The impulse-cyclone drying and the silane coupling agent (A187) modification are applied to treat wood fibers under the following conditions: 180°C, 180°C+A187, 200°C+A187, 220°C+A187 and 240°C+ A187. Then, HDPE/wood fiber composites are fabricated with a two-stage plastic extruder, and the effects of impulse-cyclone drying technique on the UV-accelerated aging properties of composites are investigated. Fourier-transform infrared spectroscopy (FTIR) reveals that the silane coupling agent chemically reacts with the hydroxyl groups on the wood fiber surfaces, the anti-UV aging properties of composites is enhanced. Mechanical test shows that during the 0–3000 h of UV aging process, the mechanical properties of samples tend to increase initially and then decrease within a period of time. After 3000 h of UV aging, the specimen 4 exhibits the least loss of mechanical properties, with flexural modulus, flexural modulus and impact strength of 65.40 Mpa, 2082.08 Mpa and 12.85 Mpa, respectively. The effects of impulse-cyclone drying technique on the UV-accelerated aging properties of composites are investigated through Spectrophotometry and Surface microstructure observation. indicates that the ΔL* and ΔE* values increase greatly at the stage of 0–1000 h aging, which though tend to stabilize after 1000 h. The degree of discoloration changes little for specimen 4,and the number of surface cracks is relatively small, which exhibits the optimal aging resistance. In conclusion, the addition of wood fibers treated by impulse-cyclone drying (220°C) and A187 modification is effective in enhancing the anti-UV aging properties of HDPE/wood fiber composites. Nevertheless, such enhancing effect turns to decline when the temperature of impulse-cyclone drying treatment is excessively high.
Restoration techniques were explored for the patterns, materials, and surface pigments of the pigments decoration art of Kaiping Diaolou and Villages, a world cultural heritage site in southern China. Field investigation was supplemented by scanning electron microscopy, microscopic Raman spectroscopy characterization, colorimetric tests, and tensile tests. Materials and concepts for the restoration of the Kaiping Diaolou pigments were analyzed. Raman spectroscopy was used to characterize the surface pigments display of pigments decorative patterns. The main colors of restoration included green, red, white, and blue. The green color was a mixture of colored copper arsenate minerals. The red color was made of hematite (Fe2O3). White was calcite, and blue was lapis lazuli or synthetic ultramarine. SEM revealed both pigments show similar flake flocculent section morphologies. UV accelerated aging experiments showed that the Ultraviolet absorber and antioxidants effectively inhibited the degradation of the interface matrix. The interface was less prone to cracking. The tension test showed that the bond stress reached a maximum value of 0.193 MPa at a curing temperature of 20 °C under 95% ambient humidity. The results provide strong evidence for pigment restoration in Kaiping Diaolou. This study also provides a scientific reference for the pigment conservation of other architectural decorations from the same historical period.
Wood fiber was modified by impulse-cyclone drying treatment with poplar and montmorillonite as reinforcing materials; mMMT/polypropylene/wood fiber foaming composite was prepared by the hot compression process. The effects of modification, temperature, and content of montmorillonite on physical and mechanical properties of the composite were analyzed. Mechanical properties, porosity, shrinkage, water absorption, and thickness swelling tests showed that when mMMT reinforcement was 5 wt%, the best performance was achieved. The scanning electron microscopy observations showed that bubble holes were distributed widely and evenly, and mMMT appeared in the cell gap and was encapsulated by polypropylene, which maximized the bonding effect. Flexural strength was 27.5 MPa, flexural modulus was 2110 MPa, tensile strength was 20.0 MPa, and impact strength was 6.30 KJ/m2. When absolute volume of dense solid reached 70.8 cm3, porosity was 21.4% and shrinkage was 1.17%, which indicated that the water absorption increased most remarkably under that test condition. When equilibrium water absorption reached 9.28%, the thickness swelling decreased by 25%. The results showed that mMMT effectively optimized mechanical properties of wood-based foamed composites and improved hygroscopic properties.
Samples of agilawood (agarwood), which were studied in this work, were produced in Zhongshan City, Guangdong Province, China. To enhance incense production, a specific concentration of plant hormone is employed for induction. The extraction technology of agilawood essential oil was explored using supercritical carbon dioxide fluid, which exhibited a more pronounced induction effect. The pressure, temperature, and flow rate, respectively, were 8, 16, and 24 MPa; 35, 45, and 55 °C; and 20, 30, and 40 L/h. A Box-Behnken analysis was adopted for experimental data, which involved 33 experiments. The data were fitted with the equation Y = 2.18 + 0.1312X1 – 0.025X2 + 0.1236X3 – 0.0025X1X2 – 0.0125X2X3 + 0.0175X12 + 0.035X22 – 0.1275X32. Hence, the optimal process parameters in the supercritical extraction of agarwood essential oil were as follows: the pressure, temperature, and flow rate of 24 MPa, 35 °C, and 33 L/h, respectively. An analysis was conducted with the statistical analysis software Design-Expert 11, which indicated that the extraction yield of agarwood essential oil by supercritical carbon dioxide was mainly affected by the pressure and flow rate. The yield was proportional to the pressure and flow, and inversely proportional to the temperature.
For determining the effects of meta-tolyl-N-methylcarbamate (MTMC, metolcarb) on Aphrophora costalis Matsumura (ACM) and the migration and leaching law of MTMC in soil, the thin-layer chromatography method was used. The characteristics of migration and leaching of MTMC in the dark brown soils, and the most critical influences such as soil type, pH, and amount of water were considered to evaluate the impact of leaching rate. The results showed that 25% MTMC diluted 1,000 times was most effective in controlling ACM, with a mortality reaching 87.8% by root irrigation, and a mortality of up to 94.4% by root burial. For dark brown soil, clay minerals are primarily quartz, as well as small amounts of agalmatolite, mica, and kaolinite. Adsorption of MTMC by dark brown soil begins within 2 h, which increases rapidly in capacity before 16 h, and tends to balance with a decrease in the gradient concentration after 16 h. The desorption capacity of MTMC exhibits a gradual increase within 2 h, showing a maximum around 12 μg·g-1, which tends to stabilize after 12 h. MTMC has moderate mobility in dark brown soil. This research has important practical significance for controlling tree diseases and insect pests and protecting the environment.
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