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The polymer model is incorporated into a simulation for the entire material system which is based on a beam idealisation and in which a strong discontinuity approach is used to simulate cracking. It is shown that this model is able to accurately simulate the experiments carried out on the LatConX system.

This thesis focuses on the thermal recycling of plastic film materials that have originated from waste sources. The problems with waste plastic film recycling are outlined. The key aspects of this work included waste management, economics, logistics, the recycling industry, aspects of polymer science and the effect of the consumer environment on material properties of polymers. The aim of the research was to determine how these problems can be best understood and solved in order to prove that plastic film recycling is a sound opportunity from a financial and engineering point of view. A series of novel experimental studies were designed and performed to evaluate the effect that a film's life-cycle has on the material properties of the product. These studies involved exposing a number of polyethylene samples to factors such as heat cycling and dust contamination whilst measuring the characteristics of the material before and after exposure. Material tests included evaluation of mechanical and rheological properties, crystallinity content and molecular weight. As a natural continuation of the behaviour and characteristic studies already highlighted, two novel products namely a geomembrane and aggregate drainage material were manufactured. Tests were undertaken to determine the suitability of these under harsh environmental conditions. It was found that both materials were capable of meeting specifications laid down for application as engineering barriers. With the effects of a products' life-cycle understood, the investigation then involved the development of a predictive model. This anticipated the effects of these life-cycle factors and calculated the resultant physical properties of a plastic film material once it had been thermally recycled. This model used correlations between the key factor and the crystallinity of the polymer in order to determine the degradative effects. Results showed that key material properties could be modelled to within 15% accuracy of those found by experimental verification. To assess the feasibility of recycling plastic film an economic model was produced to simulate the financial performance of a recycling plant. Model inputs were based on industrial experiences and were used in conjunction with a series of operating parameters to outline economic feasibility. The simulation showed that profitability was closely related to the quality of the input material, the cost of procuring waste feedstocks and the price paid for the final product. Overall the thesis showed that plastic film recycling is a viable concept, provided recyclers sufficiently improve the quality of feedstocks by separation and washing, procure a reliable source of feedstock and operate a facility that is adaptable to changes in material condition. These factors must be undertaken with sound financial management to ensure that a profitable product is produced. Although there is a small number of possible recycled products to be produced from plastic film, more development is needed to create a demand for waste feedstock materials. This will ensure that mandatory recycling targets are met for government and businesses that are required by European legislation. This investigation has outlined many of the key factors to allow film recycling businesses to expand into future markets and produce recycled products of equal quality to that of existing products made from virgin stocks.

The research described in this thesis is largely focused on monomers derived from the triptycene moiety, and their potential to form polymers of intrinsic microporosity (PIMs), organic molecules of intrinsic microporosity (OMIMs) and dendrimers of intrinsic microporosity (DIMs). Triptycene is of particular interest here due to its high internal molecular free volume (IMFV) and previously reported success in the formation of microporous materials - triptycene is in fact the basis of the most microporous PIM reported to date, and the basis of the only reported example of an amorphous molecular microporous material. The work later extends to incorporate other presumed high IMFV moieties based on spirobifluorene and propellane. The research begins by focusing on the synthesis of potentially soluble polymers. They are of interest due to their processability, which when coupled with microporosity, can potentially yield permeable membranes suitable for selective gas separation. There has been much research into PIMs and their corresponding membranes, with particular interest surrounding PIM-1, a polymer formed between a spirobisindane based monomer, and 2,3,5,6-tetrafluoroterephthalonitrile.1 The same nucleophilic aromatic substitution reaction (SNAr) as is used to make PIM-1 is employed throughout this thesis for the formation of final products. The second section of this project focused on the synthesis of network polymers based around triptycene, introducing bitriptycenes, triptycene side groups, and unsymmetrical triptycenes with new functional groups, the main focus on increased surface area. Although highly microporous materials were prepared, no enhancement over previously obtained triptycene polymers was obtained. The third section of the thesis focuses on the synthesis of novel microporous materials termed Organic Molecules of Intrinsic Microporosity (OMIMs) and Dendrimers of Intrinsic Microporosity (DIMs). These are discrete molecules lacking any long range order that cannot pack space efficiently due to their rigid structures, composed of monomer subunits with high IMFV. All materials were analysed for their apparent BET surface areas (N₂ adsorption at 77 K), which were in the range 0-700 m2 g"1.

For the first time pervaporation separation of miscible liquids have been investigated with three and five layered composite membranes with layers of Natural Rubber Latex (NRL) and layers of hydrophilic, hydrophobic or organophilic polymers which are placed on top of each other. NRL was used in all different types of the membranes, mixed with hydrophilic polymers in blend membranes and in a layer shape in the three or five layered composite membranes. Methyl Cellulose (MC), Carboxymethyl Cellulose (CMC) and Hydroxypropyl Methyl Cellulose (HMC) were used as hydrophilic polymers to increase the water selectivity of the membrane and in contrast, Ultra-High Molecular Weight Polyethylene (UHMWPE) and Polydimethylsilane were used to increase organic component selectivity in the membranes. These membranes were used to separate miscible liquid solutions including ethanolwater, propanol 2-water and acetone-waterT. he composition of organic componenti n the feed was varied within the range of 20 to 90% w/w. The temperature of operation was kept constant to 20'C. Scanning Electron Microscope (SEM) has been used to study the distribution of polymers within the membranes. Morphological features of the cross section and top surface of the membranes have been used to develop a probable mechanism of water or organic component transfer through the membrane. For the first time ever, DMTA technique has been used to identify the type of membranes which can be used to increase the water selectivity (by studying the changes in the glass transition temperatureo f the NRL, blend and compositem embranes). Both SEM and DMTA techniques have proved that the presence of hydrophilic polymers as in layer forms in the three or five layered composite membranes was the reason for good distribution of polymers throughout the membrane. It has been established that a very strong correlation exists between a good distribution of the polymer bridged clusters of rubber particles within the membrane and the maximum increase in water selectivity. The influence of using different types of alcohols (ethanol, propanol 2 and acetone) on the pervaporation separation performance of the membranes has been thoroughly examined. Using ethanol, having the lowest molecular weight as compared with the other solutions, leads to the best performance in pervaporation separation.

