Structural characteristics of some diphenyl oxide derivatives

Conclusions Data are given which question the reliability of the communication concerning the preparation of two conformational isomers of p-bromodiphenyl ether.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 143–145.     

Raman spectra of some ortho-substituted benzene derivatives containing silicon

Russian Chemical Bulletin -     

Novel test method to estimate bound rubber formation of silica-filled solution styrene-butadiene rubber compounds

Bound rubber formation was investigated in detail by applying various extraction temperatures (at room temperature, 90°C, and 180°C) and novel treatment methods (ammonia bubbling and sonication). Bound rubbers could be divided into three major components of core shell, primary layer including tightly primary layer and occluded rubber, and secondary layer including connecting filament. Bound rubber content of the core shell was measured by four successive procedures of extraction at room temperature, ammonia bubbling, extraction at 180°C and sonication. Bound rubber content of the tightly primary layer was measured by three successive procedures of extraction at 90°C, ammonia bubbling and sonication. Bound rubber content of the primary layer was measured by two successive procedures of extraction at 90°C and sonication.     

FTIR spectra and mechanical strength analysis of some selected rubber derivatives

Rubber materials have wide range of commercial applications such as, infant diapers, famine hygiene products, drug delivery devices and incontinency products such as rubber tubes, tyres, etc. In the present work, studies on mechanical properties of some selected rubber materials viz., natural rubber (NR), styrene butadiene rubber (SBR), nitrile butadiene rubber (NBR) and ethylene propylene diene monomer (EPDM) have been carried out in three states viz., raw, vulcanized and reinforced. To enhance the quality of rubber elastomers, an attempt is made to prepare new elastomers called polyblends. In the present study an attempt is made to blend NR with NBR and with EPDM. We here report, a novel approach for the evaluation of various physico-mechanical properties such as mechanical strength, tensile strength, elongation and hardness. The method is simple, direct and fast and involves infrared spectral measurements for the evaluation of these properties. With the applications of modern infrared spectroscopy, the mechanical strength of these rubber materials have been analyzed by calculating the internal standards among the methyl and methylene group vibrational frequencies obtained from FTIR spectroscopy. Also the tensile strength measurements carried out by universal testing machine. The results pertaining physico-mechanical properties of the rubber derivatives undertaken in the present study obtained by IR-based method are in good agreement with data resulted from the standard methods.     

Ageing of butyl rubber against UV irradiation

The photodegradation and stabilisation of butyl rubber have been studied in air in the temperature range of 258 to 318 K using a monochromatic light of 366 nm with a constant intensity flux of 1·68×10⁻⁸ einstein s⁻¹ cm⁻² in the absence and presence of cuprous di-isopropyl dithiophosphate. Irradiations were carried out on films at 0, 2, 4, 6, 8, 10, 12 and 14 h. An investigation into the nature and molecular changes during the irradiation with ultra-violet light (366 nm) of butyl rubber has been conducted by light scattering technique. The quantum yields of the photolysis of the polymer have been determined using a potassium ferrioxalate actinometer. Light scattering data have been processed to yield the activation energies in the absence and presence of 0·1 wt. % stabiliser. The incorporation of 0·7 wt. % cuprous di-isopropyl dithiophosphate in the matrix of the rubber film exercises the maximum protective influence on the photolytic degradation of the rubber.     

Synthesis and antimicrobial activities of some sulphur containing chromene derivatives

A series of 3,3-dimethyl-3Hbenzothieno[3,2-f][1]-benzopyran analogues modified at the pyran 1,2-double bond were synthesized. The corresponding dihydro and (+/-)-cis-diol derivatives were converted into diacetate and cyclic carbonate upon acylation. The title compounds were characterized by spectroscopic analysis and screened for their antimicrobial activity in vitro.     

Interfacial mechano-chemical grafting in styrene-butadiene rubber/halloysite nanotubes composites

SBR/unmodified HNT composites were prepared by open-mill mixing and vulcanization. The results showed that HNT could decrease the scorch and optimum cure time, and play a significant role in reinforcing SBR vulcanizates. Mechano-chemical grafting at the interface between HNT and SBR was investigated by using infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), solid-state ¹³C NMR spectra and bonded rubber content, etc. The results showed the shearing force during the mixing process can impel the grafting reaction of SBR onto the surfaces of HNT, which leads to interfacial chemical bonding between phenyl’s α-H of SBR and the surface groups of HNT with Si-OH or Al-OH. Thus, the mechanical properties of the composites were significantly enhanced.     

