abstract: Concrete is relatively brittle, and its tensile strength is typically only about one-tenth of its compressive strength. Regular concrete is therefore normally uses reinforcement steel bars to increase the tensile strength. It is becoming increasingly popular to use random distributed fibers as reinforcement and polymeric fibers is once such kind. In the case of polymeric fibers, due to hydrophobicity and lack of any chemical bond between the fiber and matrix, the weak interface zone limits the ability of the fibers to effectively carry the load that is on the matrix phase. Depending on the fiber’s surface asperity, shape, chemical nature, and mechanical bond characteristic of the load transfer between matrix and fiber can be altered so that the final composite can be improved. These modifications can be carried out by means of thermal treatment, mechanical surface modifications, or chemical changes The objective of this study is to measure and document the effect of gamma ray irradiation on the mechanical properties of macro polymeric fibers. The objective is to determine the mechanical properties of macro-synthetic fibers and develop guidelines for treatment and characterization that allow for potential positive changes due to exposure to irradiation. Fibers are exposed to various levels of ionizing radiation and the tensile, interface and performance in a mortar matrix are documented. Uniaxial tensile tests were performed on irradiated fibers to study fiber strength and failure pattern. SEM tests were carried out in order to study the surface characteristic and effect of different radiation dose on polymeric fiber. The interaction of the irradiated fiber with the cement composite was studied by a series of quasi-static pullout test for a specific embedded length. As a final task, flexural tests were carried out for different irradiated fibers to sum up the investigation. An average increase of 13% in the stiffness of the fiber was observed for 5 kGy of radiation. Flexural tests showed an average increase of 181% in the Req3 value and 102 % in the toughness of the sample was observed for 5 kGy of dose. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2018

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Orientador: João Sinézio de Carvalho Campos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-17T10:17:41Z (GMT). No. of bitstreams: 1 Almeida_RosemeiredosSantos_M.pdf: 1496479 bytes, checksum: b8bf05066c4483752cebde2f006e95c6 (MD5) Previous issue date: 2010 / Resumo: E bem conhecido o amplo uso de materiais poliméricos e o proporcional impacto que eles causam quando são descartados no meio ambiente, especialmente os "commodities" como Polipropileno (PP) e Polietileno (PE). Isso tem preocupado os cientistas, que cada vez mais procuram desenvolver tecnologias para o reaproveitamento desses materiais. Uma das técnicas existentes e o reprocessamento por meio de extrusoras e injetoras, cujos processos, no entanto, tendem a degradar o material, levando a alteração em suas propriedades mecânicas e reológicas. Tendo em vista o contexto apresentado, foi desenvolvido um estudo no qual se avaliou a influencia da velocidade de rotação da rosca no processo de extrusão do polipropileno (PP) virgem e material reciclado, proveniente do setup durante a produção de canudos para refrigerante e rebarbas da fabricação de fraldas descartáveis, absorventes em que existe uma pequena quantidade de polietileno (PE). Observou-se sob quatro diferentes rotações, a saber: 40, 80, 120 e 160 rpm e um mesmo perfil de temperatura ao longo de uma extrusora monorosca. Apos o processo de extrusão, realizado sob as condições citadas acima, injetaram-se corpos de prova para analise de propriedades mecânicas, reológicas e térmicas. Constatou-se que as diferentes rotações estudadas provocaram alterações na deformação máxima de ruptura na tração, sendo que para o material reciclado, a rotação de 160 rpm apresentou a maior alteração dentre as demais rotações estudadas / Abstract: It's well known the broad use of polymeric materials and the proportional impact they cause when discarded in the environment, especially the "commodities" known as polypropylene (PP) and Polyethylene (PE). This has worried scientists, who search to develop technology to recycle these materials. One of these techniques is the reprocessing by extrusion and injection molding, the processes, however, tend to degrade the material, leading to alteration in their mechanical and rheological properties. Considering the context presented, it was developed a study where we evaluated the influence of rotation speed of the screw in the extrusion of virgin polypropylene (PP) and material recycled obtained from soda straws and disposable diapers's burrs, where there are a small amount of polyethylene (PE). It was observed four different speeds, namely 40, 80, 120 and 160 rpm carried out in one temperature profile along a single screw extruder. After the extrusion process, conducted under the above conditions were injected samples for analysis of mechanical, rheological and thermal properties. It was found that the different rotations cause changes in rupture maximum tensile strain. The recycled material processed at 160 rpm has presented the greatest change among the studied rotations / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

