683 resultados para Polietileno Reaproveitamento
Resumo:
Neste trabalho foi feito um estudo das propriedades reolgicas, mecnicas e trmicas de blendas polimricas contendo 1 e 10% em massa de polietileno de ultra alto peso molar (PEUAPM) e polietileno linear de mdia densidade (PELMD). As blendas foram obtidas por mistura em extrusora de rosca simples e em extrusora de rosca dupla, para fins de comparao. Na extruso em rosca dupla foi acrescentado um terceiro componente - leo mineral, cera ou polietileno de muito baixo peso Molar (PEMBPM) - a fim de promover uma melhor interao entre o PELMD e PEUAPM. As amostras obtidas por moldagem por injeo, rotomoldagem e moldagem por compresso foram submetidas a testes reolgicos, trmicos e mecnicos. Foi analisada a influncia do tipo de processamento e da composio das blendas sobre morfologia e as propriedades finais destas. A reometria rotacional indicou um gradual aumento da viscosidade das blendas com o aumento da quantidade de PEUAPM adicionado. Anlises de microscopia eletrnica de varredura (MEV), microscopia tica e calorimetria diferencial de varredura (DSC) indicaram uma separao de fases nas blendas, mesmo quando o terceiro componente foi adicionado. Entretanto, as blendas que contm agente de acoplamento apresentaram diferenas na morfologia final, como observado atravs das anlises de microscopia tica durante a cristalizao do sistema polimrico e nas anlises de MEV nas amostras moldadas por injeo Para todas as blendas moldadas por injeo, a resistncia ao impacto foi menor do que a encontrada para o PELMD puro. Por outro lado, nas amostras rotomoldadas no houve diferena significativa nas propriedades das blendas quando comparadas ao PELMD puro. As amostras extrusadas em rosca dupla, contendo leo mineral ou cera e, posteriormente, moldadas por compresso apresentaram resistncia ao impacto similares aos valores encontrados para o PELMD puro, sem significativas mudanas na processabilidade. Considerando as demais anlises de propriedades mecnicas, no foi observada influncia do terceiro componente.
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A humanidade encontra-se em uma encruzilhada histrica: continuar com a forma desordenada de crescimento ou apostar em uma sociedade sustentvel com orientao ecolgica. Os sinais de fraqueza do ecossistema tm mostrado vrios sinais de esgotamento. A manifestao desta realidade o fato de estarmos vivendo em uma era de escassez de recursos e de dificuldades de expanso da base econmica das sociedades nacionais, de saturao dos depsitos de resduos das sociedades. Aprende-se desde cedo que o lixo produzido diariamente deve ser jogado fora, que sujo e fonte de problemas. A possibilidade da reciclagem de resduos deve ocorrer de forma integrada e sistmica, pois o que resduo para um matria-prima para outro. A tarefa de realizar um gerenciamento dos resduos slidos urbanos adequado ambientalmente uma tarefa que exige aes diferenciadas, articuladas e criativas. Existem vrias alternativas possveis para o tratamento adequado dos resduos slidos urbanos. O manejo dos resduos slidos pode diminuir e, em alguns casos, evitar muitos dos impactos negativos associados ao lixo. Como forma de diminuir a quantidade de lixo que destinado aos aterros, pode-se utilizar a frao orgnica, a sobra do pr-preparo de alimentos, para a criao animal, mais precisamente para criao de sunos. Dentro do que foi estabelecido como objetivo deste estudo, verificou-se que a sustentabilidade econmica da criao de sunos com o reaproveitamento de resduos orgnicos possvel de ser obtida. Foi possvel por meio da metodologia desenvolvida apurar os custos de produo do suno tratado com resduo orgnico e do suno tratado com rao comercial. Estes custos so de R$140, 27, para o primeiro e de R$153,15 para o segundo, tendo-se como padro um animal de 100kg.
