高抗冲聚苯乙烯/蒙脱土复合材料的阻燃性研究

用经十六烷基三甲基溴化铵有机化改性的蒙脱土 (OMMT)与高抗冲聚苯乙烯 (HIPS)通过熔融插层法制备了HIPS OMMT复合材料 ,用X ray衍射技术对材料结构进行了表征 ,发现钠基蒙脱土 (Na+ MMT)和有机蒙脱土的层间距分别为 1 5 1nm和 2 18nm ,HIPS OMMT(5phr)复合材料中蒙脱土的层间距因聚合物大分子的插入扩大为 3 4 4nm ;而HIPS与Na+ MMT形成的复合材料的层间距与Na+ MMT的层间距相比却没有变化 ,表明未有机化处理土没有形成插层结构 .锥形量热仪的研究结果表明HIPS OMMT复合材料的热释放速率、质量损失速率以及生烟速率等燃烧特性参数均显著降低 ,具有较明显的阻燃性和抑烟性 ,而HIPS Na+ MMT非插层型复合材料只有在Na+ MMT很高填充量下 (>2 0phr)才有一定阻燃效果 .比较了铵盐对HIPS阻燃性的影响 ,结果表明铵盐自身的阻燃作用很小 ,主要是插层复合结构起阻燃作用 .     

不同链长的聚醚铵阳离子协同插层对蒙脱土性能的影响

为了制备高性能的聚合物/蒙脱土纳米复合材料, 必须对蒙脱土(MMT)进行有机改性来改善蒙脱土表面的疏水性、提高蒙脱土与聚合物之间的相容性, 同时也需要尽可能地增大蒙脱土的层间距. 为此, 提出了一种采用不同链长的聚醚铵阳离子协同插层MMT 的新方法, 即采用D2000(或T5000)聚醚铵盐与D400 聚醚铵盐协同插层MMT, 并采用X射线衍射分析(XRD)和热重分析(TGA)研究了协同插层对改性MMT 的层间距、有机含量以及耐热性的影响. 另外, 也研究了插层过程中的搅拌方式和D400 聚醚铵盐多次插层对改性MMT 的层间距、有机含量等的影响. 研究结果表明,采用长链聚醚铵阳离子协同插层更有利于提高D400 聚醚铵盐改性MMT 的层间距和有机含量; T5000 协同插层MMT中总的有机含量(64.06%)进一步增加, 这可能是因为T5000 的支链在MMT 层间形成的笼型结构既提供了更大的空隙,又起到了屏蔽作用, 同时也得到了较大的层间距(6.86 nm).     

基于胶束插层方法制备高热稳定性和大层间距有机化蒙脱土

采用不同方法制备了多种有机化蒙脱土,并分别采用X射线衍射仪、红外光谱分析仪、热重分析仪、电感耦合等离子体发射光谱仪、元素分析仪、扫描电子显微镜对产物进行了表征,并提出了有机物插层新方式——胶束插层.结果表明:适量钠基蒙脱土(Na-MMT)、十六烷基三甲基溴化铵(CTAB)和磷酸三苯酯(TPP)在丙酮/水的混合溶剂中进行溶液插层,得到的有机化蒙脱土具有更大的层间距,比单纯采用CTAB的插层效果显著.产物中含有约21.54%的CTAB和17.47±1.05%的TPP,插层机理为CTAB-TPP胶束插层.该有机化蒙脱土的初始热降解温度比单纯CTAB插层蒙脱土最多提高了17.4℃.采用该方法制备的改性蒙脱土既可以进一步提高蒙脱土的层间距,又可以封闭TPP于MMT的片层间,阻止TPP挥发;同时克服季铵盐改性蒙脱土的热稳定性低的问题,得到了层间距大、热稳定性高的有机化蒙脱土,为有机化蒙脱土在高熔点聚合物改性方面提供了条件.     

