Ozonization of polyolefin blends with a minor component

Some regularities of degradation of PE-PP blends low in content (up to 5 wt %) of one of the components under the action of electric discharge and ozonization were studied. The electric aging is mainly explained by the effect of oxidation processes, which were investigated via estimation of the content of C=O groups, which depends on the blend composition. The data on changes in the dielectric characteristics of blends subjected to the action of electric discharge and ozone were obtained. It was shown that the blends of PE low in PP content have the highest tolerance against the electric discharge and ozonization, whereas the blends of PP with a low content of PE demonstrate the minimum stability.     

Vacuum balance and related studies of cokes used in steel production

The reactivities of cokes derived from coal blends used in the steel industry have been compared. Kinetics and rates of oxidation have been correlated with changes in surface area and porosity determined by gravimetric gas sorption using vacuum microbalances.During the earlier stages of oxidation of the cokes in carbon dioxide at 1000 °C, the surface area increases considerably, reaching a maximum at about 20 % burn-off. This change in surface area is ascribed to formation of pores at the surface, including opening of initially-closed pores as the burning proceeds.At higher percentage burn-offs, the surface area decreases to a very low value as the ash sinters with loss of porosity.     

Comparative studies of reactions of commercial polymers with molecular oxygen,singlet oxygen,atomic oxygen and ozone—II. Reactions with 1,2-polybutadiene

The oxidations of 1,2-polybutadiene by molecular oxygen, singlet oxygen, atomic oxygen and ozone have been studied using u.v. and i.r. spectroscopic methods. Some possible implications of the results of oxidation in the presence of singlet oxygen (parallel free radical oxidation) and atomic oxygen (formation of NO₂ and its reaction with polymer) are discussed. Crosslinking was observed during all types of oxidation. A new mechanism involving formation of free radicals has been considered in detail. During ozonization of 1,2-polybutadiene, formation of formaldehyde and formic acid were detected. An ozonization mechanism has been proposed.     

Surface area development of three cokes in relation to the zinc–lead blast furnace

The development of surface area on burn-off for three metallurgical cokes has been studied and correlated with rates of oxidation in carbon dioxide. The role of boric oxide, B₂O₃, as inhibitor of oxidation is discussed. The effect of ash build-up in the later stages of coke burn-off is evaluated in relation to surface area changes.     

Catalytic oxidation of toluene by ozone in the acetic acid-sulfuric acid system

Oxidation of toluene by ozone was studied in the system constituted by acetic and sulfuric acids in the presence of manganese(II) acetate and sodium bromide. The effect of sulfuric acid and the catalyst on the yield of benzoic acid and on the oxidation rate was considered. The optimal ozonization conditions were determined. A scheme of redox catalysis that accounts for experimental data was suggested.     

Heterogeneous Catalytic Ozonization of Sulfosalicylic Acid

This paper describes the potential of heterogeneous catalytic ozonization of sulfo-salicylic acid (SSal). It was found that catalytic ozonization in the presence of Mn-Zr-O (a modified manganese dioxide supported on silica gel) had significantly enhanced the removal rate (72%) of total organic carbon (TOC) compared with that of ozonization alone (19%). The efficient removal rate of TOC was probably due to increasing the adsorption ability of catalyst and accelerating decomposition of ozone to produce more powerful oxidants than ozone.     

Surface oxidation of rubber crumb with ozone

Rubber crumb derived from the grinding of used truck tread and tyres is used as a low cost filler in rubber compounds based on diene rubber. In order to expand its application to other fields, the surface modification of the rubber crumb could be an interesting and feasible solution. In fact, the surface modification of rubber crumb may be used as a tool to expand its use in applications to compounds with polar rubber matrices or where hydrophilic surface of the rubber crumb could be desirable, for example in water-based dispersion or as filler for asphalt. In the present work, ozone has been used as the active agent to cause surface oxidation and functionalisation of rubber crumb in a fluidized bed reaction. The rubber crumb reacts swiftly with ozone producing CO₂ in the initial stages of reaction and then leading to the desired surface oxidized product. The rate constant of the reaction between ozone and rubber crumb has been determined by FT-IR spectroscopy, monitoring the consumption of ozone in the gas phase in the presence of the crumb. A rate constant value of 5.03 × 10⁻³ s⁻¹  g⁻¹ of rubber crumb was determined. The degree of the surface oxidation of the rubber crumb can be determined by FT-IR spectroscopy using as reference the intensity of the ketone band at about 1710 cm⁻¹. Additionally the nominal ratio between the amount of ozone (in mg) reacted with rubber crumb (in g) can be used as a parameter for the degree of the surface oxidation. The surface oxidized rubber crumb shows surface acidity and hydrophilicity. Thermogravimetric analysis, differential thermal analysis and pyrolysis-GC clearly demonstrate that the ozonization of the rubber crumb is directed exclusively to the surface of the crumb and does not affect the bulk properties at all.     

