Rotaxane chemistry provides a new direction of research in polymer architectures. Unlike conventional polymers, polyrotaxanes are molecular composites comprised of macrocycles threaded by linear polymer backbones with no covalent bonds between the two components. This novel class of materials displays unusual chemical and physical properties due to their unique architectures. The studies include crown ether and blocking group syntheses, synthetic methodologies leading to rotaxanes and polyrotaxanes and structure-property relationships of polyrotaxanes. Crown ethers (30-crown-10, 36-crown-12, 42-crown-14, 48-crown-16 and 60-crown-20) were systematically synthesized from low molecular weight glycols with 30 - 60% yields. Bis(p-phenylene)-32-crown-4 and bis(p-phenylene)-34-crown-10 (BPP34C10) were also synthesized in 8 - 13% yields; the latter was synthesized with four different synthetic routes. All crown ethers were prepared in large quantities. A series of monofunctionalized triaryl derivatives were also synthesized as rotaxane blocking groups. A series of polyrotaxanes comprised of a polyurethane backbone and crown ethers with ring size ranging from 36 - 60 membered were synthesized via the statistical threading method. The polyrotaxane formation was proven by multiple reprecipitations, ¹H-NMR and GPC analyses. The threading efficiency (rings per repeat unit) increases from 0.16 to 0.87 with an increase in ring size of crown ethers from 36 to 60 membered at 1.5 molar ratio of crown ether to linear glycol. Host-guest complexation of paraquat dication and BPP34C10 has been studied. A series of difunctionalized paraquat dication derivatives was synthesized and used to prepare host-guest complexes (pseudorotaxanes) with BPP34C10. X-Ray crystal structures of the complexes were determined. Furthermore, a class of viologen-containing polyurethane elastomeric polyrotaxanes was synthesized via this host guest complexation. The threading efficiencies from this method were quantitative. Through rotaxane formation, polymer solubilities increase and glass transition temperatures decrease. Evidenced by DSC and WAXS analyses, the crown ether forms crystalline domains without dethreading from the amorphous polyurethane backbone. This process is kinetically "retarded". It is time and temperature dependent and reversible. It can only be observed for polyrotaxanes with large rings and high ring contents, which provide high mobilities of rings along the backbone and also wide T_m - T_g windows. The study of recrystallization kinetics has also shown that 60-crown-20 recrystallizes much slower in a polyrotaxane than in its physical blend with the model polymer. / Ph. D.

Hydroxypropyl lignins (HPLs) from several sources were reacted with propylene oxide to produce chain-extended ) hydroxypropyl lignin (CEHPL) copolymers with molar substitutions (MS) between 1 and 7 propylene oxide units. Isolated copolymers were characterized with respect to their chemical composition, molecular weight and thermal properties. These techniques confirmed the presence of a copolymer with between 20 and 67% lignin. Glass transition temperatures (Tgs) of the CEPHLs followed the behavior predicted by the Gordon-Taylor equation. Properties of the CEHPLs were independent of the original lignin source. The CEHPL copolymers were incorporated into lignin polyurethane networks (LPUs). The LPUs contained 17 to 43% lignin and showed a single Tg. Both the Tg and the Youngs modulus (MOE) of the LPUs were strongly correlated to the lignin content and type of diisocyanate used to prepare the network. Swelling studies indicated that the LPUs prepared from CEHPLs with a high MS (5-7) were not highly crosslinked networks. The LPU properties also appeared to be independent of the lignin source. In another set of experiments a HPL was separated into five fractions (F-HPLs) with molecular weights (MWs) between 1.5 and 10x10³ daltons. The Tg of the F-HPLs was correlated to molecular weight by the Fox-Flory equation. The fractionated HPLs were incorporated into polyurethane networks. The Tgs of these networks were related to the MW of the F-HPL. Swelling studies indicated that low molecular weight monofunctional fragments limited network formation. The LPUs were also used as one component in LPU/polymethyl methacrylate (PMA) interpenetrating polymer networks (IPNs). These IPNs varied in their LPU/PMMA composition and the presence of crosslinking. Dynamic mechanical and thermal analysis showed two phases in all of the IPNs. Mechanical properties were dependent on the IPN composition and phase crosslinking. For IPNs with a crosslinked LPU phase, the MOE values indicated the presence of dual phase continuity. A second series of IPNs was prepared to investigate the effects of lignin content on IPN properties. Phase separation appeared to be related to the lignin content. Mechanical properties were related to lignin content and not the phase behavior. / Ph. D.

