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During this master thesis project, various polymer materials have been studied in relation to additive manufacturing. Additive manufacturing is a 3D printing process that has facilitated the productivity of the company, Volvo Cars. The printing process is based on a design conceived from CAD software. The final design is sent in digital form to the printer from which the prototype is built, layer by layer, until the finished product is finished. This thesis project analyzed which polymers would work the best in Volvo’s car industry as to durability and sustainability. A limited number of polymers were chosen for investigation, some also with various additives to change the microstructure and properties. The tensile strength of the polymers was tested, yielding their Young´s modulus. Tests were also performed to measure the wear resistance of the samples. The design of the samples was decided to be a circular disk. The reason behind was that the samples should not be too thin or have a too complicated shape, the inner structure being solid. The primary data were the possible changes in thickness. These samples were afterwards examined under a stereo microscope in order to obtain a 2D image of how the surface had changed. From all the polymers investigated, the tensile tests showed that PA12 CF(polyamide 12 carbon fiber) had the best strength as it contains carbon fibres which stabilizes the material. However, as for wear resistance the polymers PC (polycarbonate) and TPU( thermoplastic polyurethane) could handle more punches before they fractured. PC has the advantages of being very strong, due to very strong bonds between the atoms within the polymers chains, and at the same time constituting a very flexible material. TPU is also a very strong and flexible material, and it has the extra advantage of being suitable for large components. Considering these aspects, these three materials are selected as efficient and suitable for making mechanical components. As a result from this very investigation, they are recommended for making prototypes or components that have good strength and wear resistance.

This dissertation reports a simple route to synthesis nanostructured composites by immobilizing colloidal crystals (CCs) of monodisperse SiO2 spheres in crosslinked polymer network. The resulting ordered nanocomposites exhibited the highest modulus reported yet, to the best of our knowledge, for similar materials. The ordered nanocomposites were optically active and the Bragg diffracted light in a NIR region and wavelength of the Bragg peak could be tuned simply by changing the silica concentration in the composite. They also exhibited intense angle dependent iridescence. / Chemistry

A number of nitroxide adducts and N-acyloxytrialkylammonium salts were prepared, isolated, characterized and evaluated as initiators for the controlled and living free radical polymerization of methacrylate and dimethacrylate monomers under mildly thermal and photochemical conditions. The initiators and polymerization methods that were developed could potentially be used for improving resins employed in dental applications. Using very easy synthesis strategies, the following nitroxide initiators were prepared in high purity, isolated and characterized: 1-Benzoylperoxy-2,2,6,6-tetramethyl-piperidine (BPO/TEMPO), 1-(2'-Cyano-2'-propoxy)-2,2,6,6-tetramethylpiperidine (AIBN/TEMPO), 1,1-ditertbutyl-1-(1-methyl-1-cyanoethoxy)-amine (AIBN/DBN), 1,1-ditertbutyl-1-(benzoylperoxy)-amine (BPO/DBN) and 2,2,6,6,-tetramethyl-4-oxo-1-(1-methyl-1-cyanoethoxy)-piperidine (AIBN/4-OXO-TEMPO). Using H2SO4 additive and an improved unimolecular initiation in nitroxide mediated polymerization, living and controlled polymerization of methyl methacrylate (MMA), tri-ethylene glycol dimethacrylate (TEGDMA) and ethoxylated bisphenol A dimethacrylate (EBPADMA) were accomplished, for the first time ever for most of the initiators. Linear polymers (PMMA) were produced in high yield (93 %) under mildly thermal conditions (T = 70 oC) and with excellent attributes: (PDI = 1.04-1.26), Mn (87000), Tg (122-128 oC), Td (290-410 oC). Highly crosslinked polymers, poly(TEGDMA) and poly(EBPADMA), were produced in high yield (100 %) with Td (350-400 oC). The initiators were stable for a year and half at 0 oC. Two routes were investigated for the preparation of N-acyloxytrialkylammonium salts. The more efficient of these routes was used to make several novel analogs of the salts. The salts were evaluated for the free radical polymerization of MMA, TEGDMA and EBPADMA under mildly thermal (T = 60 oC) conditions with and without H2SO4 additive. Polymerization rate, yield and polymer attributes all improved upon application of H2SO4 additive. PMMA was produced with excellent attributes (PDI = 1.01-1.06), Mn (96,000-122000), Td (330-385) and Tg (127-134). Highly crosslinked poly(TEGDMA) and poly(EBPADMA) were produced with Td ranges of 300-374 oC and 375-411 oC respectively. / Chemistry

The use of polymeric materials in the manufacturing industry has vastly increased since the 1950’s. Because of the large amounts of material involved in modern processing operations, attempts have been made over the years to numerically simulate the processes, in the hope of optimizing operating parameters. However, in contrast to other, more traditional materials such as steel or glass, there is not a well understood connection between the microscopic structure and the (highly non-linear) macroscopic physical response of polymers. Because of this lack of microscopic cause - macroscopic effect knowledge, many descriptions of the physical response of polymers are largely phenomenological ones; that is, the equations used to model the stress/strain response make no attempt to convey information about the microscopic structure of the material. In the present work, five constitutive equations - Mooney-Rivlin, Ogden, G’Sell Two-term Polynomial and K-BKZ - are used to model the stress/strain response of two different polymers commonly used in thermoforming and blowmolding operations, ABS and HDPE, to uniaxial elongation and equibiaxial extension. The models are compared to experimental stress/strain data obtained from an industrial source, and the applicability of their predictions are investigated with regards to variations in strain, strain rate and temperature. Lastly, since the vast majority of real processes involve biaxial, not uniaxial, deformations, the ability of the models to predict equibiaxial response using parameters fit solely to uniaxial data is considered, in order to investigate the possibility of being able to forego the need for expensive, difficult biaxial tests. / Thesis / Master of Engineering (ME)

This dissertation focuses on the use of novel polyethers and polydimethylsiloxanes in the stabilization of magnetite nanoparticles as well as biomedical applications. The colloidal stabilities of magnetite nanoparticles coated with polyethers containing various functional endgroups were studied. Different variables (e.g. polymer loading, polyether molecular weight and type of functional anchor group) were investigated to determine their effect on the long-term physiological stability of the polyether magnetite complexes. One-part PDMS-magnetite nanoparticle fluids were synthesized using a high shear process and magnetic separation techniques. These one-part fluids are unique in the fact that they do not require the addition of a non-functional PDMS oligomer solvent to generate a magnetic hydrophobic fluid. A series of PDMS-magnetite nanoparticle fluids containing different molecular weight stabilizers were synthesized. A magnetic separation study was performed to determine if PDMS molecular weight influences the magnetic separation profiles of the fluids. Well-defined PDMS-b-PtBA and PDMS-b-poly(acrylic acid) copolymers were synthesized using living free radical techniques from novel PDMS precursors as well as PDMS-based ionenes with different hard segment groups. / Ph. D.