Os materiais poliméricos são vastamente utilizados em várias áreas de aplicação, como na construção civil, automobilística, embalagens, indústrias em geral, entre outras, substituindo de modo versátil e eficiente os metais, cerâmicos e madeira. No entanto, existe um grande volume de descarte de resíduos industriais poliméricos que atualmente não recebem destinação adequada para reciclagem, entre eles o poliuretano (PU) termorrígido (espumas rígidas e flexíveis). O PU é um material versátil devido a sua vasta possibilidade de aplicações, porém grandes volumes de PU na forma de resíduos industriais e materiais de pós-uso são descartados em aterros industriais e sanitários todos os anos. O reaproveitamento dos resíduos de PU pelo processo de reciclagem mecânica é uma alternativa ambientalmente sustentável e correta, pois gera valor agregado a este material e promove uma melhor utilização dos recursos naturais não renováveis. O objetivo deste trabalho foi o desenvolvimento de placas aglomeradas de resíduos industriais de poliuretano skin (PUs) com a adição de diferentes retardantes de chama, além da avaliação das propriedades de reação ao fogo, morfológicas, físicas e mecânicas dos aglomerados obtidos. As composições utilizadas foram 40 a 70 % (massa) de resíduos industriais de PUs, 30 % de agente aglomerante (Elastan) e 0 a 30 % de diferentes retardantes de chama (alumina trihidratada - ATH, polifosfato de melamina - MPP, polifosfato de amônio - APP e trióxido de antimônio + óxido de decabromodifenila - TADB ). Para obtenção das placas aglomeradas, diferentes composições foram moldadas por compressão utilizando 2 a 6 kgf·cm-2 a 60 ºC por 10 min. Este estudo concluiu que as amostras PUs(40)/APP(30) e PUs(40)/TADB(30) (contendo 30 % (massa) de retardantes de chama) apresentaram os melhores resultados de reação ao fogo, com classificação V0 conforme a norma UL94-V. Foi evidenciado também que diferentes tamanhos de granulometrias de PUs não alteraram as propriedades de comportamento ao fogo dos aglomerados desenvolvidos. Os ensaios mecânicos mostraram que os aglomerados possuem resistência superior à necessária para o manuseio e aplicação dos mesmos, e os resultados de condutividade térmica mostraram que estes materiais possivelmente podem ser destinados para aplicações térmicas na construção civil e na indústria. / Submitted by cmquadros@ucs.br (cmquadros@ucs.br) on 2018-03-12T14:26:10Z No. of bitstreams: 1 Dissertacao Aguinaldo Oliveira Machado.pdf: 2434507 bytes, checksum: 6712200b80af1c8456ff6e809d6c66cb (MD5) / Made available in DSpace on 2018-03-12T14:26:10Z (GMT). No. of bitstreams: 1 Dissertacao Aguinaldo Oliveira Machado.pdf: 2434507 bytes, checksum: 6712200b80af1c8456ff6e809d6c66cb (MD5) Previous issue date: 2018-03-12 / The polymeric materials are widely used in many application areas, such as in civil construction, automotive, packaging, general industry, among others, replacing metals, ceramics and wood in a versatile and efficient way However, there is a large volume of discard of polymeric industrial waste that does not currently receive adequate destination for recycling, among them thermo-rigid polyurethane (PU) (rigid and flexible foams). The polyurethane (PU) is a versatile material because of its wide range of applications, but large volumes of PU in the form of industrial waste and post-use materials are disposed of in industrial and sanitary landfills every year. The reuse of PU waste by the mechanical recycling process is an environmentally sustainable and correct alternative, as it generates added value to this material and promotes a better use of non-renewable natural resources. The objective of this work was the development of agglomerated boards of skin polyurethane (PUs) (industrial wast) with the addition of different flame retardants, as well as the evaluation of fire reaction, morphological, physical and mechanical properties of the agglomerates obtained. The compositions used were 40 to 70 % (mass) industrial waste PUs, 30 % binder agent (Elastan) and 0 to 30 % of different flame retardants (alumina trihydrate - ATH, melamine polyphosphate - MPP, ammonium polyphosphate - APP and antimony trioxide + decabromodiphenyl oxide - TADB). To obtain the agglomerated boards, different compositions were compression molded using 2 to 6 kgf·cm-2 at 60 °C for 10 min. This study concluded that the samples PUs(40)/APP(30) and PUs(40)/TADB(30) (containing 30 % by mass of flame retardants) presented the best results of reaction to fire, with classification V0, according to the UL94-V standard. It was also evidenced that different size of PU granulometry does not alter the properties of reaction to fire of the developed agglomerates. The mechanical tests show that the agglomerates have superior resistance than necessary for the handling and application, and the results of thermal conductivity prove that these materials can possibly be destined for thermic applications in building construction and industry.

