共查询到20条相似文献,搜索用时 62 毫秒
1.
2.
3.
聚[丙烯酸甲酯-甲基丙烯酸2-(二甲氨基)乙酯]/环氧树脂IPN力学性能的研究 总被引:1,自引:0,他引:1
用同步法合成聚[丙烯酸甲酯-甲基丙烯酸2-(二甲氨基)乙酯]/环氧树脂(P(MA-DMA)/EP)互穿聚合物网络(IPN),对其力学性能进行了研究,结果表明,该体系IPN由于两网络间接枝导致相客性比较好,动态力学谱仅出现一个转变温度,当P(MA-DMA)/EP=20/80时,力学性能显示正协同效应,对环氧树脂的增韧效果最佳,不同组成比的IPNTg实-Tg计与(d实-d计)差值成正比。 相似文献
4.
5.
网络间含离子键的聚氨酯/接枝乙烯基酯树脂互穿聚合物网络 研究 总被引:2,自引:0,他引:2
分别以双酚-A型环氧树脂E-51和聚醚型环氧树脂E-46为原料合成了两种二乙胺-环氧树脂和加成多元醇(分别命名为AE-51,AE-46),将其和甲基丙烯酸一起用于合成聚氨酯/接枝乙烯基酯树脂(PU/接枝VER)互穿聚合物网络(IPN),使之在两个网络间形成离子键。实验结果表明,这类新型的IPN材料中两个网络间的互穿程度与相容性进一步提高,从而导致刚性的接枝VER对弹性的PU网络有更好的增强效果。DSC和FTIR的测定结果表明,在含AE-51的IPN中,由于离子键的作用使PU网络硬段的有序结构遭到很大程度的破坏,与AE-51和PU网络中的硬段以及VER网络有较好的相容性有关,因此这类IPN材料具有较好的力学性能。 相似文献
6.
7.
聚氨酯/环氧树脂互穿网络硬质泡沫塑料反应过程和微观结构 总被引:7,自引:0,他引:7
聚氨酯/环氧树脂互穿网络(PU/EPIPN)硬泡中异氰酸根的消耗速度较纯PU硬泡高,是由于环氧树脂的固化荆同时也是异氰酸根反应的催化荆。而PU/EP IPN硬泡中环氧基的反应速度和反应程度均较纯EP网络低,归因于互穿网络对基团扩散的阻碍。在互穿网络硬泡形成过程中,存在环氧开环中所新产生的羟基与异氰酸根的反应、大分子多元醇中羟基与环氧基的反应以及异氰酸根与环氧基形成嗯唑烷酮的反应三种形成网络间的化学键的途径。同时由于PU/EPIPN硬泡高度的交联,使得IPN硬泡中两个网络具有良好的相容性。动态力学性能表明所有IPN样品都只有一个玻璃化温度。透射电镜表明IPN样品无明显的相界面。 相似文献
8.
近年来,互穿聚合物网络(IPN)的开发受到了广泛的关注。以聚氨酯为一组分,聚丙烯腈、聚酯及环氧树脂等为另一组分的IPN体系的研究已有报道,而聚氨酯与有机硅的IPN体系的研究报道很少。在本文中,我们对聚氨酯(PU)与聚二甲基硅氧烷(PDMS)半IPN的透气性与结构的关系进行了研究。 相似文献
9.
室温固化蓖麻油聚氨酯/乙烯基聚合物互穿网络材料的一些规律及其性能 总被引:2,自引:0,他引:2
研究了蓖麻油与甲苯二异氰酸酯及丙烯酸酯或苯乙烯等乙烯基单体在室温下生成的互穿网络聚合物(IPN)的一些规律及其性能.用红外光谱追踪表明,聚氨酯的生成快于甲基丙烯酸甲酯的聚合.研究IPN凝胶点指出.凝胶点时间随聚氨酯含量增加及聚苯乙烯含量减少而缩短.丙烯酸甲酯在生成IPN过程中凝胶的生成速度要比苯乙烯的场合快.丙烯酸丁酯、丙烯腈或丙烯酸甲酯与蓖麻油聚氨酯生成的IPN的抗张强度在聚氨酯占一半时呈现最大值.透射电镜观察表明,生成速率较快的聚氨酯的微区存在于聚丙烯酸甲酯中.聚丙烯酸甲酯与蓖麻油聚氨酯形成的IPN在tanδ-T,曲线上呈现一个宽的玻璃化转变温度. 相似文献
10.
PMPS/PMAc相容性与同步互贯聚合物网络的阻尼性能研究 总被引:5,自引:0,他引:5
互贯聚合物网络是一种聚合物合金 ,其组分的热力学性质决定组分间的相容性和微相结构 ,从而影响材料的阻尼性能 .采用同步互贯聚合物网络 (SIN)技术制备了一种新型的聚苯基硅氧烷 (PMPS) 聚甲基丙烯酸酯 (PMAc)阻尼材料 ,用DMA和AFM等表征研究了其玻璃化温度转变行为与微观相态结构 .结果表明 ,由相容性好的组分制备的SIN材料阻尼值最高 ,tanδmax 可达 1 4,只有一个玻璃化温度转变峰 ,其微相结构为双相连续 ;组分介于相容与不相容之间时 ,所构成的SIN样品的tanδ≥ 0 3的温度区间最宽 ,可达 170℃ ,微相结构为单相连续 ;由相容性差的组分制得的SIN阻尼材料的内耗峰裂分为两个区间 .PMPS PMAcSIN材料的阻尼性能可以通过调节组分的相容性进行控制 . 相似文献
11.
Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
12.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
13.
N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
14.
Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
15.
In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献
16.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions. 相似文献
17.
Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described. 相似文献
18.
用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在. 相似文献
19.
An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction. 相似文献
20.
The Diels-Alder reactivity of 1,2-heteroborines (H4C4B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed. 相似文献