grafted gelatin [gel-g-P(AM-co-DMC)] were great better than the control sample, which was due to the hydrogen bonds and ionic bonds among fibres in pulp and cationic graft copolymer.

Xylan-rich Hemicelluloses (XH) isolated from wheat straw were converted to functional biopolymers by modification using succinic anhydride (SA) as reactant without catalyst in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid. The reaction was performed under various conditions such as different temperatures, different times, and the different amounts of SA, and the effect of reaction factors on the degree substitution (DS) of products were discussed. The product had the maximum DS of 1.80. The structure of modified hemicellulosic derivatives (MD) was actually confirmed by13C NMR spectroscopy. The thermal behavior of MD was monitored by means of thermogravimetry (TG) and differential thermal analysis (DTA), and the thermal stability of MD was lower than XH.

Surface characteristics including surface morphology and chemical composition of single sisal fiber and their influences on the interfacial adhesion of sisal fiber/phenolic resin composites were investigated by SEM, AFM, and XPS. The results showed that the surface of the untreated single sisal fiber contained a large amount of lignin (up to 51%). Chlorine dioxide treatment could reduce the surface lignin to a low content (20%). Removal of lignin from fiber surface could enhance the interfacial strength of sisal fiber/phenolic resin composites, giving rise to an increase by 36% in tensile strength. These results indicate that the surface properties of single sisal fiber can be tailored to improve the fiber/resin interfacial adhesion.

Chemical modification is the most important means to obtain novel biopolymers and biomaterials from the abundant biomacromolecules. In this paper, hemicellulosic succinate, which is very important biomacromolecule for the preparation of functional materials, was homogeneously prepared in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid. The influence of reaction conditions used in this work on the degree of substitution (DS) was investigated, and the chemical structure and the thermal stability of hemicellulosic succinate were characterized by FT-IR and 13 C NMR spectroscopies as well as thermogravimetry. A high DS of up to 1.80 could be achieved at short time scale in [BMIM]Cl ionic liquid without any catalysts, which is probably due to the excellent dissolving capacity and catalytic effect of ionic liquid. These results indicate that ionic liquids open up totally new opportunities for chemically functionalization of hemicelluloses.

Hemicellulose isolated fromDmMwas converted to novel functional biopolymers by maleylation using maleic anhydride as reactant and LiOH as catalyst. The reaction was performed under various temperatures, times, and the amounts of catalyst and maleic anhydride on the degree substitution (DS) of products were discussed. Comparison of the reaction in different media was discussed in detail. The product had the maximum degree of substitution (DS) of 0.75. Novel functional polymers containing with carbon-carbon double bond and carboxyl groups could be confirmed by13C NMR spectroscopy. The behavior of novel hemicellulosic derivatives was monitored by means of thermogravimetry (TG) and differential thermal analysis (DTA). It was found that the products with a high DS had a lower thermal stability than the native hemicelluloses.

During the last few years increasing attention has been paid to the exploitation of hemicelluloses as biopolymer resources because they are available in very large amounts in organic wasters from renewable forest and agricultural biomass. The efficient method to prepare the cationic biopolymers based on xylan-rich hemicelluloses from agricultural biomass has been developed in this paper. These biopolymers with cationic functional groups, having many good properties such as solubility, bio-degradation, cationic or ampholytic polymers, were synthesized by the chemical modification of sugarcane bagasse xylan-rich hemicelluloses with CHMAC and preferably with ETA in different media. These biopolymers based on xylan-rich hemicelluloses with the degree of substitution (DS) up to 0.55 could be obtained by varying the molar ratio of ETA or CHMAC to anhydroxylose units in hemicelluloses from 0.5 to 3.0. 13C NMR confirmed that cationic groups were grafted onto the backbone of hemicelluloses. In addition, their applications in papermaking as dry strengthen agent were investigated. It was found that these biopolymers could obviously improve the physical properties of hand sheets formed from old corrugated container pulp fibres. These results mentioned above highlight the remarkable potential for using the hemicelluloses-based biopolymers as wet end additives in papermaking.