Neste trabalho foram obtidos nanocompósitos contendo 0, 1, 2, 5 e 10% (m/m) de argila organofílica montmorilonita cloisite 30B, contendo terminações hidroxila, por processamento reativo entre um pré-polímero com terminações isocianato e o 1,4-butanodiol, utilizando-se um misturador fechado. Os resultados mostraram que os poliuretanos termoplásticos sintetizados foram obtidos com sucesso. A adição de montmorilonita nos TPUs ocasionou a formação de folhas de argila dispersas de maneira intercalada, parcialmente esfoliada, esfoliada e aglomerados na matriz do TPU. Com a adição da argila houve modificações nos comportamentos de cristalização, estabilidade térmcica e mecanismo de degradação, assim como um aumento nos valores de energia aparente de ativação deste processo. A mobilidade de alguns segmentos poliméricos também foi alterada com a adição da argila. Portanto modificações morfológicas e viscoelásticas foram observadas para os nanocompósitos em dependência da quantidade de argila organofílica empregada, assim como a adição da organoargila alterou o comportamento térmico do poliuretano termoplástico, tornando os nanocompósitos mais suscetíveis a mudanças nos processos de fusão e cristalização em função da exposição a temperaturas elevadas. / In this study, were obtained nanocomposites containing 0, 1, 2, 5 and 10% (w/w) of organophilic clay montmorillonite Cloisite 30B, containing hydroxyl terminations, by reactive processing between a prepolymer with isocyanate terminations and 1,4-butanediol, using a closed mixer. The analysis showed that the obtained thermoplastic polyurethanes were synthesized successfully. The addition of the montmorillonite in the TPUs resulted in the formation of sheets of clay dispersed in order intercalated, partially exfoliated, exfoliated and agglomerate in the TPU matrix. With the addition of clay there were changes in the behavior of crystallization, thermal stability and degradation mechanism, as well as an increase in the values of the apparent activation energy of this process. The mobility of certain polymer segments was also changed with the addition of the clay. Therefore viscoelastic and morphological changes were observed in the nanocomposites in dependence on the amount of organophilic clay used, as well as the addition of the organophilic decreased the thermal stability of the thermoplastic polyurethane, making nanocomposites more susceptible to changes in the melting and crystallization processes due to exposure to elevated temperatures.

