Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2017-08-18T17:45:44Z No. of bitstreams: 1 2010 - Isabel Matos de Fraga.pdf: 5201934 bytes, checksum: 6bbaeba09901aea4cbaa9f69dbb0402e (MD5) / Made available in DSpace on 2017-08-18T17:45:44Z (GMT). No. of bitstreams: 1 2010 - Isabel Matos de Fraga.pdf: 5201934 bytes, checksum: 6bbaeba09901aea4cbaa9f69dbb0402e (MD5) Previous issue date: 2010-12-08 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior, CAPES, Brasil. / The researches on recycling of industrial wastes has been stepped up around the world to enhance the quality of the recycled product and provide greater efficiency of the productive system. The recycling of plastic materials has also grown in recent years, with Brazil improving its market position. In this way, this work aimed the development of composite materials using as a matrix, the low density polyethylene recycled (PEBDrec), chemical treated with oxidizing agents and, as fillers, E-cat and waste of scale. The PEBDrec was treated with oxidizing agent in order to cause modifications over its chemical structure and to improve compatibility with the residues of scale and E-cat. Were produced composites of PEBDrec treated with hydrogen peroxide (H2O2) and scale; PEBDrec treated with hydrogen peroxide and E-cat; PEBDrec treated with potassium permanganate (KmnO4) and scale and PEBDrec treated with potassium permanganate and E-cat. Were also obtained composites of PEBDrec untreated and mixed with scale or E-cat, to evaluate the action of the oxidizing agent in the compatibility between fillers that were used and the polymer matrix. The results obtained by the analysis of FTIR, XDR, TGA, SEM and mechanicals tests presented that the composites of PEBDrec treated with oxidizing agents showed a good interaction between the dispersed phase and the polymer matrix in comparison to composites PEBDrec without chemical treatment, and this compatibility was better for the lowest proportions. But this good interaction resulted in a decrease of thermal stability of composites in relation to the polymer matrix. It was also observed that the oxidizing agent KMnO4 was more effective in increasing the compatibility between the polymer and the E-cat, while the oxidizing agent H2O2 acted more strongly on increasing the compatibility between the polymer and scale. The composites of PEBDrec untreated, compared to the composites of PEBDrec treated with H2O2 and treated with KMnO4 , had a lower water absorption, indicating that chemical treatment was effective to modify the structure of the polymer, inducing the surface to a greater polarity, giving the chemical treated composites of PEBDrec a higher affinity to water. However a material more mechanical resistant was obtained just with the untreated polymer. The incorporation of the charges in the polymer matrix did not change the density of the material composites, indicating that despite of these materials be crystalline, they present low density, being possible to be used in civil construction. / As pesquisas sobre a reciclagem de res?duos industriais v?m sendo intensificadas em todo o mundo a fim de aumentar a qualidade do produto reciclado e propiciar maior efici?ncia do sistema produtivo. O reaproveitamento de materiais pl?sticos tamb?m tem crescido nos ?ltimos anos, com o Brasil melhorando seu posicionamento no mercado. Nesse sentido, essa disserta??o objetivou o desenvolvimento de materiais comp?sitos utilizando como matriz, o polietileno de baixa densidade reciclado (PEBDrec), tratado quimicamente com agentes oxidantes e como cargas, res?duos de Carepa e E-cat. O PEBDrec foi submetido a tratamento com agentes oxidantes com o objetivo de causar modifica??es na sua estrutura qu?mica e, propiciar uma melhoria na compatibilidade com os res?duos de carepa e E-cat. Foram produzidos comp?sitos de PEBDrec tratado com per?xido de hidrog?nio (H2O2) e carepa; PEBDrec tratado com per?xido de hidrog?nio e E-cat; PEBDrec tratado com permanganato de pot?ssio (KMnO4) e carepa e PEBDrec tratado com permanganato de pot?ssio e E-cat. Tamb?m foram obtidos comp?sitos de PEBDrec n?o tratado misturado a carepa ou E-cat, para avaliar a a??o do agente oxidante na compatibilidade entre a matriz polim?rica e as cargas utilizadas. Os resultados obtidos pelas an?lises de FTIR, DRX, TGA, MEV e ensaios mec?nicos mostraram que os comp?sitos de PEBDrec tratado com os agentes oxidantes apresentaram uma boa intera??o entre a fase dispersa e a matriz polim?rica em compara??o aos comp?sitos de PEBDrec sem o tratamento qu?mico, e essa compatibilidade foi melhor para as menores