Polypropylene nanocomposites produced by in situ grafting of n‐butyl acrylate

Abstract

Nanocomposites of polypropylene and organophilic clay are produced by in situ functionalization of PP with n-butyl acrylate (BA) during melt mixing. Three strategies for incorporating materials into the mixer are analyzed and the effect of clay concentration is evaluated. The materials are examined by FTIR spectroscopy, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, thermogravimetry, and rotational rheometry. The results show that all composites prepared in the presence of BA have similar intercalated clay structure, and that the largest degree of exfoliation is obtained using the sequential mixing technique. This method, which consists in adding the initiator and functionalizing agent to the molten polypropylene followed by the addition of the clay, also produces the largest reduction in molecular weight of the polymer and the largest increase of the elastic modulus. All polymers show similar crystallization and degradation processes.

Polypropylene nanocomposites produced by in‐situ grafting of maleic anhydride using different mixing procedures

“…That is, the clay incorporated at half processing time has to be interacting with macroradicals and/or MA that may be still present in the media, limiting the degradation/functionalization of PP during the rest of the process. Previous results support this observation 24,26 . Moreover, this conclusion is reinforced by the augment of the moduli with increase in clay concentration.…”

“…Previous results support this observation. 24,26 Moreover, this conclusion is reinforced by the augment of the moduli with increase in clay concentration. Additionally, the dynamic moduli of NCs display a relatively larger increase at low frequencies with clay concentration, mainly in case of G´.…”

“…The five mixing procedures used for NCs preparation are described in Table 1. Some of them are similar to those used in a previous work where NCs of PP and oMt were studied by grafting n ‐butyl acrylate (BA) onto PP during processing 26 . Procedure I corresponds to the direct addition of all components to the mixer, while Procedures II and III include an initial step of MA impregnation of clay and/or PP before processing.…”

“…Some of them are similar to those used in a previous work where NCs of PP and oMt were studied by grafting n-butylacrylate (BA) onto PP during processing. 26 Procedure I corresponds to the direct addition of all components to the mixer, while Procedures II and III include an initial step of MA impregnation of clay and/or PP before processing. Impregnation consists in dissolving MA in methylethyl-ketone and adding this solution to the clay and/or PP, depending on the method.…”