As lesões cutâneas e queimaduras são considerados os principais causadores de danos e perdas dos tecidos moles. Em casos severos de trauma, os processos naturais de regeneração são insuficientes no reparo dos danos, resultando em lesões cutâneas crônicas. A desvitalização de matrizes homólogas ou heterólogas é uma alternativa para a produção de matrizes dérmicas. A pele porcina é bastante similar à pele humana, podendo ser utilizada como matriz de colágeno na regeneração de tecido mole. Além disso, ela tem como constituinte principal o colágeno tipo I, e, assim, pode ser utilizada em queimaduras de segundo grau. Este trabalho teve como objetivo a preparação e caracterização de matrizes extracelulares de colágeno tipo I por meio de hidrólise alcalina e reticulação com glutaraldeído (GA). As matrizes de colágeno foram obtidas a partir da hidrólise alcalina de pele porcina, com posterior reticulação com GA, em diferentes concentrações (0-0,1%) e tempos de reação (15 e 45 min). As matrizes foram caracterizadas através de determinação do conteúdo de elastina, estabilidade biológica (tripsina), Calorimetria Exploratória Diferencial (DSC), termogravimetria (TG/DTG), Microscopia Eletrônica de Varredura (MEV) e citotoxicidade in vitro. Através da determinação do conteúdo de elastina, foi possível determinar a massa média de colágeno presente nas matrizes, a qual foi de 95,2?0,2% (m/m), e a massa média de elastina, que foi de 4,8?0,2% (m/m), e também verificar que independente do tratamento, a elastina estava presente nas matrizes. O ensaio de estabilidade biológica mostrou que o tratamento com GA diminui a biodegradação do material; sendo obtidos porcentagens de degradação que variaram de 83,6%?1,1 (0% GA) a 46,1%?0,7 (0,085%-45min), indicando, assim, que com o aumento da concentração de GA e do tempo de reação, há uma diminuição da porcentagem de degradação. Pela análise termogravimétrica, foi observado que o colágeno presente nas matrizes tornou-se mais estável termicamente em conseqüência do aumento do grau de reticulação e, portanto, mais resistentes à degradação térmica. Os resultados de DSC confirmam os de termogravimetria devido ao aumento nos valores das temperaturas de desnaturação das matrizes em função do aumento do tempo de reação e da concentração de GA. Pela análise das fotomicrografias, pôde ser observado que após a reticulação com GA, as fibras de colágeno tornam-se mais organizadas e definidas; e essa definição torna-se maior com o aumento da concentração de GA. Os resultados de citotoxicidade in vitro mostraram que as matrizes analisadas são citotóxicas possivelmente devido a gordura remanescente, sendo necessário a realização de um pré-tratamento. Assim, a preparação de matrizes derivadas de pele porcina com diferentes tempos de degradação, as quais podem ser utilizadas na reconstrução de tecidos moles, é viável. / Cutaneous lesions and burns are considered the main causes of damage of soft tissues. In severe cases of trauma, the natural processes of regeneration are insufficient in the repair of the damage, resulting in chronic cutaneous lesions. Desvitalization of homologous or heterologous matrices is an alternative for the production of dermal matrices. The porcine skin is quite similar to the human skin and can be used as collagen matrix in soft tissue regeneration. Besides, it contains type I collagen as the main constituent and thus, it can be used in second degree burns. The objective of this work was the preparation and characterization of type I collagen extracellular matrices with alkaline hydrolysis and glutaraldehyde (GA) crosslinking. The collagen matrices were obtained from the alkaline hydrolysis of porcine skin, with subsequent GA crosslinking, in different concentrations (0 - 0,1%) and reaction time (15 and 45 min). Matrices were characterized by determination of the elastin content, biological stability (trypsin), differential scanning calorimetry (DSC), termogravimetry (TG/DTG), scanning electron microscopy (SEM) and a preliminar assay of in vitro cytotoxicity. Elastin and collagen content were 4,8±0,2% (m/m) and 95,2±0,2% (m/m), respectively. Biological stability results showed that GA crosslinking reduces matrix biodegradation; as degradation varied from 83,6%±1,1 (0% GA) to 46,1%±0,7 (0,085% - 45min), demonstrating, thus, that with the increase of GA concentration and reaction time, there was a decrease of degradation. For termogravimetric analysis it was observed that the collagen present in the matrices become termically more resistant as a consequence of the increasing crosslink degree and, therefore, more resistant to thermal degradation. DSC results, similar to termogravimetric ones, showed an increase in denaturation temperatures as a function of increasing reaction time and GA concentration. SEM analysis showed that after the GA crosslinking, collagen fibers become more organized and defined; and that definition improved with increasing GA concentration. Preliminar assay of in vitro cytotoxicity showed that treated matrices are cytotoxic possibly due to remaining fat, being necessary the accomplishment of a pre-treatment. Therefore, porcine skin matrices preparation with different degradation times, which can be used in the soft tissue reconstruction, are viable.