Neste trabalho foram obtidos nanocompósitos contendo 0, 1, 2, 5 e 10% (m/m) de argila organofílica montmorilonita cloisite 30B, contendo terminações hidroxila, por processamento reativo entre um pré-polímero com terminações isocianato e o 1,4-butanodiol, utilizando-se um misturador fechado. Os resultados mostraram que os poliuretanos termoplásticos sintetizados foram obtidos com sucesso. A adição de montmorilonita nos TPUs ocasionou a formação de folhas de argila dispersas de maneira intercalada, parcialmente esfoliada, esfoliada e aglomerados na matriz do TPU. Com a adição da argila houve modificações nos comportamentos de cristalização, estabilidade térmcica e mecanismo de degradação, assim como um aumento nos valores de energia aparente de ativação deste processo. A mobilidade de alguns segmentos poliméricos também foi alterada com a adição da argila. Portanto modificações morfológicas e viscoelásticas foram observadas para os nanocompósitos em dependência da quantidade de argila organofílica empregada, assim como a adição da organoargila alterou o comportamento térmico do poliuretano termoplástico, tornando os nanocompósitos mais suscetíveis a mudanças nos processos de fusão e cristalização em função da exposição a temperaturas elevadas. / In this study, were obtained nanocomposites containing 0, 1, 2, 5 and 10% (w/w) of organophilic clay montmorillonite Cloisite 30B, containing hydroxyl terminations, by reactive processing between a prepolymer with isocyanate terminations and 1,4-butanediol, using a closed mixer. The analysis showed that the obtained thermoplastic polyurethanes were synthesized successfully. The addition of the montmorillonite in the TPUs resulted in the formation of sheets of clay dispersed in order intercalated, partially exfoliated, exfoliated and agglomerate in the TPU matrix. With the addition of clay there were changes in the behavior of crystallization, thermal stability and degradation mechanism, as well as an increase in the values of the apparent activation energy of this process. The mobility of certain polymer segments was also changed with the addition of the clay. Therefore viscoelastic and morphological changes were observed in the nanocomposites in dependence on the amount of organophilic clay used, as well as the addition of the organophilic decreased the thermal stability of the thermoplastic polyurethane, making nanocomposites more susceptible to changes in the melting and crystallization processes due to exposure to elevated temperatures.

Os materiais poliméricos são vastamente utilizados em várias áreas de aplicação, como na construção civil, automobilística, embalagens, indústrias em geral, entre outras, substituindo de modo versátil e eficiente os metais, cerâmicos e madeira. No entanto, existe um grande volume de descarte de resíduos industriais poliméricos que atualmente não recebem destinação adequada para reciclagem, entre eles o poliuretano (PU) termorrígido (espumas rígidas e flexíveis). O PU é um material versátil devido a sua vasta possibilidade de aplicações, porém grandes volumes de PU na forma de resíduos industriais e materiais de pós-uso são descartados em aterros industriais e sanitários todos os anos. O reaproveitamento dos resíduos de PU pelo processo de reciclagem mecânica é uma alternativa ambientalmente sustentável e correta, pois gera valor agregado a este material e promove uma melhor utilização dos recursos naturais não renováveis. O objetivo deste trabalho foi o desenvolvimento de placas aglomeradas de resíduos industriais de poliuretano skin (PUs) com a adição de diferentes retardantes de chama, além da avaliação das propriedades de reação ao fogo, morfológicas, físicas e mecânicas dos aglomerados obtidos. As composições utilizadas foram 40 a 70 % (massa) de resíduos industriais de PUs, 30 % de agente aglomerante (Elastan) e 0 a 30 % de diferentes retardantes de chama (alumina trihidratada - ATH, polifosfato de melamina - MPP, polifosfato de amônio - APP e trióxido de antimônio + óxido de decabromodifenila - TADB ). Para obtenção das placas aglomeradas, diferentes composições foram moldadas por compressão utilizando 2 a 6 kgf·cm-2 a 60 ºC por 10 min. Este estudo concluiu que as amostras PUs(40)/APP(30) e PUs(40)/TADB(30) (contendo 30 % (massa) de retardantes de chama) apresentaram os melhores resultados de reação ao fogo, com classificação V0 conforme a norma UL94-V. Foi evidenciado também que diferentes tamanhos de granulometrias de PUs não alteraram as propriedades de comportamento ao fogo dos aglomerados desenvolvidos. Os ensaios mecânicos mostraram que os aglomerados possuem resistência superior à necessária para o manuseio e aplicação dos mesmos, e os resultados de condutividade térmica mostraram que estes