可膨胀石墨对室温硫化硅橡胶性能的影响

以α,ω-二羟基聚二甲基硅氧烷为基胶、纳米碳酸钙为填料、可膨胀石墨为阻燃剂,制得室温硫化硅橡胶.采用垂直燃烧、氧指数、热分析、拉伸和扫描电镜等手段研究了硅橡胶/可膨胀石墨体系的阻燃、热分解、力学性能,以及燃烧前后的微观形态.研究结果表明,可膨胀石墨是硅橡胶的良好阻燃剂,添加剂的质量分数为10%时,硅橡胶达到UL94 V...     

可膨胀石墨催化合成乙酸苄酯

可膨胀石墨作为一种重要的非金属材料已广泛应用于各工业领域 ,将其作为有机质反应催化剂的研究尚不多见[1～ 3] 。工业上 ,乙酸苄酯常是以浓Ｈ2 ＳＯ4、对甲苯磺酸等质子酸作催化剂由乙酸和苄醇制得[4] ,但此法腐蚀设备 ,污染环境 ,且副反应多。近年来 ,为了寻找对设备腐蚀性小的酯化反应催化剂进行了一些研究 ,如曾报道的酯化反应催化剂有 :四氯化锡复合物[5] 、复合固体超强酸[6] 、稀土硫酸盐[7]等。本文报道可膨胀石墨催化乙酸苄酯的合成 ,与其它催化剂相比 ,具有催化活性高 ,反应温度低 ,反应时间短 ,收率高 ,易分离及再生处理简单等…     

可膨胀石墨催化的一锅法合成3,4-二氢嘧啶-2-酮衍生物

在可膨胀石墨催化下, 由芳香醛、β-酮酸酯和尿素(摩尔比1∶1∶1.5)三组分缩合制备3,4-二氢嘧啶-2-酮衍生物, 反应时间1.5～2 h, 产率可达72%～93%, 且催化剂可回收重复利用. 产物的结构经¹H NMR, IR确证.     

Preparation of Boron-coated Expandable Graphite and Its Application in Flame Retardant Rigid Polyurethane Foam

A novel boron-coated expandable graphite(BEG) material was prepared by first wrapping polyvinyl alcohol(PVA) onto expandable graphite(EG) and then condensing with boric acid. The obtained BEG was characterized by scanning electron microscopy(SEM), Fourier transform infrared(FTIR) spectroscopy, X-ray photoelectron spectroscopy(XPS), and thermogravimetric analysis(TGA). The fire performance and mechanical properties of the rigid polyurethane foam(RPUF) filled with BEG were investigated by limiting oxygen index(LOI), horizontal and vertical burning, cone calorimetry(CONE), and electronic tensile tests. BEG shows an improved compactness of the char layers upon thermal expansion, which is effective for the flame retardancy of RPUF. With a loading of 10%, RPUF/BEG exhibited a higher LOI, >10% reduction in heat release rate and carbon monoxide release, as well as a decrease in smoke release during the beginning of combustion compared to RPUF/EG. Moreover, the compressive strength and modulus of RPUF/BEG were increased. The improved flame retardancy of BEG on RPUF can be attributed to the suppression of the "popcorn effect" of EG by PVA-boric acid, and the improved mechanical property can be attributed to the presence of PVA.     

低硫可膨胀石墨制备新工艺

可膨胀石墨是一种重要的无机非金属材料 .广泛用以替代易致癌的石棉类密封材料 .传统方法是将天然鳞片石墨放入ＨＮＯ3 Ｈ2 ＳＯ4 的混合酸中浸渍氧化 ,在较高温度下反应 ,经水洗、干燥而成 .由于反应温度较高 ,硝酸易挥发形成大量酸雾 ,高温膨胀时硝酸分解放出氮氧化物 ,造成严重的环境污染 .制得的可膨胀石墨其硫含量达 4 5 % [1],用其制备的柔性石墨密封材料 ,易腐蚀金属表面 ,使密封效果下降 ,严重的会导致密封失效 ,乃至发生事故[2 ].本文以少量浓硫酸和高锰酸钾为混合氧化剂 ,少量三氯化铁为插入剂 ,找出了比较理想的制备低硫可膨胀石…     

