Volume 12 Issue 1

Activated carbons (ACs) were developed from the agricultural by-products of moso bamboo by pyrolysis carbonization and the KOH activation process. N2 adsorption-desorption at 77 K, thermogravimetric analysis (TG), X-ray photoelectron spectrometry (XPS), element analysis (EA), X-ray diffraction (XRD), scanning electron microscopy (SEM), high- resolution transmission electron microscopy (HRTEM), and Fourier transform infrared spectroscopy (FTIR) were used to investigate the synthesis process, the impact of the weight ratio of KOH/bamboo charcoal (BC), and the characteristics of the bamboo charcoal and ACs produced. The results showed that the developed bamboo ACs achieved surface areas (SBET) as high as 3208 m2/g and micropores volumes (VDR) as high as 1.01 cm3/g. The carbonation and activation of the bamboo resulted in the enhancement of the microstructure of the bamboo ACs, and hence improvements in the sorption behavior and storage capacity. The highest hydrogen storage capacities achieved were 6.6 wt.% at 4 MPa and 2.74 wt.% at 1 bar, both at 77 K, which were much higher than those of a well-known commercial activated carbon.

Different factors that influence the alkaline degradation of cellulose in the pulping process were considered in this study. The factors were the reaction temperature, reaction time, dosage of NaOH, and metal ions. Microcrystal cellulose (MCC) was applied as the model compound. To measure the influence of different metal ions on the alkaline degradation of cellulose, K+ and Mg2+ were added into the reaction system. The Fourier transform infrared (FTIR) spectra of the MCC in the solution with and without K+ and Mg2+ were analyzed to clarify the reaction mechanism of the alkaline degradation of cellulose and MCC. Alkaline degradation increased with increasing reaction temperature, reaction time, and alkali concentration. When the reaction temperature was above 80 °C, the reaction time was above 2 h, or the alkali content was below 5 g/L, the degradation ratio of MCC decreased. The amount of degraded MCC and the concentration of glucose in the reaction solution exhibited a nearly linear relationship when the alkali quantity increased from 0 g/L to 5 g/L. K+ and Mg2+ had an opposite impact on the alkaline degradation. While the K+ promoted the alkaline degradation of cellulose, the Mg2+ inhibited it, along with an increase of the dosage of the two metal ions.

Effects of alkali treatment of palm kernel shells (PKS) were investigated relative to curing characteristics, tensile properties, and fatigue of PKS-filled natural rubber (NR) composites. The PKS powder was subjected to alkali treatment using 5% sodium hydroxide. The treated PKS was incorporated into the NR composites during compounding, with the concentrations of the composites ranging from 5 to 20 phr. The properties of treated PKS-filled NR composites were compared with those of untreated PKS-filled NR composites. The cure times, scorch times, and maximum torque values were all lower for alkali-treated PKS/NR composites compared with those of untreated PKS/NR composites. Tensile strength and elongation at break were higher for treated PKS composites, while the moduli (M100 and M300) were lower than those of untreated PKS/NR composites. The fatigue tests for treated PKS/NR composites also showed higher fatigue values than the untreated PKS/NR composites. Scanning electron microscopy revealed that the higher tensile strength, elongation at break, and fatigue values of treated PKS/NR composites were due to the removal of hemicellulose and lignin in PKS fillers. This removal increased in the surface roughness of the filler and led to improved rubber-filler adhesion.

This study was aimed at preparing electromagnetic interference (EMI) shielding materials based on carbon black (CB), carbon fiber (CF), bamboo charcoal (BC), and epoxy resin. The effects of adding bamboo charcoal on the mechanical properties and electrical resistivity of epoxy composites were studied. Scanning electron microscopic (SEM) analysis, electrical resistivity, and electromagnetic interference (EMI) shielding effectiveness were also investigated. The composites were prepared at 120 °C by the curing-molding method through blending the fillers in epoxy resin. The results revealed that the BC/CB and BC/CF composites had perfect conductive network structure and resulted in better dynamic thermal mechanical properties. The electrical resistivity declined with the increase of bamboo charcoal contents; consequently, the EMI shielding effectiveness improved gradually. The lowest electrical resistivity, down to 0.071 Ω·m, corresponded to the best EMI shielding effectiveness of BC/CF composites, which could be above 60 dB over a frequency range of 30 MHz to 1500 MHz while the carbon fiber content was at 40 wt.%.

The thermal behavior of cotton straw briquette (CSB), municipal solid waste (MSW), and their blends was investigated using a thermogravimetric analyzer under N2/O2 and CO2/O2 atmospheres at 20 °C/min from an ambient temperature to 1000 °C. The kinetics and synergistic interaction between MSW and CSB in the co-combustion process were evaluated. The results indicated that MSW blended with CSB improved the ignition and burnout characteristics of the blends, while decreasing the comprehensive combustion characteristics index. The suitable proportions of CSB were less than 60% and 40% separately under 80N2/20O2 and 80CO2/20O2 atmospheres, respectively. The inhibitory effect of CO2 induced burnout temperature and residual mass increased, and the high-temperature stage reaction varied. Kinetic analysis of the blends indicated that blending with CSB could promote MSW combustion in the first reaction stage, while the second and third decomposition stages were complicated because of the synergistic interaction between MSW and CSB in the co-combustion process. The nth order reaction model fit the mass loss of theca-combustion process for the blends very well.

Palm petioles fibers (PPF) are used widely in China to make mattresses. The changes of the properties of PPF after heat treatment is an important factor that should be considered. This study focuses on the fiber tensile test after heat treatment under different temperatures and at different times. As the temperature of treatment was increased, the Young’s modulus of PPF increased, while the breaking strength and elongation declined. The turning point of the tensile properties was 160 °C. The heating time also had a significant influence on the tensile properties. As the heating time increased, the Young’s modulus grew, while the breaking strength and elongation declined.

To maximize the value of poplar wood in manufacturing of laminated veneer lumber (LVL), its radial (from pith to bark) and longitudinal (from bottom to top) variations were examined in terms of the density and dynamic modulus of elasticity (ED) of veneer. The veneer sheets were rotary-peeled from seven representative poplar butt bolts (the bottom part of a stem) and seven representative poplar second bolts (the middle part of a stem). A grading strategy for selecting veneer was proposed based on the requirements of LVL products. In this study, the ED value of each poplar veneer sheet was non-destructively measured by the ultrasonic method. The results showed that there was a weak correlation between veneer density and ultrasonic wave velocity. The bolt class (butt or second bolt) did not significantly influence the variation of veneer density and ED. However, the among-bolt variation played a significant role in the variability. A large difference in diameter between two ends of a bolt (i.e. the within-bolt variation) resulted in a low veneer ED. According to the sorting criteria of Chinese Standard “Laminated Veneer Lumber”, the estimated grade yields of the poplar veneer studied were 45.2% for G1, 39.3% for G2, 13.1% for G3, and 2.4% for G4.