The catalytic ozonization of model lignin compounds in the presence of Fe(III) ions

The ozonization of several model lignin compounds (guaiacol, 2,6-dimethoxyphenol, phenol, and vanillin) was studied in acid media in the presence of iron(III) ions. It was found that Fe³⁺ did not influence the initial rate of the reactions between model phenols and ozone but accelerated the oxidation of intermediate ozonolysis products. The metal concentration dependences of the total ozone consumption and effective rate constants of catalytic reaction stages were determined. Data on reactions in the presence of oxalic acid as a competing chelate ligand showed that complex formation with Fe³⁺ was the principal factor that accelerated the ozonolysis of model phenols at the stage of the oxidation of carboxylic dibasic acids and C₂ aldehydes formed as intermediate products.     

Ozonization of electronic conducting polymers: II. Degradation or doping

The ozonization of poly[3-pentylthiophene], poly[3-heptylthiophene] and poly[3-nonylthiophene] was carried out in room temperature. The DC conductivity changes during the ozonization have been recorded, revealing significant conductivity increase (up to two orders of magnitude). Moreover, an analysis of electron microscopy images has shown that ozone related swelling of polymer bundles caused the granular structure of the samples to fade away. The analysis of FTIR spectra indicated the presence of physisorbed ozone as well as oxidative degradation products in the ozonized polymer samples.     

甲基丙烯酸聚乙二醇单甲醚酯在聚(醚-氨酯)表面的臭氧化接枝

甲基丙烯酸聚乙二醇单甲醚酯在聚（醚 氨酯）表面的臭氧化接枝王晨晖王安锋车波周彩华苏琳丽林思聪（南京大学高分子科学与工程系生物材料分子工程与控制释放分子工程室南京２１００９３）王炳坤（南京大学环境科学系南京２１００９３）关键词臭氧化，表面接枝，大...     

Inclusion Behavior of 4-Nonylphenol into Cyclodextrin Derivatives

The solubilities of 4-nonylphenol in five kinds of hydroxypropyl-cyclodextrin (HP-CDs) solutions were investigated in order to evaluate them for soil remediation. The relative aqueous-phase concentration of 4-nonylphenol linearly increased with the increasing HP-CD concentration. The addition of HP-beta-CD (degree of substitution, D.S.=0.6) produced the largest change because the inner core of HP-beta-CD is the most hydrophobic. The solubility of 4-nonylphenol in the HP-CD solutions depended upon the cavity diameter and the degree of HP-CD substitution. Both ozone and activated carbon treatments have been using for removing organic compounds and foul odor compounds from tap water. As the inclusion complexes moved into the groundwater, the ozone degradation of the inclusion complexes was estimated. The 4-nonylphenol-HP-CD inclusion complexes were easily degraded by ozone. The degree of degradation increased with the increasing ozonization time. Weakly acidic compounds were produced from the 4-nonylphenol-HP-CD inclusion complexes by ozonization. HP-CDs could be used for the removal of 4-nonylphenol from soil. Copyright 2001 Academic Press.     

Ozone interaction with conjugated polymers—II. Polyphenylacetylene

Free-standing films of cis-transoidal polyphenylacetylene, when treated with ozonized air at 1–2% by weight O₃ concentration, undergo a cis-trans isomerization induced by ozone as shown by electronic spectra. Moreover, the presence of the radical cation of polyphenylacetylene can be observed during ozone addition. The cis-trans isomerization is also confirmed by FT-IR spectra of polyphenylacetylene ozonized in solution. Hydroperoxidic groups, as well as peroxidic and aldehydic, are observed by FT-IR spectroscopy on ozonized polyphenylacetylene; in addition, ozonide groups are clearly present. The kinetics of ozonization of cis-transoid and trans-cisoid polyphenylacetylene was followed by electronic spectroscopy. The curves obtained as a function of ozonization time have a characteristic sigmoid shape. Polyphenylacetylene reacts more slowly with ozone than with the isolated double bonds of cis-1,4-polyisoprene, and thus it cannot act as an antiozonant.     

The ozonization of sodium lignosulfonate in the presence of hydrogen peroxide

The kinetics of ozonization of sodium lignosulfate (LS) in the presence of H₂O₂ was studied. The effective rate constants for the oxidation of LS and the total ozone consumption were determined. The k _eff = 30 ± 8 M^?1 s^?1 value was found to be independent of the concentration of H₂O₂. The total ozone consumption decreased as the concentration of H₂O₂ increased from 1.0 × 10^?4 to 1.0 × 10^?3 M because of the participation of the radicals generated in the O₃ + H₂O₂ reaction in LS transformations. The kinetic and UV and IR spectroscopy data allowed the conclusion to be drawn that the destruction of the LS aromatic system in the LS + O₃ + H₂O₂ reaction was caused by the interaction of LS with O₃, whereas radicals generated in this system contributed to deeper destruction of LS in the interaction of aliphatic LS macromolecule fragments with low-molecular-weight polymer oxidation products. The depth of polymer oxidation could be changed by varying the content of hydrogen peroxide in the system for LS ozonization.     