Rapid carboxymethylation of xylan-rich hemicelluloses from wheat straw biomass with sodium monochloroacetate and sodium hydroxide in the ethanol/water medium under microwave irradiations was investigated in this paper. The effects of reaction conditions such as the reaction time, the reaction temperature, and the amounts of sodium hydroxide and sodium monochloroacetate on the degree substitution (DS) of carboxymethylated hemicelluloses were discussed. The structures of hemicelluloses before and after the chemical modification were analyzed by13C nuclear magnetic resonance (NMR) spectra. Gel permeation chromatography (GPC) was used to characterize the carboxymethylated hemicelluloses. During the chemical modification, it was found that the remarkable degradation of hemicelluloses occurred under microwave irradiations.

Chemical modification is the most important method to design novel biopolymer and biomaterials from the abundant and biocompatible hemicelluloses. In this paper, an efficient method to synthesize hemicellulosic derivatives with bifunctional groups was developed by the etherification of hemicelluloses with acrylamide in the butanol/water medium. Varying the reaction condition such as reaction time, reaction temperature, and the amount of acrylamide and so on, the optimized hemicellulosic derivative with a higher total degree of substituent (DS) of 0.92 and with the 0.43 ratio of carbamoylethy groups and carboxyethyl groups was obtained. 13C NMR analysis showed that the etherification occurred preferably at C-3 position of xylose. A significant degradation of the polymers occurred during the etherification. The shear-thinning of the hemicellulosic derivatives became more dramatic. The solution of the hemicellulosic derivatives showed lower viscosity and modulus as compared with the native hemicelluloses, exhibiting a less elastic behavior.

The double-inlet valve and inertance tube are the two main phase shifters of pulse tube refrigerators. They are crucial for the pulse tube refrigerators to obtain an appropriate phase relationship between pressure and mass flow. In the past decades, much attention has been given to understand the separate functions of the two phase shifters, and the present work will try to investigate their coupling functions. In this paper, the influence of the double-inlet valve on the cooling performance and characteristics of inertance tubes are numerically studied at first. Then an experimental setup is built to prove the numerical results. Based on the numerical and experimental study, it is concluded that the inertance tube cannot provide the optimum impedance for those pulse tube refrigerators with small cooling power because of turbulent flow. In such case, the double-inlet valve can help to provide a better impedance and further improve the cooling performance. On the other hand, the inertance tube can provide the optimum impedance for those pulse tube refrigerators with large cooling power and the double-inlet is not necessary in such a case.

Quaternized carboxymethyl chitosan (QCMC) was intercalated into the interlayer of rectorite (REC) to prepare QCMC/REC nanocomposite. XRD and TEM results revealed that REC was well dispersed in the polymer matrix and obtained the largest interlayer distance when the mass ratio of QCMC to REC was 2:1. FTIR, NMR and zeta-potential analyses showed that the intercalation of QCMC did not destroy the structure of REC layer, but there were hydrogen-bonding and electrostatic interactions between QCMC and REC. Quaternized chitosan (HTCC)/REC nanocomposite was prepared and studied in parallel. The comparative analysis of the two biopolymer/clay nanocomposites indicated that the free volume and positive charge density of biopolymers were important factors that affected the intercalation of biopolymer into clay. At last, thermal analysis indicated that QCMC/REC nanocomposites had obviously higher thermal stability in comparison with QCMC. This study shows that the combination with clay materials is a functional way to expand the possible application of QCMC as drug controlled-release carriers, antimicrobial agent and pulp-cap. (C) 2010 Elsevier Ltd. All rights reserved.

