Abstract The present work is to study the production and characterization of biochar produced at two different temperatures (400 and 900 °C) and its influence on the interaction of biochar with elastomers of different polarity, aiming at the replacement of carbon black in elastomer compounds, based on the rheometric, physical, chemical and mechanical properties. The biochar production temperature of 900 ºC affected the optimum vulcanization time (t90), with compounds containing NR and NBR having the shortest vulcanization times because temperatures above 400 ºC produce an alkaline biochar that accelerates vulcanization. The biochar interacted with the two elastomers, being superior to NBR due to the oxygen concentration. Therefore, the blends with biochar showed a demonstrated reinforcement of the tensile strength, even if the biochar had a surface area of 3 m2.g-1 for the observed irregular surface, in addition to the mechanical properties, analogous to the blends with carbon black.

Composites consisting of waste cotton yarn (CF) from the textile industry and postconsumer expanded polystyrene (EPS) was followed during 90 days of exposure in simulated soil. The mechanical properties, morphologies and chemical natures of the composites were determined before and after exposure in simulated soil. The composites were made using a single-screw extrusion, a twin-screw extrusion and injection molding. The composites showed an increase of the mechanical properties nearly 50% in relation to the recycled expanded polystyrene (rEPS). After exposure in simulated soil the composites presented losses of mechanical properties. Evidence of the oxidation of the samples was demonstrated by the increase in the values of the carbonyl index after 30 days of exposure in simulated soil. Changes in the color of the surface of the sample were observed after 90 days of exposure and are due to the fungi and bacteria colonization on the surface.

This work examined the influence of different chemical blowing agents (CBA), one endothermic and one exothermic, at the same concentration (2% by mass), on poly(acid lactic), PLA foams. The CBA was incorporated into the PLA in a single-screw extruder, and the foams were expanded by heating in an electric oven under free pressure conditions. Foam degradation in a simulated soil was performed according to the ASTM G160-03 standard. Changes in the physical-chemical, morphological and mechanical properties were used to evaluate the degradation. The results indicated that the different chemical blowing agents led to different mechanical and morphological properties for the foams, which resulted from the nature and decomposition rate of the blowing agents. Cells in the foams accelerated the degradation since they facilitated the infiltration of water toward the interior of the polymer and triggered the degradation process by hydrolysis.

O poli(cloreto de vinila) (PVC) é um dos polímeros utilizado no campo das embalagens e no setor calçadista, e, em função da sua aplicação diversificada, apresenta elevados percentuais em aterros domésticos e industriais. É um polímero amorfo podendo apresentar diferentes teores de plastificante e outros aditivos responsáveis pela sua estabilização, os quais podem influenciar no tempo de vida útil e nas propriedades do produto final. Este trabalho apresenta o estudo da degradação química e biológica de filmes de poli(cloreto de vinila) flexível (PVC-f), no aterro sanitário São Giácomo, na cidade de Caxias do Sul/RS, antes e após 330 dias de disposição. As amostras de PVC-f antes e após a disposição no aterro sanitário foram avaliadas por análise térmica (TGA), estrutural (FT-IR) e morfológica (MEV e MO). Observou-se que as amostras de PVC-f dispostas no aterro sanitário (PVC-fa), apresentam um único evento de perda de massa, em relação ao PVC-f não degradado ou virgem (PVC-fv), além de um maior % de perda de massa e de mudanças estruturais. Nas amostras de PVC-fa foram observadas modificações morfológicas importantes para descrever os fenômenos de degradação como erosão da superfície, bioerosão, que propiciaram a ação das leveduras, bactérias e fungos presentes no meio no polímero aterrado.

The poly (vinyl chloride) (PVC) is one of the polymers used in the field of packing materials and footwear sector, and due its diversified applications, it has presented in a high percentage of domestic and industrial landfills It is an amorphous polymer and may present different levels of plasticizer and other additives responsible for its stabilization, which can influence the lifetime and the properties of the final product. This work presents the study of the chemical and biological degradation of poly (vinyl chloride) flexible (PVC-f) films, at São Giácomo landfill, in Caxias do Sul city after 330 days of disposition. The samples of PVC-f were evaluated by thermal (TGA), structural (FT-IR) and morphological (MEV and MO) analysis after disposition. Samples of PVC-f disposed to landfill (PVC-fa) showed a single event of weight loss, when compared to PVC-f undegraded or virgin (PVC-fv), besides a higher weight loss and structural changes. In the PVC-fa samples, morphological modifications were observed, which are very important to describe the degradation phenomenon as superficial erosion and bioerosion, which propitiated the action of the yeast, bacteria and fungi present in the environment on the disposed polymer.

