Made available in DSpace on 2017-07-21T20:42:37Z (GMT). No. of bitstreams: 1 Josiane Silvano.pdf: 1614432 bytes, checksum: 60d9480513d2bdb73b9204ec6606dd81 (MD5) Previous issue date: 2012-07-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The nanocomposites of polypropylene (PP) and montmorillonite (MMT) were prepared using a twin screw extruder and reprocessed five times. Whereas the nonpolar nature of the PP was used two different types of coupling agent grafted the polypropylene with maleic anhydride (PP-g-MA) and polypropylene grafted with Acrylic Acid (AA-g-PP) in order to improve the merge process. Samples containing 1,3 and 5% clay obtained at the 3:1 mass ratio of compatibilizer / clay and evaluated the effect of degradation was quantified by X-ray diffraction, infrared spectroscopy,rheological behavior. Formation of color through the system CIE lab and crystallization kinetics. The results of FTIR and Colorimentry followed the same trend with formation of carbonyl number of reworks and rheological analysis show a reduction on molecular weight due to the process of thermo-mechanical degradation of PP and also showed that for the sample containing 5% clay PP-g-MA as a compatibilizer network percolated presented showing that a good dispersion to formulation. Regarding the process of crystallization was observed that the incorporation of MMT promoted a nucleating effect on the PP. The influence of the compatibilizing agent was observed that the PP-g-AA had a nucleating effect additional to the PP / MMT. Regarding the compatibilizer PP-g-MA was observed that the nucleating effect does not occur on the PP Pure occurring including the inhibition of the nucleating effect on the PP/MMT. The influence of the number of extrusions on the crystallisation process, there is generally a strong effect of accelerating the crystallization kinetics due to the increased number of reprocessing. / Os nanocompósitos de polipropileno (PP) e montmorilonita (MMT) foram preparados utilizando extrusora dupla rosca e reprocessados por cinco vezes. Considerando o caráter apolar do PP foi utilizado dois diferentes tipos de agente de acoplamento o polipropileno graftizado com anidrido maleico (PP-g-MA) e o polipropileno graftizado com ácido acrílico (PP-g-AA) a fim de melhorar o processo de intercalação. As amostras contendo 1, 3 e 5% de argila obtiveram na proporção em massa de 3:1 de compatibilizante/argila e foram avaliados o efeito da degradação sendo quantificados por difração de raio X, espectroscopia de infravermelho (FTIR), análises reológicas, formação de cor através do sistema CIE lab e cinética de cristalização. Os resultados de FTIR e colorimentria seguiram a mesma tendência de formação de carbonila com número de reprocessos e as análises reológicas mostram uma diminuição de massa molar devido ao processo de degradação termo-ecânica do PP e mostrou também que para a amostra contendo 5% de argila com PP-g-MA como compatibilizante apresentou uma rede percolada evidenciando uma boa dispersão para essa formulação. Com relação ao processo de cristalização observou-se que a incorporação da MMT promoveu um efeito nucleante sobre o PP. Quanto a influência do agente compatibilizante observou-se que o PP-g-AA apresentou um efeito nucleante adicional em relação ao PP/MMT. Com relação ao compatibilizante PP-g-MA observa-se que não ocorre o efeito nucleante sobre o PP puro ocorrendo inclusive à inibição do efeito nucleante da MMT sobre o PP. Quanto à influência do número de extrusões sobre o processo de cristalização, observou-se em geral um forte efeito de aceleração na cinética de cristalização em função do aumento do número de reprocessos.

Made available in DSpace on 2017-07-21T20:42:39Z (GMT). No. of bitstreams: 1 Arieny Rodrigues.pdf: 4134209 bytes, checksum: f2bb4f78c29e8485988b3c7e58f3478f (MD5) Previous issue date: 2011-12-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The use of polymeric mixtures has been extensively studied and has great prominence on account of obtaining a material with modified properties from others pre-existing. The polymer composites filled with wood or other natural fibers are a major attraction for presenting a number of advantages over inorganic fillers, for example, low density, and are derived from renewable sources. However, additional efforts are made to improve the interfacial adhesion between these components, because of the lack of compatibility between the wood, a highly polar substance, and polymer materials, nonpolar or with relatively low polarity. The objective of this work was to study the properties of polypropylene composites, both virgin (01 extrusion) and recycled (02 extrusions), using wood flour as reinforcements, compatible with polypropylene-co-acrylic acid (PP-g-AA) and polypropylene-co-maleic anhydride (PP-g-MA), at different concentrations. The materials were mixed in a twin-screw extruder and the characterizations were performed by means of infrared spectroscopy (FTIR), paralell plate rheology, impact tests, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). This last technique was used to study isothermal and non-isothermal crystallization kinetics / A utilização de misturas poliméricas tem sido muito estudada e apresenta grande destaque por conta da obtenção de um material com propriedades modificadas a partir de outros pré-existentes. Os compósitos de matriz polimérica e carga de madeira ou outras fibras naturais constituem um grande atrativo por apresentar uma série de vantagens sobre cargas inorgânicas, como, por exemplo, baixa densidade, além de serem oriundas de fontes renováveis. No entanto, outros esforços são feitos para se melhorar a adesão interfacial entre estes componentes, por causa da falta de compatibilidade entre a madeira, substância altamente polar, e os materiais poliméricos, apolares ou com polaridade relativamente baixa. O objetivo do presente trabalho foi estudar as propriedades de compósitos de polipropileno, tanto virgem (01 extrusão) quanto reciclado (02 extrusões), utilizando a farinha de madeira como reforço, compatibilizados com polipropileno-co-ácido acrílico (PP-g-AA) e com polipropileno-co-anidrido maleico (PP-g-AM), em diferentes concentrações. Os materiais foram misturados em extrusora dupla-rosca e as caracterizações foram realizadas a partir de espectroscopia por infravermelho (FTIR), reologia de placas paralelas, testes de impacto, análises microscópicas (MEV), e calorimetria exploratória diferencial (DSC). Esta última técnica foi utilizada para estudar a cinética de cristalização isotérmica e não-isotérmica.