Resumo:
Em plantas de polimerizao, uma das principais propriedades relacionadas qualidade do produto o ndice de fluidez, ou MI. Esta propriedade geralmente medida em laboratrio, em intervalos de algumas horas. Por outro lado, as variveis de processo esto disponveis continuamente e so controladas com o objetivo de atingir as propriedades desejadas do produto. O desenvolvimento de um analisador virtual, que permita a estimao do MI de forma contnua, com base nestas variveis medidas, pode levar a um melhor controle da qualidade do produto final. Este trabalho desenvolve um analisador virtual de MI para uma planta de polietileno de alta densidade (PEAD). Existem vrios tipos de modelos que podem ser utilizados na implementao de um analisador virtual, assim como vrias formas de correo on-line das suas estimativas. Este trabalho direciona especial ateno aos modelos semi-empricos, e ao uso de um filtro de Kalman estendido (EKF) na correo das estimativas e dos parmetros do modelo. O objeto de estudo desse trabalho foi um conjunto de produtos, cuja produo realizada em dois reatores em srie. Foram usados 21 conjuntos de dados representando diferentes perodos de operao da planta. Estes conjuntos de dados continham as principais variveis de planta e os resultados de MI medidos em laboratrio. A partir destes dados, foram estimados os parmetros do modelo para cada reator. Tambm foi proposta e testada uma metodologia para a sintonia dos parmetros do EKF. De posse dos modelos, do filtro e de seus respectivos parmetros, foram gerados os resultados do analisador.
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The study aimed at the treatment of attapulgite for the development and characterization of composite recycled low density polyethylene - PEBD_rec embedded with natural attapulgite - ATP_NAT, sifted - ATP_PN and attapulgite treated with sulfuric acid - ATP_TR in different compositions (1, 3 and 5%) and compared with the PEBD_rec. The atapulgitas, natural, screened and treated, were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size analysis, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and determining the area specific surface (BET). The composites were characterized by thermogravimetry (TG), differential scanning calorimetry (DSC), Xray diffraction (XRD), torque rheometry, scanning electron microscopy (SEM) and traction. The composite PEBD_rec / ATP (natural, sieved and treated) were produced by mixing in the molten state in a single screw extruder matrix wire with subsequent reprocessing matrix tape. It was found that the screening of attapulgite not reduce the quantity of quartz and the acid treatment completely extracted dolomite aggregate impurities of the channels attapulgite, and increase their surface area. The addition of attapulgite in PEBD_rec acts as a catalyst, reducing the thermal stability of the polymer. The increased concentration of attapulgite, increases resistance and reduces the elongation at break and modulus of elasticity of the composite PEBD_rec / attapulgite
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Estudou-se o efeito de diferentes embalagens de polietileno em figos cv. Roxo de Valinhos, sob condies de frigoconservao. Os frutos colhidos no incio do estdio de maturao, foram limpos e selecionados, sendo aps embalados em filmes plsticos de polietileno de diferentes espessuras, constituindo assim os tratamentos: 1(controle), 2 - PEBD com 6 m de espessura, 3 - PEBD com 10 m de espessura, 4 - PEBD com 15 m de espessura, 5 - PEBD com 22 m de espessura. Os frutos foram ento armazenados em cmara fria com temperatura de -- 0,5 C e 85-90 % de UR, por oito dias. As anlises foram realizadas diariamente, avaliando-se os seguintes parmetros: perda de massa fresca, aspecto visual, firmeza de polpa, slidos solveis totais (SST), acidez total titulvel (ATT) e relao SST/ATT. Ao final, verificou-se que os frutos embalados em PEBD de 22 m apresentaram maior firmeza de polpa, melhor aspecto visual, menores teores de slidos solveis totais, maiores nveis de acidez total titulvel e menores valores na relao SST/ATT, quando comparados aos demais tratamentos. No parmetro perda de massa fresca, todos os tratamentos foram estatisticamente superiores ao controle.
