This master’s thesis is aimed on design of polymer coating machine that sprays polymer sliding coatings onto surfaces of crankshaft journal bearings used in car engines. At the beginning of this master’s thesis, basic overview of crankshaft bearings design and materials that are used for sliding coatings is given. Then suitable manufacturing technologies for different materials of coatings are described. After describing basic principles of coating technologies and how crankshaft bearings work, main components used for design of the spraying machine are introduced. Three prototypes of the machine are created in virtual environment to verify ergonomics of control and to fulfill safety requirements. In main part of the thesis, description of all parts and subassemblies, such as frame, spraying circuit, pneumatic regulators and safety features is given. Also functions of all parts of the machine are explained in details. Moreover system for handling and manipulation with coated bearings during all necessary technological operations was created. In addition functionality of the machine was verified and checked by spraying of polymer coating on testing samples and crankshaft bearings.

Polymer coatings are thin films of polymer deposited on different substrates for various applications. Such surface coatings can serve a functional purpose (adhesives, photographic films), protective purpose (anticorrosion), or decorative purpose (paint). Additionally, their composite coatings containing ceramic, or metal particles are often used to enhance durability, functionality, or aesthetics. Electrophoretic deposition (EPD) and dip coating are two promising methods for the fabrication of polymer and composite coatings due to the ease of fabrication, low cost, and high-volume production. EPD involves the electrophoresis of charged particles and their deposition on the electrode surface, which requires the colloidal particles to be charged in a stable suspension as a precursor solution for deposition. Many polymers cannot be deposited by EPD directly because of their charge neutrality and poor dispersion. Therefore, it is critical to develop efficient charging dispersants to modify electrically neutral polymers for their EPD. The approach was inspired by the strong solubilization power of bile acids in the human body. Two types of bile salts, cholic acid sodium salt and sodium chenodeoxycholate, and three types of biosurfactants, carbenoxolone sodium salt, glycyrrhizic acid, and 18β-glycyrrhetinic acid, which share similar structures with bile salts, were discovered for charging, dispersion, and EPD of different materials. The electrically neutral polymers (PTFE and PVDF), chemically inert materials (diamond, nanodiamond, graphene, carbon dots, carbon nanotubes and Zr-doped hydrotalcite (MHT)), and their composites can be well dispersed in suspension and deposited using these bio-surfactants as dispersants. It was found that the unique chemical structures of these biomolecules play vital roles in the surface modification and EPD of different materials. Moreover, the deposited polymer (PVDF, PTFE) and composite (PTFE-MHT) coatings can provide outstanding corrosion protection for stainless steel. The biomimetic and versatile strategy opens a way for the deposition of other electrically neutral materials through EPD. These findings also provide a promising strategy for selecting new dispersants for EPD. The deposition of high molecular weight (MW) polymers such as poly(ethyl methacrylate) (PEMA) at high concentrations in non-toxic solvents continues to be a challenge for dip coating. In this work, we firstly proposed using water-isopropanol as a co-solvent to dissolve high MW PEMA at high concentrations. It was found that water molecules can solvate carbonyl groups of PEMA and facilitate their dissolution. This method avoided the usage of toxic solvents and a long-time heating procedure for their removal. Moreover, it allows the fabrication of high-quality PEMA and composite coatings containing different flame retardant materials (FRMs), including double hydroxide LiAl2(OH)7.2H2O (LiAlDH), huntite, halloysite and hydrotalcite, through the dip coating method. A novel solid state synthesis method was proposed to fabricate LiAlDH, which is promising for the fabrication of other advanced DHs. Such composite coatings combined advanced properties of PEMA and functional properties of FRMs, such as corrosion inhibition and FR properties. / Thesis / Doctor of Engineering (DEng) / Polymer and composite coatings have been utilized for a wide range of applications due to their barrier properties, scratch and abrasion resistance, chemical resistance, and biocompatibility. Various techniques have been developed to fabricate polymer and composite coatings, such as electrophoretic deposition (EPD) and the dip coating method. However, limitations remain. EPD unitizes an electrical field to drive charged particles in a suspension toward conductive substrates to achieve film deposition. This process requires a stable suspension with charged particles, therefore, the electroneutral polymers present difficulties in their EPD. In addition, dissolving high molecular weight polymers at high concentrations in a non-toxic solvent is currently challenging, which is vital to utilize dip coating technique. The objective of this work was to develop advanced charging dispersants for EPD of electroneutral polymers and non-toxic solvents for dip coating of high molecular weight polymers. New biomimetic and versatile approaches have been developed for EPD of different electrically neutral polymers, chemically inert materials, and their composite coatings. A non-toxic co-solvent was proposed to dissolve high molecular weight polymer at high concentration for dip coating of the polymer and its composite coatings containing flame retardant materials. The results presented in this work showed the formation of high-quality films with multifunctionality and paved new strategies for further developments.