The plastic mulch films, which are mostly made from LDPE, are used in order to increase the yields and to prevent the weed growth by covering the top of the soil by leaves or straw in nature. After a period, the mulch films turn into unmanageable quantities of soiled plastic films, which cause an environmental problem. Using degradable mulch films for agricultural purposes can be a solution for the environmental problems caused by the plastic mulch films. In this study, to introduce biodegradability to mulch films, a natural biopolymer starch was used. Before blending, starch was transformed into thermoplastic starch in order to make the starch processable. The need, to provide adhesion and interaction between thermoplastic starch and LDPE, citric and stearic acid were considered as compatibilizers. To accelerate the degradation of the LDPE matrix, three pro-oxidants cobalt(II) acetylacetonate, iron(III) stearate and manganase(II) stearate were used. The films prepared were characterized by FTIR spectroscopy / their thermal and mechanical properties were analyzed and buried under soil. The films recovered from soil after 76 days were characterized by FTIR spectroscopy, their weight loss were measured and their thermal and mechanical properties were analyzed. Studies showed that the use of cobalt(II) acetylacetonate gave improved results in terms of the mechanical properties and thermal stabilities of the films. Additionally, it is observed that the use of citric acid as a compatibilizer improved the thermal stabilities of starch in the films. Lastly, it is observed that the mechanical properties of the films were affected by the interactions between compatibilizers and pro-oxidants.

One of the current problems faced by mankind is the problem of safe disposal of waste rubber. Statistics show that the number of waste tires is continuously increasing at a very rapid rate. Since rubber materials do not decompose easily (due to their crosslinked structure), they end up being a serious ???environmental problem???. An intuitive solution to prevent the accumulation of the scrap tires is to continuously reuse them. A new patented reclamation method was discovered in our laboratory, which makes use of a twin screw extruder (TSE) in order to produce reclaimed rubber (referred as devulcanized rubber (DR) from here on) of very high quality. Also, this method has proven to be more economical than other commercial reclaiming methods. Products made solely from a reclaimed material face challenges from those made by virgin materials because of relatively poor properties. However, the striking advantage of using reclaimed rubbers is the cost reduction. Hence, it is important to work on establishing methods by which these reclaimed rubbers could be efficiently used and incorporated into present day products. The deterioration of properties could be minimized by blending them with varying amounts of other materials. A possibility in this direction is manufacturing of thermoplastic vulcanizates (TPVs) using reclaimed rubber and general purpose thermoplastics. In accordance with this idea, the focus of this research is to prepare DR and polypropylene (PP) based TPVs. DR is unique as the rubber itself consists of two phases- one phase consisting of uncrosslinked (including devulcanized rubber molecules), and the other phase consisting of crosslinked (un-devulcanized) rubber. These un-devulcanized crumbs act as stress concentrators because they do not break-up easily, and lead to poor physical properties. Hence, this project tries to find out ways to increase the interfacial adhesion between the rubber and PP by using reactive and non-reactive techniques. Preliminary experiments were carried out in a batch mixer to compare DR and rubber crumb (CR). DR based TPVs showed better properties than CR based TPVs, however, the properties were not useful for commercial applications. Sulphur based dynamic vulcanization was studied in a batch mixer and found to be not effective in improving the properties of DR based blends. On the other hand, DCP/ sulphur based curing system was found to show significant improvement in properties. Therefore, DCP/sulphur based curing package was studied in detail on the blends consisting of DR and PP. The optimum ratio of DCP/sulphur was found to vary depending on the ratio of DR/PP. A hypothesis regarding the mechanism of DCP/sulphur curing has been proposed, which seem to correlate well with the experimental results observed. Additionally, it was determined that DR prepared from tire rubber (DRT) performed better than DR prepared from waste EPDM (DRE) for the curing system used. Accordingly, experiments on a TSE were carried out using DRT and a combination of compatibilizing resins and curatives. This combination showed a drastic improvement in blends properties and once again the optimum ratio of compatibilizing resins seemed to depend on the ratio of DRT/PP. As a result of the work, successful strategies based on reactive compatibilization techniques were developed in order to prepare useful TPVs having up to 70% DR. A series of compatibilization techniques has been evaluated using design of experiments and various characterization techniques such as mechanical tests, scanning electron microscopy, thermal analysis and crosslink density measurements. This led to the development of a formulation, which could improve the blend properties significantly. A tensile strength of around 10 MPa and an elongation-at-break of 150-180 % could be achieved for devulcanized rubber (70%) based TPVs, which has broadened the scope for its commercial applications. In addition to that, the process was established on a TSE that has enabled a continuous and steady production of these TPVs with reasonable throughputs.

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