Orientador: Maria Helena Andrade Santana / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T09:43:37Z (GMT). No. of bitstreams: 1 Martinez_RenataMiliani_M.pdf: 2560469 bytes, checksum: b2891306de29653ef82ffcbbab2a7cb3 (MD5) Previous issue date: 2013 / Resumo: O uso de matérias-primas sustentáveis, biodegradáveis e biocompatíveis é de grande interesse em aplicações farmacêuticas e cosméticas. O mercado cosmético situa-se em pleno processo de desenvolvimento, principalmente na área de produtos capilares, apresentando vendas expressivas no Brasil. Esse crescimento acarreta na necessidade de produtos inovadores, polivalentes e seguros para oferecimento aos consumidores. Neste âmbito, as partículas poliméricas coloidais têm ocupado posição de destaque no cenário mundial, marcando a presença da nanotecnologia em produtos cosméticos. Uma grande variedade de matérias-primas naturais ou sintéticas são polieletrólitos, cuja reticulação eletrostática em condições controladas produz partículas coloidais. A pectina cítrica e as peptonas vegetais fazem parte dos polieletrólitos, cuja origem vegetal tem sido preferida para as aplicações em cosméticos, em substituição a produtos de origem animal ou inorgânica. Neste trabalho, foi estudada a produção de partículas coloidais de pectina cítrica e das peptonas de soja e trigo, reticuladas com cloreto de cálcio e goma guar quaternizada. Em todos os casos, a produção das partículas foi realizada em processo descontínuo, simples, escalonável e na ausência de solventes orgânicos, envolvendo o gotejamento de solução do agente reticulante sobre a solução do polieletrólito sob agitação mecânica. Os resultados mostraram que para a pectina cítrica, o tamanho e a polidispersidade das partículas foram controlados pelo grau de esterificação, agente reticulante e concentração inicial de eletrólito em solução. Para obtenção de partículas em escala nanométrica, a concentração da pectina foi de 10,0 g/l e a concentração do agente reticulante foi 1,0% (m/v). As partículas obtidas conferiram viscoelasticidade à mistura de solução de pectina e copolímero catiônico (poliquaternium-7). A viscoelasticidade foi dependente da proporção e do diâmetro das partículas de pectina, com contribuição semelhante das partículas micro e nanométricas para formações viscoelásticas. No caso das peptonas vegetais, as de trigo tiveram o seu melhor desempenho na formação de nanopartículas com menor polidispersidade. As partículas obtidas atenderam às características físico-químicas de composição, tamanho e polidispersidade requeridas para aplicações em cosméticos. As partículas de pectina, em particular, apresentaram-se promissoras para aplicações em produtos cosméticos capilares devido tamanho reduzido e potencial viscoelástico. Os fios de cabelo submetidos aos processos de transformação capilar foram o foco para a aplicação dessas partículas na tentativa de minimizar os danos pré-existentes / Abstract: The use of sustainable, biodegradable and biocompatible raw materials show great interest for pharmaceutical and cosmetic applications. The cosmetic market is situated in development process, particularly in the area of hair products, with significant sales in Brazil. This growth brings the need for innovative, versatile and safe products to consumers. In this context, polymeric colloidal particles have occupied a prominent position on the world stage, marking the presence of nanotechnology in cosmetics. A variety of materials are natural or synthetic polyelectrolytes, whose electrostatic crosslinking in controlled conditions produces colloidal particles. The citrus pectin and vegetables peptones are part of polyelectrolytes, whose vegetable source has been preferred for applications in cosmetics, replacing animal products or inorganic materials. In this work, we studied the production of colloidal particles of citrus pectin and soybean and wheat peptones, all crosslinked with calcium chloride and quaternized guar gum. In all cases, production of particles was performed in a batch process, simple, scalable and in the absence of organic solvents, involving the drip of crosslinking agent on the polyelectrolyte solution under mechanical stirring. The results showed that for citrus pectin, size and polydispersity of the particles was controlled by the degree of esterification, crosslinking agent and initial concentration of electrolyte in solution. To obtain nanometer scale particles the concentration of the pectin was 10.0 g/l and the concentration of crosslinking agent was 1.0% (m / v). The particles obtained impart viscoelasticity to the mixture of pectin and cationic copolymer (polyquaternium-7). The viscoelasticity depended on the proportion and the particle diameter of pectin, as the micro and nanometric particles were similar to viscoelastic formations. In the case of peptones, wheat had the better performance in the formation of nanoparticles with low polydispersity. The obtained particles met the physico-chemical composition, size and polydispersity required for applications in cosmetics. The pectin particles, in particular, were very promising for applications in cosmetic hair due small size and potential viscoelastic. Capillary transformation processes were the focus for the application of these particles in an attempt to minimize the pre-existing damaged hair / Mestrado / Engenharia de Processos / Mestra em Engenharia Química