Cette thèse porte sur la conception de carbonates cycliques originaux et d’amines dérivés des huiles végétales dans le but de synthétiser des poly(hydroxyuréthane)s entièrement bio-sourcés. D’une part, deux voies d’accès à des amines dérivées d’acides gras utilisant des conditions douces ont été étudiées. La première consiste en l’oxydation sous air d’alcools aliphatiques en nitriles en présence de TEMPO supporté sur silice, suivi par une hydrogénation des dinitriles en diamines. Egalement, des diènes dérivés d’acides gras ont été couplés à la cystéamine via une chimie thiol-ène, permettant l’accès à des diamines aliphatiques bio-sourcées. D’autre part, des carbonates cycliques substitués à 5 chaînons ont été synthétisés à partir de dérivés d’acides gras et de glycérol, dans le but d’augmenter leur réactivité vis-à-vis de l’aminolyse. En insérant un groupement fonctionnel éther, thio-éther ou ester en position α ou β des carbonates cycliques, la réactivité de ces derniers vis-à-vis des amines a pu être ajustée. L’étude de la sélectivité, des réactions secondaires et de la catalyse de la voie carbonate/amine a été menée afin de mieux appréhender cette voie d’accès à des polyuréthanes sans isocyanates. Des poly(hydroxyuréthane)s entièrement oléo-sourcés ont été synthétisés avec succès, montrant des propriétés physico-chimiques contrôlables selon la structure des monomères. / In this thesis, vegetable oils were used as a platform to design original cyclic carbonates and amines with the goal to synthesize fully bio-based poly(hydroxyurethane)s. On the one hand, two routes to fatty acid-based amines were implemented in mild conditions. First, the oxidation of aliphatic alcohols into nitriles was performed under air in the presence of supported TEMPO on silica, followed by hydrogenation of nitrile compounds into corresponding amines. Second, thiol-ene chemistry was performed on unsaturated fatty acid substrates to design original aliphatic bio-based diamines. On the other hand, substituted 5-membered cyclic carbonates were designed from fatty acids and glycerol derivatives to enhance their reactivity towards aminolysis. By inserting ether, thio-ether or ester functionalities in α- or β-position of the cyclic carbonates, their reactivity towards amines could be tuned. Investigations on the selectivity, side reactions and catalysis of the carbonate-amine reaction were carried out to apprehend this route to non-isocyanate polyurethanes. Fully vegetable oil-based PHUs with tunable physico-chemical properties with respect to the monomer structures could be easily achieved.

Thesis (PhD (Process Engineering))--University of Stellenbosch, 2006. / Existing thermoplastic polyurethanes (TPUs), used in the manufacturing of cardiovascular devices, still have unproven long-term biostability and may be prone to excessive plastic deformation when subjected to cyclic loading. These negative aspects can be attributed to, among other factors, the weak nature of virtual crosslinking through microphase separation. The modification and covalent crosslinking of existing medical grade polyurethanes with unsaturated acyl chlorides are thus proposed to improve these properties. A model compound study was used to find a suitable acyl chloride (4-pentenoyl chloride), confirm the intended carbamate nitrogen as successful reaction site and to optimize the chemistry of the reaction. Two medical grade polyurethanes, Pellethane® 2363- 80AE (Pellethane) and PurSil 35-80A (PurSil), were subsequently successfully modified with 4-pentenoyl chloride. The degree of modification could be accurately controlled (R2 = 0.99) to between 4.5% to 20.0% and between 11.5% to 18.5% for the respective polyurethanes. The degree of modification and method of crosslinking were then optimized to obtain the required mechanical properties (i.e. minimum hysteresis). The hysteresis and creep of the modified and crosslinked Pellethane were reduced by 42.5% and 44.0%, respectively, while the hysteresis of the modified and crosslinked PurSil was reduced by 12.9%. The chemical stability of Pellethane (control) modified Pellethane (15% modification) and crosslinked Pellethane (Pell15.0) was evaluated in an in vitro degradation study. The hysteresis of the crosslinked polymer was at least 27.5% better when compared to Pellethane, and showed a significant resistance to surface degradation (as studied with scanning electron microscopy). Although the soft phases in both polyurethanes are vulnerable toward degradation, it was not as pronounced in Pell15.0, mainly due to the restriction of chain movement resulting from the crosslinking. Small-diameter tubular constructs, with similar fiber and wall thicknesses, were electrospun from Pellethane and the 15% modified Pellethane. A standard electrospinning technique was used in the case of the former while in the case of the latter a novel “reactive” electrospinning technique was used for the in situ crosslinking of the novel material, while simultaneously forming the tubular constructs. It is suggested that the manufacturing of Pell15.0 be scaled up to produce adequate amounts of material to enable the extrusion and in vivo evaluation of e.g. pacemaker leads. A circulatory animal model, e.g. a senescent baboon model, could be used to evaluate and further optimize the electrospun tubular constructs.