Research Articles

The curing kinetics of foam prepared from the tannin of spruce tree bark was investigated using differential scanning calorimetry (DSC) and the advanced isoconversional method. An analysis of the formulations with differing amounts of components (furfuryl alcohol, glycerol, tannin, and a catalyst) showed that curing was delayed with increasing proportions of glycerol or tannins. An optimum amount of the catalyst constituent was also found during the study. The curing of the foam system was accelerated with increasing temperatures. Finally, the advanced isoconversional method, based on the model-free kinetic algorithm developed by Vyazovkin, appeared to be an appropriate model for the characterisation of the curing kinetics of tannin-based foams.

5-hydroxymethylfurfural (HMF) is an important bio-based platform chemical, and its aerobic selective oxidation to 2,5-diformylfuran (DFF) still remains a challenge. This work dealt with active manganese dioxide (AMD) and efficiently catalyzed HMF oxidation to DFF with a yield of ~73% at 393 K and 60 bar O2 in N,N-Dimethylformamide (DMF). Through analysis of liquid products and the catalyst characterization using X-ray diffraction (XRD), a scanning electron microscope (SEM), a transmission electron microscope (TEM), and an elemental analyzer, it can be seen that this AMD catalyst is a low-cost, efficient, and environmentally benign heterogeneous catalyst for the aerobic selective oxidation of HMF to DFF in a one-pot technique. These research results may provide guidance for the development of more efficient catalysts for the future industrial production of high-value added DFF.

In a previous study, a soybean meal-based adhesive was developed by mixing soybean meal flour with a self-made cross-linking agent. The objective of this study was to investigate the effects of retention agents on the properties of the adhesive. Soybean meal flour (together with a cross-linking agent) and two kinds of additives (SDS and cationic PAM) were used to develop the soybean meal-based adhesive. The water resistance of the adhesive was measured by testing the wet shear strength of the resulting three-ply plywood samples and the residual rate of the different adhesives themselves. The apparent viscosities of the adhesives were also measured. Cross sections of the cured adhesives were imaged with a scanning electron microscope (SEM). Results showed that adding 0.5% SDS to the adhesive formulation improved its wet shear strength by 38.6%, from 0.83 to 1.15 MPa, and increased the residual rate by 1.3%, from 76.5 to 77.5%. Adding 0.01% PAM improved the water resistance of the adhesive by 38.6%, from 0.83 to 1.15 MPa, and increased the residual rate by 2.2%, from 76.5 to 78.2%. Adding 0.2% SDS and 0.01% PAM together improved the water resistance of the adhesive by 55.4%, from 0.83 to 1.29 MPa. The plywood bonded with the soybean meal/SDS/PAM adhesive met interior plywood requirements. SEM results showed fewer holes and cracks on the cross section of the cured adhesive with the addition of SDS and PAM.

Ground calcium carbonate (GCC) was modified with a starch/sodium stearate complex and used to prepare different coating weights by controlling the starch dosages. Modified GCC was characterized by scanning electron microscopy (SEM) and particle size analysis. The effects of starch dosage (based on the dry weight of GCC) on the size of modified GCC, the coating weight of modified GCC, and the utilization rate of starch were evaluated. Four kinds of modified GCC with different coating weights obtained by controlling the starch dosage were studied in the last part of this paper. The starch dosage was found to play an important role in the coating weight of starch/sodium stearate complex used in preparing the modified GCC and the utilization rate of starch, but did not have as much of an effect on the size of modified GCC. The higher coating weight was beneficial for retention of the filler retention and for enhancing paper strength properties at the same ash content. The higher coating weight, however, caused a decrease in the paper ash content at the same initial added filler.