Orientador: Lucia Helena Innocentinni Mei / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T09:55:20Z (GMT). No. of bitstreams: 1 Carvalho_IviMartinsde_M.pdf: 1540327 bytes, checksum: 645ccaa60b4cb1206d1e1a77feb19416 (MD5) Previous issue date: 2012 / Resumo: Plastissois de PVC reticulados na presença de resina epóxi polifuncional foram obtidos através de espalmagem. Foi possível inferir que a presença de um acelerador tipo amina, ao menos nas condições de processamento utilizadas neste estudo, mostrou-se imprescindível para a ocorrência do processo de reticulação. Resultados de grau de reticulação mostraram que só houve formação de gel nas amostras onde o acelerador foi utilizado concomitantemente com a resina epóxi. Apesar da comprovação da reação química ser dificultada pelo grande número de diferentes sinais de FTIR presentes na formulação, resultados de teor de gel e módulo de Young parecem confirmar a hipótese de formação de uma rede tridimensional entre as moléculas do PVC e a resina epóxi, porém serão necessários estudos mais aprofundados no futuro para identificação do polímero hiper-ramificado formado / Abstract: Crosslinked PVC plastisols in the presence of polyfunctional epoxy resin were obtained from spreadcoating. It was possible to infer that the presence of an amine type accelerator, at least in the conditions used in this study proved to be essential for the occurrence of the crosslinking process. The results of reticulation degree showed that gel formation only happened in samples where the amine has been used concomitantly with the epoxy resin. Despite the evidence of chemical reaction is complicated by the large number of molecules present in the formulation, Young's modulus results seem to confirm the hypothesis of the formation of a three-dimensional network between the molecules of PVC and epoxy resin, but further studies are needed in the future to identify the hyperbranched polymer formed / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

Jusqu'à récemment, l'industrie chimique se contentait de développer des produits en répondant exclusivement à des contraintes de prix et de performance sans accorder d'importance à l'origine et à la toxicité des matières premières utilisées. Cependant, face à la diminution des ressources pétrolières et aux enjeux environnementaux, le développement de produits durables a connu un fort essor au cours des dernières années et confronte dorénavant les chimistes à de nouvelles contraintes sanitaires et environnementales. Dans ce contexte, la vieille chimie des peintures alkydes a été remise à l’ordre du jour, puisqu'utilisant un liant issu d'une polycondensation entre des matières premières renouvelables. Le séchage d’une peinture alkyde implique à l’heure actuelle un mécanisme oxydatif nécessitant d'être catalysé par des sels de Cobalt pour se produire en moins de 6 h. Ces catalyseurs sont potentiellement cancérogènes et soumis au règlement REACH. Après un état de l'art sur les alkydes et les alternatives aux sels de cobalt, trois mécanismes de réticulation ont été proposés afin d'offrir une alternative viable au séchage oxydatif. Ces trois mécanismes reposent sur une réaction chimique à température ambiante entre deux groupements fonctionnels. Plusieurs résines alkydes biosourcées et ainsi fonctionnalisées ont été synthétisées et caractérisées par mesures physico-chimiques. Leurs performances de séchage ont ensuite été évaluées et comparées au séchage oxydatif d'une résine alkyde conventionnelle par mesure de leur dureté Persoz, leur jaunissement dans le temps, leur brillance ou encore par mesure d'angle de contact. / Up to recently, the origin and toxicity of raw material were not a major concern for the chemical industry, the main drivers of innovation being cost and performance. Increasing awareness of sustainability, supported by both public opinion and governments, is now adding a new constraint for chemists to take into account the origin of the raw materials used. In this context, alkyd coatings are making a huge comeback, because based on a binder obtained by polycondensation reactions of renewable raw materials. Conventional alkyd paints chemically dry through an oxidative mechanism, which requires cobalt salt to occur in less than 6 h. Chemical regulations such as REACH tend to limit the use of colbalt salts, because of their potentially carcinogenic effect. After reviewing the current state-of-the-art regarding conventional alkyd resins and cobalt salts alternatives, we proposed three new non-oxidative drying mechanism, each involving a chemical reaction between two key functional groups. Several biobased alkyd resins bearing these chemical groups were synthesized and characterized by physico-chemical analysis. Their drying performances were evaluated by following over time the Persoz hardness, the gloss, the yellowing or the contact angles. These non-oxidative crosslinking mechanisms were then compared with the oxidative drying of a conventional alkyd binder.