A reciclagem de elastômeros vulcanizados tem sido um problema para as empresas geradoras de resíduos elastoméricos, e ao mesmo tempo um amplo campo de estudo para pesquisadores da área. Diante da possibilidade de recuperação desses resíduos, deu-se início a este trabalho, relacionado à incorporação de pó de pneu de automóvel (STR-r) como uma carga, em uma formulação típica para banda de rodagem de pneu de motocicleta (formulação base - FB). O estudo teve início com a caracterização do STR-r, com base na análise granulométrica, análise termogravimétrica (TG) e calorimetria exploratória diferencial (DSC). A incorporação do STR-r na FB foi realizada em misturador aberto, nas proporções de 5 a 20 phr. Foram calculados os parâmetros reométricos de vulcanização e determinadas as propriedades mecânicas como resiliência, dureza (Shore A), resistência à abrasão, à tração e ao rasgamento dos compósitos preparados. Os resultados foram comparados aos da FB de um processo produtivo de uma empresa de pneus para motocicleta. A partir da análise dos resultados dos diferentes compósitos, foi escolhida a formulação com 10 phr de STR-r para ser produzida em escala industrial, ou seja, em misturador fechado, tipo Banbury. Os cálculos do custo de produção foram realizados com o objetivo de avaliar a viabilidade econômica deste desenvolvimento.

The recycling of vulcanized elastomers represents a problem for companies generating elastomeric residues and has become a wide field of study for researchers in this area. This study addresses the possible use of these residues and investigates an alternative for their recovery through incorporation of tread powder of cars tires (STR-r) as a filler into a typical formulation for motorcycle tire tread (base formulation - BF). The study began with the characterization of the STR-r, based on granulometric, thermogravimetric (TGA) and differential scanning calorimetry (DSC) analyses. The incorporation of STR-r into BF was carried out in an open mixer, in the proportions of 5 to 20 phr. The rheometric parameters of the vulcanization and the mechanical properties of the composites prepared, such as elongation at break, hardness (Shore A), abrasion resistance, tensile and tear strength, were determined. The results were compared with those of BF used in the production process of a motorcycle tire company. Following the analysis of the results for the different composites, the formulation with 10 phr of STR-r was selected to be produced on an industrial scale, that is, in a closed Banbury-type mixer. The calculation of the production cost was carried out in order to evaluate the economic viability of this recycling option.

Uma alternativa para as empresas geradoras de resíduos elastoméricos é a incorporação dos mesmos em suas formulações. Esse trabalho tem como objetivo preparar compósitos a partir da incorporação de resíduos industriais de SBR (copolímero de butadieno-estireno) e de EPDM (terpolímero de etileno-propileno-dieno), em formulação ASTM específica para cada tipo de elastômero. Foram avaliadas as propriedades reométricas, mecânicas e morfológicas dos compósitos desenvolvidos. A incorporação do resíduo permitiu a obtenção de produtos que vulcanizam em menores tempos quando comparados a composições sem resíduo. A quantidade de resíduo, para o melhor resultado de resistência à tração foi de 37 e de 196 phr para os compósitos com SBR e EPDM, respectivamente. As micrografias de MEV corroboraram os resultados mecânicos dessas composições, indicando melhor homogeneidade do resíduo na respectiva matriz elastomérica.

One alternative for elastomeric scraps generation is its incorporation in conventional formulations in the industry itself. In this work, compositions with incorporation of SBR (styrene butadiene rubber) and EPDM (ethylene propylene diene rubber) industrial scraps, in specific ASTM formulation for each elastomer, were prepared. Rheometric characteristics, mechanical properties and the morphology of the compounds developed were evaluated. With the ground scraps incorporation the vulcanization time decreases, comparing with compounds without ground scraps. The amount of scraps for the best tensile strength properties was 37 and 196 phr for SBR and EPDM compositions, respectively. Micrographs corroborated the mechanical results, indicating the best homogeneity of the scraps in the elastomeric matrix for these compositions.