铜双季铵盐蒙脱土催化卤代芳烃与氨水的偶联

利用合成的两种不同联结基的双季铵盐修饰蒙脱土(MMT),并通过浸渍还原的方法将铜负载到双季铵盐MMT层间形成了两种铜双季铵盐MMT催化材料Cu-Q1-MMT和Cu-Q2-MMT.将这两种催化材料用于催化卤代芳烃与氨水偶联形成苯胺的反应.实验结果表明:两种催化剂均能在温和条件下,无需氮气保护,高活性和高选择性催化卤代芳烃与氨水反应生成伯胺.其中,Cu-Q2-MMT具有更高的催化活性,通过简单分离,能够重复使用17次而没有明显的活性下降.     

几种聚醚胺改性蒙脱土对环氧树脂固化过程的影响

首先制备了五种聚醚胺改性蒙脱土(MMT), 并将这五种聚醚胺改性蒙脱土加入到双酚A 型环氧树脂E51 和聚醚胺D400体系中, 采用差示扫描量热法(DSC)考察了五种聚醚胺改性MMT对环氧树脂升温固化进程的影响. 随后, 优选一种EP/MMT 混合体系即EP/D400-T500-MMT 混合体系, 系统地研究了该体系与纯环氧树脂体系在130, 140, 150 及160 ℃等几个温度下的等温固化过程, 考察了等温固化时间对固化度和固化度变化速率的影响以及固化度与固化度变化速率之间的关系, 并利用Kamal 模型进行拟合计算了固化动力学参数. 研究结果表明, 与纯环氧树脂相比, 几种聚醚胺改性MMT 的固化放热峰均向高温迁移, 同时聚醚胺D400 协同插层MMT 降低了高分子量聚醚胺插层MMT 所导致的环氧树脂DSC 曲线的畸变情况; EP/D400-T500-MMT 混合体系和纯环氧体系的等温固化反应过程符合Kamal 模型;在相同的固化温度下, EP/D400-T5000-MMT 混合体系的反应速率常数k₁ 和k₂ 值以及反应级数m 均比纯EP 体系小, 而反应级数n 以及总反应级数m+n 值比纯EP 体系大, 表明两种聚醚胺协同插层的改性蒙脱土D400-T5000-MMT 的加入降低了环氧体系固化反应速率. 另外, EP/D400-T5000-MMT 混合体系的活化能E_a1 和E_a2 与纯EP 体系的相比也略有升高.     

季铵盐插层蒙脱土及其去除海洋卡盾藻的研究

利用插层法制备了5种季铵盐改性的蒙脱土,通过FTIR、XRD和DTG等表征表明5种季铵盐已成功插入蒙脱土中;随后以中国典型赤潮藻海洋卡盾藻(Chattonella marina)为研究对象,考察了5种季铵盐改性蒙脱土的除藻效果。发现以双溴化十四烷基二甲基乙基溴化铵改性的蒙脱土在用量为8mg·L-1时,24h内对海洋卡盾藻的去除率最高,可达100%,而未改性蒙脱土在相同条件下除藻率仅为5.64%;除藻效果与除藻剂的结构有密切关系,在官能团相同时,链长数为14的脂肪族季铵盐除藻率最高,24h可达67.03%;在链长数相同时,含吡啶官能团的季铵盐比脂肪族季铵盐除藻率高,24h为33.62%,且随时间延长明显提高。渗溢性评估实验显示,改性蒙脱土经72h浸泡后表观插层率从71.9%降低到69.6%,表明除藻剂在水体中基本不释放。     

聚苯胺/离子液体/蒙脱土纳米复合材料的制备及其导电性能研究

采用1-羧甲基-3-甲基咪唑氯化盐离子液体对钠化蒙脱土进行插层改性,然后用苯胺的盐酸溶液进行二次插层,以过硫酸铵为氧化剂,盐酸溶液为掺杂剂,使进入离子液体/蒙脱土(CMMIm/MMT)层间的苯胺(An)发生氧化聚合反应,制备了一种具有良好导电性的聚苯胺/离子液体/蒙脱土复合材料(PANI/CMMIm/MMT).用红外光谱、X-射线衍射,热重分析和DSC对样品进行了表征.结果表明当离子液体/蒙脱土用量为7.5%、盐酸浓度为1mol/L、过硫酸铵与苯胺的摩尔比为1∶1、0℃下反应6h时制备的PANI/CMMIm/MMT纳米复合材料电导率最高,达到了0.3S/cm,是相同条件下聚苯胺/钠化蒙脱土纳米复合材料电导率的2.5倍,聚苯胺的7.5倍.     