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Objetivou-se, neste trabalho, determinar os balanos de radiao e energia da cultura de alface (Lactuca sativa, L. cv. Vernica) em estufa de polietileno. O experimento foi realizado em uma estufa tipo tnel alto com cobertura de polietileno (100 mim de espessura) e em uma rea externa, ambas com 35 m. Durante o ciclo da cultura, foram monitoradas as radiaes global e refletida, saldo de radiao, fluxo de calor no solo e temperatura do ar (seca e mida) nos dois meios. Utilizou-se um Datalogger que operou na freqncia de 1 Hz, armazenando mdias de cinco minutos. A partir das integraes dirias das irradincias global (K) e refletida (K), verificou-se que a transmissividade mdia da radiao global (Kin / Kex) foi aproximadamente constante, em torno de 79,59%, enquanto a razo das radiaes refletidas (Kin / Kex) foi igual a 69,21% com coeficiente de variao de 8,47%. As curvas normalizadas do saldo de radiao de ondas curtas em relao radiao global (K* / K), nos dois meios, mostraram ser aproximadamente constantes no incio do ciclo e decrescentes no final. A relao (Rn/ K) foi maior no meio externo, em torno de 12%, a partir da fase em que a superfcie verde da cultura cobriu o solo. O balano mdio (L*) de radiao de ondas longas foi maior no exterior, em torno de 50%. O balano de energia, estimado em termos de fluxos verticais, mostrou, em mdia, que: no exterior, 83,07% do saldo de radiao foi convertido em calor latente (LE), 18,00% em fluxo de calor no solo (G) e 9,96% em calor sensvel (H), enquanto que, no interior da estufa, 58,71% do saldo de radiao foi convertido em LE, 42,68% em H e 28,79% em G.
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The scarcity of farmland, reducing the supply of irrigation water and lack of technologies for conservation, makes the globalized world facing serious difficulties in the production of food for its population. The most viable outlet for this dilemma is the dissemination of technologies, economically viable and available to the whole population, for dehydration of perishable foods produced. This paper presents a solar dryer of direct exposure to the production of dried fruit, made from recycled polyethylene drum of 200 liters, used for storing water or trash. The drum was sectioned in half in its longitudinal axis and has its halves together forming a trough-like structure. It describes the processes of construction and assembly of solar dryer proposed, whose main characteristic its low cost, and was designed for use by people with low income, for processing fruits widely available in our region (mango, banana, guava, cashew, pineapple, tomato and others) in dried fruit and flour, contributing significantly to increase the life of these foods. The nuts and flours can be used for own consumption and for marketing jobs and income generation. Tests were conducted to diagnose the feasibility of using solar dryer for the various types of tropical fruits. Were also compared parameters such as drying times and thermal efficiency obtained with the prototype found in the specialized literature in food dehydration. The drying times in the dryer were obtained competitive with those obtained in other models of dryers LMHES developed
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As an auxiliary tool to combat hunger by decreasing the waste of food and contributing for improvement of life quality on the population, CEASA/RN has released from August/03 to August/05 the program MESA DA SOLIDARIEDADE. Despite of the positive results of this program, that has already distributed around 226 tons of food, there is still food being thrown in the trash as the deliver of the same food in its natural form would be a health risk to those who would consume it and only the correct processing of this food can make it edible. This work has as a goal the reuse of solid residues of vegetal origin generated by the CEASA/RN, through the Program MESA DA SOLIDARIEDADE and the characterization of the product obtained so it might be used as a mineral complement in the human diet. To the collecting of samples (from September until December /2004) it was developed a methodology having as a reference the daily needs of mineral salts for infants at the age of seven to ten. The sample was packed in plastic bags and transported in an ambient temperature to the laboratory where it was selected, weighted, disinfected, fractionated and dried to 70C in greenhouse. The dry sample was shredded and stored in bottles previously sterilized. The sample in nature was weighted in the same proportion of the dry sample and it was obtained a uniform mass in a domestic processor. The physical-chemical analyses were carried out in triplicate in the samples in nature and in the dry product, being analyzed: pH, humidity, acidity and soluble solids according to IAL (1985), mineral salts contents (Ca, K, Na, Mg, P and Fe) determined by