Alkylated phenolic resins as antioxidants for rubber

Polymeric antioxidants based on p‐nonyl phenol formaldehyde resin (PNPF) and p‐dodecyl phenol formaldehyde resin (PDPF) were prepared by the condensation reaction of the respective phenols with formaldehyde in the presence of an acid catalyst. The reactions were monitored by thin layer chromatography, and the melting points of the products were determined. These compounds were incorporated in natural rubber mixes to evaluate their antioxidant properties. The compounded mixes were characterized for their rheometric properties. The compression‐molded rubber sheets were tested for their mechanical properties. The effects of aging on the mechanical properties of these molded sheets were evaluated. Both PNPF and PDPF showed better antioxidant properties than the conventional styreneated phenol antioxidant. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2649–2651, 2006     

多乙烯多胺桥联受阻酚类抗氧剂的合成及其清除DPPH·性能

以二乙烯三胺和三乙烯四胺为桥联基,β-(3,5-二叔丁基-4-羟基苯基)丙酰氯为抗氧化功能基团,通过酰胺化缩合反应合成了两类具有不同对位桥联基团的受阻酚类抗氧剂。采用傅里叶红外光谱和核磁共振氢谱证实了合成的多乙烯多胺桥联受阻酚类抗氧剂的化学结构。DPPH法研究了多乙烯多胺桥联受阻酚类抗氧剂清除自由基的性能,并探索了酚羟基个数和对位桥联基结构对受阻酚类抗氧剂清除自由基性能的影响。结果表明,多乙烯多胺桥联受阻酚类抗氧剂具有良好的清除DPPH·能力,且随着抗氧剂分子中酚羟基个数的增加,清除DPPH·的活性增加,分子中含有4个酚羟基的三乙烯四胺受阻酚类抗氧剂的抗氧化效率（AE）达到2.65×10^-2 L/(mol·s)。对位桥联基结构对受阻酚类抗氧剂清除DPPH·能力有较大影响,季戊四醇为桥联基的受阻酚类抗氧剂1010清除DPPH·能力最强,其抗氧化效率（AE）为3.08×10^-2L/(mol·s);乙二胺为核的1.0代树枝状受阻酚类抗氧剂清除DPPH·能力最弱,其抗氧化效率（AE）为2.60×10^-2 L/(mol·s)。     

ABS树脂光泽度与黄色指数的测定

使用Color-view分光光度计同时测定了几个常用ABS树脂的光泽度和黄色指数(YI),着重试验分析了不同的样品规格或尺寸对测定结果的影响。结果表明:样片的厚度不仅对光泽度的测定结果造成了影响,而且对黄色指数的测定结果也形成了较为明显的影响;同时样片上是否有加盖物及加盖物的颜色对测定结果也构成了一定程度的影响;另外,样品的形式对黄色指数的测定结果形成了显著的影响。     

受阻酚类抗氧剂结构与其抗氧化性能的影响关系

选取了3种酚羟基个数不同的受阻酚类抗氧剂为研究对象,通过性能测试、氧化诱导温度测试以及羰基指数测试等对添加抗氧剂后合成的聚乙烯进行对比分析,考察抗氧剂结构对聚乙烯性能的影响。结果表明,虽然受阻酚类抗氧剂中酚羟基的个数增多可以提高抗氧剂的抗氧化效果,但耐老化性能变弱,因此优选适宜的酚羟基个数对于提升受阻酚类抗氧剂的抗氧化性能十分必要。     

Theoretical methods used in elucidating activity differences of phenolic antioxidants

The effectiveness of the existing theoretical methods used in prediction of antioxidant activity, including structure-activity relationships (SAR) and theoretical index, were evaluated. In most cases, it was found that the theoretical predictions were consistent with the experimental data. Although only one mechanism, free radical scavenging, was considered in the theories, the methods were valuable in predicting the activity of antioxidants to protect lipid oxidation.     