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / Polyurethanes (PUs) are finding increasing application and use in many industries due to their advantageous properties, such as a wide range of flexibility combined with toughness, high chemical resistance, excellent weatherability, and very low temperature cure. PUs do however have some disadvantages, for instance, PU is considered an expensive polymer, especially when considered for solvent based adhesives. A motivation for this study was to consider a largely unstudied area of PU chemistry by combining PUs with polyacrylates. Polyacrylates are well known adhesives and can carry specific functionality, but have the disadvantage that their flexible backbones impart limited thermal stability and mechanical strength. In this study PU was incorporated into acrylates in an effort to obtain acrylate-g-urethanes with good properties. The mode of incorporation chosen was urethane macromonomers (UMs), a hardly mentioned substance in literature, yet one deserving investigation. UMs having different urethane chain lengths (X) were synthesized by the polyaddition polymerization of toluene diisocyanate (TDI) and ethylene glycol (EG) by the prepolymer method, which was terminated by 2-hydroxy ethyl methacrylate (HEMA) and isopropanol. The UMs were characterized by Fourier-transform infrared spectroscopy (FTIR), proton NMR (1H NMR), carbon NMR (13C NMR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Various percentages of the respective UMs (0-40 wt % according to acrylate monomers) were then incorporated into methyl methacrylate (MMA) and into normal butyl methacrylate (n-BMA) backbones via solution free radical copolymerization. The resulting methyl methacrylate-urethane graft copolymers (PMMA-g-urethane) and normal butyl methacrylate-urethane graft copolymers (n-PBMA-g-urethane) were characterized by GPC, 1H NMR and 13C NMR, FTIR, TGA, and DMA. Phase separation between the urethane segment and acrylate segment in the yield of graft copolymerization products was investigated by DMA and transmission electron microscopy (TEM). As the concentration of the UMs in the free radical copolymerization feed increased, lower yields of both graft copolymers PMMA-g-urethane and n-PBMA-g-urethane were observed and more UM was incorporated into the PMMA and n-PBMA backbones. It also was found that the thermal stability of the PMMA-g-urethane and n-PBMA-gurethane copolymers increased with increasing UM concentration. DMA results showed that in most graft copolymer products the two respective component parts of PMMA-g-urethane or n-PBMA-g-urethane were completely compatible as only one Tg was observed. Two glass transitions, at temperatures of 22.0 and 76.0 oC, corresponding to the n-PBMA and urethane moieties, were observed when the chain length of the UMs was increased from X=4 to X=32 [the amount of this UM used in the copolymerization feed was increased to 40%, and microphase separation was indicated].

O presente trabalho tem como intuito o estudo da reciclagem química de espumas rígidas de poliuretano através do processo de glicólise em um reator de micro-ondas utilizando o dietilenoglicol como agente decompositor, além de avaliar as propriedades de reaplicação e desempenho mecânico da espuma reciclada frente a uma espuma padrão de mercado. Uma fase de estudos preliminares foi estabelecida para avaliação comparativa entre catalisadores, considerando no estudo o hidróxido de sódio, o dilaurato de dibutil estanho e a dietanolamina, onde o hidróxido de sódio se mostrou como sendo o catalisador mais interessante para o escopo do trabalho. Para estudo das melhores condições reacionais, foi elaborado um desenho de experimentos avaliando as faixas ótimas para temperatura e concentração de catalisador utilizados no processo da glicólise onde foi constatada a temperatura de 230 °C e concentração de catalisador de 0,68% como valores mais adequados para a reciclagem. Os produtos da glicólise foram analisados quanto ao seu espectro no infravermelho e ressonância magnética nuclear de carbono-13, além de serem avaliados em relação ao seu número de hidroxila, basicidade e viscosidade. O conteúdo de polióis base de uma formulação de espuma rígida foi substituído por diferentes porcentagens de poliol reciclado sua reatividade e propriedades mecânicas como resistência à compressão e estabilidade dimensional foram analisados apontando um bom desempenho para os padrões de reatividade e propriedades mecânicas em uma substituição de até 40% dos polióis virgens pelo reciclado. / The present work has studied the chemical recycling of polyurethane rigid foams through microwave assisted glycolysis process using the diethyleneglycol as decomposing agent, and evaluating the reapplication and performance of the recycled foams in comparison to a market standard rigid foam. A preliminary study was set up to evaluate and compare the performance of catalysts such as sodium hydroxide, dibutiltin dilaurate and diethanolamine, where the sodium hydroxide presented the best overall performance. A design of experiments was performed in order to evaluate the optimum values of the processing temperature and catalyst concentration, which resulted in 230 °C and 0,68% as the optimum conditions to temperature and catalyst concentration, respectively. The glycolysis products were analyzed via infrared spectroscopy and carbon-13 nuclear magnetic resonance and were also evaluated regarding their hydroxyl number, basicity and viscosity. The base polyols from a standard rigid foam formulation were replaced by different amounts of recycled polyol and the reactivity profile as well as the physical properties such as the compression resistance and dimensional stability of the new formulations were measured pointing out a good performance of the reactivity profile and physical properties of the formulations with polyol replacement up to 40%.

