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1.
聚氯乙烯接枝丙烯酸稀土的研究   总被引:5,自引:1,他引:5  
将无机稀土有机化后与聚氯乙烯(PVC)进行接枝共聚。探讨了氧化稀土与丙烯酸反应、PVC接枝丙烯酸稀土的原理和方法,并通过红外光谱、扫描电镜对接枝共聚物进行定性表征,用微量热天平对接枝共聚物的热性能进行测定。实验结果表明,经丙烯酸稀土接枝共聚后的PVC,其耐热分解性能和韧性有了明显的提高。  相似文献   

2.
以羧酸共生稀土作为PVC塑料紫外光氧化降解的光敏剂,采用人工加速老化实验、户外曝晒实验等方法进行降解试验,并用红外光谱,紫外光谱和凝胶色谱等方法对含羟酸共生稀土光敏剂可降解PVC塑料的可降解性能进行了研究。初步探讨了羧酸共生稀土敏化PVC膜光氧化降解的作用机理。结果表明,羟酸共生稀土(如La、Ce、Pr等)对PVC分子的结构具有明显的光敏化降解作用,并具有抑制PVC在光照过程中发生交联的作用。  相似文献   

3.
稀土PVC稳定剂的作用机制研究   总被引:22,自引:0,他引:22  
稀土化合物可以作为聚氯乙烯稳定剂,硬脂酸稀土是稀土复合稳定剂的重要成分。本文通过研究PVC与硬脂酸镧及其它硬脂酸盐作用前后的红外光谱,探讨了硬脂酸盐对PVC的热稳定作用机制,发现了稀土化合物对PVC的特殊稳定机制,即改变PVC的构象和抑制脱氯化氢的作用,并对稀土稳定剂独特的协同作用做出了解释。  相似文献   

4.
本研究进行富稀土金针菇和农用硝酸稀土对小鼠生长、发育及耐力的对比试验。结果表明,饲喂富稀土金针菇的小鼠,三周后体脏重及耐力均显著高于无稀土的金针菇对照组(E组),且表现出一定的剂量效应。与饲喂硝酸稀土的小鼠(D组)相比,当添加的稀土量相等时,饲喂富稀土金针菇的小鼠(B组)体重和脏器重明显增加,游泳时间延长28.6%,游泳后B组血乳酸含量的变化明显低于C、D、E组,血糖含量下降率较小。可见,将适量富  相似文献   

5.
稀土元素对低铬半钢热疲劳性能的影响   总被引:1,自引:0,他引:1  
研究了稀土元素对低铬半钢铸态及经热处理后组织中的共晶碳化物形状的影响,在此基础上着重研究了该材料的热疲劳性能。结果表明:稀土元素能改善共晶碳化物的形状,抑制热疲劳裂纹的萌生与扩展,提高其热疲劳性能,尤其稀土变质后再经热处理后效果更明显。当试样经0.20%(质量分数)稀土变质后经950℃,3h正火处理时,热疲劳性能最佳。  相似文献   

6.
热处理对Mg-Nd-Zr挤压合金性能与组织的影响   总被引:1,自引:0,他引:1  
在Mg-Nd-Zr挤压材料中,稀土相为Mg_(12)Nd相。经时效处理后,由于Mg_(12)Nd相的大量析出,抗拉强度与屈报强度明显提高;而经淬火+时效处理后,发生了晶粒长大,导致屈服强度明显下降。时效或淬火+时效处理皆降低材料的塑性。  相似文献   

7.
含羧酸稀土光敏剂降解PVC塑料的可降解研究   总被引:8,自引:0,他引:8  
以羧酸共生稀土作为PVC塑料紫外光氧化降解的光敏剂,采用人工加速老化实验、户外曝晒实验等方法进行降解试验,并用红外光谱,紫外光谱和凝胶色谱等方法对含羧酸共生稀土光敏剂可降解PVC塑料的可降解性能进行了研究。初步探讨了羧酸共生稀土敏化PVC膜光氧化降解的作用机理。结果表明,羧酸共生稀土(如La、Ce、Pr等)对PVC分子的结构具有明显的光敏化降解作用,并具有抑制PVC在光照过程中发生交联的作用。  相似文献   

8.
高温固体氧化物燃料电池中的阴极材料   总被引:6,自引:0,他引:6  
针对稀土材料在固体氧化物燃料电池中的应用,综述了稀土复合氧化阴极材料的合成方法,讨论了具有钙钛矿型结构的稀土复合化物的阴极材料的物理性能,化学性质及掺杂机制。  相似文献   

9.
ABS/PVC共混体系的相容性,力学性能和形态   总被引:7,自引:0,他引:7  
通过掺和各种橡胶聚合物如ABS、MBS和天然橡胶等,使聚氯乙烯(PVC)的低抗冲击强度和难加工性得到改进「‘,’‘.ABS和PVC的共混物具有优异的抗冲击强度、刚性、韧性和耐化学性等.这与两聚合物的组份比、相容性及形态结构密切相关“,“.将丙烯睛(SAN)共聚单体引人聚苯乙烯(陀)和丁二烯(孤)后,使*踞/**C具有好的相容性D’.本文对*踞”*C共混体系的不同共混组份,同一共混条件下的相容性,力学性能和形态结构进行了研究.ABS(通用型301树脂,兰州化学工业公司);PVC-SG-3型(吉林化学工业公司),稳定剂…  相似文献   

10.
兼具热和光稳定性的稀土稳定剂,对降低聚氯乙烯(PVC)加工成本,提高PVC的生产效率和打开稀土稳定剂的应用领域具有重要的意义,因此,通过人工加速紫外老化实验和户外自然光老化实验,研究了2,4-二羟基二苯甲酮镧(LBP)、 2-苯甲酰苯甲酸镧(LBA)及三元复合稳定剂对PVC光稳定性能的影响。结果表明:添加含LBP和含LBA的两种三元复合稳定剂(LBP∶ZnSt2∶PE=2∶1∶2, LBA∶ZnSt2∶PE=1∶1∶3)的PVC片材,人工紫外老化10 d后,失重率分别为2.7%和6.2%,自然光老化35 d后,拉伸强度保留率分别为87.6%和81.8%,复合稳定剂提高PVC的光稳定性能最佳。稀土稳定剂可以吸收PVC降解产生的氯化氢,降低氯化氢的浓度,从而减弱氯化氢对PVC降解的催化作用,抑制PVC脱去HCl形成双键,防止双键在氧作用下,形成过氧化物生成羰基化合物。  相似文献   

11.
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.
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 6ag and imidazo[1,5-a]quinoxalines 7ah by the reaction of 2-imidazolyl anilines 4ac with aryl aldehydes 5ak under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4ab 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   

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