La production de poly(chlorure de vinyle) (PVC) sous forme de suspension chez INEOS ChlorVinyls est réalisée en réacteur fermé agité, dont les parois sont en émail ou en acier inoxydable. Il se forme en cours de polymérisation un dépôt de PVC (croûte) sur les parois du réacteur qui génère de nombreux inconvénients. Afin de limiter cet encroûtement, INEOS ChlorVinyls et l’ensemble des producteurs de PVC appliquent à chaque batch (par exemple pour INEOS ChlorVinyls 50 fois par jour pour ses 22 réacteurs) un revêtement organique. L’application systématique du revêtement et la formation de croûtes ont des conséquences économiques non négligeables (arrêts de production, coût de main d’œuvre et matière, coût de traitement des déchets, qualité du PVC contaminé par le revêtement…).La compréhension du phénomène d’encroûtement en vue de développer un revêtement permanent devient donc nécessaire pour améliorer la qualité des produits, diminuer les coûts et dégager un avantage concurrentiel favorable à INEOS vis-à-vis de ses concurrents. Le sujet de thèse a été divisé en deux parties bien distinctes avec premièrement l’étude du mécanisme d’encroûtement et la mise en place d’un scénario permettant d’expliquer de manière physique et chimique la formation de la croûte sur les parois du réacteur. Une seconde partie a été dédiée au développement d’un revêtement polymère avec la sélection d’un système résistant au milieu réactionnel de polymérisation en suspension du chlorure de vinyle puis à l’optimisation de l’adhésion du revêtement polymère sur acier inoxydable afin d’obtenir des performances maximales et durables. / The suspension synthesis of PolyVinyl Chloride (S-PVC) at the INEOS ChlorVinyls facility in Mazingarbe (FRANCE) is realized thanks to a closed-reactor technology with reactor walls made of stainless steel or enamel. One of the major problems during the production of PVC by suspension polymerization is the formation of a deposit (called crust or scale) on the reactor walls. The formation of scale leads to numerous sorts of drawbacks like a decrease of the reactors’ productivity, the need to clean the reactors after each batch, the exposure of the operators to VinylChloride Monomer (VCM) which is classified CMR, some quality issues… At the moment, a coating is applied before each batch (50 times per day for the 22 reactors at Mazingarbe) in order to lower the amount of scale formed during the S-PVC batch. The application of the coating added to the formation of scale leads to important extra costs. The comprehension of the scale formation mechanism with the aim of then developing a durable protective coating becomes a priority in order to increase the final product quality, lower the costs and gain a competitive advantage for INEOS ChlorVinyls. The Ph.D. subject was divided into two parts with the first year dedicated to the comprehension of the scale formation mechanism and the establishment of a complete scenario explaining the formation of scale from a chemical and physical point of view. The second part of this project was dedicated to the development of a polymer coating with the selection of an adapted polymer candidate and then the optimization of its adhesion onto stainless steel in order to obtain the optimal performances and the durability of the coating.