磷酸铵与多聚磷酸铵插层可膨胀石墨的制备

Expandable graphite intercalated by ammonium phosphate (AP) or ammonium polyphosphate (APP) was prepared by direct intercalation and two-step method, respectively. The products from two-step method show higher expansion volume, more weight increase and more weight loss after expansion, suggesting that the two-step method is a favorable method for preparation of APP intercalated EG. XRD provides convincing evidence for successful formation of APP-EG by showing strong diffraction peak at much lower 2θ angle. Scanning electron microscopy (SEM) with energy dispersive X-ray Spectroscopy (EDS) gives more evidence for intercalation of APP in the graphite layers.     

Synthesis of Novel Triazolyl-substituted Carboxylic Acid Esters and Their Aminolysis

Russian Journal of Organic Chemistry - Recyclization of 4-oxo-1,3-benzoxazinium perchlorates under the action of hydrazinobenzoic acids gave previously unknown 1,2,4-triazolylbenzoic acids which...     

Triton-B Catalyzed Efficient One-Pot Synthesis of Dithiocarbamate Esters

Summary. A novel process for the one-step chemoselective conversion of alkyl halides into dithiocarbamates as protected amines was developed using benzyltrimethylammonium hydroxide (Triton-B) in presence of carbon disulfide. Thus, dithiocarbamates of different amines were prepared in very good to excellent yields. This protocol is mild, chemoselective, and efficient compared to other methods. Present address: Institute of Organic and Biomolecular Chemistry, Georg–August University, D-37077 G?ttingen, Germany     

有机锡催化酯交换反应合成羧酸酯的研究

有机锡催化酯交换反应合成羧酸酯的研究田来进，傅芳信，田君濂，刘树祥（曲阜师范大学化学系曲阜２７３１６５，东北师范大学化学系长春）关键词有机锡，催化，酯交换反应，羧酸酯有机锡化合物是一种近乎中性的均相催化剂，不仅不腐蚀金属设备，而且反应物分子中的其他功...     

氧化程度对微细鳞片可膨胀石墨结构及膨胀性的影响

以平均粒径为19.71μm的天然微细鳞片石墨为原料,通过化学氧化法制备了具有不同氧化程度的可膨胀石墨,采用XRD、FTIR、Raman、SEM等对可膨胀石墨的结构与膨胀性进行了表征。结果表明:当氧化程度较低时制得的微细鳞片可膨胀石墨由石墨、石墨层间化合物和氧化石墨三相组成;随着氧化程度的增加,氧化石墨相含量与可膨胀石墨结构无序程度逐渐增高,石墨层间化合物相含量先增加后减少,石墨相含量则逐渐降低;氧化促使HSO4-或SO42-插入石墨层间,插入层间的HSO4-或SO42-量是决定可膨胀石墨膨胀容积的关键因素,制备的微细鳞片膨胀石墨的膨胀容积可达65.9mL·g-1。     

氧化程度对微细鳞片可膨胀石墨结构及膨胀性的影响

以平均粒径为19.71μm的天然微细鳞片石墨为原料,通过化学氧化法制备了具有不同氧化程度的可膨胀石墨,采用XRD、FTIR、Raman、SEM等对可膨胀石墨的结构与膨胀性进行了表征。结果表明：当氧化程度较低时制得的微细鳞片可膨胀石墨由石墨、石墨层间化合物和氧化石墨三相组成;随着氧化程度的增加,氧化石墨相含量与可膨胀石墨结构无序程度逐渐增高,石墨层间化合物相含量先增加后减少,石墨相含量则逐渐降低;氧化促使HSO₄^-或SO₄^2-插入石墨层间,插入层间的HSO₄^-或SO₄^2-量是决定可膨胀石墨膨胀容积的关键因素,制备的微细鳞片膨胀石墨的膨胀容积可达65.9mL·g^-1。     