spectrophotometry of Atomic Absorption, caloric power through a calorimetric bomb and presence of fecal traces and E. coli through the colilert method (APHA, 1995). During this period the dry food a base of vegetables presented on average 5,06% of humidity, 4,62 of pH, acidity of 2,73 mg of citric acid /100g of sample, 51,45Brix of soluble solids, 2.323,50mg of K/100g, 299,06mg of Ca/100g, 293mg of Na/100g, 154,66mg of Mg/100g, 269,62mg of P/100g, 6,38mg of Fe/100g, caloric power of 3,691Kcal/g (15,502KJ/g) and is free of contamination by fecal traces and E..coli. The dry food developed in this research presented satisfactory characteristics regarding to its conservation, possessing low calories, constituting itself a good source of potassium, magnesium, sodium and iron that can be utilized as a food complement of these minerals
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In last years it has talked a lot about the environment and the plastic waste produced and discarded. In last decades, the increasing development of research to obtain fuel from plastic material, by catalytic degradation, it has become a very attractive looking, as these tailings are discarded to millions worldwide. These materials take a long time to degrade themselves by ways said natural and burning it has not demonstrated a viable alternative due to the toxic products produced during combustion. Such products could bring serious consequences to public health and environment. Therefore, the technique of chemical recycling is presented as a suitable alternative, especially since could be obtain fractions of liquid fuels that can be intended to the petrochemical industry. This work aims to propose alternatives to the use of plastic waste in the production of light petrochemical. Zeolites has been widely used in the study of this process due to its peculiar structural properties and its high acidity. In this work was studied the reaction of catalytic degradation of high-density polyethylene (HDPE) in the presence HZSM-12 zeolites with different acid sites concentrations by thermogravimetry and pyrolysis coupled with GC-MS. The samples of the catalysts were mixed with HDPE in the proportion of 50% in mass and submitted to thermogravimetric analyses in several heating rates. The addition of solids with different acid sites concentrations to HDPE, produced a decrease in the temperature of degradation of the polymer proportional the acidity of the catalyst. These qualitative results were complemented by the data of activation energy obtained through the non-isothermal kinetics model proposed by Vyazovkin. The values of Ea when correlated to the data of surface acidity of the catalysts indicated that there is a exponential decrease of the energy of activation in the reaction of catalytic degradation of HDPE, in function of the concentration of acid sites of the materials. These results indicate that the acidity of the catalyst added to the system is one of the most important properties in the reaction of catalytic degradation of polyethylene
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Catalytic processes are widely present in everyday life. This results in large number of studies seeking materials that may combine the low cost catalytic efficiency. Based on this assumption, the clays have long been used as catalysts, with its huge availability, diversity and possibility of improving their properties from structural changes, primarily responsible for this great use. Among the natural clays, vermiculite due to their characteristic properties (high cation exchange capacity and expansion), is suitable for various applications including as catalysts and catalyst supports. In this work, the acid leaching of clay vermiculite was performed, coming from Santa Luzia-PB, with nitric acid (2, 3 and 4 mol / L) and subsequent calcination of the materials obtained. The materials were named as Vx/400, where x is the acid concentration employed and 400 used in calcination temperature. The effectiveness of changes made was determined by XRD techniques, FT-IR, EDS, TG/DTG, nitrogen physisorption and DTP of n-butylamine. Acid leaching has improved some properties of the clay - specific area and acidity - but the control of the acid concentration used is of vital importance, since the highest concentration caused the partial destruction of vermiculite entailing a decline in their properties. For analysis of the catalytic activity of the modified clay was made a comparative study with the SBA -15 mesoporous materials, synthesized via hydrothermal method, using the pyrolysis of low density polyethylene (LDPE). The results showed that the acid plays a fundamental role in the conversion of the polymer into smaller molecules, the material V3/400 was more selective for the source monomer (ethylene) due to their increased acidity, which promotes more breaks bonds in the polymeric chain, while materials and V0/400 V2/400, lower acidity, showed higher selectivity to light hydrocarbons, the range of fuel (41.96 and 41.23%, respectively), due to less breakage and secondary condensation reactions chains; already V4/400 SBA-15/550 and resulted in lower percentages of light hydrocarbons and the partial destruction of the structure and low acidity, respectively, responsible for the inefficiency of materials
