Cure time is often the bottleneck of composite manufacturing processes, therefore it is important to understand the cure of today's thermosetting adhesives. This research attempts to characterize the cure rate of two commercial phenol-formaldehyde adhesives. Two methods are used, parallel-plate rheometry and dielectric spectroscopy. Viscosity data from a parallel-plate rheometer may be used to track the advance of polymerization as a function of temperature. This data can then be used to optimize press conditions and reduce production times and costs. The research will further examine resin cure through dielectric analysis; such a technique could monitor resin cure directly and in real-time press situations. Hot-pressing processes could conceivably no longer require a set press schedule; instead they would be individually set based on dielectric data for every press batch. Such a system may lead to a more efficient and uniform product because press times could be based on individual press cycles instead of entire product lines. A more likely scenario, however, is the use of in situ adhesive cure monitoring for troubleshooting or press schedule development. This research characterized the cure of two phenol-formaldehyde resins using parallel-plate rheometry, fringe-field dielectric analysis, and parallel-plate dielectric analysis. The general shape of the storage modulus vs. time curve and the gel and vitrification points in a temperature ramp were found. Both dielectric analysis techniques were able to characterize trends in the resin cure and detect points such as vitrification. The two techniques were also found to be comparable when the cure profiles of similar conditions were examined. / Master of Science

Visando o gerenciamento dos artigos têxteis advindos do descarte doméstico e dos refugos gerados nos processos de fabricação, a reciclagem e a reutilização surge como uma resposta emergencial aos problemas ambientais do setor de têxtil e moda. O presente estudo teve como principais objetivos realizar uma revisão bibliográfica sobre técnicas de reuso e reciclagem de têxteis, principalmente das fibras de algodão, bem como temas relacionados à ecologia industrial, ao design de moda e ao eco design. Na sua parte experimental também visou realizar ensaios de microscopia e de determinação de regain da fibra de algodão, bem como ensaios de tração, alongamento e microscopia em compósitos produzidos com três diferentes tipos de resinas termorrígidas (epóxi, poliéster ortoftálico e poliuretano) reforçadas com fibras têxteis de algodão, sugestão possível para a diminuição dos refugos têxteis em aterros sanitários. Para tais compósitos foram apontadas aplicações no setor de moda. Conclui-se que os compósitos produzidos a partir de resíduos têxteis poderiam trazer benefícios ao meio-ambiente, pois além de possuírem atribuições como resistência e coesão, podem ser destinados à área de moda, entre outras áreas, pelos atributos visuais que proporcionam. Assim, são capazes de suprir necessidades específicas de consumo do mercado, ávido por novidades, bem como de suprir a demanda por estudos de novos materiais no setor de têxtil e moda, que carece de bibliografia especifica que reúna uma análise técnica e estética abrangendo todas as fases produtivas de materiais, processos, criação e design. / Aiming management of textiles coming from household waste and scrap generated in the manufacturing processes, recycling and reuse arise as emergency responses to the environmental problems of the textile and fashion industry. The present study main objectives were to perform an interdisciplinary literature review focused on techniques of reuse and recycling of textiles, mainly cotton fibers, as well as topics related to industrial ecology, the fashion design and eco design. On experimental part it also aimed to carry out tests of microscopy and regain determination of cotton fibers as well as microscopy, tensile and elongation tests in composites made with three different types of thermoset resins (epoxy, polyester orthophthalic and polyurethane) reinforced with textile cotton fibers, configuring possible suggestion for the reduction of textile waste in landfills. For applications such composites were pointed in the fashion sector. It is possible to conclude that the composites made from textile waste could bring benefits to the environment, because besides possessing strength and cohesion functions, they could be assigned to fashion design field from the visual attributes they provide. Thus, they are able to supply specific needs of the consumer market, eager for news, and to furnish the demand for studies of new materials in the textile and fashion sectors, which lacks specific bibliography that bring together aesthetic and technical analysis covering all production phases of materials, processes, creation and design.