propor??es. Por?m, essa boa intera??o acarretou em uma diminui??o da estabilidade t?rmica dos comp?sitos, em rela??o a matriz polim?rica. Tamb?m foi poss?vel observar que o agente oxidante KMnO4 foi mais eficaz no aumento da compatibilidade entre o pol?mero e o E-cat, enquanto que o agente oxidante H2O2 atuou mais fortemente no aumento da compatibilidade entre o pol?mero e a carepa. Os comp?sitos de PEBDrec n?o tratado, em compara??o aos comp?sitos de PEBDrec tratados com H2O2 e tratados com KMnO4, apresentaram uma menor absor??o de ?gua, indicando que o tratamento qu?mico foi eficaz para modificar a estrutura do pol?mero deixando sua superf?cie com maior polaridade e conferindo aos comp?sitos de PEBDrec tratado quimicamente uma maior afinidade pela ?gua. Por?m um material mais resistente mecanicamente s? foi obtido com o pol?mero n?o tratado. A incorpora??o das cargas na matriz polim?rica praticamente n?o alterou a densidade desses materiais comp?sitos, indicando que apesar de eles serem materiais cristalinos, eles apresentam baixa densidade, sendo poss?vel suas aplica??es no ramo da constru??o civil.

The primary reason for incorporating pigments into plastic materials is to impart the desired colour to finished articles. Some pigments however, may interact with the polymer leading to unexpected deleterious effects. Organic pigments, especially phthalocyanines, are favourable for their brilliant shade but are also well known for causing part distortion or warpage. This causes problems in parts which require good dimensional stability such as crates, containers, trays, caps and closures. Despite that, there are not many published studies on the root cause and mechanism of warpage induced by the pigment. Hence, the objective of this research is to study the influence of such pigments on the dimensional stability, crystallisation behaviour and morphology of polyethylenes in order to have a better understanding on the mechanism of warpage, which could possibly lead to a solution in overcoming this problem.

SOLUTION AND MELT BEHAVIOUR OF HIGH-DENSITY POLYETHYLENE - Successive Solution Fractionation mechanism - Influence of the molecular structure on the flow In the field of polyethylene characterization, one of the most challenging research topic is certainly an accurate molecular structure determination of industrial products, in terms of molar mass distribution (MMD), corresponding average-molar masses and molecular architecture (branching nature, content and heterogeneity). Solution to this long-term problem necessarily calls for a multi-disciplinary approach. Therefore, respective advantages of molecular structure characterization in solution and in the melt are exploited. In solution, chromatographic and spectroscopic methods allow determination of MMD, average branching content and intermolecular heterogeneity within their detection limits. Rheological testing in the melt could be a very powerful molecular structure investigation tool, due to its extreme sensitivity to high molar mass (MM) tailing or long chain branching (LCB) traces. But when the rheological tests results are in hand, we often still wonder what kind of molecular structure gives rise to such results. Indeed, melt signal depends on MM, MMD and LCB presence. MMD determination and LCB quantification by melt approach is impossible as long as respective effects of these molecular parameters are not clearly quantified. The general purpose of the present work is to contribute to a better molecular structure characterization of high-density polyethylene by developing, in a first time, a preparative fractionation method able to provide narrow-disperse linear and long chain branched samples, essential to separate concomitant effects of MM, MMD and LCB on rheological behaviour. Once such model fractions isolated, influence of MM and LCB on both shear and elongational flow behaviours in the melt is studied. /Dans le domaine du polyéthylène, un des sujets de recherche les plus investigués à l'heure actuelle est la détermination précise de la structure moléculaire de résines industrielles, en termes de distribution des masses molaires (MMD), de masses molaires moyennes correspondantes et d'architecture moléculaire (nature, teneur et hétérogénéité). La résolution de cette problématique nécessite une approche multi-disciplinaire, afin d' exploiter simultanément les avantages d'une caractérisation en solution et à l'état fondu. En solution, certaines méthodes chromatographiques et spectroscopiques permettent de déterminer une MMD, une teneur moyenne en branchement et leur distribution, dans leurs