Three organic solvents and one aqueous alkaline solution for fully fractional dissolving hemicelluloses from mild ball-milled cell wall of lignified barley straw and maize stems are described: 90% neutral dioxane, 80% dioxane containing 0.05 M HCl, dimethyl sulfoxide (DMSO), and 8% aqueous KOH. The four successive extractions resulted in dissolution of 94.6% and 96.4% of the original hemicelluloses and 93.7% and 95.3% of the original lignin from barley straw and maize stems, respectively. The structures of the hemicellulosic fractions released during the treatment with the neutral solvents of 90% dioxane and DMSO was found to remain intact, while the extractions with 80% acidic dioxane and 8% KOH under the conditions used resulted in a partial depolymerization of dissolved polysaccharides by cleavage of the glycosidic bonds and saponification of the ester groups in the polymers. The 90% neutral dioxane-soluble hemicellulosic fractions consisted mainly of the more branched arabinoxylans and mixed-linkage glucans such as β-glucans, whereas the hemicellulosic fractions solubilized during the sequential treatments with 80% acidic dioxane, DMSO, and 8% KOH are composed of arabino-(4-O-methyl-d-glucurono) xylans as the major hemicellulosic materials. In addition, the hemicellulosic polymers contained small amounts of ferulic and p-coumaric acids and lignins, revealing that the hemicelluloses removed are mostly unbound to the lignins in the cell walls of cereal straws. This non-degradative cell wall dissolution offers the potential to analyze polysaccharide components for the first time, and improve current hemicellulosic isolation method by using high concentration of aqueous alkali from the delignified cell walls.

The sequential treatment of dewaxed sugarcane bagasse with H(2)O and 1 and 3% NaOH at a solid to liquid ratio of 1:25 (g mL(-1)) at 50 degrees C for 3 h yielded 74.9% of the original hemicelluloses. Each of the hemicellulosic fractions was successively subfractionated by graded precipitation at ethanol concentrations of 15, 30, and 60% (v/v). Chemical composition, physicochemical properties, and structures of eight precipitated hemicellulosic fractions were elucidated by a combination of sugar analysis, nitrobenzene oxidation of bound lignin, molecular determination, Fourier transform infrared (FT-IR), (1)H and (13)C nuclear magnetic spectroscopies, and thermal analysis. The results showed that the sequential treatments and graded precipitations were very effective on the fractionation of hemicelluloses from bagasse. Comparison of these hemicelluloses indicated that the smaller sized and more branched hemicelluloses were extracted by the hot water treatment; they are rich in glucose, probably originating from alpha-glucan and pectic polysaccharides. The larger molecular size and more linear hemicelluloses were dissolved by the alkali treatment; they are rich in xylose, principally resulting from l-arabino-(4-O-methylglucurono)-d-xylans. In addition, noticeable differences in the chemical composition and molecular weights were observed among the graded hemicellulosic subfractions from the water-soluble and alkali-soluble hemicelluloses. The Ara/Xyl ratio increased with the increment of ethanol concentration from 15 to 60%, and the arabinoxylans with higher Ara/Xyl ratios had higher molecular weights. There were no significant differences in the structural features of the precipitated hemicellulosic subfractions, which are mainly constituted of l-arabino-(4-O-methyl-d-glucurono)xylan, whereas the difference may occur in the distribution of branches along the xylan backbone.

In this work the application of different hemicellulosic derivatives including different degrees of substitution (DS) cationic hemicelluloses and carboxymethyl hemicelluloses in sulfate kraft pulp were investigated in detail. It was found that cationic hemicelluloses and carboxymethyl hemicelluloses could improve the physical properties of hand sheets, while the cooperation of cationic hemicelluloses and carboxymethyl hemicelluloses could enhance sharply the physical properties of hand sheets. When the dosages of cationic hemicelluloses with DS of 0.37 and carboxymethyl hemicelluloses with DS of 0.35 were 1.0% and 1.0% (based on dry pulp weight), respectively, the physical properties of hand sheets was significantly improved, breaking lengthen and tear index of hand sheets increased by 21.1% and 54.6% compared with the control hand sheets without any additives added. The fiber intertexture of the hand sheets was observed by SEM. The results indicated that hemicelluloses could be used as the source for the production of wet-end additives in papermaking, which might represent an important strategy for sustainable use of the agricultural residue.

Wheat straw hemicelluloses were converted to novel bifunctional hemicellulosic derivatives by etherification using acrylamide as reactant and sodium hydroxide as catalyst. The degree of substitution can be monitored by altering the molar ratio of acrylamide to xylose unit in hemicelluloses in the range of 1.0-10.0 and the molar ratio of sodium hydroxide to xylose unit in hemicelluloses in the range of 0.5-1.6, without changing the structure of the hemicelluloses. Comparison of the reaction in different media is discussed in detail. The optimized product with a high DS value of 0.58 was obtained by varying the condition parameters. Novel hemicellulosic derivatives containing carbamoylethyl and carboxyethyl groups could be confirmed by FT-IR, (1)H NMR, and (13)C NMR spectroscopies. The behavior of hemicellulosic derivatives was monitored by means of thermogravimetry (TG) and differential thermal analysis (TGA). It was found that the product with a high DS had a lower thermal stability than the native hemicelluloses.