Magnetite (Fe3O4) and Maghemite (&amp / #947 / -Fe2O3) are well-known iron oxide phases among magnetic nanoparticles due to their magnetic properties, chemical stability, and nontoxicity. They have gained acceptance in several fields of application of nanomaterials such as magnetic recording systems, magnetic refrigeration, magneto-optical devices, magnetic resonance imaging, magnetic separation techniques and separation and purification of biological molecules. Recently, there is a growing interest in the synthesis of magnetic iron oxide nanoparticles in a polymeric, glassy or ceramic matrix since the preparation of pure phase iron oxide composite material involves, presently, some difficulties partially arising from different oxidation states of iron which can lead to the presence of various oxides. Matrix support, in principle, modifies the properties of nanomaterials, thus opening new possibilities for the control of their performance. In addition, the chosen matrix, polymer or sol-gel, provides binding of the functional groups and also prevents grain growth and agglomeration. Therefore, extensive research is conducted on this subject. Sonochemical technique is an effective method to synthesize magnetic nanoparticles with many unique properties due to extreme reaction conditions. Besides, a microscopic mixing in the synthesis procedure is obtained because of the microjet effect which comes from the collapse of the bubbles. This effect creates relatively uniform reaction conditions. Thus, well-dispersed and stable nanoparticles are obtained by using ultrasound. In this study, &amp / #947 / -Fe2O3, maghemite nanoparticles are accommodated in an inert, inorganic, transparent and temperature resistant sol gel matrix to achieve stabilization. The nature and concentration of the salt used, evaporation conditions of the sols, the following heat treatments had been investigated and shown that they had great influence on the particle size and the final iron oxide phase in the sol-gel. The Fe2O3/SiO2 nanocomposites were characterized using X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) techniques. In addition, magnetite (Fe3O4) nanoparticles were synthesized via co-precipitation in the presence of poly(methacrylic acid) (PMAA) in aqueous solution. PMAA, which was used as the coating material, prevents magnetite nanoparticles from oxidation towards a lower saturation magnetization iron oxide phases. In order to achieve small particle size and uniform size distribution of the magnetite nanoparticles in PMAA matrix, ultrasonic irradiation was applied during co-precipitation. The polymer coated Fe3O4 nanoparticles were characterized using scanning electron microscopy (SEM), laser particle sizer, X-ray diffraction, (XRD) and vibrating sample magnetometry (VSM) techniques and zeta potential measurements.

[pt] O aço carbono é amplamente utilizado na confecção de equipamentos e tubulações que atendem às necessidades dos processos de produção e transporte de combustíveis fósseis. Sabe-se que o aço carbono em contato com o ambiente de CO2 sofrem corrosão, levando à perda de qualidade no processo e consequentemente impactos nos custos de produção. Os revestimentos não-metálicos podem ser utilizados como método de prevenção contra à corrosão, assegurando a qualidade do produto final e diminuindo os custos de produção. Este trabalho tem como objetivo avaliar o comportamento do aço AISI 1020 revestido por nanocoating em um meio contendo CO2. Os testes foram realizados em solução salina de 3 por cento wt de NaCl saturada com CO2 a 75 bar de pressão, temperturas de 50 graus Celsius e 100 graus Celsius e tempos de exposição que variaram de 15 a 30 dias. O comportamento da corrosão foi avaliado através de técnicas eletroquímicas, tais como, Resistência à Polarização Liner (RPL), Impedância Eletroquímica (EIS) e Curvas Tafel e pela variação de massa. A Microscopia Eletrônica de Varredura (MEV) foi utilizada para avaliar a morfologia do filme formado e a Difração de Raios X (DRX) e Espectroscopia de Energia Dispersiva (EDS) foram utilizadas para determinar a composição química. O melhor resultado do revestimento foi observado para o tempo de 15 dias a 50 graus Celsius, mesmo assim há formação de uma camada de corrosão. Em todas as outras condições estudadas não houve proteção efetiva do revestimento. Para as condições estudadas, os resultados obtidos indicam que este tipo de revestimento não pode ser utilizado para temperaturas acima de 50 graus Celsius. / [en] Carbon steel is widely used in the manufacture of equipment and piping to meet the needs of the production and transportation of fossil fuels. It is well known that carbon steel in contact with the CO2 environment will corrode leading to the loss of quality in the process and consequently impacts in production and repair costs, among others. Non-metallic coatings can be used as a method of preventing corrosion, ensuring the quality of the final product and reducing production costs. The objective of this work was the evaluation of a nano coated AISI 1020 steel in a CO2 environment. Corrosion tests were performed in a brine solution of 3 per cent wt NaCl saturated with CO2, at a pressure of 75 bar and temperatures of 50 Celsius degrees and 100 Celsius degrees for 15 and 30 days. The corrosion rate behavior was evaluated through electrochemical techniques, such as, Linear Polarization Resistance (LPR), Electrochemical Impedance (EIS) and Tafel Curves and mass variation. Corrosion products were analyzed using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) and Energy Dispersive Spectroscopy (EDS). For the conditions tested the coating with nanotubes and polymeric matrix withstand the maximum of 15 days at 50 Celsius degrees, although a corrosion layer was observed. No effective coating protection was observed for the other conditions studied, indicating that this type of coating can not be used for temperatures above 50 Celsius degrees.

