Due to the frequent use of plastics in daily life, encountering microplastics as pollution and trace evidence in forensic investigations is a common occurrence. Nylons are a plastic class known to be strong and durable, and they are used in a variety of products. Nylon is also a popular choice among 3D printing materials, and its strength and durability lend themselves to printing tools like keys and firearms. The analysis of microplastics is typically performed using any combination of microscopy, infrared spectroscopy, Raman spectroscopy, and mass spectrometry. Nylons are known to have fluorescent impurities created during the polymer’s synthesis and processing, so this work set out to develop a method to analyze nylon microplastics non-destructively using room-temperature fluorescence spectroscopy. By analyzing impurities in the sample, fluorescence spectroscopy can provide additional information about the microplastic’s source that other non-destructive methods do not. Excitation-emission matrices, excitation and emission spectra, and synchronous fluorescence spectra were collected from pellets of four different nylons. Using these spectra, all nylons could be distinguished from one another. A trace evidence simulation was then performed with fragmented pellets and a 3D printed key, and the trace microplastics were shown to have spectra that were consistent with those of the bulk plastic. This method was then improved by applying chemometric algorithms to the fluorescence data. Fluorescence spectra, excitation spectra, and excitation-emission matrices collected from Nylon 6 and Nylon 6/12 were found to be indistinguishable by visual comparison. Using synchronous fluorescence spectra from the two nylons in conjunction with Principal Component Analysis and Common Dimension – Partial Least Squares – Discriminant Analysis, the two nylons could be fully discriminated. Overall, this work presents a powerful new method to non-destructively analyze nylon microplastics and generate more reliable conclusions about the source of the microplastic than current methods alone.

Members of the elderly population is disproportionately prone to experiencing mobility impairment due to their aging bodies and as a result have frail bodies that are at a higher risk of grave injury due to falling. In order to combat this assistive mobility devices such as exoskeletons have been developed to help patients enhance their range of motion. With additive manufacturing techniques, such as fused deposition modeling (FDM), becoming a more mainstream form of design, the inclusion of lightweight polymers such as nylon 12 as primary construction materials for these devices has increased. In this thesis computer aided design (CAD) software was used to design a prototype lower body exoskeleton and simulation software was used to give the device the characteristics of Stratasys' nylon 12 carbon fiber FDM material to verify it if could be used as the primary construction material for this device when extruded from a FDM printer on either the XZ or ZX printing plane. From the simulations it was found that the material printed along the XZ plane could create a device that could withstand the weight of an average elderly male patient (200 lbs.) as well as the 35 lbs. of force applied to the device by a linear actuation motor that would be used to extend and contract the exoskeleton leg.

O objetivo deste estudo clínico foi comparar a influência do tipo de material e da estrutura física de dois fios dentais em liberar pirofosfato tetrassódico, no espaço interdental. Este estudo crossover foi conduzido em uma população de 10 indivíduos (ambos os sexos) com faixa etária variando entre 18 e 30 anos. Os sujeitos da pesquisa foram alocados aleatoriamente em uma das seguintes seqüências de uso dos fios dentais: (AB ou BA), onde A = polipropileno entrelaçado e B = nylon texturizado de acordo com o material e a estrutura com que os fios dentais foram produzidos. Cada indivíduo usou uma única vez, perfazendo 6 passadas por área-alvo (sendo definido como área alvo as duas faces interproximais dos dentes contíguos selecionados, ou seja, 3 passadas em cada face) cada fio da seqüência a ele alocada. Antes do uso do primeiro fio dental, assim como entre a permuta de fios, foi realizado um washout de uma semana sem fazer uso de qualquer produto que contivesse o princípio ativo (sal anti-tártaro). O fluido gengival