Thermal cross-linking and anti-meltdrop properties of copolyester containing phosphorus/magnesium salt composites by in situ polymerization

Polyester is widely used in household products because of its good mechanical properties and wears resistance, but polyester is easy to ignite and inclined to produce droplet, so its application range is limited. The cross-linkable magnesium hydroxide nanoparticles were incorporated into flame-retardant polyester, which enables the phosphorus-containing copolyester with thermal cross-linking and anti-meltdrop properties. The nanoparticles were achieved by in situ polymerization and acted as a nucleating agent for improving the crystalline properties of the copolyester. Furthermore, the nanoparticles also enhanced anti-meltdrop properties and reduced the heat and gas release during the combustion process of the copolyester. The maximum heat release rate and total smoke release reduced by 39.8% and 74.4% compared with pure polyester. Specifically, the combustion products of the nanoparticles and phosphorus flame retardant could act a barrier role by covering the carbon layer to isolate air and heat, thereby resulting in excellent anti-meltdrop properties. The simple modification method reported here realizes the collaborative modification of flame retardant and anti-meltdrop properties of phosphorous flame-retardant copolyesters by thermal cross-linking.     

PAN/FPU Composite Nanofiber Membrane with Superhydrophobic and Superoleophobic Surface as a Filter Element for High-Efficiency Protective Masks

Recently, because of the outbreak of COVID-19, the demand for various types of filter elements in protective materials has increased globally. Furthermore, new requirements for the filtration performance of PM2.5 liquid (oil) particles have been put forward. In this work, Superhydrophobic and superoleophobic composite nanofibers with excellent filtration capacity for oil and salt particles are developed through the modification of polyacrylonitrile (PAN) by fluoro-polyurethane (FPU) doping. The results show that the PAN/FPU composite nanofibers doped with 9 wt% FPU has a uniform fiber morphology with a diameter of 240 ± 30 nm. Compared to the pure PAN nanofibers, the water-based contact angle of PAN/FPU increases from 90 ± 5° to 151 ± 5°, and the oil-based contact angle increases from 58 ± 2° to 152 ± 3°. Importantly, at a high flow rate of 95 L min⁻¹, the filtration efficiency of the PAN/FPU nanofiber membrane for 0.3 µm oil particles increases from 92 ± 1% to 99.2 ± 0.1%. After cyclic loading, the filtration efficiency of 0.3 µm oil particles remains above 98%. Meanwhile, the filtration efficiency for 0.3 µm salt particles remains at 98.23 ± 0.1%. The PAN/FPU nanofiber membrane developed in this work is effective in applications and has good market prospects as a protective filtration material.     

数控高效放电展成加工技术

较详细地介绍了数控高效放电展成加工技术,采用简单超长圆电极,通过计算机控制电极与工件的相对运动并对电极损耗进行在线检测和补偿,展成加工复杂形面的特殊材料的零件.电、机结合达到对难加工特殊材料的高效、高精度的展成加工.     

Preparation of Porous Silver Nanowires-Melamine Formaldehyde Hybrid Composite Materials and Their Electromagnetic Shielding and Flame-Retardant Properties

Along with the booming development of communication technology and electronic equipment, higher requirements of flame-retardant and EMI shielding performances for electromagnetic interference (EMI) shielding materials are put forward. Herein, the ultralight and porous silver nanowires (AgNWs)-melamine formaldehyde (MF) hybrid composite with unique micro-/nanostructure is developed by a facile dip-coating method, which uses the AgNWs as 1D conductive coating and MF foam (MF foam) as 3D skeleton template. Benefiting from the unique porous micro-/nanostructure, the resultant hybrid composite displays low density, excellent EMI shielding performances, and superior flame-retardant property. The EMI shielding effectiveness (SE) and specific EMI SE (SSEt) of the hybrid composite in X-band (8.2–12.4 GHz) can be up to 77 dB and 26971.4 dB cm⁻² g⁻¹, respectively. At the same time, the hybrid composite also passes the vertical burning test and shows an increased LOI value of 40.6%. The combination of flame-retardant and EMI shielding performances for EMI shielding materials makes the AgNWs-MF hybrid composite great application potential in civil and military fields. This work provides a new guide for the design of multifunctional high-performance EMI shielding materials.     

莱钢2号连铸机及热送热装的改造

分析了连铸机改造前和高效改造后新老系统在控制上的特点 ,着重介绍了改造后控制系统硬件和软件特点 ,该系统投运后不仅解决了本连铸机的自动控制 ,而且完成了连铸 热送 轧钢生产线的顺利贯通。     

宁夏北部引黄灌区高效节水灌溉发展思路与建议

在总结引黄灌区高效节水灌溉成就基础上,分析了灌区高效节水灌溉推广存在的问题,提出了灌区发展高效节水灌溉的思路与模式.结合灌区“十二五”高效节水灌溉规划,提出了推广高效节水灌溉的建议,认为要推动灌区高效节水技术广泛应用,在政府的扶持、调控和引导下,除了设计单位优化设计、确定合理灌溉制度,施工单位保质保量完成工程外,还需抓好推广服务体系建设,开展节水设备产品检测认证工作,并进行节水技术培训与宣传工作.     

华能上安电厂4#机组循环水泵节能改造理论与应用

对华能上安电厂4#机组的循环水泵进行了节能改造,增大了叶轮的出口宽度,采用了较大的叶轮叶片出、入口宽度比和较小的叶片包角;为了提高泵的水力效率,泵壳体采用流线型设计,同时加大了壳体的通流面积.改造后取得了预期的效果,同改造前相比,4A泵、4B泵效率分别提高了11.20%和13.38%,总输入功率减少了576.3 kW,运行2年即可收回改造投资.     

磷系阻燃聚酯纤维的研制

采用反应型阻燃剂对阻燃剂添加量不同的PET纤维进行了试纺。结果表明，对于阻燃剂添加量从4％～12％的阻燃聚酯纤维可采用同一纺丝工艺，且可纺性良好；阻燃剂添加量增大，阻燃性能提高，极限氧指数最高可达到34％左右，纤维的抗张强度减小，但强度降低不超过10％。     

微胶囊技术在阻燃材料中的应用进展

阐述了微胶囊技术的方法和原理，介绍了微胶囊阻燃材料的阻燃机理，综述了国内外有关研究现状，并对微胶囊阻燃材料的发展作了展望。     

数控电熔爆机床的应用与发展

数控电熔爆机床是为轧辊加工、蜂窝密封材料加工、大型轧辊切割等加工而研制的专用加工设备，并已成功应用。电熔爆机床专用数控系统研制过程中，应将对机械运动的控制与对电源的监测控制相结合。数控电熔爆机床可在某些加工场合取代金刚石砂轮磨削、碳弧气刨加工。几乎没有切削力、工件基体保持常温、污染低等加工特点，可适应一些特殊加工要求。