Bamboo was hydrothermally torrefied in hydrochloric acid solution assisted by microwave heating at 180°C for 5−30 min. For bamboo torrefied in water, the yield of the torrefied bamboo decreased slightly from 96.15% to 85.83% and the hemicellulose content decreased from 31.78% to 25.71% with increased torrefaction severity from 3.27 to 3.89. Whereas for bamboo torrefaction in acid solutions, the yield of the torrefied bamboo was below 51% and hemicellulose was completely removed as evidenced by the fact that the solid residue contained no hemicellulose. The carbon content of bamboo was 48.82% and it increased slightly after torrefaction in water. It raised largely up to 67.03% under torrefaction with 0.4 M HCl solution at 180°C for 30 min. The atomic H/C and O/C ratios of bamboo were 1.479 and 0.694, and as bamboo was wet torrefied, they were in the range of 0.891−1.454 and 0.313−0.676, respectively. The higher heating value (HHV) of the torrefied bamboo increased by 45.20% after torrefaction at 0.2 M HCl for 30 min, which (24.86 MJ kg −1 ) was higher than that of Converse School-Sub C coal (21.67 MJ kg −1 ) and comparable with that of German Braunkohole lignite (25.10 MJ kg −1 ). In addition, the structural modifications of bamboo during the torrefaction process were investigated by chemical component and elemental analyses, CP/MAS 13 C NMR, FTIR, XRD complemented with TG/DTA.

No abstract

A flexible strain sensor is of significant importance in wearable electronics since it can help monitor the physical signals from the human body. Among various strain sensors, the polyurethane (PU)-based ones have received widespread attention owing to their excellent toughness, large working range, and nice gas permeability. However, the hydrophobicity of these sensors is not good enough, which may affect their use life and sensitivity. In this work, a highperformance strain sensor composed of PU, reduced graphene oxide (rGO), polydopamine (PDA), and 1H,1H,2H,2H-perfluorodecane-thiol (PFDT) was designed and prepared. The results revealed that this PU/rGO/PDA/PFDT device possessed good superhydrophobicity with a water contact angle of 153.3°, a wide working strain range of 590%, and an outstanding gauge factor as high as 221 simultaneously. Because of these above advantages, the sensor worked effectively in detecting both subtle and large human movements (such as joint motion, finger motion, and vocal cord vibration) even in a high humidity environment. This strain sensor with high sensitivity, wide working range, and suitable modulus may have great potential in the field of flexible and wearable electronics in the near future.

No abstract

Improving the surface activity of lignin through chemical modification for preparation of anionic surfactant.