das áreas-alvo foi colhido no espaço interdental, com cones de papel absorventes esterilizados (calibre # 35), nos seguintes tempos: (00) antes, (0) logo após; 1, 2, 4, (1, 2 e 4) horas após o uso de cada fio dental. A presença de pirofosfato nas amostras foi verificada por meio de cromatógrafo de íons IC 2000 (coluna AS-11 e pré-coluna AG-11). Os teores de pirofosfato foram comparados entre os dois tipos de fios dentais e entre os tempos de colheita das amostras. O pirofosfato tetrassódico foi detectado no fluido gengival de ambos os grupos em 95% das amostras no tempo 0 - imediatamente após o uso, em 45% das amostras no tempo 1 - após uma hora do uso e em 10% das amostras após 2 horas do uso. Após 4 horas do uso, em nenhuma das amostras foi detectada a presença do princípio ativo em níveis terapêuticos. Conclui-se que a composição do material e a estrutura física dos fios dentais não exerceram influência na liberação e na permanência do agente anti-tártaro, que permaneceu em níveis terapêuticos por um período de até 2 horas após o uso único. / The aim of this investigation was to compare the influence of the type of material and the physical structure of two antitartar dental flosses in releasing tetrasodium pyrophosphate in the interdental space. This crossover study involved 10 subjects (both genders) with ages ranging from 18-30 years old. The individuals were randomly assigned to one of the following sequences of use of the dental flosses (AB or BA), where A = tangled polypropylene and B = texturized nylon according to the structures and the materials what the dental flosses were made, forming two groups of five individuals each. Each individual used the floss 6 times in the target areas (defined as both interproximal surfaces of the selected teeth, 3 times in each surface). Before the use of the first dental floss and between the employments of the two flosses, a one week washout period was done without the use of products containing tetrasodium pyrophosphate. The gingival crevicular fluid of the target areas was sampled with sterile paper points (tapering # 35) in the following times: (00) before the use of the dental floss, (0) soon after the use; 1, 2, 4, (1, 2 and 4 hours after the use, respectively). The pyrophosphate contents in the samples were verified using an ion chromatograph IC 2000 (column AS-11 e pre-column AG-11). The contents of pyrophosphate were compared between the two flosses and among the sample collection times. Pyrophosphate was detected in the gingival crevicular fluid of both groups in 95% of the samples soon after their use, 45% after 1h and 10% after 2h of the use. After 4h, none of the samples had pyrophosphate at detectable levels. Both dental flosses released tetrasodium pyrophosphate at therapeutic levels for up to 2 hours after flossing. Based in the results it can be concluded that the material composition and the physical structure of the flosses had no influence in releasing the antitartar agent, which remained in therapeutic levels for a 2 hours period after the single use.

[pt] Processamento e Caracterização de Nanocompósitos de Nylon 11 reforçados por Nanotubos de Titanatos Modificados com Surfactantes estuda a influência da adição de nanotubos de titanato (TTNTs) nas propriedades mecânicas do Nylon 11 (Poliamida 11). De acordo com estudos prévios, espera-se que pequenas quantidades de TTNTs melhorem propriedades como resistência mecânica e rigidez. No entanto, a incorporação dessas nanopartículas também pode acarretar numa piora dessas propriedades, caso não haja uma dispersão eficaz na matriz polimérica. Assim sendo, também foram avaliados compósitos de Nylon 11 e nanotubos de titanato modificados com 2 tipos de surfactantes, um catiônico (CTAB) e outro aniônico (SDS) para investigação do efeito destes surfactantes na dispersão dos TTNTs e por consequência nas propriedades finais dos compósitos comparados ao Nylon 11 puro. Foi realizado também um estudo da dispersão dos nanotubos com e sem mistura com surfactante em água e butanol, em três intervalos de tempo, 15, 30 e 60 min a fim de se escolher os melhores parâmetros para a dispersão. Foram produzidos compósitos em uma microextrusora e uma microinjetora. Os compósitos com TTNTs tratados com CTAB apresentaram aumentos de 15 por cento e 10 por cento no módulo de elasticidade e os compósitos com TTNTs tratados com SDS apresentaram aumentos de 26 por cento e 20 