limites de détection. La mesure du comportement rhéologique à l'état fondu pourrait s'avérer un formidable outil de caractérisation de la structure moléculaire en raison de son extrême sensibilité à certains détails moléculaires, tels que la présence de traces de LCB ou de très hautes masses molaires (MM). Malheureusement, le signal rhéologique dépend de manière conjointe de la MM, MMD et de la présence ou non de LCB, de telle sorte que la détermination d'une MMD ou d'une teneur en LCB par cette voie est impossible aussi longtemps que les effets respectifs de ces paramètres moléculaires sur le comportement rhéologique n'ont pas été clairement et distinctement établis. L'objectif global de cette thèse est de contribuer à une meilleure caractérisation de la structure moléculaire du polyéthylène haute densité en développant, dans un premier temps, une méthode préparative de fractionnement capable de produire des échantillons, linéaires ou branchés, à MMD la plus étroite possible, indispensables en vue de séparer les effets concomitants de la MM, MMD et LCB sur le comportement rhéologique à l'état fondu. Une fois de tels objets modèles isolés, l'influence de la MM et du LCB sur le comportement rhéologique, en cisaillement et en élongation, sera étudié.

Cotxes, camions, tractors, avions... tots necessiten els neumàtics com a component imprescindible per al seu funcionament. Malauradament, degut al desgast per ús, els neumàtics tenen una vida útil limitada que obliga a renovar-los cada cert temps passant a ser Neumàtics Fora d'Ús (NFU). Paradògicament, els neumàtics són formulats per a suportar condicions extremes d'ús i, entre d'altres matèries primeres contenen cautxú vulcanitzat, una elevada quantitat d'estabilitzants i d'altres additius que fan dels neumàtics un material no biodegradable. Fins al 2006, era possible desar els NFU en abocadors però aquesta pràctica va ser prohibida per la Comunitat Europea (directiva 1993/31/EC). Aquesta directiva conjuntament amb la creixent consciència mediambiental ha potenciat la investigació per a trobar noves aplicacions per les 3.4milions de tones de NFU que es generen a l'any a Europa. Els NFU són emprats com a font d'energia o en aplicacions civils, però cada vegada més, són emprats en autopistes o per usos decoratius després de patir un procés de separació i trituració (NFU triturat). Les propietats físico-químiques dels NFU en fan un material molt interessant per la comunitat científica internacional que es centra en buscar noves vies de reciclatge mitjançant aplicacions d'alt valor afegit.Una opció per reciclar grans volums de NFU és utilitzar-los granulats com a càrrega en matrius termoplàstiques, encara que aquesta és una tasca difícil degut a la baixa compatibilitat entre aquests dos materials. Les seves característiques superficials són les responsables d'aquesta baixa compatibilitat. Cal afegir també que el tamany de les partícules de NFU obtingudes a partir de processos industrials és entre 400 and 600μm, sent aquest un tamany massa gran per poder ser fàcilment embolcallades per qualsevol matriu. D'altra banda, el cautxú dels neumàtics és troba altament vulcanitzat i, per tant, aquest reaccionarà químicament amb dificultats amb d'altres materials. Totes aquestes propietats fan dels NFU un material difícil de treballar-hi. La present tesis estudia diferents mètodes de compatibilització d'un Polietilè D'alta Densitat (PEAD) de grau d'injecció i NFU triturat obtingut a partir de processos estàndards de molturació. La resina de PEAD va ser escollit com a matriu degut al seu ampli rang d'aplicacions d'injecció. L'objectiu principal és explorar diferents mètodes de compatibilització d'aquests dos materials per obtenir òptimes propietats mecàniques, tèrmiques i morfològiques en aplicacions d'injecció. Els composites són optimitzats per a que continguin la màxima quantitat de NFU, una adequada transformació i el mínim cost. Després d'un estudi preliminar de composites basats en NFU i PEAD s'han estudiat tres mètodes diferents per millorar l'adhesió entre aquests dos materials. El primer mètode consisteix en oxidar la superfície de les partícules de NFU granulat amb tractament basats en àcids, amb l'objectiu de proporcionar rugositat per a un anclatge mecànic. En el segon mètode s'han emprat additius humectants i ceres, ja que aquestes substàncies redueixen la tensió interfacial entre les partícules de NFU i la matriu de PEAD. En l'últim mètode, es va estudiar la influència de l'Etilè Propilè Diè Monòmer (EPDM). Amb aquest mètode, les partícules de NFU són embolcallades per l'EPDM, aquest efecte pot ser millorat