The use of stereolithography tools for injection moulding allows plastic parts to be produced in a very short time due to the speed of mould production. The process's greatest advantage is that it can provide a low volume of parts that are produced in the same material and process as parts that would be produced by the conventional hard tooling, but in a fraction of the time and cost. However, this work has demonstrated different rates of polymer shrinkage are developed by parts produced by stereolithography tools and conventional tooling methods. These revelations defy the greatest advantages of the stereolithography injection moulding tooling process—the moulded parts do not replicate parts that would be produced by conventional hard tooling. The aim of this work is to acquire an understanding of the mechanisms in stereolithography tooling that induce these different part properties and develop a modification of the process that could change these, which would allow the moulded parts to demonstrate characteristics like those produced by conventional means.

The work disseminated within this Thesis pertain to an industrially funded study whose primary aims were to enhance the understanding of the effect of a range of process variables on the underlying microstructure of a rinse-off Hair Conditioner. The study utilised a range of analytical techniques namely; rheology, microscopy, SAXS and thermal transition. Findings herein have demonstrated that through process optimisation, more resource efficient processes are achievable which offer the possibility to significantly reduce raw materials use whilst maintaining a desired viscosity. In some cases a significant raw material reduction of 40 % could be realised (calculated on the amount of FA, CS & QUAT in the formulation) if the following steps are applied; i. Initial formation of the FA, CS & QUAT lamellar system such that the morphological makeup is predominantly a QUAT/CS rich Lβ microstructure - this is primarily a function of process temperature whilst ensuring fine state of dispersion of this product intermediate. ii. Followed by a dispersive and distributive mixing step to reduce QUATS rich Lβ microstructure domain size via a low temperature, high shear post processing operation – a function of increasing deformation rates within mixing equipment. In addition to this, the Controlled Deformation Dynamic Mixing technology was found to be an efficient device at delivering the required deformation rates to the hair conditioner product, compared to the other mixing technologies tested. Deformation rates have been characterised with respect to [1] extensional (a function of process flow-rate), [2] rotational shear rates (a function of mixer rotational speed) and more importantly [3] Mixer design (a function of equipment geometry). The trio determines the deformation rates available to process fluids during an operation, and likewise vital to any scale-up operation for geometrically similar CDDM devices. The main commercial outputs for this work therefore can be estimated using Euromonitor figures, which state that the total UK market for hair conditioner alone is £324.4 million per annum. Thus if we assume even a fraction of the raw material costs can be realised in the supply chain, saving of several million per annum are conceivable.

This project uses experimental techniques to explore the effects of surface active agent (surfactant) adsorption on a droplet of oil suspended in a flow. The fluorescent surfactant Rhodamine-6G was used to enable the use of optical techniques to visualise the build-up of surfactant at the rear of the droplet and its effects on the internal circulation within the droplet. This was done to enable an exploration of how surfactant accumulates behind a droplet with the aim of predicting the behaviour based on the internal circulation for non- fluorescentt surfactants. An experiment was designed along with calibration procedures in order to utilise the non-intrusive measurement techniques laser-induced fluorescence and particle image velocimetry to measure the volume of surfactant held behind the droplet, the angle of the visible cap caused by the build-up of Rhodamine-6G, and the cap angle of the stagnant region obtained by measuring the velocity of the circulation within the droplet. Laser-induced fluorescence (LIF) was used to visualise the development of a surfactant-rich cap that formed at the rear of the oil droplet as it rose through an aqueous solution, with different bulk concentrations of surfactant. The aqueous solution soluble surfactant, adsorbed to the forwards facing part of the droplet, was transported around to the rear where it accumulated in a surfactant cap before being swept back into the ow behind the droplet. The fluorescent properties of Rhodamine-6G were utilised to measure the size of the visible surfactant cap angle and the volume of surfactant stored within the cap. The results showed that increased concentrations of surfactant caused a larger volume of surfactant to be held behind the droplet with larger droplets resulting in smaller surfactant cap angles. Particle image velocimetry (PIV) was used to explore the effects of surfactant at the interface on the internal circulation within the droplet. As surfactant accumulated an area of very low velocity at the rear of the droplet appeared. This was quantified by measuring the tangential velocity around the droplet with the area of low velocity signifying the presence of a stagnant cap. Measuring the internal velocity around the droplet close to the interface showed that the stagnant cap angle had large growth over the initial region of the tank, with larger droplets resulting in smaller surfactant cap angles. The visible cap angle measured by LIF was related to the stagnant cap angle measured by PIV to compare how the results for each technique developed over the height of the tank. The angles for both techniques exhibited the same trends as the droplet height increased, although they showed different magnitudes revealing that the experimental procedure could be improved in the future to obtain better agreement.