Biobased thermoset resins were synthesized by functionalizing the tall oil fatty acid with hydrogen peroxide and then methacrylic anhydride. The obtained resins were characterized by FTIR to confirm the conversions. The cross-linking ability of the resins were checked by curing experiments and followed by DSC analysis regarding the extent of cross linking. TGA analysis was conducted to identify the thermal degradation patterns of cured resins. The obtained resins (blended with or without 33wt% styrene) were used as matrix and knitted viscose fibers were used as reinforcements to make bio-based composites. Ten layers of knitted viscose fibers were stacked crosswise (0/90⁰С) and hand lay-up impregnation was performed. The fiber ratio of all composites was around 63-66%. The composites were characterized by flexural testing, dynamic mechanical thermal analysis and charpy testing. This work demonstrates that manufacture of composites with both matrix and reinforcement fiber coming from renewable resources is feasible, and the resulted composites have satisfied mechanical performance. / Program: MSc in Resource Recovery - Sustainable Engineering

<p>Diffusion of liquids into and through polymers is an important factor that negatively may influence the durability or lifetime of a polymer structure used in industrial applications. In this work two types of polymers, a liquid crystalline polymer (LCP, Vectra A950) and various thermoset resins as used in fibre reinforced plastics (FRP) process equipment were studied with regard to barrier properties, chemical resistance and long-term performance. LCP are known for their outstanding chemical resistance and barrier properties. FRP used in process equipment may be a cost-efficient solution in chemically aggressive environments where standard carbon or stainless steel cannot be used due to its limited corrosion resistance. Transport properties of typical industrial environments were determined for the LCP and the influence of annealing and orientation was investigated to study whether the barrier properties can be improved. The possibility to use LCP as cost-effective lining for FRP was explored. Special focus was put on the diffusion of water and its effect on long-term transport properties and stability of thermoset resins as the performance of FRP is strongly related to the diffusion of water. </p><p>The results showed that Vectra A950 was suitable for organic solvent and non-oxidising acid environments. Its transport properties were gravimetrically determined and found to be 10 to 102 times lower than that of a high barrier fluoropolymer of type FEP. The degree of molecular packing increased with annealing time both below and above the melting point. Below the melting point this was – at least – partly due to crystal formation whereas above the melting point other mechanisms were involved. The effects of annealing and orientation on the transport properties in LCP were, however, very small or not significant and probably significantly longer annealing times are required. LCP has potential to be used as lining material for FRP as the use of an LCP-lining substantially reduced the permeability of and the solute sorption in a bisphenol A epoxy-based vinyl ester resin. The bonding strength was improved significantly by a combined abrasive and oxygen plasma treatment.</p><p>The long-term sorption of water in thermoset resins including bisphenol A epoxy-based vinyl ester, novolac-based vinyl ester, urethane modified vinyl ester and bisphenol A polyester resins was found to increase with exposure time whereas the diffusion coefficient was not significantly affected. It was shown that the presence of water induced relaxation processes that were considered to be the primarily reason for the increase in sorption coefficient in comparison to degradation processes, such as hydrolysis, causing osmotic processes. A general relationship for the estimation of the sorption coefficient at 80ºC in dependence of the water activity and the sorption coefficient at unit activity independent of the resin type was established.</p>