por cento para essa mesma propriedade, respectivamente nas concentrações de 0.5 e 2 por cento wt de TTNTs, em relação ao Nylon 11 puro. / [en] Processing and Characterization of Nylon 11 Nanocomposites Reinforced with Titanates Nanotubes Modified by Surfactants has investigated the effect of titanate nanotubes (TTNTs) in the mechanical properties of Nylon 11 (polyamide 11) polymer. According to the existing literature small amounts of TTNTs in polymer matrix improve properties such as tensile strength and stiffness. However, the addition of these nanoparticles may also lead to a decrease of strength of the composite if the nanotubes are not well dispersed in the polymer matrix. Therefore, Nylon 11 composites with TTNTs treated with 2 kinds of surfactant - a cationic (CTAB) and an anionic (SDS) - were also investigated. The surfactants act as dispersion agents leading to a better dispersion state of nanotubes and as a final result, promote enhancement of composites mechanical properties. Also, the dispersion of nanotubes was studied with and without mixing surfactants in distilled water and butanol, in three different time intervals (15, 30 and 60 minutes) to assess the optimal dispersion parameters. Composites were produced in a microextruder and a microinjector. The composites with TTNTs treated with CTAB displayed an increase of 15 percent and 10 percent in the Young s Modulus and the composites with TTNTs treated with SDS displayed an increase of 26 percent and 20 percent in the same property, respectively in the concentrations of 0.5 and 2 percent wt of TTNTs, compared to pure Nylon 11.

Polymer-based piezoelectric and triboelectric generators form the basis of well-known energy harvesting methods that are capable of transforming ambient vibrational energy into electrical energy via electrical polarization changes in a material and contact electrification, respectively. However, the low energy conversion efficiency and limited thermal stability of polymeric materials hinder practical application. While nanostructured polymers and polymer-based nanocomposites have been widely studied to overcome these limitations, the performance improvement has not been satisfactory due to limitations pertaining to long-standing problems associated with polymeric materials; such as low crystallinity of nanostructured polymers, and in the case of nanocomposites, poor dispersion and distribution of nanoparticles in the polymer matrix. In this thesis, novel functional polymeric nanomaterials, for stable and physically robust energy harvesting applications, are proposed by developing advanced nanofabrication methods. The focus is on ferroelectric polymeric nanomaterials, as this class of materials is particularly well-suited for both piezoelectric and triboelectric energy harvesting. The thesis is broadly divided into two parts. The first part focuses on Nylon-11 nanowires grown by a template-wetting method. Nylon-11 was chosen due to its reasonably good ferroelectric properties and high thermal stability, relative to more commonly studied ferroelectric polymers such as polyvinylidene fluoride (PVDF) and polyvinylidene fluoride-trifluoroethylene (P(VDF-TrFE)). However, limitations in thin-film fabrication of Nylon-11 have led to poor control over crystallinity, and thus investigation of this material for practical applications had been mostly discontinued, and its energy harvesting potential never fully realised. The work in this thesis shows that these problems can be overcome by adopting nanoporous template-wetting as a versatile tool to grow Nylon-11 nanowires with controlled crystallinity. Since the template-grown Nylon-11 nanowires exhibit a polarisation without any additional electrical poling process by exploiting the nanoconfinement effect, they have been directly incorporated into nano-piezoelectric generators, exhibiting high temperature stability and excellent fatigue performance. To further enhance the energy harvesting capability of Nylon-11 nanowires, a gas -flow assisted nano-template (GANT) infiltration method has been developed, whereby rapid crystallisation induced by gas-flow leads to the formation of the ferroelectric δʹ-phase. The well-defined crystallisation conditions resulting from the GANT method not only lead to self-polarization but also increases average crystallinity from 29 % to 38 %. δʹ-phase Nylon-11 nanowires introduced into a prototype