Advances in biomaterials have enabled medical practitioners to replace diseased body parts or to assist in the healing process. In situations where a permanent biomaterial implant is used for a temporary application, additional surgeries are required to remove these implants once the healing process is complete, which increases medical costs and patient morbidity. Bio-absorbable materials dissolve and are metabolized by the body after the healing process is complete thereby negating additional surgeries for removal of implants. Magnesium alloys as novel bio-absorbable biomaterials, have attracted great attention recently because of their good mechanical properties, biocompatibility and corrosion rate in physiological environments. However, usage of Mg as biodegradable implant has been limited by its poor corrosion resistance in the physiological solutions. An optimal biodegradable implant must initially have slow degradation to ensure total mechanical integrity then degrade over time as the tissue heals. The current research focuses on surface modification of Mg alloy (MZC) by surface treatment and polymer coating in an effort to enhance the corrosion rate and biocompatibility. It is envisaged that the results obtained from this investigation would provide the academic community with insights for the utilization of bio-absorbable implants particularly for patients suffering from atherosclerosis. The alloying elements used in this study are zinc and calcium both of which are essential minerals in the human metabolic and healing processes. A hydrophobic biodegradable co-polymer, polyglycolic-co-caprolactone (PGCL), was used to coat the surface treated MZC to retard the initial degradation rate. Two surface treatments were selected: (a) acid etching and (b) anodization to produce different surface morphologies, roughness, surface energy, chemistry and hydrophobicity that are pivotal for PGCL adhesion onto the MZC. Additionally, analyses of biodegradation, biocompatibility, and mechanical integrity were performed in order to investigate the optimum surface modification process, suitable for biomaterial implants. The study concluded that anodization created better adhesion between the MZC and PGCL coating. Furthermore, PGCL coated anodized MZC exhibited lower corrosion rate, good mechanical integrity, and better biocompatibility as compared with acid etched.

Les revêtements polymères stimuli-sensibles permettent d'ajuster les propriétés de surface par des stimuli externes (i.e. des variations des conditions environnementales) via des changements dans leur conformation physique, la chimie de surface, ou les deux. Cette capacité permet leur utilisation comme éléments fonctionnels dans les nanotechnologies tels que des valves dans les dispositifs microfluidiques, comme lubrifiants, ou comme substrats pour la culture de tissus biologiques. Cependant, de tels revêtements souffrent généralement d'un inconvénient majeur, afin de déclencher un changement de la conformation physique du revêtement polymère (gonflement) via un stimulus, il est nécessaire de changer au moins une de ses propriétés physico-chimiques qui produit des variations simultanées des propriétés de surface (i.e. potentiel de surface, adhésion). Ce travail vise à surmonter cette limitation en étudiant une nouvelle génération de revêtements hiérarchiques fonctionnels dont les propriétés physiques et la chimie de surface peuvent être modulées indépendamment et de manière réversible en utilisant différents stimuli tels que la température et le pH. Les revêtements hiérarchiques sont constitués de matrices des microgels à base de poly-(N-isopropylacrylamide) bidimensionnelles fonctionnalisés en surface avec des polymères dont les dimensions caractéristiques et les propriétés de surface peuvent être contrôlées indépendamment par différents stimuli en fonction des propriétés de surface souhaitées. Ce travail démontre que les dimensions caractéristiques (i.e. diamètre hydrodynamique, épaisseur de couche) peuvent en effet être contrôlées sans affecter les propriétés de surface (i.e. potentiel de surface, adhérence) des réseaux de microgels fonctionnalisés. La réactivité des revêtements fonctionnels a été étudiée à l'aide de la Diffusion Dynamique de la Lumière et de l'Appareil de Forces de Surface permettant de déterminer avec précision l'adhésion, la friction, le potentiel de surface, le diamètre hydrodynamique et l'épaisseur de la couche sous différents stimuli. Enfin, la capacité de ces substrats