Polypropylene/clay nanocomposites: Combined effects of clay treatment and compatibilizer polymers on the structure and properties

Abstract

Combined effects of clay treatment and compatibilizer polymers on the structure and properties of polypropylene/clay nanocomposites were studied. Dynamic mechanical analysis was used to analyze comparatively the dynamic mechanical response of different nanocomposites prepared from polypropylene and montmorilloniterich bentonite, and to relate such response with the material microstructure. Two different bentonites were used: a purified Spanish natural bentonite was organophillized by means of 11-undecyl-ammonium ion and a commercial bentonite organophillized with dimethyl dehydrogenated tallow ammonium ion. Three different polar copolymers were employed as compatibilizer agents in some of the formulations: maleic anhydride-grafted polypropylene, maleic anhydride-grafted poly(styrene-co-ethylenebutyleneco-styrene), and poly(ethylene terephthalate-co-isophthalate) (PET). To ascertain the microstructure characteristics in the nanocomposites, wide angle X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry techniques were used. The nanocomposites containing both bentonite organophillized with 11-undecylammonium ion and PET, and maleated PP as compatibilizer system, were found to have the highest storage modulus and the smallest loss factor values, which was mainly due to the better clay platelets dispersion. The dynamic mechanical response of nanocomposites prepared with bentonite organophillized with dimethyl dehydrogenated tallow ammonium ion and maleated SEBS was strongly affected by the presence of this compatibilizer. The temperature of PP and a, b, and g relaxations strongly depended on the interactions between the different phases in the nanocomposites.

The effect of matrix morphology on dynamic-mechanical properties of polypropylene/layered silicate nanocomposites

“…If the molecular chain is restricted, motion or relaxation of the chain segment becomes difficult at the original glass transition temperature and becomes possible only at higher temperatures. Similar behavior has also been reported by other researchers [40,76,79]. However, Samal et al [76] reported a decrease in T g for PP nanocomposites, indicating that the amorphous molecules become mobile at lower temperature as compared to virgin PP, which in this case was assigned to the existence of low-molecular-weight intercalants in nanoclays.…”

“…An increase in T g was reported for PP-based nanocomposites [35,38], whereas on the contrary, significantly decreased T g was reported in [39]. The characteristics of , , and  relaxations, and the activation energy of  relaxation of PP in PP/clay nanocomposites, have been analyzed by Velasco et al [40]. It has been observed that , , and  relaxations of PP depend strongly on the interaction between the different phases in the nanocomposites.…”

Block copolymer–nanoparticle composites: Structure, functional properties, and processing

“…Nanoparticle properties have been studied extensively [163][164][165][166][167][168][169]. The incorporation of nanoparticles into block copolymer matrices can improve existing properties or impart new properties such as mechanical [26,[170][171][172][173][174][175][176][177][178][179][180][181], optical [182], electrical [170,181,[183][184][185][186][187][188], photovoltaic, thermal [149,[189][190][191][192], and barrier [17]. Thus such incorporation opens opportunities for combining functional properties along with a prescribed morphology.…”

Oxygen barrier property of polypropylene-polyether treated clay nanocomposite

“…In order to overcome this challenge in trial experiments with this treated clay, maleic anhydride grafted polypropylene (PP-g-MA) was used as a compatibilizer [24]. PP-g-MA reacted with -OH groups on the clay surface, increasing the compatibility between clay and PP.…”

“…The higher polarity of PS-g-MA resulted in exfoliation. Clay interlayer expansion depends on compatibility between polymer and organic intercalant and interactions between the two phases [24]. MMT clay is composed of regularly arranged tactoids and galleries.…”