A series of novel water-soluble hemicellulosic derivatives, containing carbamoylethyl and carboxyethyl groups, were heterogeneously synthesized from wheat-straw hemicelluloses with acrylamide (AA) under alkaline conditions. The factors such as reaction temperature, reaction time, molar ratio of catalysis to xylose unit in hemicelluloses and molar ratio of acrylamide to xylose unit in hemicelluloses, were investigated. The average degree of substitution (DS) was calculated by (1)H NMR spectroscopy. DS values up to 0.23 in a one-step synthesis of hemicelluloses derivatives were obtained. Under optimum conditions (60°C, NaOH to xylose unit in hemicelluloses molar ratio of 0.8, AA to xylose unit in hemicelluloses molar ratio of 8.0, reaction time of 1h) an expected ratio of carbamoylethyl group to carboxyethyl group of 4.8 in the hemicellulosic derivatives was obtained. The structural features of the hemicellulosic derivatives were characterized by FTIR, NMR spectroscopy, and by elemental analysis. The current work provides a facile method for the synthesis of hemicellulose derivatives with bifunctional groups, which could be used as wet-end additives in the papermaking industry.

Hemicellulose-based hydrophobic biomaterials with degrees of substitution ranging from 0.46 to 1.54 were synthesized under mild conditions in homogeneous media (N,N-dimethylformamide-lithium chloride) by reacting the native wheat straw hemicellulosic polymers with lauroyl chloride using 4-dimethylaminopyridine as a catalyst. Other catalysts such as N-bromosuccinimide, N-methyl pyrrolidine, N-methyl pyrrolidinone, and pyridine were also investigated. Under optimum reaction conditions (2 equiv of lauroyl chloride and triethylamine per hydroxyl group, 5% 4-dimethylaminopyridine, 40 degrees C, 35 min), a high DS value of 1.54 was obtained. The biomaterials were characterized by FT-IR spectroscopy and (13)C NMR spectroscopy as well as by thermal analysis. The results showed that the lauroylation occurred preferably at the C-3 hydroxyl group of beta-D-Xylp units in the hemicelluloses, and the thermal stability of the hydrophobic polymers increased by esterification.

Hemicelluloses isolated from sugarcane bagasse were converted to carboxymethyl hemicelluloses (CMH) by carboxymethylation using sodium monochloroacetate and sodium hydroxide in ethanol/water medium. The reaction was performed under various temperatures, times, times of alkaline activation, the ways of the addition of alkali, and the amounts of sodium hydroxide and sodium monochloroacetate. The product had the maximum degree of substitution (DS) of 0.56. The structure of the resulting polymers was characterized with Fourier transform infrared (FT-IR) and 13C nuclear magnetic resonance (NMR) spectroscopies. Destructive methods such as thermal analysis and non-destructive techniques such as gel permeation chromatography (GPC) were used to characterize the carboxymethyl hemicellulose preparations. It was found that a significant degradation of the polymers occurred during carboxymethylation. The thermal stability of carboxymethyl hemicelluloses was higher than that of the native hemicelluloses.

Wheat straw hemicelluloses were acetylated with acetic anhydride using iodine as a novel catalyst in 1-butyl-3-methylimidzolium chloride ([C 4 mim]Cl) ionic liquid (IL). Acetylated hemicelluloses with yield and degree of substitution (DS) from 70.5% to 90.8% and between 0.49 and 1.53, respectively, are accessible in a complete homogeneous procedure by changing the reaction temperature, reaction duration, the dosage of catalyst, and the dosage of acetic anhydride. The preferred reaction parameters that resulted in the highest DS were follows: 20:1 reactant molar ratio, 100 °C, 30 min, 15% iodine, in which about 83% hydroxyl groups in native hemicelluloses were esterified. The structural features of the acetylated hemicelluloses were characterized by 13 C NMR and FT-IR spectroscopy. The thermal stability of the acetylated hemicelluloses increased upon chemical modification. It is the first time that we have demonstrated that ILs could be used as an environmentally friendly solvent for the chemical modification of hemicelluloses.

