动态固化聚丙烯/环氧树脂共混物的研究

将动态硫化技术应用于热塑性树脂 热固性树脂体系 ,制备了动态固化聚丙烯 (PP) 环氧树脂共混物 .研究了动态固化PP 环氧树脂共混物中两组分的相容性、力学性能、热性能和动态力学性能 .实验结果表明 ,马来酸酐接枝的聚丙烯 (PP g MAH)作为PP和环氧树脂体系的增容剂 ,使分散相环氧树脂颗粒变细 ,增加了两组分的界面作用力 ,改善了共混物的力学性能 .与PP相比 ,动态固化PP 环氧树脂共混物具有较高的强度和模量 ,含 5 %环氧树脂的共混物拉伸强度和弯曲模量分别提高了 30 %和 5 0 % ,冲击强度增加了 15 % ,但断裂伸长率却明显降低 .继续增加环氧树脂的含量 ,共混物的拉伸强度和弯曲模量增加缓慢 ,冲击强度无明显变化 ,断裂伸长率进一步降低 .动态力学性能分析 (DMTA)表明动态固化PP 环氧树脂共混物是两相结构 ,具有较高的储能模量 (E′)     

双酚A型环氧改性R-122环氧树脂的研究

用双酚A环氧树脂(E-44)改性脂环类环氧树脂(R-122),通过对改性R-122环氧树脂力学性能和热性能的测定,探讨了固化工艺,固化荆体系对改性R-122环氧树脂韧性的影响。结果表明：改性R-122环氧树脂冲击强度提高40％,弯曲强度提高75％,断裂能提高81％,而热变形温度和玻璃化转变温度基本不变。R-122树脂基复合材料随E-44的加入冲击强度和弯曲强度分别提高12％和18％。     

两种不同化学组成的超支化聚氨酯改性环氧树脂

利用芳香族二元异氰酸酯和脂肪族二元异氰酸酯分别与二乙醇胺反应,设计合成了不同化学组成的超支化聚氨酯,考察了其对环氧树脂的改性作用.运用核磁共振、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)、弯曲、拉伸、冲击强度、储能模量、示差扫描量热法(DSC)以及热失重(TGA)等对超支化聚氨酯的结构及其性能进行了证实和表征,并发现基于芳香族超支化聚氨酯改性的环氧树脂共混体系表现出均相结构,而脂肪族超支化聚氨酯和环氧树脂共混后却形成了非均相体系.均相的共混体系证明超支化聚合物自身能够有效地改善环氧树脂的力学性能和热学性能.     

铜纳米粒子改性酚醛树脂的合成及其性能

利用甲醛与硫酸铜还原反应,通过添加铜晶核,控制反应液的pH和温度等条件,在酚醛树脂合成体系内原位生成了球形、粒度分布30~50 nm的铜纳米粒子,制得铜纳米粒子改性酚醛树脂,其结构和性能经红外光谱、X-射线衍射、透射电镜、热重分析和冲击试验表征。结果表明：与纯酚醛树脂相比,铜纳米粒子对酚醛树脂的耐热性和韧性有显著影响,初始分解温度提高51 ℃,冲击强度可提高约52%。     

端羟基丁腈橡胶增韧环氧树脂研究

本文研究了端羟基丁腈橡胶(HTBN)对环氧树脂的增韧作用。加入10—20phr的HTBN,环氧树脂性能可以大幅度提高,粘接碳钢剪切强度30MPa,冲击强度9×10~(-2)J/cm~2,浇注试样抗张强度61MPa,伸长10％,玻璃化温度115℃;不加HTBN的环氧树脂固化物,剪切强度24MPa,冲击强度34×10~(-2)J/cm~2,抗张强度30MPa,伸长5％,玻璃化温度124℃。 本文还通过DSC、SEM研究观察到增韧环氧树脂的两相结构。     

含磷聚芳醚酮颗粒层间增韧碳纤维/双马树脂RTM复合材料

选用一种在RTM双马来酰亚胺树脂(BMI)注射温度下不溶解的含磷聚芳醚酮(P-PAEK)热塑性树脂作为增韧剂,制备层间颗粒增韧碳纤维增强双马来酰亚胺树脂基复合材料.研究了不同热塑树脂含量对树脂浇铸体冲击性能的影响,利用扫描电镜表征了复相体系的微观形貌并分析其增韧机制,并通过层间断裂韧性测试表征了RTM双马树脂基复合材料增韧前后的层间韧性性能.结果表明,当附载热塑颗粒面密度为2 g/m2时,复合材料的I型层间断裂韧性(GIC)为0.54 k J/m2,II型层间断裂韧性(G_(IIC))为1.36 k J/m~2,较未增韧复合材料分别提升约56%和42%.增韧后的复合材料在保持原有力学性能的同时,其冲击后压缩强度(CAI)提升约29%,层间剪切强度达到111.7 MPa.     

