Nanostructured polyolefins/clay composites: role of the molecular interaction at the interface

Abstract

The extent of interphase interactions between polymer phase and inorganic particles is the driving force addressing the preparation/properties design in the field of the corresponding micro‐ and nanocomposites. In the case of preparation of nanocomposites based on polyolefins (POs) and inorganic compounds as potentially nanodispersed phase, the use of a PO with proper functional groups is necessary for the interface adhesion and stabilization of the nanostructured morphology. According to this approach, ethylene/propylene copolymers with a different propylene content were used for the preparation of nanocomposites through melt mixing with organophilic montmorillonites (OMMT). By taking into account the important role of functionalities grafted onto POs, two different synthetic approaches were compared here: (1) the dispersion of the inorganic filler was obtained by using previously functionalized POs bearing carboxylate groups as matrices; (2) the nanocomposites were prepared by performing contemporaneously the functionalization of POs (by using maleic anhydride (MAH) and/or diethyl maleate (DEM)) and the dispersion of the filler in a one‐step process. The morphology of the nanocomposites as well as the variation of solubility and glass transition temperature (Tg) of the PO matrix were evaluated and tentatively discussed with reference to functionalization degrees, structure of PO, and preparation procedure. Copyright © 2008 John Wiley & Sons, Ltd.

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

“…This conclusion agrees with FTIR analysis, that suggests that the simultaneous mixing of the clay, polymer, peroxide and functionalizing agent (Method I) is less effective in regard to the modification of PP. Passaglia et al ., while analyzing a propylene copolymer with low ethylene content, also found that the application of mixing methods equivalent to our Methods II and III produce a reduction of the molecular weight of the polymer (as revealed by the drop in the final torque during mixing). They also found that sequential mixing (equivalent to Method III) produces a larger reduction in molecular weight and a better dispersion of the clay particles.…”

“…Although the use of low concentrations of a compatibilizer is the most used scheme among melt mixing methods, various other strategies of compatibilization between inorganic loadings and PP have been reported. For example, pretreatment of the loading with coupling agents; generation of radicals which react with both, the PP free radicals generated during processing and with the loading via , for example, electron transferring; incorporation of monomers which undergo grafting onto PP during processing using a peroxide to initiate the grafting, etc. In particular, the in situ functionalization of PP during blending with o‐MMT is an interesting alternative among melt mixing methods because it is easily implemented in current industrial processes and may promote clay exfoliation.…”

“…Passaglia et al . used a similar approach to synthesize nanocomposites based in four different ethylene/propylene copolymers, two functionalizing agents (MA and diethyl maleate) and one o‐MMT.…”

Nanocomposites Based on Phyllosilicates: From Petrochemicals to Renewable Thermoplastic Matrices

“…Consequently, two different synthetic approaches were very recently compared for the preparation of EPM and PP OLS nanocomposites [89] (Figure 13.9 ):…”

Progress in Understanding of the Interactions between Functionalized Polyolefins and Organo‐Layered Double Hydroxides

“…Literature data further indicate that the number of grafted functional groups as well as the molecular weight and polymer architecture affect the degree of intercalation/exfoliation . Similarly, effective interactions between functionalized POs and clay lamellae are evidenced by blending a diethyl maleate (DEM) functionalized EPM with increasing amounts of an organo‐layered silicate . Interestingly, it has been found that the grafted ester groups interact via hydrogen bonds with the OH groups present on the surface of the clay.…”