Nanocompósitos de borracha nitrílica com argilas montmoriloníticas e bentonitas / nonoonono

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

26/03/2010

RESUMO

The search for new materials has been a constant in the humanity history. However, there are no plans to replace elastomers, even in long term, due to their unique mechanical properties. Among the various types of elastomers used nowadays, Nitrile Butadiene Rubber - NBR is a choice when one wants a material with good mechanical properties and excellent resistance to organic solvents. This work studies vulcanization, rheological and mechanical properties of NBR with two kinds of clay, nanosilic and nanocalcium carbonate. The clays used were Montmorilonita MMT, which is an imported clay and a Brazilian Bentonite, being the first of them used in two versions: treated to enhance their organofilic characteristic and also sodic. Emphasis will be put on replacing high-cost imported clay, by a national alternative with great potential. Two different grades of rubber were used: NBR 3330 and NBR 3350. Rubbers, vulcanization formulation and fillers were mixed in an open two roll mill during 30 minutes for each composition, and the samples vulcanization were done by using an hydraulic press, at 160C for 4 minutes. Several tests were then made with the vulcanized samples: mechanical, X-ray diffraction, DMTA and rheometric. The mechanical tests results showed that, in general, the mechanical properties values of nanocomposites matrix NBR 3350 increased in comparison to the values of pure rubber, reinforcing the hypothesis that mechanical tensions during the mixing act directly in the dispersion of filler, because NBR 3350 is more viscous than NBR 3330, which generates greater tensions during the mixture. Concerning the X-ray diffraction results, a tendency of lamellar exfoliation in matrix NBR was verified with small concentrations of filler and, with the increase in this concentration, the intercalation was then observed, but the interlamellar spacing was greater than the initial value of pure clay. Comparisons between nanocomposites produced by solution presented a greater degree of intercalation and/or exfoliation when compared with the produced by bulk. According to the results obtained by DMTA, in general, there was a reduction in storage and loss modulus of all NBR 3330 e 3350 nanocomposites/3phr of nanofiller in relation to the pure rubber. The tan δ values didnt suffer variations in relation to the pure rubber. There was also an increase in the Tg values of nanocomposites NBR/different types of nanofillers in relation to pure rubber. The rheometric tests results showed that the presence of clay didnt affect significantly the Ea values obtained. There was also a tendency to reduction in storage modulus and increase in loss modulus of all samples with the increase in the clay concentration present in low elongations, indicating a possible reduction in the number of cross-links in the samples analyzed. Therefore, the method used in this work is efficient, quick, simple and viable in the nanocomposites preparation.

ASSUNTO(S)

montmorilonita bentonita argilas nanocompósitos nbr abnt nanocomposites nbr clays montmorilonite bentonite rubber ciencias

ACESSO AO ARTIGO

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