materiais possivelmente podem ser destinados para aplicações térmicas na construção civil e na indústria. / The polymeric materials are widely used in many application areas, such as in civil construction, automotive, packaging, general industry, among others, replacing metals, ceramics and wood in a versatile and efficient way However, there is a large volume of discard of polymeric industrial waste that does not currently receive adequate destination for recycling, among them thermo-rigid polyurethane (PU) (rigid and flexible foams). The polyurethane (PU) is a versatile material because of its wide range of applications, but large volumes of PU in the form of industrial waste and post-use materials are disposed of in industrial and sanitary landfills every year. The reuse of PU waste by the mechanical recycling process is an environmentally sustainable and correct alternative, as it generates added value to this material and promotes a better use of non-renewable natural resources. The objective of this work was the development of agglomerated boards of skin polyurethane (PUs) (industrial wast) with the addition of different flame retardants, as well as the evaluation of fire reaction, morphological, physical and mechanical properties of the agglomerates obtained. The compositions used were 40 to 70 % (mass) industrial waste PUs, 30 % binder agent (Elastan) and 0 to 30 % of different flame retardants (alumina trihydrate - ATH, melamine polyphosphate - MPP, ammonium polyphosphate - APP and antimony trioxide + decabromodiphenyl oxide - TADB). To obtain the agglomerated boards, different compositions were compression molded using 2 to 6 kgf·cm-2 at 60 °C for 10 min. This study concluded that the samples PUs(40)/APP(30) and PUs(40)/TADB(30) (containing 30 % by mass of flame retardants) presented the best results of reaction to fire, with classification V0, according to the UL94-V standard. It was also evidenced that different size of PU granulometry does not alter the properties of reaction to fire of the developed agglomerates. The mechanical tests show that the agglomerates have superior resistance than necessary for the handling and application, and the results of thermal conductivity prove that these materials can possibly be destined for thermic applications in building construction and industry.

INTRODUÇÃO: O tratamento cirúrgico das estenoses uretrais com enxertos limita-se ao emprego de materiais orgânicos, mais freqüentemente autoenxertos. O sucesso no uso de biomateriais sintéticos em diferentes áreas da medicina motivou a pesquisa desses materiais na reconstrução uretral. A informação de que o uso de prótese mamária de silicone recoberta com espuma de poliuretano revelou menor retração cicatricial que as próteses convencionais e o fato desses polímeros já serem empregados como elastômero na confecção de cateteres urinários, levou à escolha deste material para estudo. MÉTODOS: Foi realizada a ressecção de segmento dorsal da uretra anterior de 20 coelhos machos NZW. O defeito uretral foi tratado com o implante no leito uretral dorsal de uma placa não tubularizada de silicone, revestida externamente com espuma de poliuretano (Si-Pu). Como controle foi confeccionado o grupo Sham (GS) com 12 animais. Este grupo foi submetido à uretrotomia dorsal longitudinal e uretrorrafia, sem qualquer tipo de implante. As análises foram feitas com 2, 4, 8 e 24 semanas após a cirurgia. Analisaram-se alterações da circunferência da uretra e complicações cirúrgicas. Fez-se estudo histológico com coloração de Tricrômico de Mason, Hematoxilina-eosina e Picrosírirus red. Foram avaliadas: intensidade e características da resposta inflamatória, espessura da parede da uretra (edema) e concentração do colágeno na submucosa da uretra. Foi realizada análise microbiológica e pesquisa de incrustação do implante por termogravimetria. Os achados foram comparados com os dados de três coelhos que não sofreram qualquer intervenção. RESULTADOS: Não foram encontradas fístulas, estenoses, obstrução, calcificação, retração cicatricial ou deiscências. Ocorreu expulsão do implante em 1/5 dos animais após 4 semanas, em 2/5 com 8 semanas e em 3/5 com 24 semanas. Não houve redução da circunferência da uretra na comparação entre os grupos Experimental (GE) e GS, exceto para o intervalo de 8 semanas. Ocorreu infecção do sítio cirúrgico em 11 de 12 animais do GS e em 13 de 20 animais do GE. As bactéria mais comumente encontradas foram Staphylococcus DNAse negativa (9/32) e Escherichia coli (5/32). A presença de infecção por Enterobacter cloacae foi acompanhada de menor ganho de peso pelos animais (P=0,02), fato não observado na infecção com outras bactérias. A circunferência uretral foi maior (P=0,006) na vigência de