Visando o gerenciamento dos artigos têxteis advindos do descarte doméstico e dos refugos gerados nos processos de fabricação, a reciclagem e a reutilização surge como uma resposta emergencial aos problemas ambientais do setor de têxtil e moda. O presente estudo teve como principais objetivos realizar uma revisão bibliográfica sobre técnicas de reuso e reciclagem de têxteis, principalmente das fibras de algodão, bem como temas relacionados à ecologia industrial, ao design de moda e ao eco design. Na sua parte experimental também visou realizar ensaios de microscopia e de determinação de regain da fibra de algodão, bem como ensaios de tração, alongamento e microscopia em compósitos produzidos com três diferentes tipos de resinas termorrígidas (epóxi, poliéster ortoftálico e poliuretano) reforçadas com fibras têxteis de algodão, sugestão possível para a diminuição dos refugos têxteis em aterros sanitários. Para tais compósitos foram apontadas aplicações no setor de moda. Conclui-se que os compósitos produzidos a partir de resíduos têxteis poderiam trazer benefícios ao meio-ambiente, pois além de possuírem atribuições como resistência e coesão, podem ser destinados à área de moda, entre outras áreas, pelos atributos visuais que proporcionam. Assim, são capazes de suprir necessidades específicas de consumo do mercado, ávido por novidades, bem como de suprir a demanda por estudos de novos materiais no setor de têxtil e moda, que carece de bibliografia especifica que reúna uma análise técnica e estética abrangendo todas as fases produtivas de materiais, processos, criação e design. / Aiming management of textiles coming from household waste and scrap generated in the manufacturing processes, recycling and reuse arise as emergency responses to the environmental problems of the textile and fashion industry. The present study main objectives were to perform an interdisciplinary literature review focused on techniques of reuse and recycling of textiles, mainly cotton fibers, as well as topics related to industrial ecology, the fashion design and eco design. On experimental part it also aimed to carry out tests of microscopy and regain determination of cotton fibers as well as microscopy, tensile and elongation tests in composites made with three different types of thermoset resins (epoxy, polyester orthophthalic and polyurethane) reinforced with textile cotton fibers, configuring possible suggestion for the reduction of textile waste in landfills. For applications such composites were pointed in the fashion sector. It is possible to conclude that the composites made from textile waste could bring benefits to the environment, because besides possessing strength and cohesion functions, they could be assigned to fashion design field from the visual attributes they provide. Thus, they are able to supply specific needs of the consumer market, eager for news, and to furnish the demand for studies of new materials in the textile and fashion sectors, which lacks specific bibliography that bring together aesthetic and technical analysis covering all production phases of materials, processes, creation and design.

Diffusion of liquids into and through polymers is an important factor that negatively may influence the durability or lifetime of a polymer structure used in industrial applications. In this work two types of polymers, a liquid crystalline polymer (LCP, Vectra A950) and various thermoset resins as used in fibre reinforced plastics (FRP) process equipment were studied with regard to barrier properties, chemical resistance and long-term performance. LCP are known for their outstanding chemical resistance and barrier properties. FRP used in process equipment may be a cost-efficient solution in chemically aggressive environments where standard carbon or stainless steel cannot be used due to its limited corrosion resistance. Transport properties of typical industrial environments were determined for the LCP and the influence of annealing and orientation was investigated to study whether the barrier properties can be improved. The possibility to use LCP as cost-effective lining for FRP was explored. Special focus was put on the diffusion of water and its effect on long-term transport properties and stability of thermoset resins as the performance of FRP is strongly related to the diffusion of water. The results showed that Vectra A950 was suitable for organic solvent and non-oxidising acid environments. Its transport properties were gravimetrically determined and found to be 10 to 102 times lower than that of a high barrier fluoropolymer of type FEP. The degree of molecular packing increased with annealing time both below and above the melting point. Below the melting point this was – at least – partly due to crystal formation whereas above the melting point other mechanisms were involved. The effects of annealing and orientation on the transport properties in LCP were, however, very small or not significant and probably significantly longer annealing times are required. LCP has potential to be used as lining material for FRP as the use of an LCP-lining substantially reduced the permeability of and the solute sorption in a bisphenol A epoxy-based vinyl ester resin. The bonding strength was improved significantly by a combined abrasive and oxygen plasma treatment. The long-term sorption of water in thermoset resins including bisphenol A epoxy-based vinyl ester, novolac-based vinyl ester, urethane modified vinyl ester and bisphenol A polyester resins was found to increase with exposure time whereas the diffusion coefficient was not significantly affected. It was shown that the presence of water induced relaxation processes that were considered to be the primarily reason for the increase in sorption coefficient in comparison to degradation processes, such as hydrolysis, causing osmotic processes. A general relationship for the estimation of the sorption coefficient at 80ºC in dependence of the water activity and the sorption coefficient at unit activity independent of the resin type was established.