No description available.

by Stephen D. Lewis. / Bibliography: leaf [26]. / NSF Grant #GS41519.

Surface active agents have been successfully employed in numerous industrial, agricultural and biomedical applications for decades. Trisiloxane surfactants in particular have proved to be exceptionally effective as wetting enhancers; hence the name ‘superspreaders’. Since the early ‘90s these extraordinary surfactants have become an irreplaceable component in various products and processes. However, the true nature of their specific wetting behaviour has not been fully revealed and their underlying wetting mechanisms are still poorly understood despite substantial scientific interest during the last decades. In this thesis is an attempt to shed light on specific wetting and spreading behaviour of trisiloxane solutions. Commercial superspreader products were tested in various environments in order to get further insight into their performance in specific practical applications. Experimental investigation of wetting of superspreader solutions on surfaces of different hydrophobicity and comparison to that of a conventional surfactant revealed superiority of trisiloxanes. Exceptional interfacial activity was explained in terms of the specific chemical structure and ‘T’-shape of the molecule. However, sensitivity of the trisiloxane head to low pH and long-time ageing in aqueous environment was revealed. Performance of binary mixtures of commercial superspreaders and conventional surfactant was also assessed. Behaviour of trisiloxanes in the capillary action was studied. Finally, a comprehensive mathematical model for trisiloxane wetting, which incorporates diffusion as the governing factor of the wetting process, was developed.

No description available.

The project contributes to the general theme of complex chemical systems and strengthens ties with Innospec, a multi-national chemical company. Sodium lauroyl methyl isethionate (SLMI. Trade name “Iselux”) is a newly developed surfactant with attractive product properties for personal care applications. Little is known about the fundamental surface and solution properties of SLMI, and it is not currently possible to use information on available surfactants to predict phase behaviour. We characterise the solution and liquid crystalline phase behaviour of the SLMI/water system using a combination of optical microscopy, X-ray scattering and differential scanning calorimetry techniques. SLMI is synthesised using a batch process that leads to variable component concentrations. Preliminary studies conducted by Innospec indicate that the presence of particular process components has a significant influence on SLMI formulation rheological properties. We investigate the effects of synthesis-derived components on the rheological properties of the SLMI/sodium {(3-(dodecanoylamino)propyl)(dimethyl)ammonio)}acetate/water system using rheology and light scattering (static and dynamic) techniques. SLMI is often formulated into personal care products on mixing aqueous formulation components. Micelle growth occurs via a mechanistic process that is not understood and the equilibrium viscosity is attained at a time after mixing that ranges from seconds to weeks. Developing an improved understanding of the micelle growth mechanism is of both academic and industrial value. We utilise static light scattering and nuclear magnetic resonance techniques to probe a range of samples in the viscoelastic region of the SLMI/(carboxymethyl)hexadecyldimethyl ammonium hydroxide/water system. Experimental findings improve our current understanding of micelle growth process and provide a platform for future research on non-equilibrium mixing kinetics. In the final section we investigate salt-induced cloud point and precipitation phenomena in the SLMI/salt/water system. The cloud point is commonly observed in surfactant and protein systems by increasing the solution temperature above a critical value, resulting in phase separation of solute-rich and solute-depleted layers. Cloud point induced phase separation may also be prompted by addition of salt. The mechanistic process driving electrolyte-induced cloud point phenomena is not understood. We use a combination of turbidimetry measurements and lightscattering (static and dynamic) techniques to measure cloud point curves andcharacterise micellar behaviour prior to clouding.