triboelectric generator are shown to give rise to a six-fold increase in output power density as observed relative to the δʹ-phase film-based device. Interestingly, based on the accumulated understanding of the template-wetting method, Nylon-11, and energy harvesting devices, it was found that thermodynamically stable α-phase Nylon-11 nanowires are most suitable for triboelectric energy generators, but not piezoelectric generators. Notably, definitive dipole alignment of α-phase nanowires is shown to have been achieved for the first time via a novel thermally assisted nano-template infiltration (TANI) method, resulting in exceptionally strong and thermally stable spontaneous polarization, as confirmed by molecular structure simulations. The output power density of a triboelectric generator based on α-phase nanowires is shown to be enhanced by 328 % compared to a δʹ-phase nanowire-based device under the same mechanical excitation. The second part of the thesis presents recent progress on polymer-based multi-layered nanocomposites for energy harvesting applications. To solve the existing issues related to poor dispersion and distribution of nanoparticles in the polymer matrix, a dual aerosol-jet printing method has been developed and applied. As a result, outstanding dispersion and distribution. Furthermore, this method allows precise control of the various physical properties of interest, including the dielectric permittivity. The resulting nanocomposite contributes to an overall enhancement of the device capacitance, which also leads to high-performance triboelectric generators. This thesis therefore presents advances in novel functional polymeric nanomaterials for energy harvesting applications, with improved performance and thermal stability. It further offers insight regarding the long-standing issues in the field of Nylon-11, template-wetting, and polymer-based nanocomposites.

In order to reach the Swedish environmental quality objectives, the Environmental ProtectionAgency has expressed a desire that consumption must be highlighted. The difficulty of assessingthe environmental impact of consumption lays in various calculation approaches, but one way toillustrate consumption is life cycle assessment (LCA). IVL, Swedish Environmental ResearchInstitute (IVL) has an ongoing project together with Chalmers about Urban Metabolism, wheredifferent branches of consumption are highlighted. In the current situation, the textile industryaccounts for approximately 2-10% of Europe's environmental impacts and until now, no complete LCA model over the Swedish textile consumption has been developed. The main goal of this thesis was to develop a LCA model for the Swedish textile consumption and to study the environmental impact that the consumption entails. Using data from StatisticsSweden, net consumption between 2000 and 2013 was analysed. The results showed thatclothing and household textiles account for the largest proportion of consumed textiles (68%) and cotton, wool, viscose, polyester and nylon are the most common fibres. With the GaBi software a general life cycle model for the years 2000, 2007 and 2013 wasdeveloped. The model included 25 different clothing and household articles. For each article, themodel covers raw material extraction, product manufacturing, use phase and waste management.The environmental impact categories; Acidification Potential (AP), Eutrophication Potential(EP), Global Warming Potential (GWP), Human Toxicity Potential (HTP), TerrestrialEcotoxicity Potential (TETP) as well as energy and water use were analysed. The model showedthat the production phase (including raw material production) has a great influence on theenvironmental impacts, but the use phase was equally important in certain impact categories.The major processes affecting the life cycle were energy use in manufacturing of the fabric,production of natural fibres, detergent as well as energy consumption in tumble dryers. Withconscious decisions the consumer has great opportunities to influence the overall environmentalimpacts. In addition, increased recycling and reuse can potentially decrease the environmentalimpacts from the production stage. The model is considered good enough for the results to be reliable and useful in order to predictthe environmental impacts of the Swedish textile consumption. The results are also validatedwith results from other studies which increases