The objective of this work was to investigate the possibility of using Na-bentonite as a raw material to produce aluminum salt-modified bentonite (AlMB) for desilication of green liquor. Batch experiments were carried out by varying the experimental parameters to find the optimum conditions. The optimum adsorbent dose was 20 g/L. The maximum adsorptions of 96.37% and 87.22% took place at pH 7.4 when the initial concentrations of silicate in green liquor were 4 and 6 g/L, respectively. The kinetic models showed that the process included physical adsorption and chemical adsorption. Finally, this study showed that the extent of desorption was 56.78% for silicate after desorption of AlMB in 2 M NaOH solution. The AlMB is an efficient and novel adsorbent for desilicating that can provide a good reference for the “silicon influence” in a papermaking mill.

Acetic acid-catalyzed steam explosion pretreatment was applied to wheat straw at temperatures of 190 and 210 °C for 2, 6, and 10 min of residence time. The effects of pretreatment conditions on the total gravimetric recovery, hemicellulose sugars, glucose content, and yield of the enzymatic hydrolysis of cellulose were studied. The results indicated that the total gravimetric recovery decreases while the solubility of hemicellulose and the yield of cellulose enzymatic hydrolysis increase as the pretreatment severity increases. Pretreatment at 190 °C with a 2-min residence time resulted in the highest total gravimetric recovery, 58.9%. The optimum defiberation, glucose content, and enzymatic hydrolysis yields of 70.4 and 79.6%, respectively, occurred following pretreatment at 210 °C with a 10-min residence time. The optimal pretreatment condition was determined to be 190 °C for 10 min. Under the optimum conditions, the recovery yield of all sugars reached 42.7%. This pretreatment resulted in the highest recovery yield of all sugars.

Cellulose acetate (CA) was successfully synthesized by the acetylation of TCF cellulose pulp from oil palm empty fruit bunches (OPEFB) at room temperature, using acetic anhydride as the acetylating agent and acetic acid as the solvent in the presence of sulfuric acid/sodium bisulfate as catalysts. Degree of substitution (DS) was controlled by the variables of acetylation time and acetic anhydride to cellulose ratio, under the heterogeneous state. The product (CA) obtained was characterized through Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results indicate that the CA obtained has characteristics similar to commercial CA, and DS is significantly dependent on acetylation time and the acetic anhydride-to-cellulose ratio.

Aging means that a polymer material’s performance gradually deteriorates, with the loss of use value due to the comprehensive effect of internal and external factors. In this work, a starch-based aqueous polymer isocyanate (API) adhesive joint structure of crosslinking in bonding interface was investigated. The compression shear strength was recognized as a key evaluation index, and the hygrothermal aging experiment tests were accelerated to study the damage mode and failure mechanism of the glue joint structure. The results showed that the adhesive properties of fracture were ductile fracture, and with an increase of aging time, the damage mode of the bonding was transformed from a cohesion damage mode to a cohesion damage with interface damage mode. In the early stages of the aging tests, the effect of temperature on the compression shear strength was most important; however, with the increase of aging time, the effect of humidity became most important.

This work presents a techno-economic analysis of two modelled microcrystalline cellulose (MCC) production facilities, a stand-alone mill, and a mill integrated into a chemical pulp mill, with annual production levels of 30,000 tons/year. These results indicate that both options can be very profitable when the return on investment and the added value of the purchased chemical pulps are used as indicators. However, the integration of MCC production will yield about 19% greater net profit than the non-integrated alternative. Integration also reduces the economic risk of investment, since operation of the MCC plant can be halted for maintenance and chemical pulp can be produced in a normal manner.

This work presents a techno-economic analysis of two modelled microcrystalline cellulose (MCC) production facilities, a stand-alone mill, and a mill integrated into a chemical pulp mill, with annual production levels of 30,000 tons/year. These results indicate that both options can be very profitable when the return on investment and the added value of the purchased chemical pulps are used as indicators. However, the integration of MCC production will yield about 19% greater net profit than the non-integrated alternative. Integration also reduces the economic risk of investment, since operation of the MCC plant can be halted for maintenance and chemical pulp can be produced in a normal manner.