amb l'ús de peròxids. Les propietats dels "composites" són bastant diferents en funció del mètode emprat.Després d'una comparació dels "composites" obtinguts pels tres mètodes, s'ha trobat que el que conté 30% d'EPDM i dos peròxids, corresponent a la formulació:: 30% NFU + 40% PEAD + 30% EPDM + 0.5% Trigonox 311 + 0.1% Peròxid de Dicumilcompleix els objectius fixats en la tesis: bona adhesió entre les partícules de NFU i el PEAD on l'elevat valor d'elongació n'és una conseqüència directa, la seva obtenció mitjançant un procés de compatibilització de cost reduït, un nou material amb una elevada quantitat de NFU (30%), la seva facilitat de transformació,, i el més important, una nova via de reciclatge dels NFU per a una aplicació d'alt valor afegit. / Cars, trucks, tractors, airplanes. all need tyres as essential component to work. Unfortunately, due to its continuous use, tyres suffer from wear and have a limited lifetime; therefore, they must be changed every certain time becoming end of life tyres (EOL tyres). Paradoxically tyres are formulated to withstand difficult conditions and among other raw materials, they contain vulcanizated rubbers, high amount of stabilizers and other additives that turn tyres into non biodegradable material. Until 2006, disposal of EOL tyres in landfills was a common practice but it was banned by the European Community (directive 1993/31/EC). This European legislation together with an increasing environmental consciousness has instigated researchers to find applications for 3.4million tonnes of used tyres generated per year in Europe. Some extended uses for EOL tyres are energy recover and civil applications but the use of tyres after separation and grinding processes (material know as Ground Tyre Rubber - GTR), has increased during the last decade. Physical and chemical properties of EOL tyres make them an interesting material for the international research community focused today on finding new ways to recycle tyres for value added applications. A good option to recycle big volumes of discarded tyres is using GTR particles as filler in thermoplastic matrixes, although this is a difficult task due to the low compatibility between the two materials. The surface characteristics of the GTR particles are responsible of this low compatibility. Despite these facts, the particle size obtained from standard industrial grinding processes is between 400 and 600μm. These particles are too large to be entrapped easily in polymeric matrixes. These characteristics in conjunction with the fact that GTR is made of highly crosslinked rubber with difficulties to react chemically to other materials, make GTR a material very difficult to work with.The present thesis deals with the study of different compatibilization methods for an injection moulding grade of High Density Polyethylene (HDPE) and GTR obtained from standard industrial grinding process. The HDPE resin was chosen due to its wide range of injection moulding applications. The aim is to explore different methods to mix these two materials and obtain optimum mechanical, thermal and morphological properties for injection moulding applications. The composites are optimized to obtain the highest GTR amount, adequate processability and minimum cost. After a preliminary study of the composites based on GTR and HDPE, three different methods to improve the adhesion between these two materials are studied. The first method consists in an oxidizing treatment on GTR particles surface in order to promote mechanical anchoring. In the second method the influence of wetting additives and waxes is studied. These substances reduce interfacial tension between GTR particles and HDPE matrix. The third and last method, study the influence of Ethylene Propylene Diene Monomer (EPDM) addition with and without peroxides. In this method, GTR particles are encapsulated by EPDM and this effect can be boosted by the use of peroxides. The composites properties are quite different depending on the used method.After a comparison of the composites obtained by the three different compatibilization methods, it is found that the one with 30% of EPDM plus two peroxides, corresponding to30% GTR + 40% HDPE + 30% EPDM + 0.5% Trigonox 311 + 0.1% Dicumyl Peroxidefulfil the objectives of the thesis. This composite has good adhesion between GTR and HDPE that results in high elongation, it is obtained by a cheap compatibilization process and contains a high amount of recycled tyres (30%), it is easy to process, and the most important thing, it represents a new route to recycle scrap tyres for a value added application.