infecção por Staphylococcus do que nas amostras estéreis. A histologia do GE mostrou processo inflamatório severo e substituição das fibras musculares da lâmina própria por colágeno com regressão do edema e das células inflamatórias, tardiamente. No GS ocorreu deposição tardia de colágeno e inflamação leve, porém constante. Houve re-epitelização da uretra nos dois grupos. A concentração de colágeno na área manipulada foi maior apenas na comparação entre os GE e GS com 24 semanas (P<0,001). O edema da parede uretral foi maior no GE que no GS nos intervalos de 2 semanas e de 4 semanas com P<0,001, e após 8 semanas com P<0,05. Após 24 semanas não se verificou diferença entre as espessuras da submucosa. Na análise descritiva da termogravimetria observou-se incrustação de material orgânico no implante, que não se mostrou significante estatisticamente na análise quantitativa de perda de massa. A incrustação de material inorgânico ao implante foi desprezível. CONCLUSÕES: O uso do Si-Pu leva à formação de cápsula colágena que permite a re-epitelização da uretra sem ocasionar retração local, funcionando como um biomolde, porém a expulsão do implante limita seu uso / BACKGROUND: Actually, the treatment of urethral stenosis employs biological grafts, usually autologous grafts. The success with synthetic biomaterials in others medical specialtys motivated the search of these materials in urethral reconstruction. The knowledge about the silicone mamarian prosthesis covered with polyurethane foam reduces capsular contracture in breast implants and because these polymers are already used in the urinary tract like catheters make the choice for these materials. METHODS: The resection of dorsal segment of anterior urethra of 20 male rabbits NZW was carried through. The urethral defect was treated with the on lay dorsal graft in urethra, compound a silicone not tabularized, coated with polyurethane foam in one face (Si-Pu). The control group (sham) was confectioned with 12 animals was submitted to longitudinal dorsal uretrotomy and suture, without any type of implantation (SG). The analyses intervals were 2, 4, 8 and 24 weeks after surgery. The circumference of urethra and surgical complications had been analyzed. Material for histological evaluation was stained with Massons thrichrome, hematoxylin and eosin and Picrosirius red. Intensity and characteristics of the inflammatory response, thickness of the urethra (oedema) and concentration of the collagen in the submucosa had been evaluated. Still, was performed microbiological analysis and research of implants incrustation with thermogravimetry. The findings had been compared with the data of three rabbits that had not suffered any intervention. RESULTS: The morfological analysis not founded fistula, obstruction, stenosis, cicatricial retraction, calcification and dehiscence. The graft was extruded after 4 weeks in 1/5 of the animals, in 2/5 after 8 weeks and after 24 weeks, 3/5 of the animals had failure of union with the surrounding tissue. Except for the interval of 8 weeks, It did not have urethral circumference reduction in the comparison between groups, Experimental (EG) and SG. Infection of the surgical place occurred in 11 of 12 animals of the GS and in 13 of 20 animals of EG. Staphylococcus DNAse-negative and Escherichia coli were the most frequent bacterium founded, and occurred in 9/32 and 5/32, respectively. The infection with Enterobacter cloacae was associated to lesser weight gain for the animals (P=0,02), fact not observed in infection with other bacteria. The Staphylococcus infection was associated to larger urethral circumference (P=0,006), when compared to sterile samples. The EG histological analysis showed early severe inflammatory process and substitution of smooth muscle fibers for collagen and regression of edema and inflammatory cells decrease laterly. Occurred delayed deposition of collagen and slight inflammation in the SG, however this process was constant. Was observed urothelial reepithelialization in both groups. The collagen concentration in urethral wall at surgical site was larger in EG with 24 weeks when compared to SG at same time (P< 0.001). There was significantly less urethral wall oedema in SG at 2 weeks, at 4 weeks (P< 0.001) and after 8 weeks (P< 0,05) than EG at the same time. After 24 weeks no difference was verified in submucosa thickness between the groups. The descriptive thermogravimetric analysis showed graft incrustation with organic material, however without statistic significance in quantitative analysis of mass loss. The inorganic graft incrustation was negligible. CONCLUSIONS: The use of Si-Pu implants in urethra originated a fibrous collagen capsule that allows reepitelialization without local contracture, like a biological skeleton. Nevertheless, grafts extrusion limits their clinical employment

