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The performances of lignin-based dye dispersant largely rely on the molecular weight and phenolic hydroxyl content of lignin. In order to evaluate their impacts, dye dispersants with different molecular weight and different phenolic hydroxyl content were prepared by fractionation, sulfonation, and etherification. Experimental results indicated that relatively high molecular weight benefits the dispersion performance. The staining grade of the dispersant to the fiber raised from 3 to 4.5 with the decrement of phenolic hydroxyl content, Noteworthily, the dispersant with Mw of 13,556 Da contains 0.91 mmol g−1 of phenolic hydroxyl and 1.55 mmol g−1 of sulfonic group, exhibiting superior heat stability at 130 °C and slight fiber staining (grade 4.5). Furthermore, the dye uptake of the dispersant with Mw of 13,556 Da reached the highest value of 84.8% in all those samples. Etherification is a promising method to raise the molecular weight of lignin and to reduce the content of phenolic hydroxyl groups, which improves the performances of lignin-based dye dispersants. [ABSTRACT FROM AUTHOR]

The molar mass (MM) and polydispersity indices (PDI) of acetylated hardwood kraft lignin (Ac-HWKL) and Ac-HWKL fractions were measured by size-exclusion chromatography with multi-angle laser light scattering (SEC-MALLS). The detectors worked at LL658 nm and LL785 nm. The MM of Ac-HWKL measured at 785 nm was much smaller than that measured at 658 nm. The number-average (Mn) and weight-average (Mw) molar masses of Ac-HWKL determined at 785 nm were approximately 6.2 and 6.5 times larger, respectively, than the values estimated using a conventional calibration curve created with authentic polystyrene standards in tetrahydrofuran (THF). Based on the Mw of Ac-HWKL fractions, the Mark-Houwink-Sakurada equation for Ac-HWKL was established to be [η]/ml g−1=0.320 M0.24 in THF and [η]/ml g−1=0.142 M0.26 in dimethyl sulfoxide (DMSO). These results demonstrate that Ac-HWKL has a more compact structure in an organic solvent than polystyrene. [ABSTRACT FROM AUTHOR]

In this work, a hemicellulose-containing hydrogel was synthesized. As the first step, a temperature- and pH-sensitive copolymer was synthesized from itaconic acid andN-isopropylacrylamide (NIPAAm). Then the hydrogel was prepared by reacting the copolymer with acylated hemicellulose and polyvinyl alcohol. The morphology, compressive strength, thermal stability, swelling/deswelling behavior, drug-release behavior performances of the hydrogels were investigated. The lower critical solution temperature of the hydrogels varied in 34–44°C when the NIPAAm and itaconic acid mass ratios ranged in 100/0–90/10. Both temperature and pH had a significant influence on equilibrium swelling ratio of hydrogels. The equilibrium swelling ratio increased with pH, but decreased with temperature. Cytocompatibility assay demonstrated that this hemicellulose-containing hydrogel was biocompatible. The release process of salicylic acid suggested that this hydrogel had a potential use in controlled drug release. [ABSTRACT FROM PUBLISHER]

An adsorbent was prepared from acetic acid lignin (AAL) to investigate the adsorption mechanism of methylene blue (MB) from water. AAL was first deacetylated in NaOH aqueous solution and then fractionated by methanol to prepare adsorbents with various acidic hydroxy groups. The adsorption capacities of MB increased with the increase in initial pH and with the decrease in adsorbent dosage. The results of adsorption kinetics indicated the dye uptake process is a chemisorption. The adsorption capacity of lignin for MB adsorption increased from 18.2 to 63.3 mg g−1as AAL was deacetylated and fractionated. [ABSTRACT FROM PUBLISHER]

Lignin with low molecular weight (LA), fractionated from soda lignin by methanol extraction, was grafted with methyl methacrylate (MMA) and used for interfacial modification for poly (vinyl chloride) (PVC)/wood flour composites. By sequential extraction with chloroform and aqueous NaOH solution, the grafting product was separated into three fractions by the different solubility of various components in these solvents. The data of lignin contents in the three fractions indicate that more than 80% of the lignin participated in the copolymerization. As indicated by the contact angle, data the hydrophilic wood surface was transformed into a hydrophobic one by the grafting product treatment. The grafting product exhibited a positive influence on improving the mechanical performances of PVC/wood flour composites. In comparison with untreated ones, the tensile and impact strengths of composites containing 30 phr of wood flour treated with 2 wt% grafting product (MMA/LA = 1:1) were increased by 18.7% and 25.9%, respectively. Furthermore, the optimum ratio of MMA/LA was 2:1, for which the increments in tensile and impact strengths were 20.9% and 35.3%, respectively. A significant increase in storage modulus (E′) was observed upon the incorporation of treated wood flour. SEM (scanning electron microscope) images showed that the dispersion of treated wood flour in the polymer matrix was improved. It can be inferred that the polymer-wood interfacial bonding was strengthened. [ABSTRACT FROM PUBLISHER]

Porous hydrogels were prepared from hydroxyethyl cellulose (HEC) using citric acid (CA) as a cross-linker with the pores formed by a freeze-drying technique prior to the cross-linking reaction. The pore size increased with the increase of the mass ratio of water to HEC during the preparation of the hydrogels. The porous structure of the hydrogels was in favor of the protein adsorption. The results of thermogravimetry demonstrated that the thermal stability of HEC was improved by cross-linking with CA. The data of percent weight remaining in buffer solution with different pH indicated that the hydrogels were stable in both weak acid and base media. The data of the swelling ratio demonstrated a fast swelling property of the hydrogel. [ABSTRACT FROM AUTHOR]