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Orientadores: Rogerio de Fraga, Paulo Cesar Rodrigues Palma / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-12T22:24:52Z (GMT). No. of bitstreams: 1 Cardia_FishilerPimentelZitenfeld_M.pdf: 1370656 bytes, checksum: 9c1061423f4725bab06c637f1e6c0958 (MD5) Previous issue date: 2009 / Resumo: A crescente utilização de telas de polipropileno em cirurgia pélvica reconstrutiva levou ao aparecimento de complicações inerentes ao uso dos materiais sintéticos, tais como retração, exposição e infecção. Com o objetivo de avaliar a retração de telas de polipropileno de media gramatura e melhorar a incorporação da mesma através de orifícios de 5 mm de diâmetro, realizamos um estudo experimental "in vivo". Método: No presente estudo, avalia a morfologia e a densidade volumétrica das fibras de colágeno em malhas com e sem orifícios padronizados, bem como; a retração das mesmas, por meio de mensuração radiográfica e direta da tela. A amostra consistiu de 14 ratas fêmeas da raça Wistar, que foram sacrificadas 90 dias após o implante. O abdômen foi ressecado e radiografado antes de ser preparado o estudo histológico e estereológico. A distribuição do colágeno foi avaliada por estereologia nos três compartimentos: pele, fascia de Colles e na região do implante da Tela entre a fascia de Colles e a aponeurose dos músculos retos abdominais. Resultados: Não houve retração das telas de polipropileno nas aferições radiográficas e medidas diretas. A estereologia evidenciou deposição de fibras de colágenos organizadas nos orifícios. Ao contrário nas telas sem orifícios, a deposição de colágeno foi maior e desorganizada, com cistos de inclusão. Outro dado relevante foi que a estrutura das fibras de colágeno apresentou-se morfologicamente normal nos animais de tela com orifício, e houve uma maior proximidade entre a pele e a musculatura no local do orifício. Conclusões: A análise histológica revelou menor reação inflamatória nas telas com macro orifícios. A avaliação estereológica da densidade volumétrica das fibras de colágeno nas telas com e sem orifícios, permitiu observar que os macro orifícios agiram como fator facilitador da integração do enxerto e que poderá representar implicações na parte clinica médica. Palavras chaves: Polipropileno; Telas cirúrgicas / Abstract: The meshes in reconstructive pelvic surgery have led to complications inherent to the use of synthetic materials, such as retraction, exposure and infection. In order to improve mesh integration we created standardized orifices, 5 mm in diameter of monofilament polypropylene mesh and compared local tissue reaction with regular meshes in an animal study. Method: We evaluated the morphology and volumetric density of collagen fibers in meshes with and without standardized orifices, as well as its retraction through radiographic and direct measurement of the meshes. The sample consisted of 15 female Wistar rats, which were sacrificed 90 days after the implant. The abdominal wall was removed and x-ray was taked before its preparation for histological and stereological study (estimate the density of an element of a homogeneous area). The volumetric density of the collagen fibers was calculated by stereological tool in three compartments: skin, Colles' fascia and mesh, the latter located between the Colles' fascia and the aponeurosis of the rectus abdominalis muscles. Results: There was no retraction of the polypropylene meshes. The histological and stereological analysis disclosed organized collagen fiber deposition in the orifices and less inflammatory reaction than the control meshes with no orifices. Conclusions: There was no mesh retraction in both groups. The histological and stereological results suggest that the standardized orifices facilitated tissue integration and may have clinical application. Keywords: Polypropylene; Surgical meshes / Mestrado / Cirurgia / Mestre em Cirurgia

Orientadores: Helena Teixeira Godoy, Marisa Padula / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-23T04:09:43Z (GMT). No. of bitstreams: 1 Oliveira_WellingtondaSilva_M.pdf: 956439 bytes, checksum: 3f0a6d0735f71f0d97e159bbf8fce38f (MD5) Previous issue date: 2013 / Resumo: No Brasil, mais de 50% da população utiliza mamadeiras durante a amamentação de crianças. Após a proibição do uso do bisfenol A em mamadeiras de policarbonato, outros polímeros como o polipropileno e o Tritan® passaram a ser utilizados com essa finalidade. Embora estes materiais sejam liberados para uso como material de contato com alimentos há uma lacuna no que diz respeito à migração de compostos oriundos do plástico utilizado na fabricação de mamadeiras. Estudos voltados para a identificação de substâncias não intencionalmente adicionadas e migrantes, em mamadeiras, são necessários para avaliar a segurança no uso destes materiais. Diante disso, o