The monomer, p-acryloyloxybenzoic acid (ABA) was synthesized by condensation reaction of acryloyl chloride and p-hydroxybenzoic acid in alkaline medium. Polymerization of the monomer and grafting of the produced polymer (PABA) onto high density polyethylene (HDPE) were expected to be carried simultaneously in melt mixing at high temperature. The graft copolymerization was studied at varying concentrations of the monomer in the reaction mixture at constant temperature (200 0C). Grafted HDPE samples were investigated by several techniques such as DSC, FTIR, MFI and mechanical testing. The tensile tests of PABA-g-HDPE showed an improvement particularly in stress at yield and Young&rsquo / s modulus whereas the strain at break values showed a decrease for all compositions compared to neat HDPE.

Polymer pipes, typically high density polyethylene (HDPE), can be pulled-into-place, avoiding traditional cut-and-cover construction, using pipe bursting and horizontal directional drilling (HDD) pipe installation techniques. Of particular interest, are the ground displacements, induced by cavity expansion, associated with these techniques and the strains that develop in existing pipes in response to these displacements. Further, the axial stress-strain response of the new HDPE pipe during and after the cyclic pulling force history required to pull the pipe into place is of interest. Surface displacements and strains in an adjacent polyvinyl chloride (PVC) pipe induced by static pipe bursting were measured during the replacement of a new unreinforced concrete pipe. For the pipe bursting geometry tested, the maximum vertical surface displacement measured at the ground surface was 6 mm, while the distribution of vertical surface displacements extended no more than 2 m on either side of the centreline. The maximum longitudinal strain measured in the PVC pipe was less than 0.1% and its vertical diameter decreased by only 0.5%, suggesting that pipe bursting did not jeopardize the long-term performance of the water pipe tested. In addition, results from identical stress relaxation and creep tests performed on whole pipe samples and coupons trimmed from a pipe wall were compared, and these demonstrated that the coupons exhibited higher modulus than the pipe samples. Therefore, isolated pipe samples, as opposed to coupons, were tested to quantify the stress-strain response of HDPE pipe during the simulated installation, strain recovery, and axial restraint stages of HDD. Axial strains were found to progressively accumulate when an HDPE pipe sample was subjected to the cyclic stress history used to simulate an HDD installation. It was shown that existing linear and nonlinear viscoelastic models can serve as predictive design tools for estimating the cyclic strain history of HDPE pipe during installation. For the specific conditions examined, the tensile axial stresses redeveloped in the pipe samples, once restrained, were not large enough to lead to long-term stress conditions conducive to slow crack growth even when the short-term performance limits were exceeded by a factor of 1.5. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2009-04-01 18:19:24.434

Made available in DSpace on 2014-12-17T14:07:03Z (GMT). No. of bitstreams: 1 LuandaGD_DISSERT.pdf: 2374976 bytes, checksum: 5b49cc11854aa2427f22f38d6ff109c2 (MD5) Previous issue date: 2012-08-24 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / 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 / O trabalho teve como objetivo o tratamento da atapulgita para o desenvolvimento e a caracteriza??o de comp?sito de polietileno de baixa densidade reciclado PEBD_rec incorporado com atapulgita natural ATP_NAT, peneirada ATP_PN e com atapulgita tratada com ?cido sulf?rico ATP_TR, em diferentes composi??es (1, 3 e 5%) e comparado com o PEBD_rec. As atapulgitas, natural, peneirada e tratada, foram caracterizadas por difra??o de raios X (DRX), fluoresc?ncia de raios X (FRX), an?lise granulom?trica, microscopia eletr?nica de varredura (MEV), espectroscopia de energia dispersiva (EDS) e determina??o da ?rea superficial espec?fica (BET). Os comp?sitos foram caracterizados por an?lise termogravim?trica (TG), calorimetria diferencial explorat?ria (DSC), difra??o de raios X (DRX), reometria de torque, microscopia eletr?nica de varredura (MEV) e tra??o. Os comp?sitos de PEBD_rec /ATP (natural, peneirada e tratada) foram produzidos por meio de mistura no estado fundido em uma extrusora monorosca com matriz de fio com posterior reprocessamento com matriz de fita. Verificou-se que o peneiramento da atapulgita n?o reduziu o teor de quartzo e que o tratamento ?cido extraiu completamente a dolomita, impureza agregada nos canais da atapulgita, al?m de aumentar sua ?rea superficial. A adi??o da atapulgita no PEBD_rec atua como catalisador, reduzindo a estabilidade t?rmica do pol?mero. O aumento da concentra??o de atapulgita aumenta a resist?ncia e reduz o alongamento na ruptura e o m?dulo de elasticidade do comp?sito PEBD_rec / atapulgita

