Lap Shear Strength Comparison Between Two Types of Random Carbon Fiber-Reinforced Thermoplastic Matrix Composites Bonded Using Variable-Frequency Microwaves (VFM) Irradiation

Fiber-reinforced thermoplastic matrix composite material have enjoyed very strong development in the last 10–12 years because of their potential advantages and unique characteristics that cannot be found in their thermoset counterparts. This paper compares the lap shear bond strengths of two types of random carbon fiber-reinforced thermoplastic matrix composites joined by microwave energy. Variable-frequency microwave (VFM) (2–18 GHz) facilities are used to join thirty 3% by weight random carbon fiber-reinforced low-density polyethylene [LDPE/CF (33%)] and thirty 3% by weight random carbon fiber-reinforced polystyrene [PS/GF (33%)]. With a given power level, the composites were exposed to various exposure times to microwave irradiation. The lap shear strengths of the joints were compared with those obtained using fixed-frequency (2.45 GHz) microwave facility configuration. The VFMF was operated under software control, which provided automatic data logging facilities.     

中空玻璃微珠含量对回收聚对苯二甲酸乙二醇酯/聚碳酸酯基复合泡沫材料性能的影响

采用回收聚酯饮料瓶片(R-PET)为主要原材料,以乙烯-丙烯酸甲酯-甲基丙烯酸缩水甘油酯(E-MA-GMA)为增容剂,将硅烷偶联剂KH560处理后的中空玻璃微珠(HGM)与R-PET/PC/E-MA-GMA(70/30/10)在双螺杆挤出机中熔融共混制备复合泡沫材料。通过红外光谱、扫描电镜、差示扫描量热、表观密度、极限氧指数、导热系数和力学性能测试,考察了0~50 phr HGM对复合泡沫材料性能的影响。研究结果表明,HGM改性成功并与基体紧密结合,HGM的加入使RPET的结晶性下降,拉伸强度和冲击强度降低,但是所得的复合泡沫材料的表观密度减小,最小达到0.729 g/cm3,基体的隔热性提高,导热系数减小到0.089 W/(m·K),燃烧过程熔融滴落现象得到改善。     

Determination of Selected Perfluorinated Acids (PFCAs) and Perfluorinated Sulfonates (PFASs) in Food Contact Materials Using LC‐MS/MS

Perfluorinated compounds, including perfluorinated acids and perfluorinated sulfonates, are environmentally persistent. These compounds are commonly used in consumer products as stain/water/grease repellents in carpets and clothing, in cooking utensils as nonstick coating and in food contact materials as a coating. This paper explores the potential application of liquid chromatography coupled with tandem mass spectrometry (LC‐MS/MS) system for the measurement of selected perfluorinated acids and perfluorinated sulfonates in three different brands (A, B and C) of food contact materials, including wrapping papers, breakfast bags, baking papers and roasting bags. In this study, the highest contents of selected perfluorinated acids were identified for the breakfast bag samples (2.54–6.60 pg/cm²), especially for B and C brands with the concentration of 6.60 and 5.35 pg/cm², respectively, while the lowest content was noted in roasting bag samples (0.27–0.40 pg/cm²). The contents of perfluorinated sulfonates were inversed as compared with those of perfluorinated acids. The highest contents of selected perfluorinated sulfonates were found in roasting bag samples (1.38–5.17 pg/cm²), especially for B brand. The analysed perfluorinated sulfonates were not detected in any of the breakfast bag samples. The highest content of perfluorinated compounds were reported for B brand food contact materials. The data indicate a risk of food contamination by perfluorinated compounds from the commonly used food contact materials. Copyright © 2015 John Wiley & Sons, Ltd.     

CuS纳米片修饰Bi5O7I复合材料用于光催化还原Cr(VI)水溶液

光催化技术以其高效、安全、低成本的优势,被广泛研究用于去除污水中有毒副作用的重金属Cr(VI).制备半导体复合材料是一种可以有效提高半导体光催化性能的途径.本研究通过简单的水热法合成了CuS纳米片修饰的Bi5O7I复合材料,并且表征和评估了其在可见光下对Cr(VI)的光催化还原活性.与纯Bi5O7I微米棒及纯CuS样品...     

不同N源无定形TiO2/g-C3N4光催化还原Re(VII)性能

为探究不同N源对无定形TiO₂/g-C₃N₄(TCN)复合材料光催化还原Re(VII)的影响, 通过热分解不同前驱体(尿素Urea、硫脲Thiourea和三聚氰胺Melamine)制备g-C₃N₄, 再分别与无定形TiO₂复合, 制备了三种TCN复合光催化剂。通过不同分析手段对材料进行表征, 并比较了不同TCN复合材料光催化还原去除Re(VII)的活性差异。结果表明, U-TCN(尿素为N源)具有更均匀的表观形貌, 最大的比表面积(474 m²/g), 最优异的光吸收性能, 对Re(VII)的光催化还原效率(90%)明显高于T-TCN(20%)和M-TCN(15%)。通过复合材料的瞬态光电流和电化学阻抗(EIS)分析光催化机理, 证明U-TCN光生电子空穴分离效率最高; 电子顺磁共振波谱(EPR)分析表明U-TCN产生的羟基自由基(?OH)更多, 因此与甲酸反应产生的强还原性?CO₂^-自由基更多, 从而更有利于Re(VII)的还原; 利用同步辐射X射线吸收光谱分析Ti元素价态及配位环境, 表明U-TCN还具有优异的光化学稳定性。本研究揭示了不同N源对所制备TCN复合材料光催化性能的影响, 并发现了一种可用于实际废水中光催化还原去除Tc(VII)的优选材料。