Tetrahydrofuran Ring Opening with Acyl Chlorides or Anhydrides Catalyzed by Gallium Triiodides: A Novel and Facile Method for the Preparation of Iodo Esters

Recently gallium and its compounds are gradually attracting attention as useful reagentsin organic synthesis'-'. Gallium enolate-mediated intermolecular aldol reaction andaddition reaction of Q -bromoketone with imine, a straightforward and versatilepreparation of propargylic alcohols from l-alkynes and aldehydes via Gal, and aminehave been documented3. Kobayashi reported that gallium reagents could efficientlypromote the glycosidation of glycopyranosyl fluorides'. The reaction of alkyne with…     

悬浮法生产可发性聚苯乙烯(EPS)虚拟仿真实验平台的设计与开发

为实现我校高分子材料与工程专业人才培养目标,即培养高素质工程应用型人才,弥补教学过程中实际操作的缺陷与不足,我们开发了基于实际工业生产的悬浮法生产可发性聚苯乙烯的虚拟仿真实验平台.详述了该平台的设计开发思路与理念,平台主题结构,以及实验主控界面设计思路和主要内容.实践证明,该平台不仅包含工程应用的相关知识,而且极大的提...     

可膨胀石墨阻燃体系在聚丙烯中的作用

采用可膨胀石墨(EG)为主阻燃剂,包裹红磷(MRP)为阻燃协效剂制备阻燃聚丙烯(PP)。在mEG∶mMRP≥2时,阻燃效果最佳。阻燃剂(FR)含量达到30%后,阻燃效果大幅度提高,氧指数大于28。采用热失重和流变学方法分析了炭层质量,探讨了在mEG∶mMRP≥2时,阻燃效率最高的原因。相容剂马来酸酐接枝聚丙烯(PP-g-MAH)能够改善阻燃剂和聚丙烯之间的相容性,提高粘结力,改善炭层质量,提高材料的氧指数,PP-g-MAH用量为30%时,材料的氧指数达到31.4。     

碘催化合成三乙基膦酰乙酸酯

首次报道了碘对M ichaelArbuzov重排反应的催化作用.以亚磷酸三乙酯与2-卤代乙酸乙酯为原料,碘作催化剂,反应温度80℃,反应时间2 h,三乙基膦酰乙酸酯的产率达到90%-98%.     

电解氧化法膨胀石墨形成机理研究

采用现代测试方法对电解氧化法制备的膨胀石墨各阶段产物进行了表征 ,对其形成机理作了一些探讨。结果证实 ,在氧化过程中 ,层间表面的石墨被氧化后 ,与嵌入层间的H2 SO4、H2 O等生成层间化合物 ,该化合物瞬间受高热而分解 ,产生的推力使石墨沿C轴方向膨胀 ,而层平面碳 -碳结构未被破坏。     

Novel Catalytic Method for Synthesis of Glycosyl Esters by Combining PTC with DMAP

This article presents a novel catalytic method by combining phase-transfer catalyst,benzyltriethylammonium chloride,with 4-dimethylaminopyridine for the syntheses of glycosyl esters from substituted phenoxyacetic acids and the peracetate of α-D-1-bromosugars to produce eight novel β-glycosyl esters in high yields.The structures of the synthesized compounds were established by IR,MS,1H NMR,and 13C NMR spectra and elemental analyses.     

制备低硫可膨胀石墨的新方法

以乙酸酐为介质、酸性高锰酸钾作氧化剂，制备了低硫可膨胀石墨，制备的最佳条件为：鳞片石墨∶乙酸酐∶９８％硫酸∶高锰酸钾＝１∶１．０∶０．１３∶０．０６（质量比），反应温度２５℃，反应时间２ｈ。采用ＵＶ－Ｖｉｓ、ＸＲＤ手段对产品进行了分析。     

二苯胺甲烷磺酸盐催化合成丙酸异戊酯

以二苯胺甲烷磺酸盐为催化剂,合成了丙酸异戊酯,考察了反应时间、催化剂用量、醇酸摩尔比等因素对酯化率的影响。结果表明,在最佳条件下,酯化率可达97．7％。