fonctionnels pour produire un détachement cellulaire déclenché par des stimuli dans le cadre de la culture cellulaire a été étudiée. / Stimuli-responsive polymer coatings enable surface properties to be tuned by external stimuli (i.e. variations of environmental conditions) via changes in their physical conformation, surface chemistry, or both. This capacity enables their use as functional elements in nanotechnologies such as valves in microfluidic devices, as lubricants, or as substrates for culture of biological tissues. However, such coatings usually suffer from a major shortcoming, in order to trigger a change in the physical conformation of the polymer coating (swelling) via a stimulus, it is necessary to change at least one of its physicochemical properties which results in simultaneous variations of the surface properties (i.e. surface potential, adhesion). The present work aims to overcome this limitation by investigating a new generation of responsive hierarchical coatings whose physical properties and surface chemistry can be tuned independently and reversibly using different stimuli such as temperature and pH. The hierarchical coatings consist of two-dimensional poly-(N-isopropylacrylamide) microgel arrays surface-functionalized with polymers whose characteristic dimensions and surface properties can be independently controlled by different stimuli according to the desired surface properties. This work shows how the characteristic dimensions (i.e. hydrodynamic diameter, layer thickness) can indeed be controlled without affecting the surface properties (i.e. surface potential, adhesion) of the functionalized microgel arrays. The responsiveness of the functional coatings was investigated using Dynamic Light Scattering and the Surface Forces Apparatus allowing adhesion, friction, surface potential, hydrodynamic diameter, and layer thickness to be accurately determined under different stimuli. Finally, the ability of these coatings as functional substrates to produce stimuli-triggered cell detachment during cell culture was studied.

O alto nível de poluição gerado pelo descarte inadequado de materiais poliméricos vem motivando pesquisas por sistemas e técnicas ambientalmente corretos, tais como a aplicação de polímeros biodegradáveis e a substituição dos sistemas de pintura à base de solventes por aqueles com alto teor de sólidos, à base de água ou, praticamente isentos de compostos orgânicos voláteis (VOCs) e curáveis por radiação. Todavia, os revestimentos poliméricos curados são insolúveis e infusíveis, aumentando o grau de complexidade do seu reprocessamento, da sua reciclagem e da degradação desejável. Assim, este trabalho apresenta, como objeto de contribuição científica, a obtenção de tintas modificadas com agentes pró-degradantes, curadas por reações químicas induzidas por radiação ultravioleta ou feixe de elétrons (UV/EB), para impressão em embalagens plásticas, biodegradáveis ou não, para produtos de baixa vida útil. Foram estudadas combinações de seis revestimentos, sendo um verniz não pigmentado e cinco tintas nas cores amarela, azul, branca, preta e vermelha; três agentes pró-degradantes (estearatos de cobalto, cério e manganês), cinco substratos poliméricos (Ecobras®, polietileno de baixa densidade e suas respectivas modificações com os agentes pró-degradantes). Os revestimentos foram aplicados nos substratos e curados por radiação UV ou EB, resultando em 180 amostras. Estes materiais foram, então, expostos ao envelhecimento acelerado em câmara tipo QUV e à compostagem em ambiente natural. De modo a se compreender o efeito dos revestimentos poliméricos no processo de degradação das amostras, foram selecionadas aquelas com valores extremos de grau de conversão, a saber: amarela e preta, as quais foram expostas à compostagem em ambiente controlado via respirometria, reduzindo de 180 para 16 o número de amostras. O composto orgânico gerado pelo processo de biodegradação foi analisado por testes de ecotoxicidade. Foi observado que a camada de revestimento atua como barreira que inibe a degradação do plástico quando exposto às intempéries. Adicionalmente, constatou-se que quanto maior o grau de conversão das formulações pigmentadas pastosas em sólidas durante a cura por radiação ultravioleta, maior foi sua mineralização em ambiente de compostagem. As amostras curadas por EB apresentaram menor taxa de biodegradação do que as curadas por UV. Isso se deu em virtude da rede de ligações cruzadas entre as cadeias poliméticas, geradas