Devulcanization of Elastomers and Applications

In no other phase of human development was produced such amount of waste as currently. Its composition and quantity are directly related to the way the population lives, socioeconomic condition and the ease of access to consumer goods. The irregular disposition of such waste may cause harmful environmental impacts. One of the most dangerous solid wastes is the vulcanized rubber, which, besides having high natural degradation time, has many chemical additives on its formulation and the possibility to store rain water when disposed in landfills and may become a breeding place for vectors. So, recycling comes against this problem and devulcanization is a way of recycling that restores the fluidity of the rubber. One of the applications of this devulcanized rubber is in the production of polymeric blends. Devulcanization of rubbers, the application of this material in polymeric blends based on thermoplastic/recycled rubber, and the parameters involved during the processing of these materials will be addressed in this work

Pros and Cons of Plastic during the COVID-19 Pandemic

Since the beginning of the first cases of the new coronavirus, opinions and laws on the use of plastic materials have been questioned around the world. Their importance in the manufacture of hospital devices and personal protective equipment (PPE) is unquestionable, as they contribute largely to the reduction of the virus spread, helping health systems from all edges of the world and, most importantly, saving lives. However, the same material that is a protector, becomes a polluter when inadequately disposed of in the environment, generating or worsening socio-environmental problems, such as pollution of water bodies by plastic. A critical overview of the role of plastic during the COVID-19 pandemic is provided in this paper. A future panorama is attempted to be outlined. The real possibility of the virus spread from the use of plastic is discussed, as well as the recycling of plastic during the pandemic, correlating its use with problems that it may cause

Étude des mélanges de polyéthylène renforcé avec des nanocharges et résidus de pneus régénérés par micro-ondes

The main objective of this work was the production of dynamically revulcanized blends containing HDPE and GTR devulcanized by microwaves. It comes against a big global problem which is the waste disposal of vulcanized elastomers, especially tires, which bring with them serious environmental and public health problems, since these materials require long periods of time to degrade naturally due to their structure of cross-linkings, and the presence of stabilizers and other additives in its formulation. A way of using the GTR that has been widely studied by researchers is as polymer blends in which one of the phases is a thermoplastic polymer. In this context, the role of elastomers devulcanization is to increase the interaction between raw and recycled material, reducing the degradation of properties of the finished product with its incorporation and making it possible the increase of the recycled rubber amount in the compound recycled rubber/thermoplastic. The devulcanization transformes devulcanized elastomer into a fluid material, allowing a better control of the particle size during the mixing process of the blend by breaking processes in the application of high shear rates. In addition, by becoming a fluid material, it is possible the incorporation of a higher amount of elastomer to the thermoplastic without great damage to its processability. However, the literature does not have works in which the study of the processing parameters of dynamically revulcanized blends containing devulcanized elastomer, as well as the influence of addition of clays from different shapes (lamellar and tubular) on their final properties, especially on rheological properties, which sets out the present work. Summarizing, this work aims to propose a possible solution to the problem of solid waste disposing by producing a dynamically revulcanized blend containing HDPE and GTR devulcanized by microwaves, in addition to decrease some gaps observed currently in the literature from the obtained results.Ces dernières années, la recherche de solutions au problème de l'élimination de déchets polymères, notamment les déchets issus de pneumatiques qui posent de graves problèmes environnementaux, connait un développement croissant. Dans ce contexte, ce projet de recherche a pour objectif de contribuer au développement et à la promotion de solutions innovantes qui font appel aux connaissances développées dans les domaines des nanotechnologies, de la science et l’ingénierie des matériaux nouveaux et du génie des procédés et des produits. Il s’agit plus particulièrement de d’étudier la possibilité de valoriser les déchets issus de pneumatiques en les utilisant comme matière première (en tant que agents de renfort ou agents de modification de la résistance aux chocs) pour l'élaboration de matériaux nanostructurés. Ce travail met l'accent sur l'étude des mélanges de polyéthylène haute densité (PEHD) contenant des particules d’argile (dispersées à l'échelle du nanomètre) et des déchets de caoutchouc issus de pneumatiques usagés (ou Ground Rubber Tire ou GRT). Il est attendu que ce matériau présente des propriétés typiques des mélanges de polymères appelés Vulcanisats Thermoplastiques (TPVs), résultant de la vulcanisation dynamique de la phase de caoutchouc pendant le traitement à l'état de fondu (extrusion). Dans le système étudié, la matrice est le PEHD et la phase dispersée de la poudrette de pneu, préalablement dévulcanisée par micro-ondes. L'argile dispersée dans la phase de la matrice, agit comme un agent compatibilisant entre les phases du mélange et comme agent de renforcement, apportant une amélioration des propriétés mécaniques des matériaux préparés. La caractérisation des mélanges met l'accent sur leur morphologie et leur structure ainsi que sur leurs propriétés rhéologiques, thermiques et mécaniques. Une étude approfondie de l'évolution de la morphologie du mélange au cours de l’extrusion a été effectuée car ce paramètre est la clé pour optimiser le procédé et obtenir les meilleures propriétés pour le matériau final. Ceci représente la contribution plus importante de ces travaux de recherche

