Preparation of borate–modified expandable graphite and its flame retardancy on acrylonitrile‐butadiene‐styrene resin

A borate‐modified expandable graphite (written as MEG) was prepared through one step intercalating reaction of natural graphite, using KMnO₄ as oxidant, H₂SO₄ and sodium tetraborate as intercalator and assistant intercalator, respectively. The dilatability, structure, element contents, thermal stability, and flame retardancy on acrylonitrile‐butadiene‐styrene (ABS) were investigated. Compared with the normal expandable graphite (written as EG, which was prepared with only H₂SO₄ as intercalator), the results show that MEG exhibits higher expandable property, thermal stability and flame retardancy on ABS. The EDS, FT‐IR, and XRD results reveal that borate has been inserted into graphite layers. With the addition of MEG or EG at a 30 wt%, LOI of 70ABS/30MEG composite improved to 27.9%, 2.2% higher than that of 70ABS/30EG. Moreover, the synergistic effect between MEG and traditional intumescent flame retardant (IFR, consists of ammonium polyphosphate (APP), pentaerythritol (PER), and melamine (MEL) with a mass ratio of 7.5:4.5:3.0) improves the LOI of 70ABS/15MEG/15IFR composite to 32.6%, and the UL‐94 level reaches V‐0. This synergistic efficiency is attributed to the formation of continuous and compact residual char. Addition of MEG together with IFR changes the ABS pyrolysis behavior, and there is not only physical synergy, but also chemical reaction. POLYM. COMPOS., 37:2673–2683, 2016. © 2015 Society of Plastics Engineers     

上海长江隧道抗浮模型试验与理论研究

饱和软土盾构隧道施工中,对于刚脱出盾尾的隧道经常会出现局部或整体上浮,隧道直径越大、覆土越浅,上浮现象越为突出,表现为隧道错台大、螺栓被剪断乃至轴线偏位,影响到隧道的稳定和施工质量等,传统抗浮设计未能考虑处于时变特性单液浆中隧道的浮力动态因素,现行相关设计规范也没有对隧道抗浮设计和施工措施做出明确的规定。文章首先介绍了上海长江隧道抗浮模型试验与结果,确定了超大直径隧道动态上浮力,以此为基础提出了隧道上浮稳定机理,并建立了盾构隧道上浮计算的理论模型,据此进行了上海长江隧道抗浮验算,并提出了相应的抗浮技术措施。     

滤波电路电容器联接方法对滤波效果影响的分析

文章对滤波电路电容器的联接方法进行分析,得出联接方法对谐波效果有很大影响的结论。尤其是零序谐波,采用角型连接的电容器,没有滤波作用。目前大部分厂商采用角型连接电容器串接14．5％电抗器滤除3次谐波,其实作用甚微。提出了解决方法和需注意事项。     

异戊二烯选择性加氢非负载Ni-Mo催化剂的制备与性能

以柠檬酸为络合剂,采用溶胶-凝胶法制备了非负载Ni-Mo复合氧化物催化剂,采用N2吸附-脱附、X射线衍射(XRD)、扫描电镜(SEM)和傅立叶红外光谱(FT-IR)等手段对催化剂进行表征,以含体积分数1%异戊二烯的正辛烷溶液为模拟原料,在连续固定床上考察了Mo与Ni物质的量之比和溶剂量对催化剂二烯烃选择性加氢性能的影响。结果表明:溶胶-凝胶法制备的Ni-Mo复合氧化物催化剂具有较高比表面、分散性和双介孔结构,当Mo与Ni物质的量之比为0.6和每摩尔Ni和Mo所用溶剂量为480 mL时,Ni-Mo复合氧化物催化剂活性较高。     

基于GDOP的分布式雷达网航迹关联阈值选择新方法

分布式雷达组网的航迹关联不仅与网内各雷达的性能有关,而且与目标的相对位置有关。本文提出一种新的雷达组网航迹关联方法,该方法在综合网内各雷达性能的基础上,将组网雷达定位精度几何稀释模型引入航迹关联算法当中。根据各雷达对观测同一目标定位精度的差异为参考,给出一种新的航迹关联门限阈值选择算法。本文介绍了航迹关联阈值的计算过程,并利用该方法对真实航迹数据进行了仿真。     

精细化学品合成课程教学改革与实践

精细化学品合成是应用化学专业的专业主干课程,为了使学生具备开阔的知识面、良好的素质和较高的科研能力,以适应培养应用化学专业技术人才的需要,我们对教学方法与教学内容进行了改革探索,采用多元化的实践性教学,确立绿色工程理念,培养学生社会责任感,通过有意识强化学生素质和培养科研能力的实践,教改取得了良好的教学效果。     

论ISO14064与广东省温室气体减排

在介绍ISO14064来源的基础上,说明ISO14064的组成、目的和实施要求等关键问题。分析广东省温室气体减排现状,提出广东企业或其它组织实施ISO14064所需注意和解决的关键问题。     

魔芋葡甘聚糖接枝聚二甲基二烯丙基氯化胺生物絮凝剂的制备

以过硫酸胺和硫代硫酸钠为氧化还原引发体系,采用L9(34)正交试验法制备魔芋葡甘聚糖接枝聚二甲基二烯丙基氯化胺(KGM-g-PDADMAC)生物絮凝剂。研究结果表明:在反应温度60℃,pH=8的条件下,当引发剂用量为3%,PDADMAC与KGM糖环单元分子质量比为10时,最高接枝率为65.4%,引发剂用量是主要影响因子。     

化工园区废水达标排放技术研究

化工行业废水具有有机污染程度高、可生化性差、含盐量高等特点。通过对天津市某化工园区水质情况的实际考察,提出了具有针对性的废水处理工艺,即综合采用微生物强化+膜分离+高级氧化技术。该工艺可实现对废水中难降解、溶解性有机污染物及特征污染物的有效去除,满足废水的达标排放。     

The biological properties of carbon nanofibers decorated with β-tricalcium phosphate nanoparticles

Carbon nanofibers decorated with β-tricalcium phosphate (β-TCP) nanoparticles (β-TCP/CNFs) have been prepared by sintering electrospun polyacrylonitrile fibers with calcium nitrate tetrahydrate as the calcium source and triethyl phosphate as the phosphorus source. Microstructure and phase composition analysis indicate that the resulting materials are composed of β-TCP nanoparticles and CNFs. And the long β-TCP/CNFs can be cut into organism-eliminable short CNFs gradually in hydrochloric acid solution due to the solubilization of β-TCP nanoparticles. The materials exhibit good biocompatibility, and have comparable effect on cell growth with pure CNFs, with their tuning ability in degradation.