na cura por EB. A adição dos agentes pró-degradantes promoveu uma aceleração no processo de degradação, ocasionando, inclusive, a migração do íon metálico para o meio, porém sem afetar a qualidade do meio de compostagem. / The high level of pollution generated by the inadequate disposal of polymeric materials has motivated the search for environmentally friendly systems and techniques such as the application of biodegradable polymers and the replacement of the solvent-based paint systems by those with high solids content, based water or cured by radiation, practically free of volatile organic compounds. However, the cured polymer coatings are neither soluble nor molten, increasing the complexity of the reprocessing, recycling and degradation. Thus, this work aimed to develop print inks modified with pro-degrading agents, cured by ultraviolet radiation or electron beam, for printing or decoration in plastic packaging products of short lifetime, which are biodegradable or not. Six coatings (varnish and inks in five colors: yellow, blue, white, black and red), three pro-degrading agents (cobalt stearate, cerium stearate and manganese stearate), five polymeric substrates (Ecobras®, low density polyethylene and its respective modifications with pro-degrading agents). The coatings were applied to the substrates and cured by ultraviolet radiation or electron beam, resulting in 180 samples. These materials were then exposed to accelerated aging chamber, type \"QUV\", and composting in natural environment. In order to assess the effects of the polymer coatings on the degradation process of the specimens, only the yellow and black samples were exposed to a controlled composting environment via respirometry, reducing to 16 the number of samples. The organic compound generated by the biodegradation process was analyzed by the ecotoxicity tests. It was observed that the coating layer acted as a barrier that inhibits degradation of the plastic when exposed to weathering. The addition of pro-degrading agents promoted acceleration in the degradation process, promoting the migration of the metal ion to the medium without affecting the final quality of the organic compost.

O alto nível de poluição gerado pelo descarte inadequado de materiais poliméricos vem motivando pesquisas por sistemas e técnicas ambientalmente corretos, tais como a aplicação de polímeros biodegradáveis e a substituição dos sistemas de pintura à base de solventes por aqueles com alto teor de sólidos, à base de água ou, praticamente isentos de compostos orgânicos voláteis (VOCs) e curáveis por radiação. Todavia, os revestimentos poliméricos curados são insolúveis e infusíveis, aumentando o grau de complexidade do seu reprocessamento, da sua reciclagem e da degradação desejável. Assim, este trabalho apresenta, como objeto de contribuição científica, a obtenção de tintas modificadas com agentes pró-degradantes, curadas por reações químicas induzidas por radiação ultravioleta ou feixe de elétrons (UV/EB), para impressão em embalagens plásticas, biodegradáveis ou não, para produtos de baixa vida útil. Foram estudadas combinações de seis revestimentos, sendo um verniz não pigmentado e cinco tintas nas cores amarela, azul, branca, preta e vermelha; três agentes pró-degradantes (estearatos de cobalto, cério e manganês), cinco substratos poliméricos (Ecobras®, polietileno de baixa densidade e suas respectivas modificações com os agentes pró-degradantes). Os revestimentos foram aplicados nos substratos e curados por radiação UV ou EB, resultando em 180 amostras. Estes materiais foram, então, expostos ao envelhecimento acelerado em câmara tipo QUV e à compostagem em ambiente natural. De modo a se compreender o efeito dos revestimentos poliméricos no processo de degradação das amostras, foram selecionadas aquelas com valores extremos de grau de conversão, a saber: amarela e preta, as quais foram expostas à compostagem em ambiente controlado via respirometria, reduzindo de 180 para 16 o número de amostras. O composto orgânico gerado pelo processo de biodegradação foi analisado por testes de ecotoxicidade. Foi observado que a camada de revestimento atua como barreira que inibe a degradação do plástico quando exposto às intempéries. Adicionalmente, constatou-se que quanto maior o grau de conversão das formulações pigmentadas pastosas em sólidas durante a cura por radiação ultravioleta, maior foi sua mineralização em ambiente de compostagem. As amostras curadas por EB apresentaram menor taxa de biodegradação