受阻酚抗氧剂对NBR/WCB共混胶耐热老化性能的影响

研究了抗氧剂2-叔丁基-6-(3-特丁基-2-羟基-5-甲基苯基)-4-甲基苯酚丙烯酸酯(简称GM)、抗氧剂264和抗氧剂2246对NBR/WCB共混胶的硫化特性、力学性能和耐热老化性能的影响,并通过TG分析表征NBR/WCB共混胶的耐热稳定性。结果表明,与抗氧剂264和抗氧剂2246相比,抗氧剂GM对NBR/WCB共混胶具有防止焦烧、加快硫化速度和软化胶料的作用。添加抗氧剂GM的共混胶比加入抗氧剂264和2246的共混胶具有更优异的耐热老化性能。TG分析表明,在3种抗氧剂中,加入抗氧剂GM的NBR/WCB共混胶的耐热稳定性最高。     

Synthesis and antioxidant activities in polyolefin of dendritic antioxidants with hindered phenolic groups and tertiary amine

Two novel primary antioxidants with dendritic structure and hindered phenolic groups were synthesized using 3‐(3,5‐diter‐butyl‐4‐hydroxyphenyl) propionic acid as raw material and dendritic poly(amidoamine) (PAMAM) as linker in chloroform. The antioxidant activities of the dendritic antioxidants were evaluated in polyolefin by melt flow index (MFI), yellowness index (Y.I.), and oxidation induction time (OIT). The dendritic antioxidants had excellent processing property and oxidation resistance behavior in polyolefin. At the same weighed amount of antioxidant, the MFI and Y.I. values of mulitiple‐extruded polyethylene (PE) stabilized with the dendritic antioxidants were smaller than those of the commercial antioxidants, as well as the OIT values of polyethylene (PE) stabilized with the dendritic antioxidants were larger. Applying to polypropylene, the antioxidant ability of the second‐generation dendritic antioxidant (G2.0 dendritic antioxidant) with larger molecular weight was superior to the commercial antioxidants and that of the first‐generation dendritic antioxidant (G1.0 dendritic antioxidant) was equal to the commercial antioxidants. The dendritic antioxidants can prevent polyolefin from breaking of macromolecular chain in processing and had stabilizing effect in polyolefin in service life by donating H‐atoms and electron to free radicals. The dendritic antioxidants combined with Irgafos 168 had improvement of antioxidant activities of the dendritic antioxidants in polyolefin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

MgO-CaO-C砖用抗氧化剂的研究

在MgO－CaO－C砖中分别加入3％B4C、BN、ZrB2和A1，在1O00℃，2h、1400℃，2h和1500℃，0.5h下，于空气中进行氧化试验。试验结果表明，B4C是一种非常优异和理想的抗氧化剂。进一步试验还说明，MgO－CaO－C砖中加入1％B4C其抗氧化效果已很明显。     

Thermoplastic Ternary Hybrids of Polyurethane,Hindered Phenol and Hindered Amine with Selective Two‐Phase Dispersion

A novel ternary hybrid of thermoplastic polyurethane/hindered phenol/hindered amine was designed and prepared. Selected hindered phenols and hindered amines were settled down, respectively, in the soft and hard phases of TPU with molecular‐level dispersion. As a result, the ternary hybrid showed a prominent enhancement in the tan δ peak value and distinct broadening of the glass transition region, due to the formation of strong interactions (hydrogen bonding) between segment and small polar molecules occurred in each phase of TPU, which demonstrated the promising future as high‐performance damping material of this ternary hybrid.