objetivo deste estudo foi avaliar o potencial de migração dos materiais utilizados na confecção de mamadeiras. Foram avaliadas 32 mamadeiras, de 3 marcas diferentes, feitas de Tritan (A) e polipropileno (B, CT e CP). Entre as marcas, três eram transparentes e com desenhos (A, B, CT), e uma era completamente pigmentada (CP). Inicialmente, foi feito a caracterização das mamadeiras e confirmação do material por espectroscopia no infravermelho por transformada de Fourier (FT-IR). Na caracterização foram avaliadas a espessura mínima, o diâmetro, o volume, a massa e altura das mamadeiras. Em seguida, foram realizados ensaios de migração de acordo com a RDC 51/2010 da Agência Nacional de Vigilância Sanitária (ANVSA), que recomenda a utilização de etanol 50% como simulante de leite. A simulação foi realizada mantendo a mamadeira em contato com o simulante a 70°C por 2h. Neste ensaio foi feita a identificação dos migrantes com base na biblioteca de espectros de massas do National Institute of Standards and Technology (NIST). Um método para determinação de di(2-etilhexil) ftalato (DEHP) e dibutil ftalato foi validado para os parâmetros limite de detecção (LD) e quantificação (LQ), linearidade, repetitividade e precisão intemediária. O perfil de antioxiandantes foi determinado utilizando um cromatógrafo líquido com detector de arranjo de diodos. Com base na caracterização, foi observado que as mamadeiras das marcas B, CT e CP apresentaram maior uniformidade nos parâmetros avaliados que as mamadeiras da marca A, que apresentaram dimensões com coeficientes de variação maiores que 20%, indicando falta de padrão em mamadeiras de um mesmo lote. Na seleção e identificação de migrantes foi observada a migração de mais de 20 compostos, dentre eles o DEHP e o DBP. O método validado apresentou limites de detecção e quantificação de 16 µg/L e 52 µg/L para o DBP e 10 µg/L e 30 µg/L para o DEHP. O método mostrou-se linear nas faixas de 52-660 µg/L para o DBP e 52-1100 µg/L para o DEHP, com boa repetitividade e precisão intemediária com CV abaixo de 20%. Todas as mamadeiras apresentavam concentrações de DEHP abaixo do LQ. Em relação ao DBP, somente as mamadeiras da marca CP apresentaram migrações acima do limite de migração específa (0,3 mg/kg) recomendado pela ANVISA. Em todas as mamadeiras foram encontrados os antioxidantes Irganox 1010 e Irgafos 168. Estes compostos não têm restrição de uso, podendo ser usados em materiais de contato com alimentos. Das três marcas de mamadeiras analisadas, somente as marcas B e CT apresentaram resultados satisfatórios para utilização em contato com o leite. As mamadeiras da marca A deformaram após o ensaio de simulação. As mamadeiras da marca CP apresentaram níveis de migração acima do limite de migração especifica (0,3 mg/kg) preconizado pela ANVISA / Abstract: In Brazil, more than 50% of the population uses baby bottles to feed children. After banning the use of bisphenol A in polycarbonate baby bottles, other polymers such as polypropylene and Tritan® have been used for this purpose. Although these materials were approved for using as food contact material, there is a vacuity with regard to the migration of plastic derived compounds used in the manufacture of baby bottles. Studies aimed at the identification of non-intentionally added substances and migrants, in baby bottles, are needed to assess the safety of these materials. Thus, the aim of this study was to evaluate the migration potential of materials used in the baby bottles manufacture . Thirty-two baby bottles of three different brands made of Tritan (A) and polypropylene (B, CT, and CP) were evaluated. Among the brands, three were transparent and drawings (A, B, CT), and one was completely pigmented (CP). Initially, were made a characterization the material baby bottles and then its materials were confirmed by infrared spectroscopy Fourier transform (FT-IR). The characterization was based on minimum thickness, diameter, volume, mass and height of the baby bottles. Then, migration assays were performed according to the RDC 51/2010 of the National Agency for Sanitary Vigilance (ANVISA), which recommends the use of 50% ethanol as a milk simulant. The simulation was done by putting the baby bottles in contact with the simulant at 70 ° C for 2 h. In this assay the identication of the migrant was done based on the mass spectra library of the National Institute of Standards and Technology (NIST). A method for the determination of di (2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) was validated for the parameters detection (LOD) and quantification (LOQ) limit, linearity, repeatability and accuracy-intermediate. The antioxiandants profile was determined using a liquid chromatograph with a diode array detector. The materials used in the baby bottles manufacture, as declared on the labels were confirmed. Based on characterization, it was observed that the baby bottles of brands B, CT, and CP showed greater uniformity in the parameters evaluated than brand A, which had dimensions with variation coefficients (CV) greater than 20%, indicating the lack of standard in the same