Degradation of lignin by ozone. III. The fate of the carbohydrate matrix during the degradation of spruce protolignin by ozone

Solvent-extracted spruce wood meal was ozonized in 45% aqueous acetic acid at room temperature. The ozone-treated wood meal was then extracted with dilute alkali at 65°C for 1 h. Lignin, α-cellulose, and hemicellulose content and the viscosities of the pulped wood-meal samples were measured as a function of the time of ozonization. Results indicate that although the attack on the wood components by ozone is not selective in this medium cellulose and hemicelluloses are degraded slowly compared with lignin. Lignin degraded approximately four times faster than the carbohydrates. At the fiber liberation point the pulp retained 78% of the original hemicelluloses and about 90% of the α-cellulose compared with 25% of the lignin. The pulp samples obtained during ozonization of the wood meal showed a slow decrease in the average degree of polymerization (DP); the limit reached near 350 was attributed to the inaccessibility of the ordered regions in native cellulose to ozone.     

臭氧化法在高分子生物材料表面改性中的应用

综述了臭氧化法在高分子生物材料表面改性中的应用及研究，介绍了臭氧化法的特点，过氧化物浓度的测定及臭氧化反应和过氧化物引发接枝共聚的反应机理。     

Ozonization at the vacancy defect site of the single-walled carbon nanotube

The ozonization at the vacancy defect site of the single-walled carbon nanotube has been studied by static quantum mechanics and atom-centered density matrix propagation based ab initio molecular dynamics within a two-layered ONIOM approach. Among five different reaction pathways at the vacancy defect, the reaction involving the unsaturated active carbon atom is the most probable pathway, where ozone undergoes fast dissociation at the active carbon atom at 300 K. Complementary to the experiments, our work provides a microscopic understanding of the ozonization at the vacancy defect site of the single-walled carbon nanotube.     

改性活性炭对噻吩的吸附性能研究

用过硫酸铵、臭氧对椰壳活性炭和煤基活性炭进行氧化改性,研究了改性活性炭对噻吩的吸附性能,材料结构袁征结果表明,经两种方法氧化处理后,椰壳炭的孔结构基本保持不变,而煤基炭的比表面积和孔容有所增加.Boehm滴定发现氧化后活性炭表面含氧官能团数量增加并由FT-TR图谱得到证实.氧化处理提高了噻吩在活性炭表面的吸附容量与Langmuir和Freundlich两种吸附等温线方程的相关性.采用拟一级、拟二级和粒子内扩散模型速率方程来考察吸附动力学,并计算了这些动力学模型的速率常数,拟二级模型和实验数据之间有较好的相关性.同时对影响吸附性能的因素进行了分析.     

Hybrid biomaterials prepared by ozone-induced polymerization. I. Ozonation of microporous polypropylene

We employed an ozone-induced grafting process to prepare membrane-hydrogel hybrid biomaterials. Exposure of isotactic polypropylene to ozone resulted in surface oxidation, as detected by ESCA, and the formation of peroxides and hydroperoxides. The amount of oxygen-bearing moieties, as detected by FT–IR, was increased when a microporous membrane with a large surface area was used. Ozonation for an extended period of time, 1–2 h, resulted in a degradation of microporous PP, observed with SEM as an enlargement of pores and brittle characteristics of the material. The molecular weight of PP was dramatically reduced after as little as 5 min of ozonation. Exposure to ozone for longer periods of time contributed to further reductions of the molecular weight and gradual modification of chemical composition of polypropylene, restricted, however, to the surface or intercrystalline amorphous regions. It was possible to graft 2-hydroxyethylmethacrylate (HEMA) to the ozonated samples, such that the graft copolymer acted as continiuous matrix consequently linked to and reinforced by the PP crystals. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1461–1467, 1997     

Synthesis of 2- and 4-Nitropyrimidines and 2-Nitro-sym-triazines by ozonization of hydroxyamino and nitroso derivatives

The action of ozone on aryl(methyl)-substituted 2- and 4-hydroxyamino- or -nitrosopyrimidines in chloroform gave 2- and 4-nitropyrimidines. The unambiguous character of the process depends on the molar ratio of the substrate and ozone; the side formation of azoxy-, chloro-, and hydroxypyrimidines is possible. 2-Nitro-sym-triazines were obtained by ozonization of substituted 2-hydroxyamino-sym-triazines.See [1, 2] for our preliminary communications.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 657–661, May, 1990.