Les polymères thermosets sont largement employés dans les revêtements, les composites et les adhésifs du fait de leurs excellentes propriétés mécaniques et thermiques. Malheureusement, ils ne peuvent pas être recyclés et génèrent des déchets non réutilisables, ce qui doit être amélioré pour s'adapter aux nouvelles directives environnementales. Notamment, l’utilisation d’adhésifs démontables permettrait un meilleur recyclage de ses substrats, ce qui est particulièrement intéressant pour la fin de vie des véhicules, ou des pièces électroniques. Une grande partie des adhésifs sont formulés à partir de polyuréthanes (PUs). De manière classique, les PUs sont obtenus par polymérisation entre poly-isocyanates et polyols, et la plupart de temps, ils sont réticulés pour donner un collage irréversible. Le démontage du collage peut se faire par intégration de liaisons clivables sur réponse à un stimulus donné, la température étant préféré dans l'industrie. La réaction de Diels-Alder (DA) et la retroDiels-Alder (rDA) est un système thermoréversible bien connu et déjà utilisé dans de nombreux travaux. La réaction de DA produit un adduit qui peut se dissocier sous traitement thermique pour donner le diène et le diénophile de départ. Le couple furane/maleimide est choisi pour leur excellente réactivité. Toutefois, la rDA commence souvent à des températures inférieures à 100°C, ce qui est trop bas pour certaines applications. Par ailleurs, la rDA ne se produit pas lorsque l'adduit est sous forme solide (sauf dans des conditions critiques). Nous avons cherché à augmenter la température de rDA en utilisant un adduit de DA solide à haut point de fusion. Pour s'assurer de la miscibilité de l'adduit dans les formulations industrielles, l'adduit est intégré de manière covalente dans des structures PPG par polymérisation, ou bien en ajoutant un segment PPG sur le composé furanique. Ainsi, plusieurs oligomères diols intégrant le motif adduit solide sont synthétisés pour être polymérisés avec des isocyanates au centre de recherche de l'entreprise. De plus, une nouvelle voie d'accès simple et en une étape à des structures bismaleimides a été développée. Ces bismaleimides ont été fonctionnalisés et formulés dans des formulations industrielles donnant des adhésifs PU dont les propriétés thermiques sont étudiées. Par ailleurs, les isocyanates sont dangereux pour la santé humaine et l'environnement. La synthèse de polyhydroxyuréthanes (PHUs) par polymérisation de cyclocarbonates avec des amines, s'est imposé comme une alternative prometteuse. Dans une étude préliminaire, des PHUs linéaires intégrant des adduits de DA sont synthétisés, soit par polymérisation d'adduit dicyclocarbonate avec une diamine, soit par polyaddition de DA d'un hydroxyuréthane bisfuranique et d'un bismaleimide. Il a été démontré que la chaine polymère est coupée par la rDA lors de traitement thermique. Puis des adduits de DA sont intégrés dans des PHU réticulés à différentes positions dans le réseau. Il a été montré que cette position influence grandement les propriétés thermiques du polymère. Finalement, une classe de matériaux originaux, des polyuréthanes sans isocyanates réticulés thermo-démontables, a été développée et a donné des résultats prometteurs. / Thermosetting polymers are greatly used in coatings, composites and adhesives due to their good mechanical and thermal properties. They cannot be recycled, which constitutes a great deal for environmental concern. It has been pointed out that using remendable adhesives would enable to better recycle adhesives substrates. This is especially required for vehicles end-of-life or electronic waste. For adhesive applications, polyurethanes (PUs) are widely used because of their versatility. PUs are typically obtained by reaction between diisocyanates and diols and most of the time they are chemically cross-linked which makes the resulting adhesion irreversible. In order to reprocess cross-linked networks, reversible bonds which can break on demand are integrated within them. Industrially, temperature is the most practical stimulus. Diels-Alder (DA) and retroDiels-Alder (rDA) are a well-known thermoreversible system and already studied in various works. Indeed DA reaction leads to an adduct which can dissociate under thermal treatment to turn back into the previous diene and dienophile compounds (rDA). Here the furan/maleimide couple was chosen as diene/dienophile because of its (catalyst-free) good reactivity. Yet, rDA often begins under 100°C which can be problematic for some applications, but also, rDA cannot take place at solid state (). So we aimed to increase rDA temperature using a solid