Este trabalho teve como objetivo a modificação de óleo de soja por meio da sua funcionalização com grupos hidroxílicos visando seu uso na síntese de poliuretanos. As reações de funcionalização foram conduzidas em duas etapas, uma de epoxidação seguida de hidroxilação utilizando álcoois de baixo peso molecular como agente hidroxilante. Na primeira etapa do processo, a epoxidação, duas amostras foram obtidas variando o grau de funcionalidade de aproximadamente 2 mol de epóxido por mol de óleo epoxidado (F2) e, aproximadamente, 2,5 mol de epóxido por mol de óleo epoxidado (F2,5). Na segunda etapa, variou-se os álcoois utilizados como agentes hidroxilantes da amostra F2 entre metanol, etanol, isopropanol e 1-butanol; enquanto que a amostra F2,5 foi hidroxilada apenas com etanol. Os óleos modificados foram caracterizados por meio de espectroscopia na região do infravermelho (FTIR), espectroscopia de ressonância magnética nuclear de prótons (RMN 1H); determinação do percentual de epóxido, índice de hidroxila e de acidez, distribuição de massa molar e viscosidade dinâmica. Os resultados obtidos foram comparados com os valores típicos do óleo de mamona que por ser naturalmente hidroxilado é muito usado na síntese de poliuretanos. A caracterização estrutural permitiu comprovar a eficácia da síntese, apresentando evidências claras quanto às diferenças estruturais existentes entre as amostras funcionalizadas e o óleo de mamona. As técnicas de FTIR e RMN 1H mostraram a formação do grupo beta-hidroxi-éter, vicinal à hidroxila, de acordo com o tipo de álcool usado na hidroxilação de cada uma das amostras. Variações entre a estimativa do índice de hidroxila, através do percentual de epóxido e o índice de hidroxila experimental sugeriram reações paralelas durante a síntese. A influência da acidez durante o processo e a acidez final de cada uma das amostras também foi determinada. As curvas de GPC comprovaram umas das vias paralelas sugeridas com a formação de fases oligoméricas entre os triglicerídeos. A viscosidade final apresentou grande variação, principalmente em função do grupo beta-hidroxi-éter formado em cada caso, do grau de funcionalidade, além da redução do teor de insaturações do óleo modificado. Dados sobre a energia de ativação de escoamento do fluido em função da temperatura mostraram que o fator mais significativo na variação da viscosidade é o índice de hidroxila final das amostras. As amostras sintetizadas foram usadas na polimerização de poliuretanos. A reatividade das amostras foi determinada através de ensaios de cura acompanhados por FTIR, além de uma caracterização mecânica dos poliuretanos finais feita por Análise Dinâmico Mecânica (DMA). As amostras apresentaram uma alta variação quanto à reatividade no processo de polimerização. Os ensaios de DMA mostraram a relação direta entre a temperatura de transição vítrea e o grau de funcionalidade, além do efeito plastificante gerado pelas cadeias livres contidas na fase flexível formada pelos triglicerídeos parcialmente funcionalizados. / The objective of this work was the modification of soybean oil by its functionalization with hydroxyl groups for its use in the synthesis of polyurethanes. Functionalization reactions were conducted in two steps, one epoxidation followed by hydroxylation using low molecular weight alcohols as hydroxylating agent. In the first step, two samples were obtained varying the degree of functionality of approximately 2 moles of epoxide per mole of epoxidized oil (F2) and approximately 2.5 moles of epoxide per mole of epoxidized oil (F2,5). In the second step, the process was varied using different alcohols as hydroxylating agents of the F2 sample, which were methanol, ethanol, isopropanol and 1-butanol; while the F2.5 sample was hydroxylated only with ethanol. The modified oils were characterized by Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (1HNMR), determination of the percentage of epoxide, hydroxyl and acidity index, molar mass distribution and dynamic viscosity (Brookfield viscosity). The obtained results were compared to the typical values of castor oil which, because it is naturally hydroxylated, is widely used in the synthesis of polyurethanes. The structural characterization allowed proving the efficacy of the synthesis, presenting clear evidence regarding the structural differences between the functionalized samples and castor oil. The results from FTIR and 1HNMR techniques showed the formation of the beta-hydroxyl ether group, side to the hydroxyl, according to the type of alcohol used in the hydroxylation