聚苯乙烯/蒙脱土纳米复合材料的制备及结构研究

以可与苯乙烯发生共聚的阳离子表面活性剂乙烯苄基二甲基十八烷基氯化铵(VOAC)为插层处理剂改性蒙脱土(VC18-MMT),有机蒙脱土在超声波强剪切作用以及乳化剂作用下预分散在乳化剂溶液中,然后引入苯乙烯单体进行原位乳液聚合制备聚苯乙烯/蒙脱土纳米复合材料.采用XRD和TEM对纳米复合材料的结构进行了表征.结果表明,绝大多数的蒙脱土被剥离成单个片层均匀的分散在聚合物基体中;动态力学分析表明,纳米复合材料的储能模量和玻璃化温度均有所增加,而动态损耗有所降低;接枝在蒙脱土片层上的聚合物通过与锂离子进行阳离子交换反应提取下来,采用GPC和NMR对接枝聚合物的结构进行了表征,结果表明,接枝聚合物是较基体分子量低且分布很宽的苯乙烯和乙烯苄基二甲基十八烷基氯化铵的共聚物,计算表明每一个共聚物分子链上平均含有大约25个乙烯苄基二甲基十八烷基氯化铵分子.     

悬浮缩聚法制备酚醛树脂/蒙脱土纳米复合材料

采用悬浮缩聚方法在酸性催化剂作用下制备了酚醛树脂/蒙脱土纳米复合材料。以三种不同的蒙脱土：天然土、带有脂肪链季铵盐修饰蒙脱土和带有苯环基团的插层剂修饰的蒙脱土为原料制备了纳米复合材料,并考察了不同插层剂对纳米复合材料形貌的影响,发现带有苯环的插层剂修饰的蒙脱土与酚醛树脂的相容性能更好;研究了固化过程对纳米复合材料形貌的影响,XRD和TEM的结构表明固化过程可以促进带有脂肪链季铵盐修饰的蒙脱土进一步剥离,对其他两类的影响不大;此外还用TGA研究了纳米复合材料的热性能。     

双单体原位接枝插层法制备聚丙烯纳米复合材料的研究Ⅰ.制备、表征及力学性能的研究

用有机插层剂处理蒙脱土原土 ,制得有机蒙脱土 (O MMT) .采用双单体 (马来酸酐和苯乙烯 )原位接枝插层法 ,制备了聚丙烯 蒙脱土纳米复合材料母料 .将母料与聚丙烯基体在双螺杆上共混挤出 ,制得聚丙烯 蒙脱土纳米复合材料 (PP Montmorillonetenanocomposites,PMNC) .这是制备聚合物纳米复合材料的一种新方法 .通过X 射线衍射测试 (XRD)表明 ,有机蒙脱土片层 0 0 1面间距从原土的 1 4 9nm扩大到 2 96nm ,复合材料中蒙脱土片层 0 0 1面间距由有机蒙脱土的 2 96nm扩大到 4 0nm .力学性能测试表明 ,复合材料的力学性能明显优于PP基体 ,在提高材料拉伸强度的同时 ,缺口冲击强度也得到很大的提高 .用扫描电镜 (SEM)对材料的冲击断面形貌进行了研究 ,并从理论上分析了断裂机理 .随着蒙脱土含量的增加 ,冲击断裂形式逐渐从脆性断裂变成韧性断裂     

Hemicellulose in Dissolving Pulp and its Behaviour during its Processing to Viscose

The amount of “hemicellulose” in pulps varies according to wood species, and the pulping processes including their bleaching agents. Making viscose cellulosic and non-cellulosic material is removed during mercerisation which is the first processing step. Low molecular weight material is also formed during the reduction of the degree of polymerisation in order to fit the alkali cellulose for xanthation and dissolving, respectively. In this work commercially available dissolving pulps with respect to their behaviour during the preparation of viscose fibres shall be discussed. For these investigations a Eucalyptus sulphite and a Eucalyptus pre- hydrolysed sulphate pulps were selected.     

