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Organic solar cells (OSCs) have gained considerable attention from the scientific community in recent decades due to their remarkable power conversion efficiency (PCE), flexibility, and cost-effectiveness in producing large-area batteries. Despite the ongoing research efforts that have led to a PCE exceeding 19% for single-junction OSCs and surpassing 20% for multi-junction OSCs, the commercialization of these devices is hampered by their poor stability, reliance on specific additives, and the use of toxic solvents. To address these shortcomings, this study focuses on investigating the 3 * 3 thermosets matrix to facilitate the selection of precursors for in-situ crosslinking thermosets. Furthermore, in this study, we fabricated the devices using green solvents to narrow the gap between PCE and stability under environmentally friendly conditions. We utilized PTQ10: BTP-BO4Cl as the model system and employed tetrahydrofuran (THF) as an eco-friendly solvent. The research focused on examining the thermoset's glass transition temperature (Tg), modulus and morphology properties. The resulting cross-linked thermoset network has high-density hydrogen bonding and network grids, which helps to stabilize the morphology of the active layer. The findings indicated that selecting a thermoset with high Tg, high modulus (4-8 MPa), and good uniformity as an in-situ crosslinking additive would be beneficial. These results can guide the selection of universal in-situ crosslinking thermosets and aid in improving the stability of various organic electronic devices.

Experimental and theoretical characterization techniques are developed to illuminate relationships between molecular architecture, processing strategies, and physical properties of several model epoxy-amine systems. Just beyond the gel point partially cured networks are internally antiplasticized by unreacted epoxy and amine which leads to enhanced local chain packing and strain localization during deformation processes. Additional curing causes the antiplasticization to be removed, resulting in lower modulus, density, yield stress, and less strain localization. Physical and mechanical probes of network formation are discussed with respect to several different partially cured model epoxy-amine chemistries. The non-linear fracture energy release rate and the molecular architecture of virgin and healed epoxy networks are related through an effective crack length model. The inelastic component of the fracture energy release rate is attributed to the failure of network strands in a cohesive zone at the crack tip. Data from fracture and healing experiments are in good agreement with the model over more than three orders of magnitude. Changes in the shape of the process zone and deviation from planar crack growth cause deviations from the model for the toughest networks tested. Double network epoxies are created from stoichiometric blends of an epoxy resin cured sequentially with aliphatic and aromatic amine curing agents. Unreacted epoxide and aromatic amine functionality antiplasticize the partially cured materials. The thermal and mechanical properties of the fully cured networks vary according to composition. No evidence of phase separation is observed across the entire composition and conversion range. However, the breadth of the glass transition in the double networks increases due to the difference in the molecular stiffness of the two curing agents. Techniques are developed to monitor the evolution of residual stresses and strength in complex multicomponent epoxy-amine based coatings. The evolution of properties is attributed to loss of volatile small molecules from the coatings. The stresses that develop in biaxially constrained membranes are monitored through mechanical excitation. The strength of the membranes is determined by monitoring the size and shape of center cracks. This fracture analysis technique allows the evolution of stresses and toughness of the materials to be monitored simultaneously.

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

Compared to conventional fibers, carbon nanotubes possess several significant properties, which make them as an excellent alternative reinforcement in multi-functional material industry. In this study, the possibility of dispersion of the multi-wall carbon nanotube (MWCNTs) in a thermoset bio-based resin (synthesized based on end-functionalized glycerol-lactic acid oligomers, GLA, at university of Borås) was investigated. Furthermore, the addition of the MWCNTs as reinforcement to improve the mechanical and thermal properties of was investigated. The nanocomposites were prepared in three different concentrations of MWCNTs, 0.3 wt.%, 1.0 wt.%, and 2.0 wt.%, and each sample was prepared using three different dispersion methods such as the high speed mixer(HSM), the ultra-sonication (US), and a combined method of HSM & US. The mechanical and thermal properties were analyzed by flexural test, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results confirm that the nanotubes can be dispersed in GLA but the cured nanocomposite didn’t exhibit any considerable improvement in their thermal properties. Considering to the mechanical properties, the addition of 0.3 wt. % MWCNTs to the GLA increased the flexural strength a little but increasing the nanotubes to 1.0 wt. % decreases the flexural strength to almost 50%. This is mainly due to increase in the brittleness of the produced nanocomposites. Both the distribution methods dispersed the nanomaterials in the matrix initially but they are not efficient enough to stop the re-agglomeration which leads to undesired curing dynamics and low efficiency. Thus, these dispersion methods need to be optimized for improvement of nanocomposites’ properties.

