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991.
992.
In this work, a simple and novel method was applied to prepare polymer composites by taking the advantage of melt flow shear force driving orientation of the fillers. By using this method, hexagonal boron nitride/polyethylene (hBN/PE) and hexagonal boron nitride/carbon fibers/polyethylene (hBN/CF/PE) composites were fabricated to be possessed of high thermal conductivity and mechanical properties. A high thermal conductivity of 3.11 W/mK was realized in the composite containing 35 wt% hBN and 5 wt% CF, which was over 1,200% higher than that of unfilled PE matrix. Under this component, the compressive strength and modulus of hBN/CF/PE composite were determined to be 30.1 and 870.9 MPa, respectively, which were far higher than that of unfilled PE accordingly. The bending performance was also somewhat enhanced. Meanwhile, the bulk resistivity of the composite material reached 2.55 × 1011 Ω·cm, which was basically the same as that of pure PE. The novel composites with high thermal conductivity, excellent mechanical properties, and controllable electrical insulation could be a potential thermal management material for electrical and electronics industries. 相似文献
993.
994.
995.
In order to repair and reuse remaining quenching surface(RQS)divided into severely worn surface(SWun-S)and mildly worn surface(MWun-S)of abandoned gray cast iron guide rail,inspired by the bionic theory,varying forms of bionic units such as spot(Sp-S),striation(St-S),and reticulation(Re-S)were fabricated on RQS of gray cast iron through laser processing technology.Firstly,the microstructure,phase composition,and microhardness of bionic units and RQS were analyzed by optical microscopy as well as X-ray diffraction instrument and scanning electron microscopy,respectively.Secondly,the oil lubrication wear experiment was performed on homemade line reciprocating wear machine.The results demonstrated that the bionic units had a significant effect on improving wear resistance of RQS of abandoned guide rail due to the microstructure and higher hardness.In addition,the weight loss ratios of MWun-S,Sp-S,St-S,and Re-S samples were decreased by 36.72%,36.78%,62.26%,and 80.39%,respectively,compared with that of SWun-S sample.The mechanism of wear resistance enhancement was also discussed. 相似文献
996.
表面处理剂对PVC仿木复合材料性能的影响 总被引:1,自引:0,他引:1
使用4种不同类型的含高活性反应基团的聚氨酯处理剂对木粉表面进行处理,并制备了聚氯乙烯(PVC)/木粉复合材料,研究了表面处理剂的交联度、不同用量和高活性反应基团—NCO的含量对复合材料性能及结构的影响。结果表明,使用聚氨酯处理剂对木粉表面进行处理可以明显改善复合材料的流变性能,并明显提高复合材料的力学性能;扫描电镜观察表明,木粉经聚氨酯处理剂改性后与PVC的相容性明显得到改善。 相似文献
997.
998.
基于空间信息技术的城镇化生态风险预警研究——以南充市为例 总被引:1,自引:0,他引:1
科学的生态风险预警体系是准确评价城镇化过程风险状态与变化趋势的根本前提,本文应用空间信息技术,在遥感影像解译的基础上,提取空间信息、量化生态指标,结合社会、经济统计数据,构建以压力-状态-响应为框架的生态风险预警指标体系,以镇域为空间单元预测南充市生态风险警情的空间分布格局。结果表明,现有发展模式下,在预测时期内南充市生态风险会在人为调控下降低,但是在接近人类调节所能达到的生态阈值后,资源的严重短缺会使南充市的生态风险维持在一个相对稳定的高水平状态,因此急需对城镇发展模式做出合理调整。 相似文献
999.
Occurrence and removal of pharmaceuticals, caffeine and DEET in wastewater treatment plants of Beijing, China 总被引:11,自引:0,他引:11
The occurrence and removal of 13 pharmaceuticals and 2 consumer products, including antibiotic, antilipidemic, anti-inflammatory, anti-hypertensive, anticonvulsant, stimulant, insect repellent and antipsychotic, were investigated in four wastewater treatment plants (WWTPs) of Beijing, China. The compounds were extracted from wastewater samples by solid-phase extraction (SPE) and analyzed by ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Most of the target compounds were detected, with the concentrations of 4.4 ng L−1-6.6 μg L−1 and 2.2-320 ng L−1 in the influents and secondary effluents, respectively. These concentrations were consistent with their consumptions in China, and much lower than those reported in the USA and Europe. Most compounds were hardly removed in the primary treatment, while their removal rates ranging from −12% to 100% were achieved during the secondary treatment. In the tertiary treatment, different processes showed discrepant performances. The target compounds could not be eliminated by sand filtration, but the ozonation and microfiltration/reverse osmosis (MF/RO) processes employed in two WWTPs were very effective to remove them, showing their main contributions to the removal of such micro-pollutants in wastewater treatment. 相似文献
1000.