Dinitramide and its salts

Nitration of nitramidc to dinitramide with nitryl salts is described.     

Dinitramide and its salts

A strategy of organic synthesis has been developed for a new class of inorganic compounds,viz., dinitramide and its metal, ammonium, and substituted ammonium salts. The basic concepts have been tested in model reactions of -substituted derivatives ofN-alkyl-N-nitrotoluenesulfonamides with bases and have been confirmed by the decyanoethylation ofN,N-dmitro--aminopropionitrile taken as an example.In the communications of this series, we are going to report the results of work on dinitramide carried out in 1970–1980 that could not be published previously. The synthesis of dinitramide salts was first published in the patent literature in 1992. 1,2Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 94–97, January, 1994.     

Dinitramide and its salts

Dinitramide readily adds to acrolein, methyl vinyl ketone, and phenyl vinyl ketone, but not to acrylonitrile or methyl acrylate. Treatment of dinitro compounds (O₂N)₂NCH₂CH₂COR (R = H, Me, Ph, OMe) with bases results in dinitramide salts in 66–83 % yields.For part 1, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1264–1266, July, 1994.     

微乳及其应用

微乳在生物技术、人造血管、酶固定化、能源科学、纳米材料、涂料、医药、食品、石油、选矿、环境等方面得到了越来越广泛的关注和应用。对微乳的理论研究、组成、制备方法、性质表征及应用的研究作了阐述。微乳技术具有很好的发展前景。     

Separation of Uranium Mixing with its Decayed Nuclides and its Activated Nuclides

Extractions of uranium from the acidic media, HCl and MNO₃ at different concentrations, by the tertiary amines, trilaurylamine, triisooctyllamine and trioctylamine were systematically investigated. In experiments, ²³²U was used as the tracer and aliquots of both phases after extractions were taken, ashed at 500°C, placed onto stainless steel planchets, and measured by a surface-barrier Si(Li) detector connected to an alpha spectrometer. One unique condition found useful for complete separation of uranium was that of the radioactive uranium present in 8 M HCl being extracted with 10% trilaurylamine in xylene. In that case, greater than 95% of the uranium could be extracted into the organic solution, whereas all of the radionuclides of a series of its decayed products, ²²⁸h, ²²⁴Ra, ²²⁰Rn, ²¹⁶Po and ²¹²Bi remained completely in the aqueous solution. The same procedure could also be used for the separation of uranium from a mixture with its activated nuclides. Plutonium-239 and Am were used as the tracers representing the activated nuclides of uranium. It was found that ²⁴¹Am was absolutely not extracted, but that ²³⁹Pu could be extracted with ≥95% efficiency from the medium of 8 M HCl into 10% trilaurylamine in xylene. However, ²³⁹Pu could be easily stripped using the solution mixture of 8 M HCl and 0.05 M NH₄I and excluded from the organic solution.     

Dinitramide and its salts

The preparation and physicochemical properties of salts of dinitramide HN(NO₂)₂ with uni- and bivalent metals of groups I, II, VII, and VIII of the Periodic Table are considered.For part 2,seeRuss. Chem. Bull., 1994,43, 1200.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1546–1549, September, 1994.     

Hydroxynitrobenzodifuroxan and its salts

The synthesis and properties of hydroxynitrobenzodifuroxan (5‐nitro[1,2,5]oxadiazolo[3,4‐e][2,1,3]ben‐zoxadiazol‐4‐ol‐3,8‐dioxide) ( 1 ) and its salts (four metal and three amine salts) are described. Crystal structure analyses indicate that the hydroxynitrobenzodifuroxan materials can exist in two forms. One form is the isomer in which the oxy and nitro group are in positions ortho to each other. In the other form, these groups are para to each other.     

Dinitramide and its salts

Mercury(u) dinitramidate Hg(N₃O₄)₂ (MDNA) has been synthesized. Its electronic and vibrational spectra show that in the crystalline state and in solutions in nonpolar solvents, MDNA is a covalent compound, the mercury atom being bound to the oxygen atoms. In polar solvents, MDNA dissociates to give mercury(u) cation and dinitramide anion N₃O₄ ^–.For Communication 7, sec Ref. 3Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 447–450, February, 1996.