of each of the samples. Variations between the estimation of the hydroxyl number, through the percentage of epoxide and the experimental hydroxyl number, suggested parallel reactions during the synthesis. The influence of the acidity during the process and the final acidity of each of the samples were also determined. The GPC curves confirmed one of the parallel pathways suggested with the formation of oligomeric phases between the triglycerides. The final viscosity showed great variation according to the beta-hydroxyl ether group formed in each case, the degree of functionality and the reduction of unsaturation content in the modified oil. Activation energy values of fluid flow as a function of temperature showed that the most significant factor in the viscosity variation is the final hydroxyl number of samples. The synthesized samples were used in the polymerization of polyurethanes. The reactivity of the samples was determined by curing tests monitored by FTIR technique, in addition to a mechanical characterization of final polyurethanes by Dynamic Mechanical Analysis (DMA). The samples showed a high variation in reactivity in the polymerization process. The DMTA tests showed the relationship between the glass transition temperature and the degree of functionality in addition to the plasticizing effect generated by free chains contained in the flexible phase formed by the partially functionalized triglycerides.

Na presente tese foram preparados poliésteres derivados de dois materiais renováveis o ácido 2,5-furanodicarboxílico (AFD) e a isoidida. Foram também preparados monômeros dihidroxílados para uso em poliesterificações e em reações com diisocianatos contendo um aduto de Diels-Alder (DA) formado pela reação de um grupo furano e uma maleimida (reação entre uma bismaleimida e o álcool furfurílico). Esses diois foram utilizados na preparação de poliésteres e poliuretanos termorreversíveis. A termorreversibilidade dos materiais preparados advém do fato de que os adutos de DA são termorreversíveis (rDA). Portanto, ao aquecer os poliésteres preparados com aduto-DA são originados monômeros difuncionais com grupos furano e/ou maleimida. O produto da rDA pode então ser repolimerizado, mas não via reações de poliesterificação ou isocianato/hidroxila, mas pelo acoplamento furano/maleimida (DA). Por fim uma nova rota para a obtenção de copolímeros aleatórios foi investigada. Essa rota consiste em provocar a rDA de uma mistura de dois homopolímeros distintos obtidos por polimerização em etapas contendo no interior de suas unidades repetitivas adutos de Diels-Alder e em seguida provocar a sua repolimerização via DA para dar origem a um copolímero aleatório. Os materiais foram caracterizados por suas estruturas químicas por Espectroscopia na região do infravermelho com transformada de Fourier (FTIR), ressonância magnética nuclear de próton (RMN ¹H). Foram feitos ensaios de cromatografia de permeação de gel (GPC), onde notou-se uma massa média numérica e ponderal para os poliésteres obtidos a partir do AFD e também para o poliéster e poliuretano termorreversíveis de aproximadamente 1600 g.mol¹. Nos ensaios de calorimetria exploratória diferencial (DSC) foi obtido Tgs variados para os poliésteres obtidos a partir do AFD indo de 88 a 159ºC, de 80ºC para o poliuretano termorreversível e de 106ºC para o poliéster termorreversível. Para a análise termogravimétrica (TGA) foi observado temperaturas de degradação para os poliésteres obtidos a partir do AFD em torno de 280ºC. Para a análise térmica dinâmico-mecânicas (DMTA) obteve-se Tg\'s em 117, 123 e 120ºC para o poliéster, o poliuretano e o copolímero termorreversíveis. / In this thesis it was prepared polyesters of two renewable monomers, the 2.5-furandicarboxylic acid and isoidide. Dihydroxy monomers were also prepared for use in polysterification and in reactions with diisocyanates, both containing Diels-Alder adduct in the molecule formed by the reaction of a furan group and a maleimide (reaction between bismaleimide and furfuryl alcohol). These diols were used in the preparation of thermoreversible polyesters and polyurethanes. The thermoreversibility of these materials comes from the fact that the DA adducts are thermoreversible (rDA). Therefore, heating these polymers give rise to difunctional monomers with an adduct-DA with furan and/or maleimide functions. The product of the rDA may then be polymerized not via polysterification reactions or isocyanate/hydroxyl, but by furan/maleimide coupling (DA) restoring the DA adduct. Finaly a new route to