credibility. / Det står idag klart att endast två av Sveriges 16 miljömål kommer att nås till 2020. För attSverige ska uppnå sina miljömål har Naturvårdsverket uttryckt en önskan om att konsumtionmåste belysas. Svårigheten med konsumtionens miljöpåverkan är att den inte kan mätas direktmen ett sätt att angripa problemet är att studera konsumtion genom livscykelanalys.IVL, Svenska Miljöinstitutet (IVL), har tillsammans med Chalmers ett pågående projekt omUrban Metabolism där olika typer av konsumtion nu belyses. Textilier är en typ av konsumtionoch i Europa står den marknaden för 2-10 % av den totala miljöpåverkan. Då textilkonsumtionenär relativt stor i Europa är det därför intressant att studera hur den svenska textilkonsumtionenser ut. Denna studie ämnade att skapa en modell för svensk textilkonsumtion och studera dessmiljöeffekter. Med data från Statistiska centralbyrån kunde nettokonsumtionen mellan 2000-2013 beskrivas. Statistiken visade att kläder och hushållstextilier står för den största delenkonsumerade textilier (68 %) och att bomull, ull, viskos, polyester och nylon är de fibrer somanvänds mest. Med programvaran GaBi gjordes en generell livscykelanalysmodell för åren 2000, 2007 och2013. 25 olika kläder och hushållsartiklar ingick och processerna råvaruframställning,tillverkning av produkt, användning och avfallshantering studerades.Miljöpåverkanskategorierna försurning, övergödning, global uppvärmning, humantoxicitet,ekotoxicitet samt energi-och vattenanvändning analyserades och resultatet visade attproduktionsfasen (inklusive råvaruframställning) har stor påverkan på resultatet. I vissakategorier var även användningsfasen en betydande faktor. De processer som påverkadelivscykelanalysen mest var energianvändningen i tygtillverkningen och naturfibrerna samttvättmedlet och energianvändningen hos torktumlaren i användningsfasen. Med medvetna valhar konsumenten stor möjlighet att påverka de övergripande miljöeffekterna och med en ökadåtervinning och återanvändning kan miljöeffekterna i produktionsfasen minska. Modellen som togs fram är inte fulländad och vissa processer kan förbättras för att utvecklamodellen vidare. Däremot antas modellen vara tillräckligt bra för att resultatet ska vara trovärdigtoch användbart i syfte att studera den svenska textilkonsumtionens miljöeffekter. Resultaten kandessutom styrkas med resultat från andra studier vilket ökar trovärdigheten.

O objetivo deste estudo clínico foi comparar a influência do tipo de material e da estrutura física de dois fios dentais em liberar pirofosfato tetrassódico, no espaço interdental. Este estudo crossover foi conduzido em uma população de 10 indivíduos (ambos os sexos) com faixa etária variando entre 18 e 30 anos. Os sujeitos da pesquisa foram alocados aleatoriamente em uma das seguintes seqüências de uso dos fios dentais: (AB ou BA), onde A = polipropileno entrelaçado e B = nylon texturizado de acordo com o material e a estrutura com que os fios dentais foram produzidos. Cada indivíduo usou uma única vez, perfazendo 6 passadas por área-alvo (sendo definido como área alvo as duas faces interproximais dos dentes contíguos selecionados, ou seja, 3 passadas em cada face) cada fio da seqüência a ele alocada. Antes do uso do primeiro fio dental, assim como entre a permuta de fios, foi realizado um washout de uma semana sem fazer uso de qualquer produto que contivesse o princípio ativo (sal anti-tártaro). O fluido gengival das áreas-alvo foi colhido no espaço interdental, com cones de papel absorventes esterilizados (calibre # 35), nos seguintes tempos: (00) antes, (0) logo após; 1, 2, 4, (1, 2 e 4) horas após o uso de cada fio dental. A presença de pirofosfato nas amostras foi verificada por meio de cromatógrafo de íons IC 2000 (coluna AS-11 e pré-coluna AG-11). Os teores de pirofosfato foram comparados entre os dois tipos de fios dentais e entre os tempos de colheita das amostras. O pirofosfato tetrassódico foi detectado no fluido gengival de ambos os grupos em 95% das amostras no tempo 0 - imediatamente após o uso, em 45% das amostras no tempo 1 - após uma hora do uso e em 10% das amostras após 2 horas do uso. Após 4 horas do uso, em nenhuma das amostras foi detectada a presença do princípio ativo em níveis terapêuticos. Conclui-se que a composição do material e a estrutura física dos fios dentais não exerceram influência na liberação e na permanência do agente anti-tártaro, que permaneceu em níveis