DA adduct with high melting point. To ensure its miscibility in industrial formulation, it was integrated within PPG structures by polymerization or by adding a PPG-spacer on furanic compound. Several oligomer diols with this solid DA adduct unit were synthetized and polymerized with isocyanates at Bostik research center. Furthermore, a novel pathway to easily access to bismaleimide structures was investigated. These bismaleimides were reacted to give diol adducts which were formulated into industrial formulations and their thermal behaviors were studied.Besides, diisocyanates are harmful for human health and its environment. Thus, the synthesis of polyhydroxyurethanes (PHUs) by step-growth polymerization of cyclocarbonates with amines is a promising alternative. In a preliminary study, linear PHUs integrating DA adducts have been synthetized by polymerization of a dicyclocarbonate adduct with an amine, and by DA polyaddition of a bisfuranic PHU and a bismaleimide. It was demonstrated that rDA split-up the polymeric chains. Then crosslinked PHUs integrating DA adducts at different places were studied.. It was shown that DA adduct position influences greatly polymer thermal behavior. As a result, an original class of thermoremendable isocyanate-free crosslinked polyurethane has been developed and gave promising results.

M.Sc. / The prevalence of natural organic matter (NOM) in water remains a huge challenge for water treatment companies and municipalities. NOM, however, is not a stand-alone problem as it affects water quality in many ways. NOM is largely responsible for the formation of disinfection by-products (DBPs) via its interaction with disinfectants during water disinfection. It is implicated for the undesirable colour, taste and odour of water and NOM even inhibits precipitation precursors which form the backbone of drinking water treatment. There is therefore no question that NOM, which is either a precursor to or direct cause of the problems highlighted above, should be considered as one of the critical design parameters to be considered for drinking water treatment. In our laboratories, research that involves the use of cyclodextrin (CD) polyurethanes for the removal of organic pollutants from water has been extensively investigated, and the CD polyurethanes have demonstrated the ability to effectively remove the organic species from water at low (ppb) concentrations. CDs, which are cyclic oligomers consisting of glucopyranosyl units linked together through α-1,4 glycosidic linkages, behave like molecular hosts. They are capable of forming inclusion complexes with guest molecules and hence can be utilised for the removal of organic contaminants from water. Their solubility in water, however, limits their application in the removal of organic contaminants from water. This limitation is easily resolved by polymerising the CDs into water-insoluble polymers with bifunctional linkers such as hexamethylene diisocyanate (HMDI). In this study, CD polyurethanes and ion exchange resins were used for the removal of NOM and possibly its DBPs from water. This study first investigated the local NOM source to establish its type and character, hence the study involved the characterization of the bulk water samples and fractionating the NOM using ion exchange resins for further characterization. The water samples were found to consist mainly of humic substances in the form of hydrophobic NOM, with the hydrophilic basic (HpiB) fraction being the most abundant NOM fraction in all samples. Trihalomethanes (THMs) were used as a representative of DBPs in this vii study. THMs formation studies of the individual NOM fractions indicated that all six NOM fractions were found to form THMs but in varying proportions. The HpiB fraction was found to be the most reactive precursor fraction for THMs formation. The ozonation process was also independently evaluated for its ability to remove the NOM fractions from water. Ozonation was found not to be very effective at NOM removal since it only resulted in a 12% overall decrease of the NOM in the water samples. The CD polyurethanes, when used alone, were also not very effective at removing the NOM fractions from water (maximum of 33% NOM removal). On the other hand, the combination method (i.e. the use of CD polyurethanes and ozonation for NOM removal) resulted in a good capability of the CD polyurethanes at decreasing some NOM fractions in water as evidenced by a 73% and 88% decrease of the HpiB and hydrophilic acid (HpiA) fractions, respectively. The 73% reduction of the HpiB fraction demonstrates a great success of the combination approach employed herein, as this study reports this fraction as the most reactive precursor fraction for THM formation.