do que as curadas por UV. Isso se deu em virtude da rede de ligações cruzadas entre as cadeias poliméticas, geradas na cura por EB. A adição dos agentes pró-degradantes promoveu uma aceleração no processo de degradação, ocasionando, inclusive, a migração do íon metálico para o meio, porém sem afetar a qualidade do meio de compostagem. / The high level of pollution generated by the inadequate disposal of polymeric materials has motivated the search for environmentally friendly systems and techniques such as the application of biodegradable polymers and the replacement of the solvent-based paint systems by those with high solids content, based water or cured by radiation, practically free of volatile organic compounds. However, the cured polymer coatings are neither soluble nor molten, increasing the complexity of the reprocessing, recycling and degradation. Thus, this work aimed to develop print inks modified with pro-degrading agents, cured by ultraviolet radiation or electron beam, for printing or decoration in plastic packaging products of short lifetime, which are biodegradable or not. Six coatings (varnish and inks in five colors: yellow, blue, white, black and red), three pro-degrading agents (cobalt stearate, cerium stearate and manganese stearate), five polymeric substrates (Ecobras®, low density polyethylene and its respective modifications with pro-degrading agents). The coatings were applied to the substrates and cured by ultraviolet radiation or electron beam, resulting in 180 samples. These materials were then exposed to accelerated aging chamber, type \"QUV\", and composting in natural environment. In order to assess the effects of the polymer coatings on the degradation process of the specimens, only the yellow and black samples were exposed to a controlled composting environment via respirometry, reducing to 16 the number of samples. The organic compound generated by the biodegradation process was analyzed by the ecotoxicity tests. It was observed that the coating layer acted as a barrier that inhibits degradation of the plastic when exposed to weathering. The addition of pro-degrading agents promoted acceleration in the degradation process, promoting the migration of the metal ion to the medium without affecting the final quality of the organic compost.

Introdução: Apesar dos avanços significativos no tratamento endovascular das doenças arteriais coronarianas e periféricas, a reestenose intra-stent continua sendo o principal limitante a médio prazo desses procedimentos. O mecanismo da reestenose intra-stent é principalmente a hiperplasia intimal, já que o stent impede a retração elástica aguda e resiste ao remodelamento geométrico negativo tardio. A hiperplasia intimal ocorre basicamente em resposta à formação de trombo local, à inflamação e às dissecções intimais e mediais secundárias à injúria causada pelo stent, sendo o grau de resposta intimal a base dos efeitos a longo prazo. O uso de stents com hastes menores e revestidos com drogas ou polímeros tem sido considerado uma nova alternativa para a prevenção da reestenose intra-stent. Objetivo: Analisar a resposta arterial ao implante de stent de cromo-cobalto sem e com revestimento de polímero Camouflage® em artérias carótidas de suínos, utilizando os seguintes parâmetros histológicos: grau de endotelização, conteúdo de células musculares lisas, grau de angiogênese, conteúdo de fibrina, grau de inflamação e injúria; além da análise histomorfométrica. Método: Stents balões-expansíveis de cromo-cobalto ( 8 stents CC Flex e 5 stents CC Flex Proactive) de 4 x 16 mm foram implantados em artérias carótidas comuns de oito suínos jovens, sendo um stent liberado em cada artéria. Após 30 dias, as artérias contendo os stents foram removidas, fixadas e coradas pelos métodos de hematoxilina/eosina e Verhoeff/Van Giesson. O segmento arterial contendo o stent foi dividido em 3 blocos distintos: proximal, médio e distal. Os cortes histológicos foram obtidos utilizando-se micrótomo de impacto (Polycut S, Leica, Alemanha) equipado com navalha de tungstênio de 16 cm, tipo D (Leica, Alemanha), com 5 ^m de espessura. A navalha de tungstênio mantém as hastes dos stents intactas nas secções transversas, minimizando os artefatos potenciais causados pela retirada dos stents. A avaliação foi realizada através de critérios histológicos e histomorfométricos. Resultados: Todos os stents foram implantados com sucesso e sem dificuldades técnicas. A análise histológica em 30 dias evidenciou alto grau de