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-09-26T15:00:31Z No. of bitstreams: 1 RENATA BARBOSA - TESE (PPGEP) 2009.pdf: 13292645 bytes, checksum: e1d1eb846f17881cd108a8bad8f924ec (MD5) / Made available in DSpace on 2018-09-26T15:00:31Z (GMT). No. of bitstreams: 1 RENATA BARBOSA - TESE (PPGEP) 2009.pdf: 13292645 bytes, checksum: e1d1eb846f17881cd108a8bad8f924ec (MD5) Previous issue date: 2009-06-19 / Nanocompósitos de PEAD/argila bentonítica modificada e sem modificação foram preparados por meio do processo de intercalação por fusão. Realizou-se, previamente um estudo sistemático com quatro sais quaternários de amônio e em três tipos de argilas bentoníticas. Em seguida, fez-se a escolha de um sal quaternário de amônio e de uma argila bentonítica para dar continuidade ao trabalho. A argila escolhida foi organofilizada usando-se diferentes percentuais de sal quaternário de amônio 100%, 125% e 150% baseados na capacidade de troca de cátions (CTC) da argila. Ficou evidente por difração de raios- X (DRX) que os sais foram incorporados à estrutura da argila confirmando assim sua organofilização. Em princípio, todos os sais poderão ser usados para a organofilização da argila e, consequentemente nos sistemas de nanocompósitos PEAD/argila organofílica. Porém, foi verificado que o tipo de ânion presente pode influenciar a estabilidade térmica do sal quaternário de amônio. Os nanocompósitos foram preparados em uma extrusora de rosca dupla contrarrotacional e, em seguida, corpos de prova foram moldados por injeção. Para a avaliação da inflamabilidade dos sistemas foi utilizado o teste de queima na posição horizontal segundo a norma (UL-94HB) e o método do Calorímetro de Cone. O comportamento térmico dos nanocompósitos foi avaliado por temperatura de deflexão térmica (HDT) e termogravimetria (TG). As técnicas de DRX e microscopia eletrônica de transmissão (MET) foram utilizadas para caracterizar a morfologia e analisar o grau de expansão das argilas preparadas bem como o grau de esfoliação dos nanocompósitos. As propriedades mecânicas de tração e impacto também foram analisadas. Para efeito de comparação, determinadas composições foram extrudadas utilizando-se duas configurações de roscas da extrusora ZSK-30 corrotacional, com objetivos de variar as condições de processo e melhorar as propriedades dos nanocompósitos obtidos. Observou-se que o percentual de sal de amônio e o tipo de compatibilizante polar influenciam nas propriedades finais dos nanocompósitos. / High Density Polyethylene (HDPE) nanocomposites containing unmodified and modified bentonite clay were prepared by melt intercalation technique. Initially, four quaternary ammonium salts and three types of bentonitic clays were studied. Afterwards, one type of salt and one type of clay were chosen for the study. The clay was organophilized using 100,125 and 150wt% of quaternary ammonium salt based on cationic exchange capacity (CEC) of the clay. It was evident from the X-ray diffraction (XRD) that the salts were incorporated into the clay structure confirming its organophilization. In general, all salts may be used for clay organophilization and hence, on HDPE/Organophilic clay nanocomposites. However, it was verified that the type of anion present may influence the thermal stability of the quaternary ammonium salt. The nanocomposites were prepared in a counter-rotating twin screw extruder and the samples were prepared by injection molding. For the evaluation of the flammability, horizontal burn (UL-94HB) and cone calorimeter methods were used. The thermal behavior of the nanocomposites was analyzed by Heat Distortion Temperature (HDT) and Thermogravimetry (TG). XRD and Transmission Electron Microscopy (MET) techniques were used to characterize the morphology and analyze the degree of expansion of the prepared clays, and also the degree of exfoliation of the nanocomposites. Mechanical properties (Tensile and Impact strength) were also analyzed. Some compositions were extruded using two screw configurations of ZSK-30 co-rotacional extruder with the aim of improving the properties of the nanocomposites obtained by varying the processing conditions. It was observed that the percentage of the ammonium salt and the type of polar compatibilizer influence the final properties of the nanocomposites.