Novel cationic hemicelluloses from sugarcane bagasse were synthesized by quaternization with 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHMAC) using sodium hydroxide as a catalyst in aqueous ethanol solution. The parameters including the molar ratio of NaOH/CHMAC (0.8–2.0), the molar ratio of CHMAC to anhydroxylose units in hemicelluloses (0.5–3.0), reaction time (0.5–2.5 h), and reaction temperature (50–80 °C) were optimized and the extent of quaternization was measured by yield and degree of substitution (DS). A CHMAC/hemicellulose molar ratio of 1.0 and a NaOH/CHMAC molar ratio of 1.2 were found to be an optimum condition for the reaction to proceed smoothly and to yield a product with an expected DS. The structure of the cationic hemicellulosic derivative was characterized by gel permeation chromatography (GPC), Fourier transform infrared (FT-IR), and 13C nuclear magnetic resonance (NMR) spectroscopy as well as thermal analysis. It was found that the thermal stability and weight-average molecular weight of modified hemicelluloses decreased after chemical modification.

One water-soluble and four alkali-soluble hemicellulosic preparations from perennial ryegrass leaves were comparatively studied, and their chemical composition, structural features, and physicochemical properties were examined. The relative monosaccharide compositions of the hemicelluloses were determined by high performance anion exchange chromatography after acid hydroloysis. 13 C NMR and FT-IR spectroscopic methods gave details of the anomeric linkage configuration and confirmed the structure of the hemicelluloses. The results showed that the water-soluble hemicelluloses probably consist of galactoarabinoxylans, β-glucan, and noticeable amounts of pectic polysaccharides, which had a lower molecular weight (19,360 g mol −1 ), while the four alkali-soluble hemicellulosic preparations are presumably composed of galactoarabinoxylans, l -arabino (4- O -methyl- d -glucurono)xylans, and β-glucan, which had higher molecular weights between 31,060 and 36,140 g mol −1 . Galactoarabinoxylans constitute a major fraction of both water- and two alkali-soluble hemicelluloses H 2 and H 3 , isolated with a higher concentration of alkali for a shorter period (18% NaOH or 18% KOH at 22 °C for 2 h). They consist of a linear β-(1 → 4) linked xylan backbone to which α- l -arabinofuranose units and/or short chains of sugar residues containing arabinose and galactose are attached as side residues via α-(1 → 3) and/or α-(1 → 2) linkages. On the other hand, the other two alkali-soluble hemicellulosic preparations H 4 and H 5 , extracted with a relatively lower concentration of alkali for a longer period (10% NaOH or 10% KOH at 22 °C for 16 h), mainly comprised l -arabino (4- O -methyl- d -glucurono)xylans, in which the β-(1 → 4) linked xylan backbone is substituted in O-3 and/or O-2 by signal α- l -arabinose residue and α- d -glucuronic acid or 4- O -methyl-glucuronic acid. β-Glucan, both in water- and alkali-soluble hemicelluloses, was characterized as linear homopolymers consisting of both β-(1 → 3) and β-(1 → 4) glucosidic linkages.

Direct catalytic transformation of xylan-type hemicelluloses to furfural in the aqueous system and the biphasic system were comparatively investigated under mild conditions. Screening of several promising chlorides for conversion of beech xylan in the aqueous system revealed the Lewis acid SnCl4 was the most effective catalyst. Comparing to the single aqueous system, the bio-based 2-methyltetrahydrofuran (2-MTHF)/H2O biphasic system was more conducive to the synthesis of furfural, in which the highest furfural yield of 78.1% was achieved by using SnCl4 as catalysts under the optimized reaction conditions (150°C, 120 min). Additionally, the influences of xylan-type hemicelluloses with different chemical and structural features from beech, corncob and bagasse on the furfural production were studied. It was found that furfural yield to some extent was determined by the xylose content in hemicelluloses and also had relationships with the molecular weight of hemicelluloses and the degree of crystallization.

Figure S1. SEM images of the treated corncob. Figure S2. XRD patterns of the hydrothermal treated corncobs.