Considerando o grande interesse atual em biocompósitos, seja pela utilização de fibras lignocelulósicas como reforço em compósitos poliméricos ou pela produção de matrizes oriundas de fontes renováveis, buscou-se neste estudo a melhora de propriedades do termorrígido fenólico com a inserção de fibras de sisal tratadas com lignosulfonato de sódio. As fibras de sisal, largamente produzidas no Brasil, são provenientes de fontes renováveis, possuem baixa densidade e apresentam boas propriedades mecânicas. Lignosulfonatos são obtidos através do processo de polpação sulfito da madeira, sendo considerado material renovável. As fibras de sisal foram modificadas via adsorção de lignosulfonato via aquecimento a 70 °C/1h e por meio de irradiação com ultra-som em diferentes tempos (1h e 2h) e por 14h de imersão na solução aquosa de lignosulfonato seguindo de 1 h de irradiação com ultra-som. O lignosulfonato também foi utilizado como substituinte do fenol no preparo de resinas fenol-formaldeído, o que é possível devido à presença de anéis fenólicos em sua estrutura. As fibras de sisal, antes e após os tratamentos, foram caracterizadas segundo teor de componentes majoritários, análise elementar, microscopia eletrônica de varredura (MEV), espectroscopia na região do infravermelho (IV), ensaio de tração, análise térmica (TG e DSC) e difração de raios X. Estes resultados revelaram o efeito do ultra-som sobre a superfície da fibra, a presença de lignosulfonato na superfície das fibras e aumento relativo da resistência à tração após as modificações. Os pré-polímeros fenólico e lignosulfonato-formaldeído foram caracterizados por cromatografia de exclusão de tamanho, IV, TG e DSC. Os compósitos preparados em todo trabalho foram caracterizados por ensaio de resistência ao impacto Izod sem entalhe, ensaio de resistência à flexão, análise térmica dinâmico-mecânica, TG, DSC, ensaio de absorção de água e condutividade térmica. O ensaio de resistência ao impacto para os compósitos fenólicos indicaram uma melhora nesta propriedade quando fibras modificadas (à 70 °C/1 h e ultra-som/1 h) foram utilizadas para preparar estes materiais. O ensaio de flexão também indicou melhora de propriedade quando as fibras modificadas por irradiação com ultra-som (1 e 2 h) foram utilizadas em compósitos fenólicos. Os resultados obtidos mostraram que os tratamentos com lignosulfonato de sódio associados a irradiação ultra-som é um tratamento promissor, pois modifica a morfologia da superfície das fibras sem levar à degradação química, sendo que a separação dos feixes de fibra que ocorre permite melhor interação fibra/matriz na interface. O ensaio de absorção de água, mostrou que os tratamentos aplicados à superfícies influenciam pouco na absorção de água dos compósitos fenólicos. Todos os compósitos preparados com matriz lignosulfonato-formaldeído obtiveram valores resistência ao impacto superiores que os compósitos fenólicos, sendo que o compósito preparado com fibra não-modificada alcançou 1000 J.m-1. As modificações nas fibras de sisal, para estes compósitos, não provocaram os efeitos esperados nas propriedades mecânicas destes materiais, embora se tenha observado uma boa adesão na interface fibra/matriz pelas imagens de MEV, resultado da semelhança químico-estrutural entre a matriz e a fibra de sisal. Uma melhora nas propriedades mecânicas dos materiais aqui investigados faz com que estes se tornem atraentes para aplicações nas indústrias automobilística e aeronáutica, visto que na sua produção são utilizados materiais oriundos de fontes renováveis, como as fibras lignocelulósicas e o lignosulfonato, e tratamentos físicos, como o aquecimento e a irradiação de ultra-som, estando de acordo com políticas de sustentabilidade e preservação do meio-ambiente. / Due to the great current interest in biocomposites because of both the use of lignocellulosic fibers as reinforcers of polymer matrices and the production of matrices prepared from renewable raw material, this study has sought to improve the properties of phenolic thermosets using sodium lignosulphonate as a macromonomer, and the insertion of sisal fibers, either treated or not with sodium lignosulphonate, as a reinforcer. Sisal fibers, which are widely produced in Brazil, are renewable, have low density, and present good mechanical properties. Lignosulphonates are obtained by a wood sulphite pulping process, thus using materials from a renewable source. The sisal fibers were modified by lignosulphonate adsorption by heating at 70 °C for 1 h, followed by sonication for different time periods (1 h and 2 h) or by immersion for 14 h in aqueous lignosulphonate solution, followed by sonication for 1 h. Fiber surface treatment by adsorption of a compatibilizing agent rather than by chemical reaction was chosen with the intent of minimizing the reduction of the fiber mechanical properties. The major sisal fiber components were characterized before and after treatment by elemental analysis, scanning electron microscopy, infrared spectroscopy (IR), tensile strength, thermogravimetry (TG) and