     

2,6-二叔丁基-4-氨基苯酚的合成工艺研究

以2,6-二叔丁基苯酚(DTBP)为原料通过亚硝化反应、还原反应合成2,6-二叔丁基-4-氨基苯酚(DTBAP)。通过单因素实验系统考察了反应工艺条件得出:1亚硝化反应:以95%乙醇为溶剂,以浓盐酸为酸化试剂,亚硝酸钠用量为DTBP摩尔量1.25~1.50倍,反应温度为15~20℃,反应时间2.0~2.5 h,产品收率达90%以上;2还原反应:以连二亚硫酸钠为还原剂,在50~55℃下反应60 min,连二亚硫酸钠用量为2,6-二叔丁基-4-亚硝基苯酚摩尔数的2.8倍及以上,产品收率可达到92%以上。制备方法操作简单,反应条件温和、易于控制,产物易于分离,产品总收率较高,反应原料廉价、容易采购,生产成本较低,适合于工业化生产。     

提高银白珠光颜料质量的工艺研究

以生产钛白粉的中间产物硫酸氧钛为原料,用尿素作中和剂,制备银白珠光颜料。研究了钛液中铁的含量、终点pH值、尿素加入量、升温速率和反应时间,以及加入不同掩蔽剂对云母钛珠光颜料产品白度和亮度的影响。试验结果表明,利用冷冻除铁后的钛液,调节终点pH值为1.5,尿素与TiO2质量比为(5～7)∶1,缓慢升温反应4～5h,并加入硅酸盐等掩蔽剂后,所得银白珠光颜料与纯硫酸氧钛所制的产品白度相当,且亮度很好。     

Evolution of phenolic compounds in virgin olive oil during storage

Phenolic compounds are of fundamental importance to the shelf life of virgin olive oils because of their antioxidative properties. In this paper, the evolution of simple and complex olive oil phenols during 18 mon of storage is studied by high-performance liquid chromatography (HPLC) analysis. The olive oils under examination were from various olive cultivars, harvested in two sectors in the same region at different stages of ripeness. The findings indicate that it is not the variety but rather the ripeness of the olives and the soil and climate that influence the phenol composition of virgin olive oil. In addition, a positive correlation was found between the age of the oils and the tyrosol to total phenols ratio. Lastly, gas chromatography-mass spectrometry analysis confirmed that the unidentified peaks detected by HPLC were of a phenolic nature.     

Extraction and identification of antioxidants in oats

Eight separate solvent systems were used with groats and hulls of several lines of oats to determine which system resulted in the most effective, rapid extraction of antioxidants. Antioxidant activity at room temperature was estimated by using thin-layer chromatography (TLC) along with a β-carotene spray. The greatest antioxidant activities were obtained with methanolic antioxidant extracts derived from Noble and Ogle oats and hulls. These extracts were added to soybean oil (SBO) and their effectiveness was compared with that of butylated hydroxytoluene (BHT), tertiary butyl hydroquinone (TBHQ) and a control (no additives) at 32°C, 60°C and 180°C. A petroleum ether extract of Noble oats also was tested in SBO at 180°C. Peroxide values (PV) for oils with added antioxidants during storage at 32°C and 60°C showed that the Ogle oat extract was more effective than the other oat and hull extracts or the control. There were no significant differences in effectiveness among the extracts and the control at 60°C. At 180°C, the stability of each oil was determined by measuring conjugated dienoic acid values (CD) and the relative amounts of the unoxidized fatty acid methyl esters (FAME) 18:2, 18:3 and 18:2/16:0. All oils with added oat and hull extracts had significantly lower CD and significantly higher 18:2/16:0 than oils with added BHT, TBHQ or the control during 14 days at frying temperature. Phenolic and hydroxy-phenolic antioxidant compounds with acids, alcohols, sugars or glycerides attached were tentatively identified in the oat and hull extracts by using TLC and Chromatographic sprays. To whom correspondence should be addressed at Food Science and Human Nutrition Dept., 3367 Dairy Industry Building, Iowa State University, Ames, IA 50011.     

