Guizhen Fang

Performance characterization of rigid polyurethane foam with refined alkali lignin and modified alkali lignin

The two kinds of rigid polyurethane (PU) foams were prepared with respectively adding the refined alkali lignin and alkali lignin modified by 3-chloro-1,2-epoxypropane to be instead of 15% of the polyether glycol in weight. The indexes of mechanical performance, apparent density, thermal stability and aging resistance were separately tested for the prepared PU foams. The results show that the mechanical property, thermal insulation and thermal stability for PU foam with modified alkali lignin are excellent among two kinds of PU foams and control samples. The additions of the refined alkali lignin and modified alkali lignin to PU foam have little effect on the natural aging or heat aging resistance except for decreasing hot alkali resistance apparently. Additionally, the thermal conductivity of modified alkali lignin PU foam is lowest among two kinds of PU foams and control samples. The alkali lignin PU foam modified by 3-chloro-1,2-epoxypropane could be applied in the heat preservation field.

Synthesis and swelling properties of β-cyclodextrin-based superabsorbent resin with network structure

A biodegradable, β-cyclodextrin-based superabsorbent resin was synthesized by the inverse suspension method. The microstructure, chemical structure, and thermal performance of the resin were characterized by scanning electron microscopy, Fourier transform-infrared spectroscopy, and differential scanning calorimetry. The effects of the synthesis conditions (dosage of cross-linking agent, mass ratios of acrylic acid to acrylamide, mass ratios of β-cyclodextrin to total monomer, neutralization degree, initiator dosage, and reaction time) were optimized to achieve a resin with a maximum swelling capacity. The water absorbency of the optimized resin in distilled water was 1544.76 g/g and that in 0.9 wt.% NaCl was 144.52 g/g. The resin, which is thermoplastic as well as pH-sensitive, had good salt resistance and underwent a maximum in swelling with time in CaCl(2) and AlCl(3) solutions. The fracture surface of the dry resin contained many pores. After swelling, the internal hydrogel showed a typical three-dimensional network structure. The biodegradation of the resin reached 71.2% after 18 days treatment at 30 °C with Lentinus edodes.

Hydrogenolysis and Activation of Soda Lignin Using [BMIM]Cl as a Catalyst and Solvent

To improve the reactivity of the soda lignin, an acid ionic liquid 1-butyl-3-mthylimidazolium chloride ([BMIM]Cl) was used as the catalyst and solvent to degrade the soda lignin through hydrogenolysis. Structural elucidation of the lignin samples was conducted by using a combination of analytical methods including chemical analysis, ultraviolet spectrophotometry (UV spectrophotometry), Fourier transform infrared spectroscopy (FT-IR spectra), two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC NMR) techniques, and gel permeation chromatography (GPC). The antioxidant activities of the lignin samples were evaluated using the diammonium 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS+) radical scavenging and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods. The degradation mechanism was proposed based on the characterization results. The optimal reaction condition was as follows: the concentration of [BMIM]Cl in the solution was 10 wt %, the hydrogen initial pressure was 3 MPa, and the solution was heated for 4 h at 90 °C. After the reaction, the total hydroxyl content of the soda lignin increased by 81.3%, while the phenolic hydroxyl content increased by 23.1%. At the same time, the weight-average molar mass of the soda lignin sample decreased from 8220 to 6450 g/mol with an improved antioxidant activity. In addition, approximately 56.7% of the β-O-4 linkages were degraded in the lreaction. The main effect of the acid ionic liquid [BMIM]C1 was related to the cleavage of β-O-4 linkages. This study has shown the potential of using the catalyzed soda lignin as a natural polymer antioxidant.

Separation and purification of Arabinogalactan obtained from Larix gmelinii by macroporous resin adsorption

Arabinogalactan (AG) obtained from Larix gmelinii R. was purified with the method of macroporous resin adsorption. Effects of various parameters on the adsorption, including adsorption time and temperature, the concentration and the dosage of raw AG, the reused numbers of resin, were investigated. The effect of purification was tested through the removal rate of impurity and the contents of AG and impurity. The optimal condition was determined as follows: adsorbed at 30°C for 2 h with the concentration of raw AG <0.1 g·mL−1 and its dosage < 7 mL, the dose of resin was 3 g and reused for 4 times. On the basis of these, macroporous resin column was used for AG purification. The result showed that the AG yield could reach 68.28% with sugar content of 95.02%. The analysis of IR and UV showed that the effect of macroporous resin characteristics on the purification of AG was significant. The obtained product had the same functional groups with standard sample.