differential scanning calorimentry (DSC), and X-ray diffraction. The treatments resulted in a significant increase in fiber tensile strength. The phenolic pre-polymers and lignosulphonate-formaldehyde were characterized by size exclusion chromatography, IR, TG, and DSC. The composites were characterized as to Izod impact strength, flexural strength, dynamic mechanic thermal analysis, TG and DSC, water absorption, and thermal conductivity. The phenolic composites reinforced with modified fibers (70 °C/1 h and sonication/1 h) presented improved impact strength. The flexural strength of phenolic composites reinforced with sonication modified fibers (1 and 2 h) improved. The results obtained demonstrate that fiber treatment with sodium lignosulphonate associated with sonication is a promising method, as it modifies the surface morphology of the fibers without drastically changing their properties. The resulting fiber bundle separation allows for a better fiber/matrix interaction. The water absorption assay demonstrated that the fiber surface treatment had little influence on the water absorption of phenolic composites reinforced with these fibers. All the composites prepared with the lignosulphonate-formaldehyde matrix had higher impact strength than phenolic composites; the composite prepared with non-modified fiber reached 1000 J.m-1. The modification of sisal fibers in these composites did not induce effects on the material mechanical properties. However, good adhesion was observed at the fiber/matrix interface, as shown by the SEM images, due to the chemical-structural similarity of the matrix and treated sisal fiber. In this case, the modification of the matrix formulations was the factor that most influenced the material properties. Both the thermosets and the composites had similar thermal conductivity, that is, the presence of untretated or treated sisal fibers did not alter the thermal conductivity of the material. The materials properties that were investigated here show that they may have potential application in the car and aircraft industries (non-structural applications) with the advantage that their production uses renewable resource materials, such as lignocellulosic fibers and lignosulphonate, and physical treatments, such as heating and sonication, meeting the current sustainability and environment preservation policies.

In today’s world the significance of bio-based materials are increasing rapidly because ofthe environmental concern. Material scientists are nowadays engaged in development ofsuch materials which have natural origin and degrade in its environment. Several workshave already been reported in area of thermoplastic biocomposites. However biocompositesbased on thermosets is comparatively new area of research. In this work biobasedcomposites have been developed from two different bio-based thermoset resins.The main objective of the work was room temperature curing of poly lactic acid basedresin (POLLIT™) and AESO, acrylated epoxidized soy-bean oil (TRIBEST®). These tworesin systems were impregnated with different natural fibre mats. Cure behavior wascharacterized by means of DSC (Differential Scanning Calorimeter) and results showsthat the resins have been cured at room temperature. The mechanical properties ofprepared composites were assessed by the means of flexural testing and charpy impacttesting. The viability of using these composites in structural applications are also beendiscussed. / Uppsatsnivå: D

Na indústria automobilística há uma grande preocupação em relação ao custo e ao peso das peças utilizadas em projetos e os adesivos vem sendo utilizados para substituir a solda ponto com esta finalidade. Neste contexto o adesivo epóxi estrutural Betamate 1496 vem sendo empregado pela Volkswagen do Brasil S.A para substituição de solda a ponto na fabricação da porta dianteira do veículo Pólo Hatch. O adesivo Betamate 1496 é utilizado na fabricação da carroçaria do veículo Pólo Hatch da Volkswagen do Brasil SA com essa finalidade. O objetivo do presente trabalho é propor e testar uma metodologia para avaliar o estado de cura do adesivo epóxi Betamate 1496 por meio da determinação do seu módulo de elasticidade e de sua dureza, quando este é empregado na fabricação das portas dianteiras do veículo Pólo Hatch. Estas propriedades foram determinadas pela medição das propriedades mecânicas do adesivo em amostras retiradas em seis posições da porta em duas fases de processamento: estado pré-curado, durante a montagem da porta e estado curado, após a cura final na estufa de pintura. O estudo foi realizado através do ensaio de indentação instrumentada, utilizando os procedimentos experimentais propostos por Franco Jr. e colaboradores e Pintaúde e colaboradores na avaliação das propriedades do polímero. O estado de cura do polímero foi avaliado de modo qualitativo também pela técnica de calorimetria diferencial exploratória (Differential Scanning Calormetry). Os resultados obtidos pela metodologia proposta por Franco Jr. e colaboradores apresentaram grande dispersão de