endotelização em todos os segmentos avaliados e leve à moderada infiltração de células musculares na íntima. Observou-se baixo grau de angiogênese em cerca de 50% dos segmentos avaliados e ausência completa de deposição de fibrina em pelo menos 80%, com distribuição semelhante entre os grupos. A resposta inflamatória e o grau de injúria causadas pelas hastes dos stents também foram discretas e similares entre os grupos e não houve correlação entre resposta inflamatória e injúria e desses parâmetros com a área de neoíntima. O grau de obstrução neo-intimal identificada neste período foi pequeno (15,1% +/- 8,38 CC Flex x 15,5%+/- 5,39 CC Flex ProActive) e estatisticamente não significativo entre os grupos (p=0,785). Conclusão: Os achados deste estudo experimental sugerem que o uso de stents de cromo-cobalto revestidos com polímero Camouflage® em artérias carótidas de suínos parece estar associado, pelo menos no curto prazo, a uma resposta histológica semelhante àquela encontrada após o implante de stents de cromo-cobalto não revestidos. Neste período não se observou uma menor hiperplasia intimal em virtude do revestimento de polímero. / Introduction: Despite all the advances in the endovascular treatment of coronary and peripheral artery diseases, in-stent restenosis is still the main limiting factor of these procedures in the medium and long-term. The mechanism of in-stent restenosis is mainly the intimal hyperplasia, as the stent prevents acute elastic recoil and later negative geometric arterial remodeling. Intimal hyperplasia occurs basically in response to the formation of local thrombus, inflammation and intimal and medial dissections secondary to the injury caused by the stent, with the degree of intimal response being the cause of long-term effects. Coating drug-eluting stents with polymers and drugs with thinner struts have been considered a new alternative for in-stent restenosis prevention. Objective: Analyse the arterial response to the cobalt-chromium stent implant with and without polymer coating Camouflage® in carotid arteries of pigs, using the following histological parameters: degree of endothelialization, smooth muscle cells (SMC) content, degree of angiogenesis, intimal fibrin content, degree of inflammation and injury; plus histomorphometric analysis. Method: Cobaltchromium balloon-expandable stents (8 CC Flex stents and 5 CC Flex Proactive), 4 x 16 mm, were deployed in common carotid arteries of 8 young pigs, with one stent being deployed in each artery. After 30 days, the arteries containing the stents were removed and underwent fixation and staining using the hematoxilin/eosin and Verhoeff /Van Giesson methods. The arterial segment containing the stent was divided into 3 distinct portions: proximal, middle and distal. The histological sections were obtained using impact microtome (Polycut S, Leica, Germany), equipped with a 16 cm, type D, 5 ^m thick tungsten knife (Leica, Germany). The tungsten knife maintains the stent shaft intact in cross sections, minimizing the potential artifacts caused by stent removal. The evaluation was carried out using histological and histomorfometric criteria. Results: All the stents were deployed with success and with no technical difficulties. The histological analysis performed after 30 days showed a high level of endothelialization in all the evaluated portions and mild to moderate infiltration of the SMC in the intima layer. A low level of angiogenesis of about 50% of the evaluated portions was observed and a complete absence of fibrin deposition in at least 80% of the portions, with similar distribution among the groups. The inflammatory response and the level of injury caused by the struts of the stents were also minimum and this was similar among the groups. There was no correlation between inflammatory response and injury and between the two latter parameters and the neo-intima area. The level of neo-intimal obstruction identified in this period was small (15,1% +/- 8,38 CC Flex x 15,5%+/- 5,39 CC Flex ProActive ) and no statistical significance between the groups (p=0,785). Conclusion: The findings of this experimental study suggest the use of balloonexpandable cobalt-chromium stents coated with polymer Camouflage® in carotid arteries of pigs seems to be associated, at least in the short-term, with a similar histological response to that found in the implantation of non-coated cobalt-chromium stents. In this period, a lower intimal hyperplasia was not observed with polymer coating stents.