Facile synthesis,characterization, and ab-initio DFT simulations of energy efficient NN′ dialkyl 1,4 benzene dicarboxamide monomers recovered from PET bottle waste

Aminolytic chemical recycling is performed for obtaining NN′ diethyl 1,4 benzene dicarboxamide, NN′ dibutyl 1,4 benzene dicarboxamide, and NN′ dihexyl 1,4 benzene dicarboxamide from Polyethylene terephthalate bottle waste. The compounds were characterized through Fourier transform Infrared spectroscopy, Raman spectroscopy, UV–Visible spectroscopy, ¹H NMR, ¹³C NMR, mass spectrometry, and elemental analysis. Thermal properties were also analyzed with the help of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Density Functional Theory (DFT) study has been performed at GGA-BLYP (Becke's and Lee–Yang–Parr) functional using SZ basis set to investigate the vibrational frequencies and physical parameters. Experimental vibrational frequencies were found in good accord with the experimental values. Calorific values of the products have been determined using bomb calorimeter as per standard ASTM D240. The values have been correlated with increment of methylene units from NN′ diethyl BdCA to NN′ dihexyl BdCA using standard molar enthalpies of carbon and hydrogen. SEM and EDX analysis of the char residues after combustion has also been carried out to insight the effect of N-alkyl chain length on calorific values. The calorific values of the recovered compounds are comparable to commercial solid fuels and the compounds may find potential applications in aerospace industry.     

AHP/碱木质素聚氨酯泡沫的阻燃性能

对精制后的碱木质素进行羟甲基化改性,再利用改性后的羟甲基化碱木质素部分替代聚醚多元醇,采用一步发泡法与聚合MDI制备了羟甲基化木质素基聚氨酯泡沫材料。将次磷酸铝(AHP)作为阻燃剂添加到泡沫中制备了阻燃碱木质素聚氨酯泡沫,通过极限氧指数(LOI)测试分析了羟甲基化木质素基阻燃聚氨酯泡沫的阻燃性能。利用热重分析(TG)和扫描电子显微镜(SEM)分别研究制得泡沫的热降解行为、成炭性能和残炭形貌。实验结果表明,当羟甲基化碱木质素替代聚醚多元醇的量为60%,次磷酸铝的添加量为30%时,碱木质素聚氨酯泡沫材料的极限氧指数(LOI)值达到了27.5%。因此,羟甲基化碱木质素和次磷酸铝使泡沫在燃烧时能更好的形成炭层,从而有效地隔绝空气,降低热传递,提高了材料的阻燃性能。     

[可靠性建模及试验技术]重型机床液压元件油液污染退化量分布剖面可靠性建模

针对重型机床液压系统故障频繁且多与油液中的固态颗粒污染物相关的问题，进行了油液污染趋势变化试验。通过时域分析获得了油样颗粒数的有量纲和量纲一参数，通过Q-Q图和K-S检验分析有量纲参数，污染颗粒数是退化量服从正态分布的退化数据。进行了油液污染与环境相关性分析试验，采用相关系数法分析得到，颗粒数变化量与一定范围内的温度、流量、压力的相关性小；将液压元件分为管路、阀、过滤器三类，用直径5 μm左右的颗粒和直径大于15 μm的颗粒分别研究管路及阀件的堵塞和磨损情况，以过滤器过滤精度大小的颗粒研究过滤器的堵塞情况，设定ISO4406标准20/17级对应的颗粒数为阈值，利用退化量分布建立了液压元件单一故障模式的可靠性模型；利用竞争失效模型将上述模型融合为多故障模式下的可靠性模型。     

LaCoO3 acts as a high-efficiency co-catalyst for enhancing visible-light-driven tetracycline degradation of BiOI

Exploring noble-metal-free co-catalysts highly flexible for separating the photogenerated charge carriers is of prime importance for the visible-light-driven photocatalysis. Herein, three-dimensional flower-like BiOI microspheres were fabricated and applied to support noble-metal-free LaCoO₃ co-catalysts to construct a unique LaCoO₃/BiOI hybrid photocatalyst with a higher ability in charge separation. As expected, the optimum tetracycline degradation rate of LaCoO₃ (4.0 wt%)/BiOI was up to 0.0161 min⁻¹, which was nearly 3.4 fold larger than that of pure BiOI (0.0048 min⁻¹). The enhanced photocatalytic performance was mainly ascribed to the vital role of LaCoO₃ co-catalyst, which acted as an excellent electron collector for capturing the electrons generated by BiOI, effectively promoting the separation of photogenerated charge carriers and prolonging the lifetime of photo-induced electron-hole pairs at the same time. Furthermore, the active species trapping experiments revealed that the excellent photocatalytic activity was primarily driven by photogenerated holes and superoxide radicals. This work is expected to provide a new inspiration for rationally designing and fabricating noble-metal-free co-catalyst system with high efficiency applied in environment purification.     

Photocatalytic activity of undoped and sulfur-doped TiO2 films grown by MOCVD for water treatment under visible light

Titanium dioxide ceramic coatings have been used as catalysts in green technologies for water treatment. However, without the presence of a dopant, its photocatalytic activity is limited to the ultraviolet radiation region. The photocatalytic activity and the structural characteristics of undoped and sulfur-doped TiO₂ films grown at 400 °C by metallorganic chemical vapor deposition (MOCVD) were studied. The photocatalytic behavior of the films was evaluated by methyl orange dye degradation under visible light. The results suggested the substitution of Ti⁴⁺ cations by S⁶⁺ ions into TiO₂ structure of the doped samples. SO₄^2? groups were observed on the surface. S-TiO₂ film exhibited good photocatalytic activity under visible light irradiation, and the luminous intensity strongly influences the photocatalytic behavior of the S-TiO₂ films. The results supported the idea that the sulfur-doped TiO₂ films grown by MOCVD may be promising catalysts for water treatment under sunlight or visible light bulbs.     

降解法在煤基聚丙烯生产中的应用

以中煤陕西公司煤基聚丙烯为研究对象,采用降解法制得了无纺布专用料。探讨了规模化生产存在的问题及相关工艺控制,并将其与石化基聚丙烯无纺布进行了力学性能对比。结果表明,采用降解法生产的煤基聚丙烯无纺布性能与石化基聚丙烯无纺布性能相近,且具有更好的韧性,满足无纺布力学性能的要求。