刚性有机粒子对聚氯乙烯／氯化聚乙烯共混体系形态和增韧机理的研究

刚性有机粒子对聚氯乙烯／氯化聚乙烯共混体系形态和增韧机理的研究周丽玲，吴其晔，杨文君，刘士龙，张漫（青岛化工学院橡胶系青岛２６６０４２）关键词刚性有机填料，聚氯乙烯ＰＶＣ，氯化聚乙烯（ＣＰＥ）形态，增韧机理在共混改性中，弹性体增韧硬质聚氯乙烯（ｎｙＶ...     

核－壳型弹性体对热塑性树脂的增韧

本文阐述了橡胶微粒对热塑性树脂的增韧机理，以及核－壳弹性体对塑料共混物性能的影响。其目的是为合成抗冲改性用核－壳弹性体提供参考。     

硬质PVC/ACR共混体系的增韧机理研究

通过TEM、SEM等方法研究了不同结构丙烯酸酯类抗冲改性剂（ACR）对聚氯乙烯（PVC／ACR共混体系形态结构的影响,对ACR增韧硬质PVC的机理作了探讨,当PVC中含有8phr以上完善核壳结构的ACR时,在共混体系能形成网络结构,这一结构在受冲击时产生多重银纹,并实现银纹的纯化,在PVC／ACR共混体系的增韧机理中占主导地位,同时,ACR诱发PVC产生剪切形变也是提高其增韧效果的因素。     

共混方法对聚氯乙烯/聚丙撑碳酸酯相容性影响

本文分别用溶液法和熔融法制得聚氯乙烯（PVC）与聚丙撑碳酸酯（PPC）共混试样，用DSC证明PVC／PPC共混物不相容，但它们不相容的程度受分子量、共混比例等因素的影响，并根据玻璃化转变温度（Tg）计算出溶液共混试样PPC富相中PVC的重量百分含量。NBR／PPC弹性体作偶联剂对PVC／PPC共混体系具有较好的增容作用，共混物中PPC的用量及分子量对共混体系性能有一定的影响。     

PVC/CPE/POE热塑性弹性体特性研究

研究了氯化聚乙烯（CPE）增容PVC／POE热塑性弹性体的结构与性能,通过对比使用增容剂CPE前后体系的力学性能,确证CPE对PVC／POE体系具有良好的增容效果。用DSC,SEM对热塑性弹性体的结构特性进行了研究,采用动态硫化的方法,提高了热塑性弹性体的性能。     

MMA接枝改性PVC/CaCO3纳米复合材料的力学性能

采用熔融共混法制备PMMA接枝改性纳米CaCO3增韧PVC（PVC/CaCO3）复合材料,并研究了复合材料的力学性能.结果表明,通过表面PMMA的接枝改性,可以显著提高纳米CaCO3增韧聚氯乙烯复合材料的拉伸强度和拉伸模量,在纳米CaCO3颗粒表面PMMA包覆层厚度为2nm时,复合材料的拉伸强度和拉伸模量达到极大值.对比于未处理纳米CaCO3和钛酸酯偶联剂处理纳米CaCO3,PMMA接枝改性纳米CaCO3增韧PVC复合材料的拉伸强度得到较大幅度提高.SEM显示,经过PMMA接枝改性后的碳酸钙在PVC基体中分散均匀,与基体界面结合良好.     

三元乙丙橡胶/聚丙烯热塑性弹性体

综述了三元乙丙橡胶/聚丙烯(EPDM/PP)热塑性弹性体的发展历程、市场情况以及EPDM/PP热塑性弹性体的结构、性能及其影响因素。EPDM/PP热塑性弹性体由EPDM和PP通过动态硫化技术制备而成,在室温下具有橡胶的高弹性,在加工温度下具有塑料的流动性。在性能上,EPDM/PP热塑性弹性体受加工设备、共混工艺、配合体系的综合影响。     

聚丙烯／聚烯烃弹性体共混体系的结构-性能关联

聚丙烯是目前应用最广泛的通用塑料之一。为了克服聚丙烯脆性大的弱点,人们发展了多种方法来增韧聚丙烯,其中聚丙烯和聚烯烃弹性体共混是常用的改性聚丙烯的方法。本文介绍了聚丙烯／聚烯烃弹性体共混物相容性的研究方法和较为普遍接受的增韧理论,并对近年来国内外聚烯烃弹性体增韧聚丙烯的研究进展做了介绍。     

PVC/ACR共混物微观结构与性能

本文研究了聚氯乙烯/丙烯酸酯类共聚物(PVC/ACR)共混物的应力-应变行为和冲击强度对ACR 用量的依赖关系。ACR对 PVC有良好的增韧作用,提高了PVC抗冲击性能。考察了三盐基性硫酸铅和硬脂酸钡-硬脂酸镉稳定剂对共混体系的影响,实验结果说明不同的热稳定体系对ACR改性PVC的效果有差别。动态力学性能测定结果表明PVC/ACR共混物存在两个玻璃化转变温度,证明PVC与ACR不相容性;而两个转变温度随共混物组成改变而变化,说明PVC与ACR之间存在着相互作用,PVC/ACR为部分相容体系。通过透射电子显微镜观察PVC/ACR共混物的微观结构形态表明:PVC与 ACR为两相体系,ACR呈粒状分布在PVC连续相中。但是,采用硬脂酸钡-硬脂酸镉稳定体系时,随着ACR用量增加,ACR的分散形态由粒状分散逐渐形成网络结构形态,与此相对应的共混物具有更好的抗冲击性能。     

TPU共混增韧POM的研究

通过机械共混的方法制备了聚甲醛(POM)和热塑性聚氨酯弹性体(TPU)复合材料.考察了不同硬度TPU及其含量对共混材料韧性的影响.结果表明,TPU硬度的变化对共混材料的力学性能起着非常重要的作用,硬度为65HA的TPU对POM的增韧效果较好,对POM的相形态和结晶性能影响更为显著.     

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.