terapêuticos por um período de até 2 horas após o uso único. / The aim of this investigation was to compare the influence of the type of material and the physical structure of two antitartar dental flosses in releasing tetrasodium pyrophosphate in the interdental space. This crossover study involved 10 subjects (both genders) with ages ranging from 18-30 years old. The individuals were randomly assigned to one of the following sequences of use of the dental flosses (AB or BA), where A = tangled polypropylene and B = texturized nylon according to the structures and the materials what the dental flosses were made, forming two groups of five individuals each. Each individual used the floss 6 times in the target areas (defined as both interproximal surfaces of the selected teeth, 3 times in each surface). Before the use of the first dental floss and between the employments of the two flosses, a one week washout period was done without the use of products containing tetrasodium pyrophosphate. The gingival crevicular fluid of the target areas was sampled with sterile paper points (tapering # 35) in the following times: (00) before the use of the dental floss, (0) soon after the use; 1, 2, 4, (1, 2 and 4 hours after the use, respectively). The pyrophosphate contents in the samples were verified using an ion chromatograph IC 2000 (column AS-11 e pre-column AG-11). The contents of pyrophosphate were compared between the two flosses and among the sample collection times. Pyrophosphate was detected in the gingival crevicular fluid of both groups in 95% of the samples soon after their use, 45% after 1h and 10% after 2h of the use. After 4h, none of the samples had pyrophosphate at detectable levels. Both dental flosses released tetrasodium pyrophosphate at therapeutic levels for up to 2 hours after flossing. Based in the results it can be concluded that the material composition and the physical structure of the flosses had no influence in releasing the antitartar agent, which remained in therapeutic levels for a 2 hours period after the single use.

Made available in DSpace on 2016-03-15T19:36:26Z (GMT). No. of bitstreams: 1 Renato Meneghetti Peres.pdf: 2481386 bytes, checksum: 4a0c9e9713ebe096dc1943b16d0149bd (MD5) Previous issue date: 2010-08-06 / Fundo Mackenzie de Pesquisa / Nanocomposites are nanometrical material particles embedded in a specific matrix. The degree of organization of the nanostructures and their properties depend on the nature of the organic and inorganic components of the structure that can generate synergic interactions. Polymeric nanocomposites are related to a class of hybrid materials where inorganic substances of nanometric dimensions are dispersed in a polymeric matrix. A small amount of inorganic material has a great effect on the structure performance. The nanoparticles of inorganic materials have high specific surface area that promotes the dispersion of the polymeric matrix and the properties depend on the homogeneity of the dispersion. The interaction reactions between the components can be observed on the material`s structure. The nanometrical material obtained by sol-gel process can be incorporated directly on the polymeric matrix. There is a tendency to a hard dispersion when a ceramic nanoscale particle is embedded in a polymeric matrix. This difficult can be attributed to a small spacement between the ceramic atomic planes to allow the passage of the polymeric chain between that. In this case, techniques can be used to the spacement to be enlarged with a organophilic agent action that enable a better addiction between the reinforcement and de matrix and make a influence in the mechanical, termical and rheological properties for the characterization by different techniques. In this work, the pseudoboehmite obtained by sol-gel process was treated by an octadecylamine solution to obtain a mix added to Nylon 6,12. After the mixing, the nanocomposite was dryed and processed to conformed the specimen used in the material caracterization. Mechanical, termical, reological, MEV and X-ray diffraction tests are done. The nanocomposite which contains pseudoboehmite and octadecylamine tests results were compared with the nanocomposite contained just pseduboehmite to compair and verify the octadecylamine treatment effect in the materials properties. / Nanocompósitos são materiais contendo partículas nanométricas dispersas em uma matriz específica. O