Orientador: Jose de Assis Fonseca Faria / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-08T11:53:49Z (GMT). No. of bitstreams: 1 Cardoso_ClaudioFernandes_M.pdf: 1146025 bytes, checksum: 703b38e7eec6c1ffc7f2de65b30ab581 (MD5) Previous issue date: 2007 / Resumo: O objetivo deste trabalho consistiu no processamento e avaliação de desempenho de um sistema asséptico piloto para filme de polietileno de baixa densidade (PEBD). Através da metodologia de planejamento experimental fatorial foram feitas variações de tempo de contato, temperatura do banho e concentração da solução esterilizante, bem como a variação do tempo de exposição à radiação ultravioleta (UVC). Estas variações tiveram por finalidade promover de 4 a 6 reduções decimais na população inicial de esporos de Bacillus subtilis var. globigii ATCC9372, em um curto espaço de tempo, gerando o menor residual do esterilizante em água envasada. Foram inoculados uniformemente 100µL do microrganismo teste em uma superfície de 16cm2. Testou-se como agente de esterilização química, o peróxido de hidrogênio (H2O2) e, como agente físico, a radiação UVC, sendo o primeiro aplicado na forma de banho de imersão e o segundo, por uma exposição a 2,5cm de distância do filme de PEBD logo após o banho de imersão. O sistema utilizado constituiu em uma envasadora automática e um protótipo com um tanque em aço inoxidável, desenvolvido especialmente para este tipo de teste. O H2O2 e a radiação UVC apresentaram ação esporicida significativa. O H2O2 demonstrou ação esporicida entre as concentrações de 18 e 35%, em um intervalo de temperatura de 46 a 70ºC, promovendo de 3 a 7 reduções decimais de Bacillus subtilis. A concentração de 20% de H2O2 não conferiu sabor estranho à água mineral envasada em embalagens de PEBD sanificadas, não diferindo, significativamente (p<0,05), do padrão. O residual de H2O2 das superfícies-teste sanificadas com soluções contendo de 18 a 35% de H2O2 foi superior a 0,5mg/L, nível máximo permitido pela FDA presente em água envasada sob as condições de produção. Os dados obtidos forneceram dois modelos matemáticos quadráticos, representativos da ação do H2O2 e radiação UVC, em função do tempo e da temperatura, sobre esporos de B. subtilis. Tais modelos, com R2 de 0,9349 para os tratamentos sem radiação UVC, e R2 de 0,9763 para os tratamentos com radiação UVC, limitaram-se a uma concentração de 35% de H2O2 e tempo máximo de exposição à radiação UVC de 8s. Superfícies-teste sanificadas com soluções de 28% de H2O2 a 60ºC, por 8s sem exposição à radiação UVC apresentaram 4 ciclos de redução decimal. Para as mesmas condições, porém com exposição à radiação UVC por 8s, este valor elevou-se para 7, demonstrando a existência do sinergismo entre a associação destes dois agentes. O sistema de esterilização testado apresentou desempenho satisfatório, podendo ser perfeitamente utilizado por indústrias de pequeno e médio porte na esterilização de filmes plásticos, sendo capaz de promover até 7 reduções decimais na população de esporos bacterianos / Abstract: The aim of this research consisted in the processing and performance evaluation of an aseptic pilot system for Low Density Polyethylene film (LDPE). Through the screening design methodology, variations of contact time, bath temperature, sanificant concentration and exposition time variation of ultraviolet radiation (UVC) was made. Such variations had as purpose to promote from 4 to 6 decimal reductions in the Bacillus subtilis var. globigii ATCC9372 spores, when applied to the LDPE film surface, in a short time, generating the minor residual of the sanificant in the plastic surface. Was evaluated as chemical agent, the hydrogen peroxide (H2O2) and as physical agent, UVC radiation, being the first one applied as immersion bath and the second one as an exposition