Chromatic parameters as performance indicators for stone cleaning techniques

To determine the degree of soiling of urban buildings subject to environmental pollution and, at a later stage, to assess the effectiveness of cleaning techniques on the types of stone used in the construction of these buildings, it is very useful to define the chromatic parameters (L*,a*, b*,C*,WI, and YI) before and after treatment. A comparative study of these parameters and the original color of the stone is carried out. The best cleaning performance is achieved using a hot water jet at a temperature of 90°C and a pressure of 120 bars. In areas with significant black encrusted gypsum and calcite layers, these cannot be removed completely with water. Thus, chemicals must be applied, the most appropriate being sodium hydroxide‐based products. Using these cleaning techniques, it is possible to obtain chromatic parameters that come close to those of the stone in its original state, allowing for an increase in yellow hues resulting from the preservation of the patina inherent to the natural aging process that stone surfaces undergo. © 2000 John Wiley & Sons, Inc. Col Res Appl, 25, 442–446, 2000     

Evaluation of the phenolic antioxidants of olive (Olea europaea) leaf extract obtained by a green approach: Use of reduced graphene oxide for electrochemical analysis

Abstract

Deep Eutectic Liquids (DELs) have been specially designed, and used for the extraction of bioactive natural products from a bio-waste, since they have attracted much attention from economic and ecological aspects. In this study, an easy, accurate and sensitive detection method has been developed towards a trace amount of oleuropein which is one of the most significant components of the olive leaf extract. TiO_x-modified reduced graphene oxide electrode (TiO_x-RGO@GCE) has been used as the sensing electrode for the quantitative detection of oleuropein. The structural characterization of TiO_x-RGO@GCE has been performed using diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) and atomic force microscopy (AFM) techniques. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques have been implemented to investigate the electrochemical behavior of oleuropein. The electrochemical experiments revealed that the quasi-reversible reaction is the dominant mechanism on the electrode/electrolyte interface. The linear concentration range of 1–12?µM was obtained with the detection limit of 18.7?nM for oleuropein.     

The effect of paper appearance on printed color of inkjet printer

Paper properties, including the chemical or optical characteristics influence the quality and colorimetric characteristics of final printed colors. In this study, the effect of gloss, texture, and whiteness of the paper on the printed colors were investigated. The study was applied on 10 coated papers with different texture, gloss or whiteness, and the same grammage using two inkjet printers. It was found that the reproducibility of the printer can be affected with the paper brand, and this effect is statistically dependent on the brand of printer. The kind of paper significantly influences the light fastness of the final printed colors, and this effect statistically depends on the printer. Although, the paper's properties such as gloss and whiteness affect the gamut volume, it is not totally possible to model this effect. The effect of paper on the colorimetric values of the final printed colors is statistically significant. However, the influence of the brand of printer on the color changes via the paper difference is not statistically provable. Edge frequency technique was introduced as an appropriate method for computing texture properties of papers. The texture difference computed by this method shows a suitable correlation with the color differences caused by changing the paper's texture; however, it depends on the printer's brand. Furthermore, there is a good correlation between the Edge frequency difference and the gamut volume variation for papers with different texture while the other parameters such as gloss and whiteness are the same. © 2012 Wiley Periodicals, Inc. Col Res Appl, 38, 284–291, 2013     

PVC Mixtures with Processing Aids

Abstract

The mechanical properties (dynamical, tensile) and morphology by electron microscopy have been studied on PVC mixtures with processing aids of different compatibility with PVC (copolymers of methylmethacrylate, polystyrene, polyvinylacetate) in the temperature range of 20-150°C. It has been found and interpreted that the mechanical properties of PVC in the temperature range of 100-120 °C are favourably influenced by addition of a processing aid, which is compatible with PVC, has a sufficiently high molecular weight and its glass temperature is about 20°C higher than that of PVC.     

聚合型受阻酚抗氧剂的合成及应用

研究了以对甲酚为主要原料合成聚合型受阻酚抗氧剂的工艺。结果表明，树脂缩合反应条件是对甲酚与双环戊二烯为3：1～1．25，ZnCl2催化剂为对甲酚质量分数的2．0％，反应温度为75～80℃，双环戊二烯滴加时间为2h。烷基化反应温度为70～75℃，H2S04催化剂为缩合树脂质量分数的2．0％。制得的聚合型受阻酚抗氧剂产品对聚氨酯泡沫用聚醚2802具有较好的抗氧化性，起燃温度达224℃。