lot of baby bottles. The selection and identification of migrants showed the migration of more than 20 compounds, including DEHP and DBP. The method validated in this study showed a detection and quantification limits of 16 µg/L and 52 µg/L for DBP and 10 µg/L and 30 µg/L for DEHP. The method was linear in the range of 52-660 µg/L for DBP and 52-1100 µg/L for DEHP, with good repeatability and accuracy-intermediate with CV below 20%. All baby bottles had concentrations of DEHP below the LOQ. Regarding DBP, only the baby bottles of brand CP showed migration above specific migration limit (0.3 mg / kg) recommended by ANVISA. In all bottles were found the antioxidants Irganox 1010 and Irgafos 168. These compounds have no use restriction and can be used in food contact materials. Taking into account the brands of baby bottles analyzed, only the brands B and CT showed satisfactory results for use in contact with milk. The baby bottles of brand A deformed after the simulation test. The baby bottles of the brand CP showed migration levels above the specific migration limit (0.3 mg/kg) recommended by ANVISA / Mestrado / Ciência de Alimentos / Mestre em Ciência de Alimentos

Orientador: João Sinézio de Carvalho Campos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T20:46:43Z (GMT). No. of bitstreams: 1 Lopes_SelmaAparecida_M.pdf: 4679717 bytes, checksum: b44b60b38798f2147b5fd6fe7eacc78f (MD5) Previous issue date: 2012 / Resumo: O material polimérico denominado não tecido de polipropileno (NTPP), após receber adequado tratamento químico, tem sido largamente utilizado na indústria têxtil para confecção de produtos de higiene pessoal, fraldas e absorventes descartáveis. Neste sentido o presente trabalho analisa os efeitos das técnicas de descarga corona (atmosfera ambiente) e plasma por radiofrequência (atmosferas de oxigênio (O2), nitrogênio (N2) e argônio (Ar) causados nas propriedades de superfície de amostras de NTPP em função do tempo de tratamento e nas respectivas atmosferas citadas. Recortam-se amostras de NTPP com geometria retangular (10x30mm) e espessura média de 40?m. Após tratamentos por corona e plasma submetem-se as amostras ás técnicas de medidas de ângulo de contato (método da gota séssil), de espectrometria em infravermelho (FTIR/ATR), de microscopia eletrônica exploratória (SEM) e de calorimetria diferencial exploratória (DSC); as quais têm por objetivo caracterizar a superfície do material em relação à molhabilidade, a formação de grupos polares, alterações morfológicas e comportamento de volume, respectivamente. Realizaram-se as medidas em quintuplicatas e dentre os resultados pode-se destacar que (i) o ângulo de contato tende a diminuir com o aumento do tratamento tanto corona quanto plasma, indicando que está ocorrendo aumento da molhabilidade do material, assim como comprovado por cálculos de energia livre de superfície (por exemplo: sem tratamento 18 mN/m e após tratamento 87 mN/m); (ii) as espectrometrias em infravermelho indicam a formação de grupos polares (hidroxílicos e carboxílicos); (iii) os termogramas em DSC indicam que não há alterações entre amostras com e sem tratamento, preservando assim propriedades de volume do material (estabilidade térmica de 0 á 135ºC e Tm=162ºC). Cabe ressaltar que realizaram-se medidas sobre a durabilidade do tratamento corona e os resultados mostram satisfatória durabilidade até 4 dias / Abstract: The polymeric material known as non-woven polypropylene (NTPP) upon receiving suitable chemical treatment has been widely used in the textile industry for the manufacture of personal hygiene products, diapers and disposable absorbent. In this sense the present paper analyzes the effects of corona discharge techniques (ambient atmosphere) and plasma radiofrequency (atmospheres of oxygen (O2), nitrogen (N2) and argon (Ar) caused the surface properties of samples as a function NTPP treatment time and the respective atmospheres cited. Samples were cut out NTPP rectangular geometry (10x30mm) and an average thickness of 40?m. After corona treatment and plasma samples were subjected techniques measures the contact angle (sessile drop method), infrared spectrometry (FTIR/ATR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) which are intended to characterize the material surface with respect to wettability, the formation of polar groups, and morphological behavior volume, respectively. There were measures in quintuplicatas and among the results can be noted that (i) the contact angle tends to decrease with the increase in both corona treatment and plasma, indicating that it is an increase of the wettability of the material, as evidenced by calculations of surface free energy (for example, untreated 18 mN/m after treatment 87 mN/m; (ii) infrared spectroscopy indicated the formation of polar groups (hydroxyl and carboxyl); (iii) the DSC thermograms show no charges between treated and untreated samples, thus maintaining properties of the material volume (thermal stability of 0 to 135ºC and Tm=162ºC). It should be noted that measurements were performed on the stability of the corona treatment and the results show satisfactory stability up to 4 days / Mestrado / Ciencia e Tecnologia de Materiais / Mestre em Engenharia Química