valores, provavelmente pelo fato do método propagar erros de arredondamento na aplicação do algoritmo. Conforme observado nos resultados experimentais obtidos pela metodologia proposta por Pintaúde e colaboradores, no estado pré-curado todas as amostras apresentam valores de módulo de elasticidade muito próximos, em torno de 1,0 + 0,1. GPa, independentemente da posição na porta ou do tempo de descarregamento, já no estado curado observa-se uma diferença significativa dos valores de módulo de elasticidade, E, e dureza H dependendo da posição original da amostra na porta, com as amostras retiradas das posições inferiores apresentando E=0,8 + 0,1 GPa, enquanto que as demais apresentam E=1,0+0,1 GPa, os valores de dureza, H, para todas as amostras curadas foi H=0,03 GPa. A analise qualitativa do ensaio térmico pelas as curvas obtidas no ensaio térmico de DSC mostra que as curvas da amostra no estado pré-curado e curado são idênticas, indicando o ciclo de cura do polímero já se completa na fase de montagem da porta, antes mesmo da cura final na estufa de pintura. / Cost and weight reduction are major concerns of the automobilist industry, this leads to the increasing substitution of spot weld by adhesives in the assembling of automobile parts. In this context Volkswagen do Brazil S.A uses the Betamate 1496 structural epoxy adhesive in the manufacture of the chassis of the Polo v. Hatch. The aim of the present work is to suggest and to test a methodology to evaluate the state of cure of this adhesive by means of the determination of its hardness and elastic modulus when used in the manufacture of the front doors of the Polo v. Hatch vehicle. These properties have been determined by the measurement in six samples removed from different positions at the two phases of processing: after assembling of the chassis and cured state, after final cure at painting. The study was carried through instrumented indentation testing, which used the experimental procedures suggested by Franco Jr. and collaborators and Pintaúde and collaborators. The state of cure of polymer was evaluated also in qualitative way by Differential Scanning Calorimetry. The results obtained by the Franco Jr. methodology show great dispersion of values, probable due to the fact that the method propagates rounding errors in the application of the algorithm. The experimental results obtained by the Pintaúde methodology show that, in the state after assembling of the chassis all samples present elastic modulus, E, around 1,0 + 0.1 GPa, independently of the position in the door. In the cured state is observed depending on the sample’s position at the door: samples taken from the bottom of the door shaved E=0,8 + 0,1 GPa, while the remaining showed E= 1,0 + 0,8 GPa. The hardness, H, of the adhesive is constant (H=0,03 GPa) for all samples. The comparison of DSC curves obtained from the incurred and cured samples, showed that they are very similar, suggesting that the cure cycle of the polymer is already completed at assembling stage of the door.

Vinylesters are termosets resins that have reactive double bond at the chain ends. They are produced by the reaction of various epoxies and acrylic acids by step growth polymerization. Vinylester chains are oligomers with molecular weight from 600 to 1200 g/mol. The resin viscosity is very high / therefore, diluent is used for easy application. The generally used diluent is styrene with, reactive double bonds to form a crosslink between the chains. The diluted resin viscosities are between 200 &amp / #8211 / 2000 cps. Peroxide initiators are used for network formation. The mechanical properties of vinylester resin are enhanced with reinforcements such as glass fiber, carbon fiber, Kevlar or nanoparticules to make composites. Various molecular weights of vinylester resins were synthesized and the samples were prepared with different styrene contents. The effects of the styrene content, temperature and molecular weight on the viscosity were measured and examined. The main effects were determined as styrene content and temperature, while the effect of molecular weight is negligible. The resins were characterized with IR and NMR spectroscopy. The molecular weights were determined by theoretical calculations, titration and H-NMR spectroscopy. Peroxide initiators were used to cure the resins with the cobalt complex accelerator. The resins were post-cured at different temperatures. The completion of the curing was monitored by the disappearance of the carbon-carbon double bonds of methacrylate (943 cm-1) and styrene (910 cm-1), by FT-IR spectrum. The effects of styrene content, post-cure conditions, and molecular weight on the mechanical properties were discussed. The glass transition temperatures were determined by DSC and DMA. The crosslink densities and rheological properties were determined by creep test. The important properties of vinylester resins, which are modulus, tensile and flexural strength, shrinkage, water absorption, glass transition temperature, HDT values and impact strength were investigated.