含磷有机硅杂化环氧树脂固化体系性能研究

通过磷酸与γ-环氧丙氧基三甲氧基硅烷反应得到含磷有机硅氧烷,并加入到环氧树脂/4,4'-二氨基二苯基甲烷体系中混合,通过溶胶-凝胶的方法制备了含磷有机硅杂化环氧树脂固化物.对固化体系进行了玻璃化转变温度、热失重、阻燃、拉伸强度、冲击强度测试分析.结果表明,该固化体系的阻燃性得到提高,极限氧指数在25.8～29.3,玻璃化转变温度得到提高,在161～179℃;虽然初始分解温度比纯环氧树脂固化物低,但800℃残炭率可以达到26.5%,提高了36%;拉伸强度得到提高,在71～94 MPa,冲击强度可以达到14.36 kJ/m2,提高了14%.该固化体系具有较好的阻燃性能和热性能,同时具有较好的力学性能.     

氨酯键扩链改性的669稀释剂对环氧树脂力学性能影响研究

制备了氨酯键扩链改性的669稀释剂UE6M,考察了加入不同用量的UE6M对环氧树脂进行稀释后环氧树脂混合体系的粘度变化。使用氰乙基化三乙烯四胺作为固化剂对环氧树脂混合体系进行固化,研究了UE6M的用量对环氧树脂混合体系固化物性能的影响。研究结果表明,UE6M对E51环氧树脂具有较好的稀释效果,且混合体系固化产物的韧性较纯环氧树脂固化物明显增强:UE6M用量为30%和40%的混合体系粘度仅为纯E51环氧树脂粘度的6.35%和1.43%,但其固化物的拉伸强度均在60MPa以上,分别为纯E51环氧树脂固化物的87.9%和80.9%。断裂伸长率均为纯环氧树脂固化物的8倍以上,弯曲应变为纯环氧树脂固化物2倍以上,弯曲强度及弯曲模量等未出现大幅下降,UE6M稀释剂加入环氧树脂后固化产物的韧性得到明显增强。     

双酚A型氰酸酯树脂/端羧基丁腈橡胶共混物的结构与性能

用液体端羧基丁腈橡胶（CTBN）对双酚A型氰酸酯树脂（BCE）进行增韧改性,用红外光谱、扫描电子显微镜,动态力学能谱仪等分析手段表征共混物的微观结构,测定其力学性能、耐热性等.结果表明,CTBN增韧BCE树脂体系可形成典型的海岛状共混结构;当平均粒径为2～3μm时,增韧效果最佳;当CTBN加入10份时,冲击强度提高150%,最大失重率所对应的温度只下降3.5℃;动态力学性能分析证明BCE/CTBN共混物是一个多相体系,存在橡胶CTBN相、BCE相和以BCE为主的BCE/CTBN共聚相、以CTBN为主的BCE/CTBN共聚相.     

负载PVDF的尼龙无纺布插层的碳纤维/环氧树脂复合材料的结构阻尼性能研究

以负载定量聚偏二氟乙烯(PVDF)的尼龙无纺布为插层材料,采用共固化工艺制备了碳纤维增强环氧树脂基复合材料,并系统研究了其力学和阻尼性能.测试了复合材料的弯曲强度、弯曲模量、层间剪切强度、Ⅰ型和Ⅱ型断裂韧性等力学性能,并通过动态力学分析仪测试了复合材料的储能模量、损耗模量和损耗因子的温度谱,采用单悬臂梁自由振动实验研究了其阻尼减振性能.与此同时,采用光学显微镜和扫描电镜等分析了复合材料微观结构,进而研究了阻尼机理.结果表明,在复合材料层间插入负载PVDF的尼龙无纺布能在不引起力学性能明显下降的前提下,显著提高复合材料的阻尼性能和断裂韧性.其基本阻尼机理是在共固化过程中热塑性插层材料在复合材料的层间形成了具有较高损耗因子的富树脂区,使损耗因子提高150%,而力学性能基本保持不变.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.