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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Synthesis and characterization of maleimide-based polymers /

Chen, Hua-Chin. January 1991 (has links)
Thesis (M.S.)--Rochester Institute of Technology, 1991. / Typescript. Includes bibliographical references (leaves 124-126).
2

Crystal structures and solid state reactions of maleic anhydride and of a cyclohexenone and its photoproduct

Hwang, Christine January 1988 (has links)
Two sets of structures were determined by X-ray crystallographic techniques, one of maleic anhydride (2,5-furandione) and the other of 4-phenyl-4-p-bromophenylcyclohex-2-en-1-one and its photoproduct, trans-5-phenyl-6-p-bromophenylbicyclo[3.1.0]hexan-2-one. Analysis of maleic anhydride included a room temperature redetermination of the crystal structure. This was done to improve parameters and simplify comparison of the room temperature and low temperature data. The structure determination at 104k resulted in the location of bonding electrons in the double bond. Thermal motions of both sets of data showed that translational motion was greatest along an axis parallel to the carbonyl bonds. Libration was found to be greatest about this axis also. The second set of structures was done to examine the migration pattern of aryl groups upon irradiation of a diarylcyclohexenone. The major photoproduct was formed by migration of the p-bromophenyl group. The resulting bicyclohexanone had the aryl groups trans to each other. / Science, Faculty of / Chemistry, Department of / Graduate
3

Studies in organic photochemistry

Greig, J. B. January 1966 (has links)
No description available.
4

Production And Structure/Properties Of Nylon-6 Core / Isotactic Polypropylene Sheath Bicomponent Fibers Suitable For Use In Carpeting Applications

Godshall, David Leonard 28 May 1999 (has links)
Bicomponent fibers consisting of nylon-6 and isotactic polypropylene were produced. In-situ, reactive compatibilization was achieved using a maleic anhydride functionalized polypropylene between the materials at the interface. The overall goal of the research was to produce a bicomponent fiber of these materials that would be suitable for use in commercial carpet applications. Carpet samples produced using nylon-6 core / polypropylene sheath bicomponent fibers displayed stain resistance comparable to a wholly polypropylene carpet. The wear characteristics of these fibers were found to be strongly dependent upon the maleic anhydride content and the molecular weight of the maleic anhydride functionalized polypropylene. Adhesion between the nylon-6 and polypropylene phases, and the mechanical properties of the polypropylene phase were affected by the addition of the functionalized polypropylene. Additional information regarding the processing conditions necessary to produce fibers of the desired cross-section from these materials was obtained using capillary rheometry. A number of analytical techniques including DSC, TGA, and SEM were used to better understand the structure of the maleated materials. / Master of Science
5

Influence of reprocessing on mechanical and fracture properties of filled and unfilled amorphous polymers

Chrysostomou, Alicia Sophia January 2000 (has links)
No description available.
6

The indole-maleic anhydride reaction and some related additions to heterocycles

Feinberg, Robert S. January 1965 (has links)
No description available.
7

Synthesis and X-ray Diffraction Structure of 8,9-Dichloropyrrolo[1,2-a]perimidin-10-one

Chen, Tao 08 1900 (has links)
Treatment of dichloromaleic anhydride and 1,8-diaminonaphthalene in either benzene or toluene under refluxing conditions gives low yields of the new heterocyclic compound 8,9-dichloropyrrolo[1,2-a]perimidin-10-one. This product has been isolated and characterized in solution by NMR, IR, and UV/vis spectroscopies, and the solid-state structure of 8,9-dichloropyrrolo[1,2-a]perimidin-10-one has been established by X-ray crystallography. The nature of the HOMO and LUMO levels of 8,9-dichloropyrrolo[1,2-a]perimidin-10-one has been studied by extended Hückel molecular orbital calculations.
8

The selective oxidation of n-butane to maleic anhydride.

January 2003 (has links)
Industrial catalysts used in commercial processes for the production of maleic anhydride are mainly Vanadium Phosphorous Oxide (VPO) catalysts. The VPO catalyst used is Vanadyl Pyrophosphate (VO)2P207 made from its precursor Vanadium Phosphorous Hemi-Hydrate VOHP04.O.5H20 in an non-aqueous medium. In order for the VPO catalyst to perform optimally, a metal promoter, Ru, was selected as the doping agent in this study. Four catalysts of different metal doping concentrations (undoped, 0.2%, 0.6% and 1%) were subjected to the oxidation of n-butane. Promoters are added to facilitate the oxidation of n-butane to maleic anhydride. n-Butane gas is now being used in many industrial processes, in fixed bed reactors to convert the gas to maleic anhydride. Catalysts were calcined under high temperatures under a nitrogen atmosphere. It was found that with an increase in reaction temperature, there was an increase in conversion of n-butane to maleic anhydride. Selectivity of the product also showed an increase with an increase in temperature at a Gas Hourly Space Velocity (GHSV) of 1960-2170hr-1. Catalysts were characterized using different techniques such as Electron Dispersive X-Ray Spectroscopy, Inductively Coupled Plasma-Atomic Emission Spectroscopy, Fourier Transform - Infra Red, Average Oxidation State, Brunauer Emmett and Teller (surface area), X-Ray Diffraction and Scanning Electron Microscopy. The 0.6% Ru promoted VPO catalyst showed to be most effective in terms of conversion, selectivity and yield, at a temperature of 450°C as compared to the other catalysts studied. The catalysts degenerated after being subjected to higher temperatures. The selectivity obtained by this catalyst was at 70.2% and the yield obtained was 37%. This study showed that with an increase in Ru up to a certain concentration (0.6%), an increase in selectivity and yield was observed, thereafter, with additional Ru doping, a decrease in selectivity and yield was obtained. / Thesis (M.Sc.)-University of Natal, 2003.
9

A comparative study of VPO catalysts in the oxidation of butane to maleic anhydride.