Na indústria automobilística há uma grande preocupação em relação ao custo e ao peso das peças utilizadas em projetos e os adesivos vem sendo utilizados para substituir a solda ponto com esta finalidade. Neste contexto o adesivo epóxi estrutural Betamate 1496 vem sendo empregado pela Volkswagen do Brasil S.A para substituição de solda a ponto na fabricação da porta dianteira do veículo Pólo Hatch. O adesivo Betamate 1496 é utilizado na fabricação da carroçaria do veículo Pólo Hatch da Volkswagen do Brasil SA com essa finalidade. O objetivo do presente trabalho é propor e testar uma metodologia para avaliar o estado de cura do adesivo epóxi Betamate 1496 por meio da determinação do seu módulo de elasticidade e de sua dureza, quando este é empregado na fabricação das portas dianteiras do veículo Pólo Hatch. Estas propriedades foram determinadas pela medição das propriedades mecânicas do adesivo em amostras retiradas em seis posições da porta em duas fases de processamento: estado pré-curado, durante a montagem da porta e estado curado, após a cura final na estufa de pintura. O estudo foi realizado através do ensaio de indentação instrumentada, utilizando os procedimentos experimentais propostos por Franco Jr. e colaboradores e Pintaúde e colaboradores na avaliação das propriedades do polímero. O estado de cura do polímero foi avaliado de modo qualitativo também pela técnica de calorimetria diferencial exploratória (Differential Scanning Calormetry). Os resultados obtidos pela metodologia proposta por Franco Jr. e colaboradores apresentaram grande dispersão de valores, provavelmente pelo fato do método propagar erros de arredondamento na aplicação do algoritmo. Conforme observado nos resultados experimentais obtidos pela metodologia proposta por Pintaúde e colaboradores, no estado pré-curado todas as amostras apresentam valores de módulo de elasticidade muito próximos, em torno de 1,0 + 0,1. GPa, independentemente da posição na porta ou do tempo de descarregamento, já no estado curado observa-se uma diferença significativa dos valores de módulo de elasticidade, E, e dureza H dependendo da posição original da amostra na porta, com as amostras retiradas das posições inferiores apresentando E=0,8 + 0,1 GPa, enquanto que as demais apresentam E=1,0+0,1 GPa, os valores de dureza, H, para todas as amostras curadas foi H=0,03 GPa. A analise qualitativa do ensaio térmico pelas as curvas obtidas no ensaio térmico de DSC mostra que as curvas da amostra no estado pré-curado e curado são idênticas, indicando o ciclo de cura do polímero já se completa na fase de montagem da porta, antes mesmo da cura final na estufa de pintura. / Cost and weight reduction are major concerns of the automobilist industry, this leads to the increasing substitution of spot weld by adhesives in the assembling of automobile parts. In this context Volkswagen do Brazil S.A uses the Betamate 1496 structural epoxy adhesive in the manufacture of the chassis of the Polo v. Hatch. The aim of the present work is to suggest and to test a methodology to evaluate the state of cure of this adhesive by means of the determination of its hardness and elastic modulus when used in the manufacture of the front doors of the Polo v. Hatch vehicle. These properties have been determined by the measurement in six samples removed from different positions at the two phases of processing: after assembling of the chassis and cured state, after final cure at painting. The study was carried through instrumented indentation testing, which used the experimental procedures suggested by Franco Jr. and collaborators and Pintaúde and collaborators. The state of cure of polymer was evaluated also in qualitative way by Differential Scanning Calorimetry. The results obtained by the Franco Jr. methodology show great dispersion of values, probable due to the fact that the method propagates rounding errors in the application of the algorithm. The experimental results obtained by the Pintaúde methodology show that, in the state after assembling of the chassis all samples present elastic modulus, E, around 1,0 + 0.1 GPa, independently of the position in the door. In the cured state is observed depending on the sample’s position at the door: samples taken from the bottom of the door shaved E=0,8 + 0,1 GPa, while the remaining showed E= 1,0 + 0,8 GPa. The hardness, H, of the adhesive is constant (H=0,03 GPa) for all samples. The comparison of DSC curves obtained from the incurred and cured samples, showed that they are very similar, suggesting that the cure cycle of the polymer is already completed at assembling stage of the door.