消解氨溶-火焰原子发射光谱法测定丁苯橡胶中的钾、钠

和浓硝酸消解了丁苯橡胶样品，再用氨水溶解消解产物。取适量消解产物的氨溶液，加入消电离剂Li^ 配制成试液，以工作曲线法测定。对样品处理方法、消解产物的溶解性质、线性范围、干扰及检出限进行了考察。测定结果的相对标准偏差小于3．9％，加标回收率为97．3％－103．7％。建立了快速同时测定丁苯橡胶中钾、钠的火焰原子发射光谱法。     

DSC study of stabilizing effect of antioxidant mixtures in styrene-butadiene rubber

The type of cooperation between antioxidants in the binary mixtures of four substituted diphenylamines and phenotiazine in the stabilization of styrene-butadiene rubber has been tested. Thermooxidation of the samples has been studied by differential scanning calorimetry under non-isothermal conditions. The protection factors of the individual stabilizers and their mixtures were determined. The synergy factors were applied to asses the type of cooperation of antioxidants in the mixtures. From their values it can be concluded that the type of cooperation depends on temperature. The highest synergistic effect has been observed for the mixture of phenotiazine and [4-(1-methyl-1-phenyl-ethyl)-phenyl]-phenylamine.     

Evaluation of some derivatives of 4-quinazolones as antioxidants and antirads in rubber

Derivatives of 4-quinazolones were compounded with rubber. The relation between their efficiencies as antioxidants and antirads was studied. It was found that their efficiencies as antioxidants and antirads fall in the same order but differ in degree.     

Improvement of properties of silica-filled styrene-butadiene rubber (SBR) compounds using acrylonitrile-styrene-butadiene rubber (NSBR)

Since silica has strong filler–filler interactions and adsorbs polar materials, a silica-filled rubber compound wil have poor dispersion of the filler and a poor cure characteristic. Improvement of properties of silica-filled styrene-butadiene rubber (SBR) compounds has been studied using emulsion SBR-based acrylonitrile-styrene-butadiene rubber (NSBR). The silica dispersion is improved by adding NSBR to the compound. The bound rubber content increases with increase in the NSBR content. The scorch time and cure rate become faster as the NSBR content increases. The crosslink density also increases by increasing the NSBR content. The wear property is improved by adding the NSBR. Copyright © 2003 John Wiley & Sons, Ltd.     

橡胶-填料相互作用对丁苯橡胶/白炭黑复合材料性能的影响

本文研究了硅烷偶联剂原位改性白炭黑对溶聚丁苯橡胶(SSBR)性能的影响,结果表明,通过哈克转矩流变仪对含有偶联剂的SSBR/白炭黑混炼胶进行原位热处理后可明显减弱混炼胶的Payne效应,改善白炭黑在橡胶基体中的分散.原位热处理方法能够明显提高硫化胶的300%定伸应力,降低动态压缩温升,同时可使硫化胶在0℃附近具有较高的损耗因子(tanδ),60℃附近具有较低的tanδ.对不同聚合方式得到的丁苯橡胶,即溶聚丁苯橡胶与乳聚丁苯橡胶(ESBR)/白炭黑复合材料的力学性能及动态力学性能进行了研究,结果表明,白炭黑在SSBR2305中分散效果优于在ESBR1502中;采用偶联剂原位改性白炭黑可以使SSBR2305硫化胶获得与ESBR1502硫化胶相当的物理机械性能,更理想的动态力学性能,从而得到力学性能、抗湿滑性、滚动阻力及耐磨性更加均衡的理想轮胎材料.通过对具有不同偶联效率的SSBR/白炭黑体系的微观结构与性能研究发现,随偶联效率的增加,其结合橡胶含量增加,Payne效应减弱;高偶联效率的S-SBR具有较低的动态压缩温升及较好的耐磨性.     

Aging properties of styrene-butadiene rubber nanocomposites filled with carbon black and rectorite

To better understand the effect of rectorite and carbon black (CB) on the aging performance of styrene-butadiene rubber (SBR), SBR/CB, SBR/CB/rectorite and SBR/rectorite nanocomposites with the same total filler loading were prepared. The microstructure of the three SBR nanocomposites was characterized by XRD, TEM and SEM. After thermal aging, oxygen-containing molecules were found to be formed in the SBR nanocomposites, as verified by FTIR analysis. The SBR/rectorite nanocomposite showed the highest aging coefficient and the lowest change rate of tensile strength and stress at 100% strain among the three SBR nanocomposites, indicating that the introduction of nano-dispersed rectorite layers can enhance the thermal aging resistance of the nanocomposites. For the SBR/CB/rectorite nanocomposite, the addition of CB helped to improve the interfacial compatibility between the filler and matrix, resulting in the best crack resistance as the aged SBR/CB/rectorite nanocomposite always demonstrated the least cracks on the surface during either stretching or bending experiments.     

Prevention of oxide aging acceleration by nano-dispersed clay in styrene-butadiene rubber matrix

In order to minimize the oxidative degradation of SBR at high temperature, the nano-dispersed clay layers were introduced by using the SBR/clay (100/80) nanocompound to prepare SBR/clay/carbon black (CB) nanocomposites, then the effects of nano-clay on the properties of SBR nanocomposites are investigated. The clay layers and CB are uniformly dispersed in the SBR matrix at nano-scale. The mechanical properties of the SBR/clay/CB nanocomposites mostly decrease with the increase of clay loading, however, with the increase of clay loading, the change rate of the mechanical properties of the nanocomposites decreases and the aging coefficient of the nanocomposites rises, and the length and depth of the cracks of the aged nanocomposites after bending decrease, which means that the clay layers can provide the nanocomposites excellent thermal aging resistance and heat resistance. The experiment of aging with air and without air proved the importance of oxygen during rubber aging process. The FTIR spectra show the generation of oxygen-containing group on the external surface of the nanocomposites during aging. The DSC results indicate the differences between the internal layer and the external layer of the aged nanocomposites.     