obtain random copolymers was investigated. This route consists in the rDA of a mixture of two different homopolymers obtained by polymerization in stages containing adducts producing monomers with furan and maleimide functions that can be polymerization via DA reaction to give a random copolymer. The materials were characterized by their chemical structures by infrared spectroscopy (FTIR), nuclear magnetic resonance of proton (¹H-NMR), gel permeation chromatography (GPC), experiments were made, where it was noticed a number and weight average mass for the polyesters obtained from the AFD and also for the thermoreversible polyester and polyurethane 1600 gmol¹. In differential scanning calorimetry tests (DSC) was obtained Tg\'s for various polyesters obtained from the AFD ranging from 88 to 159°C, 80°C for the thermoreversible polyurethane and 106°C for the thermoreversible polyester. For the thermogravimetric analysis (TGA) was observed degradation temperatures for the polyesters obtained from the AFD around 280°C. For dynamic mechanical thermal analysis (DMTA) Tg was obtained in 117, 123 and 120°C for polyester, polyurethane and copolymer thermoreversible.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1982. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING / Vita. / Includes bibliographical references. / by Ronald James Salig. / M.S.

A indústria do petróleo é um dos setores com maior número de sistemas produtivos empregando alta tecnologia. O Brasil é mundialmente renomado como um líder na extração de petróleo, em águas profundas e ultraprofundas. Dentro da cadeia produtiva, grande parte do petróleo e do gás produzido é escoado através de dutos flexíveis que conectam os poços de produção com as plataformas. Existem dois segmentos dessas linhas que recebem diferentes denominações de acordo com o seu local de aplicação. Quando estão apoiadas sobre o fundo do mar, em condição de serviço estático, são denominados flowlines e quando se elevam do fundo do mar até a plataforma, em condição de serviço dinâmico, são denominados risers. Os tubos projetados para aplicações dinâmicas são dotados de bends stiffeners, componentes com formato cônico e, em geral, de base uretânica que têm a função de fornecer uma transição de rigidez suave entre a estrutura dos tubos flexíveis e a extremamente rígida, à plataforma, não permitindo que este componente infrinja seu raio mínimo de operação. A adequada compreensão dos enrijecedores de curvatura e do material empregado em sua fabricação vem se tornando cada vez mais importante na indústria devido à sua crescente utilização, bem como à ocorrência de falhas que vem sendo constatada nos últimos anos. Este trabalho abordou a variação das propriedades mecânicas de poliuretanos pela ação da hidrólise, calor e pela ação dos raios-UV por envelhecimento acelerado, assim como variação de massa, considerando que esses materiais são projetados para uma vida útil superior a vinte anos para trabalhos imersos em meio aquoso. / The oil industry is one of the sectors with the highest number of production systems employing high technology. Brazil is worldwide renowned as a leader in oil and gas extraction in deep and ultra deep water. Inside the production chain, a great part of the oil and gas produced is conveyed through flexible pipelines that connect the production wells to the platforms. There are two segments of these lines that receive different names according to their application characteristics. When the pipes are laid on the seabed in a static service condition, are called flowlines and when they raise from the seabed to the platform in a dynamic service condition, are called risers. The pipes designed for dynamic applications are equipped with bend stiffeners, components with conical form and in general with urethane basis, which has the function of providing a smooth stiffness transition between the flexible structure of the pipes and an extremely rigid structure, the platform, not allowing that this component infringes their minimum operation bend radius. The proper compression of curvature stiffeners and the material used in its manufacture is becoming increasingly important in industry due to its growing use and the occurrence of failures that have been recorded in recent years. This work discussed the changes in the mechanical properties of polyurethanes due to hydrolysis, heating and UV-rays exposure by accelerated ageing, as well as mass variation, considering that these materials are designed for a service life exceeding twenty years for operation in water.