Dicyclopentadiene (DCPD), a tricyclic olefin, is available from the C5 fraction of petroleum feedstocks. Owing to its high reactivity (due to the presence of a strained alkene), low cost, and lack of other commercial uses, DCPD has been extensively pursued as a monomer for use in ring-opening metathesis polymerization processes. The olefin metathesis reaction, for which Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock received the 2005 Nobel prize, is among the most attractive approaches to polymerize olefins, allowing production of high-molecular weight polymers including linear macromolecules, block copolymers, and crosslinked materials. Polydicyclopentadiene (PDCPD), which can be produced using a variety of early- and late-transition metal catalysts, is a thermoset polymer with a highly crosslinked structure. PDCPD has excellent impact strength, high storage modulus, good chemical resistance, wide service temperature range, and low density. As a result, it has found broad commercial utility in industrial manufacturing. Additionally, the reaction injecting molding (RIM) process used for DCPD polymerization makes it possible to precisely control the shape and dimensions of PDCPD products. Owing to its lack of chemical functionality, however, polydicyclopentadiene has many limitations. Previously, our research group developed a modified dicyclopentadiene monomer by adding an electron withdrawing group – a methyl ester functional group – on the pendent cyclopentene ring of the monomer. Polymerization of this functionalized monomer led to a novel thermoset material – methyl ester functionalized polydicyclopentadiene (fPDCPD) – that exhibits tunable surface hydrophobicity. In experiments described in this dissertation, my collaborators and I confirmed the thermal crosslinking mechanism of fPDCPD using a combination of solution-state and solid-state NMR, FTIR, and Raman spectroscopy. We also explored the surface chemistry of our novel material, by harnessing the embedded functional group in order to exert finer control over hydrophobicity, and to control interactions with biological organisms through the conjugation of biologically relevant functional groups. To further extend the utility of our functionalized dicyclopentadiene monomer, we synthesized a series of statistical polymers: fPDCPD-stat-PDCPD. Once again, we used a wide range of characterization methods, and showed that we can both tune the surface hydrophobicity of the copolymers and manipulate the mechanical properties by adjusting the molar fractions of functionalized and non-functionalized monomers. Chemical structures of these copolymers were interrogated by NMR, FTIR, and Raman spectroscopy. Frontal ring-opening metathesis polymerization was applied in an effort to study the kinetics of (co)polymerization. Finally, to lay the groundwork for future fPDCPD manufacturing, we successfully optimized the production of fDCPD monomers to half-kilo scale and fPDCPD polymers at 20-gram scale, while developing a reaction-injection molding process that permitted the production of dimensionally controlled fPDCPD objects. This in turn allowed us to conduct a rigorous assessment of the mechanical properties of our fDCPD through dynamic mechanical analysis (DMA), which established for the first time that our functionalized material has a comparable storage modulus to that of the parent (unmodified) PDCPD. The development of fPDCPD is approaching a new stage where it is ready to be commercialized and mass produced. We hope that our novel fPDCPD material will soon play a crucial role in replacing traditional metallic components in vehicle design and engineering material manufacturing. / Graduate / 2021-12-14