Polymer clay nanocomposites (PCN) of poly(methyl methacrylate) (PMMA) and clay, were synthesised in-situ using a free radical suspension polymerisation technique. The weight fraction of clay in the PCN was systematically varied in order to understand the effect of clay on the physical properties of the resulting PCNs. However, unexpectedly it was found that the weight fraction of clay had a dramatic impact upon the molecular weight of the polymer matrix and a relationship between clay concentration and polymer molecular weight was established. Furthermore, it was also found that the change in molecular weight was dependent upon the clay type. Three different clay types were investigated; an organically modified montmorillonite (Cloisite 15a), a synthetic clay (Laponite RD) and a PEO modified Laponite RD. To produce the modified Laponite RD, mono amino PEO was synthesised via anionic polymerisation using dimethyl ethanol amine as an initiator. The modification of the Laponite RD clay took place in the reaction flask prior to the suspension polymerisation of the PCN. The PCN were characterised using size exclusion chromatography (SEC), X-ray diffraction (XRD), transmission electron microscopy (TEM) and oscillatory shear rheology. Morphological studies of the PCN showed that the extent of clay dispersion depended on the clay type. Within the PMMA/Laponite RD nanocomposites an unusual network structure was formed, which appeared to be continuous throughout the material. Thermal properties of the PCN were investigated using DSC, TGA and Microcalorimetry. From oscillatory shear rheology, the full master curves for the PCN were obtained by applying the time-temperature superposition (TTS) principle. To quantify the effect of the clay upon the rheology, the experimental data was compared to the time dependent diffusion model of Des Cloizeaux for polydisperse polymer melts, which enables polydispersity to be incorporated through the use of the molecular weight distribution obtained via SEC.

The aim of this work was to determine some of the effects caused by the application of a high electric field on a filler-free epoxy resin material. Two types of sample geometry were moulded. Films (55 to 300μm) were prepared to work under uniform field configurations. A frame of parallel wires (5 to 25μm radius) was introduced into the bulk to work under divergent fields. Three non-destructive complementary methods of investigation were used. In all cases the first measurements were performed before the application of thermal-electric stress to define the properties of the material itself. Measurements were repeated after a controlled period of stress. Dielectric spectroscopy measurements were used to determine the main relaxation processes. To evaluate the impact of charge injection and localise the build up of space charge, the pulsed-electro acoustic method was chosen. Luminescence experiments were carried out to investigate the luminescence excitation parameters and pathway of radiative relaxation that are found to be directly linked with the charge injection and extraction phenomena. In addition spectral analysis was performed to complete the investigation. Light emission is associated with relaxations dependent on the chromophores that are present and that are likely to be affected by an external stress. After thermal-electric stress one relaxation processes was detected by dielectric spectroscopy that was dependent on the stress. This was associated with a change in the local arrangement of the chemical network, which is altered by the field. A mechanism of trapping and de-trapping of charge was determined by the analysis of the PEA response, light emission analysis coupled with external current. The studies were completed by a computer simulation of the effect of injected charge on the electric field. The three techniques were found to be useful complementary tools to determine the effects of stress on this insulation material.

Layered manufacturing (LM) technologies are a class of additive manufacturing processes which create three dimensional geometries directly from CAD data sequentially layer by layer. This group of technologies can process a variety of metallic, polymer and ceramic materials, as liquids, powders, or solid sheets or filaments. The material can be processed using a laser, such as melting a powder or curing a polymer resin or consolidated using a binder deposited from a print head. The build methodology used in all LM is fundamentally a start-stop process since the deposition of material and processing of each layer occurs ~equentially. Hence, the build rate can be slow (2 - 6 Layers per minute); consequently, LM technologies have largely found application as prototyping tools to speed up product development. In order for these technologies to be adopted as rapid manufacturing (RM) methods to directly manufacture complex components which cannot be manufactured by other means these speed limitations need to be addressed. This Thesis describes a new high speed RM process, Spiral Growth Manufacturing (SGM), whereby 3D parts are built by simultaneously depositing, levelling and selectively consolidating thin powder layers onto a rotating build platform. This build configuration has several advantages when compared to conventional layered manufacturing systems: firstly, the process is continuous with no layer preparation overheads; secondly, the material deposition and solidification process can be performed simultaneously by the addition of further 'build stations' radially distributed about the circumference of the machine. The work presented in this thesis focused on the design, development and testing ofthe Spiral Growth Manufacturing process. Two machines were developed; one used a bank of stationary inkjet heads to print material, either as a binder into a powder layer or as hard material from mixing two printed ink solutions and the other machine used a 90 W, flash lamp pumped Nd:YAG laser to process metal powders by localised melting. The main objective ofthe testing phase was to produce simple 3D objects from solidified layers by: a) ink jet printing a binding agent into the deposited plaster powder layers; and b) ink jet printing reactive materials to form plaster directly. The second machine was developed to exploit the considerable knowledge of Selective Laser Melting (SLM) at Liverpool, with the modification of a research SLM machine to SGM operation.