Strategies for Optimizing Polypropylene−Clay Nanocomposite Structure

Abstract

The structure of nanocomposites produced by melt-mixing polypropylene and 5 wt % of organically modified layered silicates with varying amounts of different maleated polypropylene compatibilizer grades has been analyzed with X-ray diffraction, transmission electron microscopy (TEM), and melt rheology. The extent of delamination in different nanocomposites has been quantified from analysis of several TEM images for each specimen by a product of the single particle volume fraction and the intrinsic viscosity of such particles. This measure correlated directly with the low shear relative viscosity of the molten composites (relative to the silicate free mixture of polypropylene and compatibilizer). The results also indicate that the acid number alone is not a good predictor of compatibilizer effectiveness, i.e., the amount required for exfoliation. The molar ratio of functional groups to compatibilizer chains is found to be a better parameter for ranking compatibilizer effectiveness than the acid number, which is a weight ratio. With higher values of the molar ratio, lower concentrations of compatibilizer are required for significant exfoliation. With the highest molar ratio compatibilizer, an optimum compatibilizer concentration of about 10 wt % leads to a composite with the most exfoliated structure.

Exfoliation of clay layers in polypropylene matrix using potassium succinate-g-polypropylene as compatibilizer

“…It can be observed that irrespective of the method of preparation with increasing PPMA concentration the peak position shifts towards lower angles indicating improvement in the extent of intercalation of the polymer into the organoclay gallery. These results are similar to earlier reports [13,[32][33][34][35]. When the nanocomposites were prepared by direct mixing route and KPPSA was used as compatibilizer, the WAXD patterns show higher d-spacing for the clay as compared to that observed with the nanocomposites prepared using PPMA.…”

Structure and tensile properties of Nanoclay–Polypropylene fibers produced by melt spinning

“…This involves the exchange of hydrophilic cations on the clay surface with short-chain organic cations, such as alkyl ammonium ions. 11,12 The surface modification of clay, often referred to as organoclay, has shown improved compatibility with the polymeric matrix. 8,11 In some polymer matrixes, especially highly hydrophobic polyolefin polymers, organoclay could still not provide enough nanoclay-polymer interactions to produce a high degree of clay dispersion.…”

Nanocomposites Based on Phyllosilicates: From Petrochemicals to Renewable Thermoplastic Matrices

“…0.1 wt%), for achieving a good improvement in morphology. In the case of both PE and PP/OLS nanocomposites, if the grafting level was higher than this limit value, a shift or even a disappearance of the basal refl ection peak of the OLS on the XRD diffraction pattern could be observed [51,72,77,78,92] .…”

“…In fact, the hydrophilicity of the compatibilizer was seen to increase with the grafting level of MAH, thus improving the level of interaction between the polymer and the clay. In the case of the most common PO -g -MAH compatibilizers, the level of grafting ranged typically between 0.1 and 2 wt% [50,85,92,93] . In the case of MAH -functionalized PO, there was seen to be a limit value for the grafting level (ca.…”