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The chemical recycling of polyolefins has been the focus of increasing attention owing potential application as a fuel and as source chemicals. The use of plastic waste contributes to the solution of pollution problems.The use of catalysts can enhance the thermal degradation of synthetic polymers, which may be avaliated by Themogravimetry (TG) and mass spectrometry (MS) combined techniques. This work aims to propose alternatives to the chemistry recycling of low-density polyethylene (LDPE) on mesoporous silica type SBA-15 and AlSBA-15.The mesoporous materials type SBA-15 and AlSBA-15 were synthesized through the hydrothermal method starting from TEOS, pseudobohemite, cloridric acid HCl and water. As structure template was used Pluronic P123. The syntheses were accomplished during the period of three days. The best calcination conditions for removal of the organic template (P123) were optimized by thermal analysis (TG/DTG) and through analyses of Xray diffraction (XRD), infrared spectroscopy (FT-IR), nitrogen adsorption and scanning electron microscopy (SEM) was verified that as much the hydrothermal synthesis method as the calcination by TG were promising for the production of mesoporous materials with high degree of hexagonal ordination. The general analysis of the method of Analog Scan was performed at 10oC/min to 500 oC to avoid deterioration of capillary with very high temperatures. Thus, with the results, we observed signs mass/charge more evident and, using the MID method, was obtained curve of evolution of these signals. The addition of catalysis produced a decrease in temperature of polymer degradation proportional to the acidity of the catalyst. The results showed that the mesoporous materials contributed to the formation of compounds of lower molecular weight and higher value in the process of catalytic degradation of LDPE, representing an alternative to chemical recycling of solid waste
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Fundao de Amparo Pesquisa do Estado de So Paulo (FAPESP)
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OBJETIVO: Comparar implantes de polietileno poroso no estado slido e gel em cavidades enucleadas. MTODOS: Trinta e seis coelhos albinos foram submetidos enucleao do olho direito, recebendo esferas de polietileno poroso (18 animais) ou gel (18 animais), de 12 mm de dimetro. Os animais foram avaliados semanalmente por exame clnico e mensalmente por ultra-sonografia modo B, realizada 30, 60 e 90 dias aps a cirurgia, tendo sido os animais sacrificados aos 90 dias. Aps o sacrifcio, o contedo orbitrio foi removido e examinado histologicamente. RESULTADOS: Cinco animais (27,2%) que receberam os implantes de polietileno poroso tiveram extruso do implante. Houve extruso em 94,4% dos animais que receberam a esfera de polietileno gel, tendo-se observado que o dimetro das esferas gel extrudas encontrava-se aumentado em relao ao dimetro da esfera implantada. A ultra-sonografia mostrou que o implante de polietileno poroso se vascularizou e que o gel no, o que foi confirmado pelo exame histolgico. CONCLUSO: Esferas de polietileno no estado gel sofrem hidratao e aumentam de volume, sendo necessrio conhecer o seu tamanho final antes da implantao. A ultra-sonografia permite conhecer a vascularizao do implante, podendo ser usada na avaliao da integrao esfera-hospedeiro.
Resumo:
Este trabalho visou a relacionar variveis ambientais em instalao para criao de rs, com cobertura de polietileno e baias construdas usando material alternativo, com o desempenho de rs-touro (Rana catesbeiana). No interior das baias, foram medidas as temperaturas do piso, do ar ambiente (bulbo seco), de bulbo mido, globo negro e da gua do reservatrio. Foram utilizados 60 animais por baia e trs baias por galpo. As variveis de desempenho estudadas foram peso vivo, ganho de peso e converso alimentar. Nas condies experimentais, quando a temperatura do ar atingiu valores abaixo de 10 C ou superiores a 40 C, houve diminuio no consumo de rao pelos animais. Concluiu-se que o estresse predominante, neste tipo de estrutura, para as condies climticas do perodo experimental, foi devido, principalmente, s baixas temperaturas. Concluiu-se, ainda, que o uso do ndice de Temperatura e Umidade (THI), na estimativa de variveis de desempenho, melhorou a preciso da estimativa em relao ao uso exclusivo da temperatura do ar, embora valores desse ndice, considerados estressantes para animais superiores, no o tenham sido para as rs.