grau de organização das nanoestruturas e suas propriedades dependem da natureza dos componentes orgânicos e inorgânicos de sua estrutura onde podem ocorrer interações sinérgicas. Os nanocompósitos poliméricos consistem em um grupo de materiais híbridos nos quais substâncias inorgânicas de dimensões nanométricas estão dispersas na matriz polimérica. Por possuírem alta área específica, uma pequena quantidade de nanocarga pode ocasionar um grande efeito no desempenho da estrutura, no entanto é importante observar que a dispersão do nanoreforço na matriz polimérica deve ocorrer da forma mais homogênea possível, promovendo as interações sinérgicas entre matriz e reforço ao longo de toda a estrutura do material. A obtenção de um reforço cerâmico por processo sol-gel, permite a obtenção de um produto com partículas de dimensões nanométricas, sendo que o mesmo pode ser incorporado à matriz polimérica. Ainda que em dimensões na escala nano, sempre que uma cerâmica é adicionada a um polímero, existe uma tendência à dificuldade na dispersão do material devido ao pequeno espaçamento entre os planos atômicos da cerâmica para que ocorra a passagem da cadeia polimérica entre estes planos. Neste caso, o emprego de técnicas de modificação da nanocarga, onde este espaçamento pode ser aumentado pela ação de um agente organofílico, possibilitando uma melhor acoplagem do reforço à matriz e influenciando diretamente nas propriedades mecânicas, térmicas e reológicas do material quando caracterizado pelas mais diversas técnicas. Neste trabalho, a pseudoboemita obtida por processo sol-gel foi tratada com uma solução de octadecilamina obtendo-se uma mistura adicionada ao Nylon 6,12. Após a mistura o nanocompósito foi seco e processado para conformação dos corpos-de-prova utilizados na caracterização do material. Realizou-se a caracterização por meio de ensaios mecânicos, térmicos, reológicos, MEV e Difração de Raios-X. Os resultados obtidos na caracterização do material contendo pseudoboemita e octadecilamina foram comparados aos resultados obtidos na adição apenas da pseudoboemita para comparação e verificação do efeito do tratamento com octadecilamina nas propriedades do material.

Plastics are highly useful economically because of their resistance to diverse types of environmental and chemical agents and their ability to be molded into many types of products. Globally, plastic production is greater than 20 million metric tons per year. However, their widespread use and often their disposable nature results in significant plastic accumulation in the environment. Plastics are made of hydrocarbons, materials that are biodegradable depending on their molecular structure and size. It is hypothesized that pre-treatment of plastic materials could enhance their bioavailability, facilitating their microbial biodegradation. In this dissertation, a process was developed to treat nylon 6,6 polymers by acid hydrolysis to produce a microbial growth medium. The chemical composition of the medium was determined by low pressure liquid chromatography-spectrophotometry and electrospray ionization mass spectrometry and found that the medium was a mixture of molecules with molecular weight > 800 m/z and with similar chemical characteristics to polyamines. There was steady growth of Pseudomonas putida KT2440 in the medium with concomitant substrate biodegradation. Notably, the yeast Yarowia lipolytica grew well in the medium when supplemented with yeast extract. A similar medium derived from nylon 6,6 containing nylon-derived particles supported the growth of Beijerinckia sp. and Streptomyces sp. BAS1. Confocal laser scanning microscopy and flame ionization gas chromatography were used to identify and quantify the production of polyhydroxybutyrate, a type of “bioplastic”. The aforementioned microorganisms were cultivated in a bench-scale bioreactor that was developed as part of this dissertation. The bioreactor had a novel impeller design resulting in enhanced mixing and rotation and also a modular format allowing for diverse configurations. The bioreactor was notable for its durability and low cost. A detailed description of its design is included in the appendices. In summary, plastic materials can potentially be processed into growth media for microorganisms and can be used for production of value-added products. The media described herein can be used in bioconversion processes using a bioreactor.