NMR study of styrene-butadiene rubber (SBR) and TiO2 nanocomposites

The chemical behavior of styrene-butadiene rubber (SBR) and of the SBR/TiO₂ and photodegraded SBR/TiO₂ nanocomposites was investigated through nuclear magnetic resonance spectroscopy (NMR) in the solid state with magic angle spinning (MAS). The ¹³C cross polarization/magic angle spinning (CP/MAS) routine spectrum allowed us to obtain information on the polymer microstructure and also to evaluate the domain mobilities. The variation contact time and the proton spin-lattice relaxation time in the rotating frame (T₁ρH) were determinant factors to evaluate the dynamic molecular motion. The NMR spectrum of the nanocomposites was dislocated 5 ppm to higher chemical shift, indicating the presence of a strong interaction between the polymer chains and the TiO₂ nanoparticles. The VTC experiment showed a rigid domain in the SBR/TiO₂ photodegraded nanocomposite due to cross-linking reactions.     

Synthesis of some novel S-alkylated and S-glycosylated hydantoin derivatives containing pyrene moiety

3-Aryl-5-[(Z)-pyrenylmethylene]-2-alkylthiohydantoins and 3-Aryl-5-[(Z)-pyrenylmethylene]-2-(D-glycosyl)-2-thiohydantoins functionalized with different aromatic and glycoside substituents have been synthesized by the reaction of (Z)-3-(4-methoxyphenyl)-5-[(pyren-8-yl)methylene]-2-thiohydantoin with alkyl halides, cyclic and acyclic nucleosides via various routes with moderate to good yields and characterized by ¹H, ¹³C NMR and mass spectra and elemental analysis     

Thermogravimetric characteristics of barbituric acid and some of its derivatives

The thermolysis curves of barbituric acid and some of its derivatives have been determined. Barbituric acid, violuric acid and dilituric acid form hydrates while 1,3-dimethylvioluric acid and barbital are anhydrous. Barbital and 1,3-dimethylvioluric acid sublime before decomposition. The differential thermal analysis for dilituric acid showed a sharp exotherm at 190° indicating a violent explosion.     

Liquid crystals of some new tolane derivatives containing a 1,2-ethylene linkage

Abstract

Three types of nematogenic compound, 4-[2-(trans-4-alkylcyclohexyl)ethyl]-4′-alkyltolanes, 2-fluoro-4-[2-(trans-4-alkylcyclohexyl)ethyl]-4′-alkyltolanes and 4-[2-(trans-4-alkylcyclohexyl)ethyl]-4′-halogenotolanes, have been synthesized and their transition temperatures and enthalpies determined. Their bulk viscosity and birefringence have been estimated from those of mixtures with other liquid-crystalline compounds. These compounds have been found to be excellent materials for twisted nematic displays, because of their wide nematic temperature range, high birefringence (Δn = 0·26), and low viscosity (η = 21 cP at 20°C). Several related compounds having other central linkages, namely -CH₂O-, a single bond or -COO-, in place of the 1,2-ethylene group, have also been studied.     

Synthesis and biological activities of some new thiazolidine derivatives containing pyrazole ring system

As a part of systematic investigation of synthesis and biologically active compounds of thiazolidine (TZD) derivatives containing pyrazole ring system, several new pyrazole–TZD derivatives 8a , 8b , 8c , 8d and 9a , 9b , 9c , 9d have been synthesized. Compounds 8a , 8b , 8c , 8d were prepared from N‐substituted TZDs 6a , 6b , 6c , 6d and 1H‐pyrazole‐4‐carboxaldehyde 7 by Knoevenagel‐type reaction. Treatment of 8a , 8b , 8c , 8d with sodium hydride at room temperature caused dimerization reaction to afford the corresponding spirocompounds 9a , 9b , 9c , 9d . All the synthesized compounds were characterized by spectroscopic analysis. In vitro, the synthesized compounds 8a , 8b , 8c , 8d and 9a , 9b , 9c , 9d were tested for their growth inhibitory activity in A549 lung cancer, B16F10 murine melanoma, and HeLa human uterine carcinoma cells and for their differentiation of 3T3‐L1 preadipocytes to adipocytes. The results showed that compound 8c possessed growth inhibitory effect of B16F10 cells (IC₅₀ = 27 μM) and compounds 9c , 9d had induction effect on the differentiation of 3T3‐L1 preadipocytes. J. Heterocyclic Chem., (2011).     

Synthesis and properties of some acridine derivatives containing the bis-β-chloroethylamino group

A study is made of the condensation of acridine derivatives with p-nitroso-N-bis(-chloroethyl)aniline, and 12 new acridine derivatives synthesized, nine of them containing the bis--chloroethylamino group. Azomethines and nitrones prepared are reduced polarographically, and their IR spectra investigated.