Nanocompósitos poliméricos de poli (tereftalato de butileno) - PBT. / Polymer nanocomposites of poly (butylene terephthalate) - PBT.

AUTOR(ES)

Cássia Alves de Freitas

DATA DE PUBLICAÇÃO

2010

RESUMO

In this work, nanocomposites of PBT, poly (butylene terephthalate) and Brazilian clay montmorillonite (MMT) organically modified were obtained with and without further addition of toughening agent. Quaternary ammonium and phosphonium salts with different chemical structures were used to organically modify the clays. PBT nanocomposites with commercial organoclays were also obtained for comparison. The materials were mixed using a mixer and a twin screw, coupled to a torque rheometer. The efficiency of cation exchange was evaluated by X-ray diffraction (XRD), swelling and thermogravimetric analysis (TGA). The dispersion of PBT with modified clay (OMMT) was evaluated by XRD, optical microscopy and transmission electron microscopy (TEM). The toughness dispersion was evaluated by scanning electron microscopy (SEM). The flammability and mechanical properties were also evaluated. Thermogravimetric analysis (TGA) of the OMMTs and PBT / OMMTs was also studied. The basal spacing obtained from XRD analysis were shown to depend on the architecture of the quaternary salt used and were larger for long alkyl chains. The quaternary salt excess was not removed during the washing step. The highest thermal stability was obtained with quaternary phosphonium salts. After adding the PBT, it was observed that the addition of organoclay to the polymer matrix did not contribute to a significant improvement of mechanical properties and in some cases even resulted in a decrease of mechanical properties. However, the flame retardancy showed best results in the presence of organoclay. The best results for the flammability properties were observed in the presence of only quaternary phosphonium salts. However, these materials were very fragile. In order to improve the flammability properties of PBT maintaining the mechanical properties, a toughening agent P(E-co-MA-co-GMA), copolymer ethylene methyl acrylate glycidyl methacrylate was used. In doing so both the mechanical and flame retardancy were preserved.

ASSUNTO(S)

tenacificação polímeros nanocompósitos toughening polymers nanocomposites

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