Nessa dissertação foi estudada a síntese de elastômeros microcelulares de poliuretano (EMPU). Foram preparados três EMPU baseados em diisocianato de 4,4 difenilmetano (MDI), com diferentes concentrações de fase rígida (Formulações 1, 2 e 3, com 32, 35 e 42% de fase rígida, respectivamente). As amostras foram preparadas através do método de duas etapas, pelo sistema de pré-polímero. As amostras dos EMPU foram caracterizadas através de ensaios físicos, mecânicos, morfológicos, térmicos e químicos. Os resultados dos ensaios mecânicos mostraram que o aumento no percentual de fase rígida levou a um aumento na resistência à tração e na resistência ao rasgamento. O alongamento na ruptura não apresentou variação significativa com a modificação do percentual de fase rígida. As análises morfológicas indicaram que o aumento no percentual de fase rígida promoveu a formação de microcélulas menores, distribuídas de forma mais homogênea no elastômero. As análises de termogravimetria indicaram a presença de dois estágios de degradação, referentes às fases rígida e flexível, respectivamente. Os ensaios de calorimetria exploratória diferencial indicaram que os EMPU apresentam uma separação de fases à temperatura ambiente. O aumento na quantidade de fase rígida presente nos EMPU implicou em maiores valores de densidade de ligações cruzadas. O ensaio de resistência química demonstrou que os EMPU formulados apresentaram baixos índices de inchamento para solventes industriais comumente utilizados. / In this work, three different microcellular polyurethanes elastomers (EMPU) based on 4,4-diphenylmethane diisocyanate (MDI) with different rigid phase contents were prepared (Formulations 1, 2 and 3 with 32, 35 and 42% of rigid phase content, respectively). The EMPU were obtained by two steps method. The samples were evaluated with respect to physical, mechanical, morphological, thermal and chemical properties. The results showed that the formulation with higher rigid phase content has higher tensile and tear strength. The deformation at rupture not show significant variation with the change in the rigid phase content. Micrographs of SEM indicated that the higher rigid phase content promoted the best cells homogeneity in the samples. The termogravimetric analysis show the presence of the two degradation steps associated to the rigid and flexible phase, respectively. Diferential scanning calorimetry indicated that the EMPU has a phase separation at room temperature. The increase in the rigid phase content implicated in the increase of the cross-linked density of the material. Finally, the EMPU have good chemical resistence in comumm solvents.

This thesis is focused on study of biodegradability of modified polyurethane elastomeric films in synthetic medium with minerals and vitamins on tempered shaker by mixed thermophilic aerobic bacterial culture Bacillus and Thermus genera. In most cases addition of all used fillers (carboxymethyl cellulose, hydroxyethyl cellulose, acetylated cellulose, acetylated starch and glutein) led to increased biodegradability of elastomeric films with modifying agent in comparison with elastomeric films without modifying agent (referential). The growth of cultures was strongly increased in presence of elastomeric films modified by 10 % acetylated cellulose and 10 % carboxymethyl cellulose. Elastomeric film biodegradation mechanism included probably two stages: abiotic destruction of elastomeric films and consequent utilization of degradation products by bacterial culture.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 1980 / Includes bibliographical references. / by Marcos German Ortiz Molina. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Mechanical Engineering