Consumer- and pharmaceutical-based products are a major component of the chemical industry. In the personal care industry, formulations often consist of a mixture of surfactants and fatty alcohols. The addition of surfactants aids the stability of the formulation. The formulated product microstructure depends upon the preparation conditions as well as the ingredients. Controlling which microstructures form during the production of a formulated product is important as different microstructures can have wildly different physical properties, making some far more favourable than others. This thesis examines several of the processes undertaken in the manufacture of formulated products. The dissolution of a surfactant in a bulk water phase is examined. This is examined in a number of ways; firstly, the dissolution times of the surfactants are measured using electrical resistance tomography. It is found that the dissolution time varies with the agitation rate, agitator size, and addition method. The dissolution is also examined using dissipative particle dynamics to gain insight into the dissolution on a molecular scale. It is found that the surfactant breaks into wormlike micelles on dissolution. If an oil is added to the initial bulk then the dissolution process is modified so that long cylinders are produced with some spherical micelles. Finally, the break-up rate is predicted using a breakage model based on the agitator shear rate and a network-of-zones model. This produces good results. The production and post-shear processing of a sample formulated product, hair conditioner, is examined. Firstly, the mixing in a vessel is examined with electrical resistance tomography. Problems are encountered when the production method involves the use of distilled water as the conductivity is very low; however, the mixing time of the final product in the vessel can be determined. It is also shown that the majority of the structural changes in the post-shearing process are caused by the in-line rotor-stator mixer. The viscosity of the product increases in a linear fashion with the shear rate, while the conductivity increases as a function of the shear rate and the recycle rate. This allows the monitoring of the post-shearing process to be carried out using electrical resistance tomography. This thesis also looks at the possibility of producing a multiple frequency electrical resistance tomography device to monitor formulated product production; however, it has been shown that the conductivity does not vary with the voltage frequency over a usable range. This meant that no further effort was put into developing this, as it gave no advantage over the traditional single frequency technique. Nevertheless, important advances towards better understanding of mixing processes resulted due to the investigations carried out.

Hyperbranched polymers (HBP) have drawn much attention and obtained intensive research activities from both industry and academia in the last three decades. They belong to a group of macromolecules called dendritic polymers, which have peculiar and often unique properties, which derive from their three-dimensional structure and the large number of functional groups. These structural characteristics provide high possibilities for controlling functional group interactions and modifications of other polymers in coatings and therefore, they are expected to result in novel materials with desired properties. They own a highly branched backbone, which gives access to many of reactive groups; their structure gives them excellent flow and processing properties, and they are characterized by lower viscosity than those of linear polymers of comparable molecular weight. Such properties make HBP extremely interesting for coatings and UV-curing applications and for this, they have attracted a great deal of attention for application, e.g. for powder coatings, high solid coatings, flame retardant coatings, barrier coatings for flexible packaging,and they have been recently suggested as a component of a dual-cure formulation based on an UV-curable epoxy resin and a functionalized alkoxysilane additive as an inorganic precursor to achieve advanced functional hybrid coatings. By pursuing this research line, we have synthesized an aliphatic–aromatic ethoxysilyl modified hyperbranched polyester system to be used in the preparation of UV-curable epoxy hybrid organic–inorganic coatings. The addition of ethoxysilyl-modified HBP could act as a coupling agent during the formation of the inorganic domains generated in-situ via sol-gel process starting from the alkoxysilane as inorganic precursors. The cured films were characterized in terms of their dynamic-mechanical properties and surface hardness: the obtained properties were discussed in relation to the achieved morphologies. In the present work, some aromatic hyperbranched polyesters (aHBP) and aliphatic-aromatic hyperbranched polyesters (aaHBP), OH terminated have been used as matrices for nanocomposites containing TiO2. The TiO2 nanoparticles were synthesized via sol-gel directly in a solution containing the HBP polyester as a stabilizer, and then the polymer/TiO2 hybrid mixtures were thermally cured by a curing agent to obtain a hard coating or a film. In order to determine the conditions in which it was possible to get the best dispersion and the properties for the final material, the starting HBP-OH was also partially modified with alkoxysilane groups by 3-isocyanatopropyltriethoxysilane (IPTES), yielding modified aliphatic-aromatic hyperbranched polyesters aaHBP(OH)-Si and modified aromatic hyperbranched polyesters aHBP(OH)-Si, enabling it to interact with the TiO2 network. Both materials obtained were then characterized, and their properties compared.