An Investigation of the destruction of ion exchange resins

Ion exchange resins are used for many purposes in various areas of science and commerce. One example is the use of cation exchange resins in the nuclear industry for the clean up of radioactively contaminated water (for example the removal of 137Cs). However, during removal of radionuclides, the resin itself becomes radioactively contaminated, and must be treated as Intermediate Level Waste. This radioactive contamination of the resin creates a disposal problem. Conventionally, there are two main avenues of disposal for industrial wastes, landfill burial or incineration. However, these are regarded as inappropriate for the disposal of the cation exchange resin involved in this project. Thus, a method involving the use of Fenton's Reagent (Hydrogen Peroxide/soluble Iron catalyst) to destroy the resin by wet oxidation has been developed. This process converts 95% of the solid resin to gaseous CO2, thus greatly reducing the volume of radioactive waste that has to be disposed of. However, hydrogen peroxide is an expensive reagent, and is a major component of the cost of any potential plant for the destruction of ion exchange resin. The aim of my project has been to discover a way of improving the efficiency of the destruction of the resin thus reducing the cost involved in the use of hydrogen peroxide. The work on this problem has been concentrated in two main areas:-1) Use of analytical techniques such as NMR and IR to follow the process of the hydrogen peroxide destruction of both resin beads and model systems such as water soluble calixarenes. 2) Use of various physical and chemical techniques in an attempt to improve the overall efficiency of hydrogen peroxide utilization. Examples of these techniques include UV irradiation, both with and without a photocatalyst, oxygen carrying molecules and various stirring regimes.

The study and characterisation of water-based latices used for can coating interiors

Water-based latices, used in the production of internal liners for beer/beverage cans, were investigated using a number of analytical techniques. The epoxy-graft-acrylic polymers, used to prepare the latices, and films, produced from those latices, were also examined. It was confirmed that acrylic polymer preferentially grafts onto higher molecular weight portions of the epoxy polymer. The amount of epoxy remaining ungrafted was determined to be 80%. This figure is higher than was previously thought. Molecular weight distribution studies were carried out on the epoxy and epoxy-g-acrylic resins. A quantitative method for determining copolymer composition using GPC was evaluated. The GPC method was also used to determine polymer composition as a function of molecular weight. IR spectroscopy was used to determine the total level of acrylic modification of the polymers and NMR was used to determine the level of grafting. Particle size determinations were carried out using transmission electron microscopy and dynamic light scattering. Levels of stabilising amine greatly affected the viscosity of the latex, particle size and amount of soluble polymer but the core particle size, as determined using TEM, was unaffected. NMR spectra of the latices produced spectra only from solvents and amine modifiers. Using solid-state CP/MAS/freezing techniques spectra from the epoxy component could be observed. FT-IR spectra of the latices were obtained after special subtraction of water. The only difference between the spectra of the latices and those of the dry film were due to the presence of the solvents in the former. A distinctive morphology in the films produced from the latices was observed. This suggested that the micelle structure of the latex survives the film forming process. If insufficient acrylic is present, large epoxy domains are produced which gives rise to poor film characteristics. Casting the polymers from organic solutions failed to produce similar morphology.

The chemical structure and mechanical properties of phenolic resins and related polymers

Paper-based phenolic laminates are used extensively in the electrical industry. Many small components are fabricated from these materials by the process known as punching. Recently an investigation was carried out to study the effect of processing variables on the punching properties. It was concluded that further work would be justified and that this should include a critical examination of the resin properties in a more controlled and systematic manner. In this investigation an attempt has been made to assess certain features of the resin structure in terms of thermomechanical properties. The number of crosslinks in the system was controlled using resins based on phenol and para-cresol formulations. Intramolecular hydrogen bonding effects were examined using substituted resins and a synthetically derived phenol based on 1,3-di-(o-hydroxyphenyl) propane.. A resin system was developed using the Friedel Crafts reaction to examine inter-molecular hydrogen bonding at the resin-paper interface. The punching properties of certain selected resins were assessed on a qualitative basis. In addition flexural and dynamic mechanical properties were determined in a general study of the structure-property relationships of these materials. It has been shown that certain features of the resin structure significantly influenced mechanical properties. :F'urther, it was noted that there is a close relationship between punching properties, mechanical damping and flexural strain. This work includes a critical examination of the curing mechanism and views are postulated in an attempt to extend knowledge in this area of the work. Finally, it is argued that future work should be based on a synthetic approach and that dynamic mechanical testing would provide a powerful tool In developing a deeper understanding of the resin fine structure.

Production of renewable phenolic resins by thermochemical conversion of biomass: a review

This review covers the production and utilisation of liquids from the thermal processing of biomass and related materials to substitute for synthetic phenol and formaldehyde in phenol formaldehyde resins. These resins are primarily employed in the manufacture of wood panels such as plywood, MDF, particle-board and OSB. The most important thermal conversion methods for this purpose are fast pyrolysis and vacuum pyrolysis, pressure liquefaction and phenolysis. Many feedstocks have been tested for their suitability as sources of phenolics including hard and softwoods, bark and residual lignins. Resins have been prepared utilising either the whole liquid product, or a phenolics enriched fraction obtained after fractional condensation or further processing, such as solvent extraction. None of the phenolics production and fractionation techniques covered in this review are believed to allow substitution of 100% of the phenol content of the resin without impacting its effectiveness compared to commercial formulations based on petroleum derived phenol. This survey shows that considerable progress has been made towards reaching the goal of a price competitive renewable resin, but that further research is required to meet the twin challenges of low renewable resin cost and satisfactory quality requirements. Particular areas of concern are wood panel press times, variability of renewable resin properties, odour, lack of reactive sites compared to phenol and potential for increased emissions of volatile organic compounds.

Control parameters in the batchwise production of synthetic resins

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Application of computer control to the production of synthetic resins

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Optimisation of commercial production processes for polyester resins

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Commercial batchwise production of polyester resins.

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