Všeobecne, cieľom tejto diplomovej práce bola príprava a charakterizácia sieťovaných hyaluronových mikrovláken, ktoré by boli stabilné vo vodnom prostredí s vhodnými mechanickými vlastnosťami. Vlákna pripravené technikou zvlákňovania z roztoku boli sieťované pomocou roztoku so sieťovacím činidlom 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimidom alebo roztoku s dvoma sieťovacími činidlami 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimidom a N-hydroxysuccinimidom, vedúcim k amidácii a tvorbe esterových väzieb. Charakterizácia pripravených vzoriek je hlavným cieľom experimentálnej časti práce. Charakteristiky botnání boli vykonané na určenie stability vláken v troch rôznych roztokoch (s pH 7.4, 3 a 11). Na určenie termickej stability bola využitá termogravimetrická analýza a na stanovenie esterifikácie a amidácie bola použitá infračervená spektroskopia s Fourierovou transformáciou. Mechanické vlastnosti vláken boli študované pomocou testovania závislosti stress-strain. Ďalej boli testované reologické vlastnosti ako aj mikroštruktúra a povrch vláken pomocou skenovacieho elektrónového mikroskopu. Vlákna pred chemickým sieťovaním vykazovali nižšiu stabilitu vo všetkých troch roztokoch, termálna stabilita bola taktiež nižšia ako stabilita zosieťovaných vláken. Pre vlákna chemicky nemodifikované so sieťujúcim činidlom, sa objavil iba jeden typ píku pre esterifikáciu. Infračervené spektrum chemicky zosieťovaných vláken ukázalo prítomnosť dvoch píkov pre esterifikáciu, čo je prejavom efektivity sieťovacieho činidla. Amidácia bola tiež výraznejšia pri zosieťovaných vláknach, špeciálne pre vlákna sieťované dlhú dobu a v roztoku s vyššou koncentráciou sieťujúceho činidla. Kvôli nerovnomerným vláknam, mechanické vlastnosti nevykazovali žiadnu závislosť na sieťovaní. Štúdium reológie ukázalo, že viskozita vlákna rozpusteného vo vode je menej závislá na šmykovej rýchlosti ako prášok hyaluronanu sodného rozpusteného vo vode. Napriek mnohým rôznym metódam charakterizácie vláken, ktoré boli použité v tejto práci, je stále veľa možností pre lepšiu charakterizáciu a bližšie pochopenie tohto biopolymérneho materiálu.

Táto práca si dáva za cieľ chemicky zasieťovať biodegradovateľný makromonomér ,-itaconyl-PLGA–PEG–PLGA vo vodnom roztoku pri teplote okolia a pri teplote tela (37 °C). ,-itaconyl-PLGA–PEG–PLGA makromonomér môže vo vode vytvárať fyzikálnu sieť vďaka hydrofóbnym interakciám medzi hydrofóbnym PLGA a hydrofilným PEG. Vďaka dvojitej väzbe kyseliny itakonovej, ktorá je k makromonoméru pripojená na jeho koncoch, sa naskytuje možnosť dodatočného chemického zasieťovania fotopolymerizáciou. Výsledkom je hybridná sieť, ktorá zvyšuje mechanickú stabilitu a životnosť hydrogélu. Na priame sledovanie formovania siete prostredníctvom zmeny mechanických vlastností bola v práci použitá fotoreológia.

The need for sustainable packaging is growing, and plastic waste needs to be reduced. A suitable alternative could be fibre-based packaging and cartonboard, and several actions could enhance this alternative. This study investigates crosslinking, a method to create stronger bonds between the OH-groups in the material. The aim is to gather information on the potential of the concept since there is previously a limited amount of research on the specific area. The goal, in the long run, is to create stronger packaging. The study will contribute with knowledge around how crosslinking can be used to enhance the strength of cartonboard and contribute to the development of more durable material. Two research questions were formulated to investigate this.  RQ1: How does the crosslinking concept affect properties of cartonboard when applied? RQ2: What effect could the crosslinking concept have on the product area cartonboard? The research has a deductive starting point, and the project planning was agile, which allowed the study to form as the results gave new intel about the concept. The focus is on collecting qualitative data with high validity, which has been done by testing the material according to different standards. The material investigated is a folding boxboard (FBB) in four separate grammages to give an overview of the effect of the concepts. Properties evaluated include short span compression test (SCT), tensile strength, recyclability, cobb and box compression resistance tests (BCR), and more.  The results show a slight increase in SCT for the highest, 460 gsm, and lowest, 245 gsm, grammages of the materials used in this study. The recyclable is affected minimally with only a few per cent, but it remains high. However, the material becomes a bit stiffer and suffers losses in tensile strength, elongation, and tensile energy absorption. The enhanced strength seen in SCT does not show for BCR. The crosslinked material tends to crack in the creases before and after bending, especially in the highest grammage. The Cobb results indicate crosslinking shows potential to be used as a barrier to make the material more water repellent.  Conclusions drawn from the results are that even though the SCT value is enhanced for two grammages, it suffers losses in tensile strength, and the strength enhancement does not show for BCR. Therefore, the impact on the product area is not clear, and further research is recommended to understand the area more.  Suggestion for further research is to do more research in the area in general and then scale up the study to a pilot study. This would gain intel on how the concept will work in a non-laboratory situation and investigate how it could be implemented in production

No description available.

Thesis: M.S., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1980 / Includes bibliographical references. / by Dennis P. Orgill. / M.S. / M.S. Massachusetts Institute of Technology, Department of Mechanical Engineering