Govender, Nishlan. January 2002 (has links)
Co promoted and unpromoted vanadium-phosphorous-oxide (VPO) catalysts were synthesized via an organic route. The catalyst precursor was calcined and then conditioned in a reactor, forming the active vanadyl pyrophosphate, (VO)2P2O7, phase. Different promoter loaded catalysts were synthesized and their effect on the yield of maleic anhydride (MA) from n-butane oxidation was examined at different temperatures and gas hourly space velocities (GHSV). The catalysts were tested as a powder. The catalysts were examined in the oxidation of n-butane gas, over air as an oxidant, in a specially designed and constructed continuous flow, fixed-bed catalytic micro-reactor equipped with an on-line gas chromatography (GC) monitoring system. A thermal conductivity detector (TCD) was employed for carbon oxide monitoring and a flame ionization detector (FID) for all other products. The catalysts were characterised by X-ray diffraction (XRD) to determine the phases present in the precursor, calcined and used catalysts. The Brunauer-Emmet-Teller (BET) surface area was calculated for the different promoter loaded catalysts. Fourier transform infrared (FT-IR) spectra, via the KBr pellet method, and attenuated total reflectance (ATR) spectra were recorded to determine the anions present in the bulk and surface of the catalyst respectively. Energy dispersive X-ray (EDX) and inductively couple plasma-atomic emission spectroscopic (ICP-AES) techniques were employed to determine the elemental composition on the surface and in the bulk of the catalyst respectively. Scanning electron microscopic (SEM) images of the catalysts during different stages of their investigation were recorded. The average vanadium oxidation state (AV) in the bulk of the catalyst was determined via a titrimetric method. The catalysts were optimized to a high yield and selectivity of MA. The operating temperature, GHSV and promoter loading on the catalyst were the parameters that were changed during the testing of the catalyst. Different stages of the catalyst's life were characterised via the techniques mentioned above. The catalysts were monitored over a 200-hour period on average, usually taking approximately 24 hours to equilibrate. One such Co promoted catalyst yielded 45 % MA at 275°C and GHSV of 2878 hr-1 on equilibration, with an n-butane conversion of 73 %, whilst all previously reported VPO catalysts produce far lower MA yields at this temperature. / Thesis (M.Sc.)-University of Natal, Durban, 2002.
10

Modelagem matemática do processo de modificação química de polietileno por enxerto de anidrido maleico. / Mathematical modeling of the chemical modification process of polyethylene by grafting of maleic anhydride.

Ambrogi, Paula Maria Nogueira 26 June 2009 (has links)
Este trabalho tem como escopo o desenvolvimento de um modelo matemático representativo do processo de enxerto de anidrido maleico em polietileno, processo conhecido como grafting, com o objetivo de prever as modificações no grau de enxerto e teor de gel. Neste processo utiliza-se um iniciador, geralmente um peróxido, para gerar radicais livres, os quais abstraem hidrogênio das moléculas do polímero, gerando radicais poliméricos. O anidrido maleico pode reagir com estes radicais poliméricos, enxertando-se à cadeia polimérica, ou com os radicais fragmentos do iniciador. O mecanismo inclui também as reações de terminação entre os diferentes tipos de radicais presentes. O teor de gel é calculado a partir do grau de formação de ligações cruzadas utilizando-se a aproximação de Charlesby-Pinner. As constantes cinéticas do modelo foram estimadas via regressão não-linear, usando dados experimentais obtidos na literatura, e o modelo foi validado com outros conjuntos de dados, também obtidos da literatura. O modelo obtido mostrou-se capaz de representar adequadamente os dados experimentais em diferentes condições. / The scope of this work is the development of a mathematical model that can represent the process of grafting of maleic anhydride in polyethylene. The objective of this model is to preview the main modifications in polymer structure, as degree of grafting and degree of gel. In this process, an initiator, generally a peroxide) is used to generate free radicals that can abstract hydrogen from the polymer molecules, producing polymeric radicals. Maleic anhydride can react with these polymeric radicals, resulting in grafted polymer chains, or with the initiator radicals. This mechanism includes termination reactions between the different types of radicals present. Gel content was calculated from the crosslinking degree using the approximation of Charlesby-Pinner. Kinetic constants of the model were estimated through non-linear regression, by fitting the model to experimental data taken from literature. The model obtained was further tested using other data sets obtained from literature. The developed model was able to represent adequately the experimental data under different conditions.

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