Elastomeric Composites Containing SBR Industrial Scraps Devulcanized by Microwaves: Raw Material, Not a Trash

Environmental concerns about waste management systems have stimulated the search for technological and economical alternatives that introduce waste as raw material for production cycles. In this sense, this study aimed to develop and characterize styrene-butadiene rubber (SBR) composites that contain industrial rubber scraps devulcanized by microwaves (SBR-r) as a reinforcing filler. The scraps were ground under ambient conditions. From the obtained powder (SBR-r), composites were prepared, varying the exposure time of the powder to the microwaves (1, 2, and 3 min), as well as the SBR-r content. These composites were compared to a Reference sample (base formulation without SBR-r). The vulcanization parameters were determined by an oscillating disk rheometer. After vulcanization, the composites were characterized by mechanical properties (tensile and tear strength, and compression set). These properties were also evaluated after accelerated aging in an air oven and a UV chamber (ultraviolet light). The results indicated that as a result of increasing the exposure time of the waste to the microwaves, no significant influence in the composite properties was observed. Aged samples presented higher results as compared with the Reference sample (tensile strength up to 175% higher, tear strength up to 107% higher, and compression set up to 91% higher), which indicates the possibility of using these materials in technological applications, such as in the civil and automotive industries

In the Search for Sustainable Processing in Compounds Containing Recycled Natural Rubber: The Role of the Reversion Process

The production of consumption goods made of elastomers is increasing day by day, producing large amounts of vulcanized/cured residues which constitute a serious socio-environmental problem. An option for companies that produce elastomeric residues is their incorporation in the formulations, by producing polymeric blends with ground waste elastomers. Therefore, this work aims to prepare polymeric blends composed of raw natural rubber (NR)/ground waste NR in different concentrations. The influence of vulcanization reversion as result of additional heating during compression molding on the mechanical properties of the blends was analyzed, and the relationship among vulcanization characteristics, dynamic-mechanical, morphology and mechanical properties of blends was also determined

The use of atomic force microscopy as an important technique to analyze the dispersion of nanometric fillers and morphology in nanocomposites and polymer blends based on elastomers

AFM has been recognized as one of the most powerful tools for the analysis of surface morphologies because it creates three-dimensional images at angstrom and nano scale. This technique has been exhaustively used in the analyses of dispersion of nanometric components in nanocomposites and in polymer blends, because of the easiness of sample preparation and lower equipment maintenance costs compared to electron microscopy. In this review, contributions using AFM are described, with emphasis on the dispersion of nanofillers in polymeric matrices. It is aimed to show the importance of technical analysis for nanocomposites and polymer blends based on elastomers

Estudo da degradação em solo controlado de blendas contendo materiais biodegradáveis

Este trabalho visou a produção de blendas considerando tanto o ponto de vista ecológico quanto o financeiro, buscando utilizar materiais que não tivessem um custo elevado e que reunissem propriedades desejáveis, sem apresentar ameaças ao meio ambiente

Valoração do rejeito do processo do carvão: estudo preliminar

O presente trabalho tem como objetivo caracterizar os rejeitos do processamento do carvão e sintetizar sólidos que posteriormente serão analisados para aplicações na remoção de contaminantes em efluentes. Cabe salientar, que este estudo faz parte do projeto “Valoração do Rejeito do Processamento do Carvão Aplicado ao Tratamento de Efluentes” do grupo de pesquisa “Tecnologias e Soluções Sustentáveis”, portanto, resultados preliminares da pesquisa