The control of cell adhesion to synthetic polymers is a key factor in tissue engineering, resting on the ability to direct specific cell types to adhere and proliferate in order to stimulate tissue reconstruction. But often the surface properties are compromised for the sake of the bulk properties, leading to surfaces that do not support sufficiently the level of bioactivity required and accordingly the polymeric biomaterial will fail clinically. Laser treatment offers a unique means of enhancing the osteoblast cell response of the surface of a polymeric biomaterial, whilst keeping the already sufficient bulk properties intact. To this end, infra-red (IR) and ultraviolet (UV) lasers have been employed to modify the wettability characteristics of nylon 6,6, as wetting is often the primary factor dictating the adhesion and bonding potential of materials, as a route to enhancing the surface in terms of osteoblast cell response. What is more, modifying wettability characteristics in this way is a highly attractive means of estimating the biofunctionality of a polymer. IR (CO2) and UV (F2 and KrF excimer) lasers were employed to carry out two different processes: laser whole area irradiative processing and laser-induced patterning. With both CO2 and the excimer lasers changes in the wettability characteristics could be effected with subsequent enhancement of osteoblast cell response. This was also the case with both laser-induced patterning and laser whole area irradiative processing. Essentially, an approach has been established whereby the osteoblast cell response on the surfaces of laser treated nylon 6,6 can be predicted through the laser-induced wettability characteristics modification, particularly for the laser whole area irradiative processed nylon 6,6. This ultimately allows one to determine the osteoblast cell response of the laser surface treated nylon 6,6 surfaces directly from the laser operating parameters. In concurrence with established wetting theory the laser whole area irradiative processing of the nylon 6,6 surfaces caused increased surface roughness, increased surface oxygen content, increased polar component, γP , and increased total surface energy, γT ; thereby generating surfaces displaying reduced contact angle, θ, making the nylon 6,6 surfaces more hydrophilic. The laser-induced patterned samples differed from current theory insofar as the nylon 6,6 surfaces became less hydrophilic due to an increase in θ despite an increase in surface roughness, an increase in surface oxygen content, an increase in γP and an increase in γT . This phenomena can be explained by the transition in wetting regimes from a Wenzel regime to a mixed-state wetting regime. Nevertheless, collation of the wettability characteristics results revealed that θ was a strong correlative decreasing function of both γP and γT , indicating that surface energy played a large role in determining the wetting nature of the nylon 6,6. It was found that for all laser whole area irradiative processed nylon 6,6 surfaces the osteoblast cell response was an increasing correlative and therefore predictive function of θ and was a decreasing function of γP . To an extent, the surface oxygen content and surface roughness could be used indirectly to foretell the osteoblast cell response of the nylon 6,6 surfaces. This is on account of the CO2 and KrF excimer laser whole area irradiative processing bringing about increased surface toxicity, which above a certain level hindered the osteoblast cell response. For the laser-induced patterned nylon 6,6 samples there did not appear to be any particular correlative trend between the modified surface parameters and osteoblast cell response. This can be accounted for by the transition in wetting regimes. Another important factor is that cell morphologies were modulated over all samples which suggests that varying surface parameters on account of laser surface treatment gave rise to variations in cell signaling. It was determined that θ, γP and γT all had very strong correlative relationships with the cytotoxicity. The cytotoxicity reduced upon an increase in θ until a minimum constant was achieved, whereas the cytotoxicity remained constant at low γP and γT until a point at which the cytotoxicity began to increase. These results are noteworthy as they allow one to deduce that, with constant cytotoxicity levels, the osteoblast cell response appeared to be modulated by the wettability characteristics. But once the cytotoxicity increased, the toxicity began to dominate and so negated the identified positive wettability characteristic correlations with osteoblast cell response. Practically, the surface roughness and surface oxygen content could be implemented indirectly to estimate the cytotoxicity. Increase in cytotoxicity was the result of the laser processing with higher fluences generating excessive melting. As a result of this, it is possible to deduce that there was a maximum threshold fluence, beyond which the toxicity of the nylon 6,6 began to dominate, giving rise to a less enhanced osteoblast cell response. On account of the correlative trends which have been identified between the laser surface treatment, wettability characteristics and osteoblast cell response of nylon 6,6 it is likely for one to have the ability to estimate the osteoblast cell response in vitro. This is significant as it indicates that laser surface modification of polymeric materials could have tremendous potential for application within the field of regenerative medicine.