after the immersion bath, with 2,5cm of distance of the PEBD film. The system used was constituted in an automatic filling machine and an equipment with a stainless steel tank, especially developed for this type of test. H2O2 showed sporicidal action in from 18 to 35%, in temperatures of 46 to 70ºC, causing from 3 to 7 decimal reductions. The H2O2 20% did not confer off-taste in mineral water used as filling product, as well no significant difference from the standard was observed (p<0,05). The hydrogen peroxide residual surface-test after sanitation with 18 to 35% H2O2 was higher than 0,5mg/L. However, the use of hot air knives or roller pressers after the immersion bath will be able to diminish this residual. The quadratic model, with R2 of 0,9349 for the treatments without UVC radiation and R2 of 0,9763 for the treatments with UVC radiation are restricted to 35% H2O2 and UVC maximum exposition time of 8s. Surface-test treated with 28% H2O2 / 60ºC / 8s without UVC radiation exposition had presented 4 decimal reduction. In the same conditions, however with UVC radiation exposition (8s), this value was raised for 7, demonstrating the existence of synergism between these two agents. The sanification system tested showed satisfactory performance, effective to be used in small and medium industries, being capable to promote up to 7 decimal reductions in spores population / Mestrado / Mestre em Tecnologia de Alimentos

Made available in DSpace on 2016-03-15T19:36:55Z (GMT). No. of bitstreams: 1 Jessyka Meierjurgen Melo.pdf: 1463151 bytes, checksum: b96ae4642ea3139b9e867598e3bba7c1 (MD5) Previous issue date: 2015-06-15 / The present work aimed to highlight the study of polymeric composite development to be responsible with the environment and with the growth of the recycling of materials, from the use of high-density polyethylene (HDPE) with eucalyptus wood dust from the manufacturing furniture. The study started from a literature search where were analyzed the factors involving the subject in question, highlighting the concept of polymer, synthetic fibers, wood dust presence, and composites to identify and understand the problem in issue. Mechanical, morphological and rheological tests were done with composites with concentrations of 5, 10 and 20% of wood dust in relation to the polymer matrix in order to characterize and compare the obtained materials. It was noted that during the study samples with wood dust had higher mechanical performance compared to pure HDPE sample. Based on this context, this study was developed to analyze the possibilities ahead so the production of HDPE composite from different wood dust fractions. / O presente trabalho teve como objetivo destacar o estudo de desenvolvimento de compósito polimérico responsável com o meio ambiente e com o crescimento da reciclagem de materiais, a partir da utilização de polietileno de alta densidade (PEAD) com pó de madeira de eucalipto, proveniente da fabricação de móveis. O estudo iniciou a partir de uma pesquisa bibliográfica onde foram analisados os principais fatores que envolvem o tema em questão, destacando o conceito de polímero, das fibras sintéticas, a presença do pó de madeira, seus compósitos a fim de identificar e conhecer o problema em questão. O estudo desenvolveu-se a partir de ensaios mecânicos, morfológico e reológico, dos compósitos com as concentrações de 5, 10 e 20% de madeira em relação à matriz polimérica, a fim de caracterizar e comparar os materiais obtidos. Notou-se que durante os estudos as amostras com pó de madeira apresentaram maior desempenho mecânico comparado a amostra de PEAD puro. Baseado neste contexto, este estudo foi desenvolvido visando assim analisar as possibilidades frente a produção do compósito de PEAD a partir de diferentes concentrações de pó de madeira.