Compostos elastoméricos com óleo de soja modificado para banda de rodagem de pneus

A principal aplicação de compostos de poli(butadieno-co-estireno) (SBR) e poli(butadieno) (BR) é na fabricação de pneus para o setor automotivo. A origem petroquímica da maioria das matérias-primas confere aos produtos à base de borracha imagem negativa, devido ao volume de pneus descartados no meio ambiente. Matérias primas de fontes renováveis, menos ou não nocivas aos seres vivos têm sido investigadas para substituição das atuais assegurando propriedades semelhantes aos compostos elastoméricos já em uso. Neste trabalho, dois óleos de soja modificados quimicamente, um esterificado (OEST) e outro esterificadoepoxidado (OEPX), foram investigados com o objetivo de substituir o óleo naftênico (ONAF) de origem petroquímica, usado como plastificante em compostos de borracha para banda de rodagem de pneus. A formulação do composto referência foi a base de elastômeros E-SBR (produzido em emulsão) e BR, sílica precipitada como reforço e silano como agente de acoplamento, além dos demais ingredientes. Os compostos elastoméricos não vulcanizados foram avaliados quanto ao processamento, comportamento reológico e características de cura, e após cura foram avaliados quanto a morfologia e principais propriedades físico-mecânicas e dinâmicas. As propriedades dinâmicas foram correlacionadas com os principais requisitos de uma banda de rodagem de pneus automotivos (aderência no molhado, resistência ao rolamento e a abrasão). Os compostos com OEST e OEPX apresentaram menor tempo de cura (t90) que o com ONAF, o que reduz o tempo de fabricação de pneus com aumento de produtividade. Se observou maiores temperatura e torque final para as misturas com os óleos OEST e OEPX, sendo estes mais termoestáveis que o ONAF. O composto E-SBR/BR/OEST com óleo de soja modificado apresentou morfologia e dispersão da sílica mais homogêneas. Ambos os óleos de soja OEST e OEPX apresentam potencial para uso como plastificantes, uma vez que comparativamente ao ONAF, estes apresentaram propriedades similares ou superiores as apresentadas pelo composto com o óleo petroquímico. O uso de ambos os óleos de soja atende à crescente demanda por processos e produtos mais sustentáveis, por serem de fonte renovável, não aromáticos, biodegradáveis, e, portanto, menos poluentes.The main application of elastomeric compounds based on poly (butadiene-co-styrene) (SBR) and poly (butadiene) (BR) is in the manufacture of tires in the automotive sector. The non-biodegradable petrochemical origin of most raw materials gives rubber-based products a negative image, due to the volume of tires discarded in the environment. Thus, raw materials from renewable sources, less or not harmful to living beings and to the environment, have been investigated to replace the current ones, ensuring similar final properties. In this work, two chemically modified soybean oils, one esterified (OEST) and another esterified-epoxidized (OEPX), were investigated with the aim of replacing naphthenic oil (ONAF) from petrochemical origin, used as a plasticizer in green tire tread rubber compositions. A reference formulation based on the E-SBR (produced in emulsion) and BR elastomers, precipitated silica as reinforcing filler, silane as coupling agent and other ingredients were used, varying only the type of plasticizer. The non-vulcanized elastomeric compounds were evaluated for processing, rheological behavior and curing characteristics, and after curing they were evaluated for morphology and main physical-mechanical and dynamic properties. The compounds dynamic properties were correlated with the main performance requirements of automotive tire tread (wet grip, rolling resistance and wear). The compounds with oils OEST and OEPX showed shorter curing times (t90) than those with ONAF, which in practice leads to a reduction in the tire tread manufacturing time and an increase in productivity. They also showed higher temperature and torque at the end of the mixing process, the soybean oils being more thermostable than ONAF. The compound E-SBR/BR/OEST presented more homogeneous morphology and silica dispersion in the elastomeric matrix. Both OEST and OEPX soybean oils have potential for use as plasticizers, since compared to ONAF, the elastomeric compounds showed similar or superior properties to those presented by the compound with petrochemical oil. The use of both soybean oils meets the growing demand for more sustainable processes and products, as they are renewable, non-aromatic, biodegradable, and therefore less polluting

Determination of N-nitrosamines and N-nitrosables substances in rubber teats and sothers by GC-TEA

N-Nitrosamines are receiving special attention because they present high mutagenic and carcinogenic potential. They can be found in several areas. In rubber, for example, they can be found in Nipples and Pacifiers. Spiegelhalder and Pressumann, have observed that N-Nitrosamines present in nipples and pacifiers could easily migrate to artificial saliva. They have also observed that a considerable amount of N-Nitrosamines precursors, such as nitrosable amines, could migrate to saliva, increasing the possibility of N-Nitrosamines formation into the stomach of living beings. In 80's, Holland, Germany and FDA-U.S.A. have established volatile N-Nitrosamines limit levels. In 2002, in Brazil, limit levels came through Resolução RDC n° 221 of ANVISA. This resolution refers to NBR10334 and NBR 13793 standards where limits and analysis methods are specified. In this work SENAICETEPO presents the method adopted for determination of N-Nitrosamines and N-Nitrosables in nipples and pacifiers. The detection and determination limits of the analytical system as well the method uncertainty were evaluated, in order to demonstrate the adequacy of this technique to comply with the requirements of NBR10334/2003 and NBR 13793/2003 standard