The study presented aims to provide the most viable seismic retrofit solution for rural masonry. Muzffarabad is one such region where excess of unreinforced masonry structures claimed thousands of lives during 2005 earthquake. Field study was conducted in the region to familiarize with the dynamics of local construction industry before suggesting a suitable retrofit solution. Polypropylene (PP-) band retrofit has been selected as the most viable solution for retrofitting existing masonry structures in terms of cost, material availability and ease of application. To prove the efficiency of PP-band retrofit, numerical simulations and laboratory tests were conducted to assess the seismic efficiency of PP-band retrofit. Material tests were conducted in accordance with BS-EN to familiarize with the mechanical properties of locally available materials in Kashmir region and to provide material data for numerical analysis. Tests revealed lower strength and elasticity for bricks in comparison to materials found in developed countries, due to the unregulated and non-standardized manufacturing of masonry units and high water content in mortars. Shake table tests were conducted to test the effectiveness of PP-band retrofit masonry under dynamic vibrations. Results show that PP-band retrofit can enhance the post peak performance by at least 7 times in comparison to non-retrofit specimen. Real-scale structure retrofit with PP-band survived accelerations of up to 2g without any life-threatening damage, thus, proving to be an economic and efficient strengthening solution for rural communities. Following the shortcomings observed in Room-1, connection detail for PP-bands in Room-2 was revised to achieve a 100% performance enhancement. Numerical models were developed to predict cracks in masonry and analyse diagonal compression test models, in accordance with ASTM standards. The results showed 30% higher residual strength after cracking for PP- band retrofit masonry and the wall integrity was maintained for higher deformations.

The use of natural fibers as reinforcement in thermoplastics presents an interesting alternative for the production of low cost and ecologically friendly composites. One of the advantages of using natural fibres is their low specific weight, resulting in higher specific strength and stiffness when compared to glass reinforced composites. Natural fibres also present safer handling and working conditions. They are non-abrasive to mixing and can contribute to significant cost reduction. This work is divided into two phases: Phase 1 deals with developing nonwoven mats composites from flax/polypropylene (PP) and evaluating their properties. Flax/polypropylene fibres (at different weight ratios) were processed by needle-punching technique in order to form nonwoven mats. The mats were compression-molded at a temperature of 180oC to form composite materials. The mechanical, thermal and viscoelastic properties of the composites were analyzed. Composites (untreated and silane-treated) were also subjected to varying conditions of temperature and humidity and the tensile properties of the conditioned and unconditioned composites were investigated. The mechanical properties (tensile, flexural and impact) of flax/PP composites were found to increase and reach maximum values at 30 per cent fibre loading and then decrease at higher fibre content. Thermal studies revealed that the composites were stable up to 320oC and samples containing 40 per cent flax fibres were found to exhibit greater thermal stability than neat PP. The dynamic mechanical analyses of the composites showed that the incorporation of flax in the composites resulted in an increase of the storage modulus with a maximum value exhibited by composite containing 40 per cent fibre loading. Composites containing chemically modified fibres exhibited low tensile modulus after conditioning. Phase 2 is based on the investigation of the effect of nano-calcium carbonate (CaCO3) on the properties of two types of polymer matrices: recycled PP and virgin PP. In this case, composites were prepared by melt-mixing and injection molding. The mechanical and thermal properties of the composites were characterized. The tensile modulus of the nano-CaCO3 filled PP (virgin and recycled) composites were found to increase and reach maximum at 30 per cent nano-CaCO3 loading, while the tensile strength decreased with increasing filler content. Thermal studies showed that the nano-CaCO3 filled PP samples exhibited a one-step degradation pattern and are thermally stable up to 450oC. The thermal stability of the samples was found to decrease following the addition of nano-CaCO3. SEM micrographs of the tensile fractured surfaces of composites of the nano-CaCO3 filled virgin and recycled PP revealed the presence of nano-CaCO3 agglomeration.

Please read the abstract in the section, 00front, of this document / Dissertation (MEng)--University of Pretoria, 2008. / Chemical Engineering / unrestricted