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A novel method for the visualization and quantification of the state of dispersion of calcium carbonate particles in thin blown polymer films is described. Particle imaging was achieved by elemental mapping using energy dispersive spectroscopy. This generated outlines of particles and agglomerates located close to the film surface. ImageJ software facilitated the extraction of the corresponding Feret diameters. Finally, the Bootstrap technique was used to estimate confidence intervals for the kurtosis of the Feret particle size distribution. Kurtosis is a statistic that describes the shape of a distribution’s tails in relation to its overall shape. It therefore provides a measure that characterizes the degree of particle agglomeration. The proposed procedure was applied to analyze high-density polyethylene films prepared using different calcium carbonate masterbatches in which formulation parameters were varied.

The effects of filler content, filler particle size and surface coating, as well as the natures of the wax and metal stearate lubricants on the properties of calcium carbonate-filled linear low-density polyethylene compounds were investigated. The elongation at break decreased exponentially with filler loading irrespective of whether the filler was surface coated or not. The corresponding decline in the impact strength was more gradual but it dropped abruptly on reaching a filler loading of 70 wt%. The effect of shear rate on the apparent melt viscosity followed an empirically modified Carreau–Yasuda model which included the effect of filler content. It features the zero-shear viscosity and the flow consistency index as adjustable parameters. These characterize the viscosity trends at low- and high-shear rates, respectively. In the absence of additives, the melt viscosity at 60 wt% filler exceeded that of the neat polymer by a factor of three. Adding 3 wt% wax and 1.0 wt% zinc stearate returned the melt viscosity to levels just above that of the neat polymer. Calcium stearate and magnesium stearate were less effective at reducing the apparent melt viscosity but a blend of the latter with zinc stearate performed particularly well.

During melt extrusion of nanocomposites, nanoparticles can be incorporated either directly or through the masterbatch, which brings up a simple question of how the mode of nanoparticle inclusion affects the morphology and hence the rheological properties of the final composite. In the study reported here, nylon6/ethyl–vinyl-alcohol (N6/EVOH) was selected to model a blend system, and the effect of the mode of organoclay inclusion on the morphology development and melt-state viscoelastic properties of ternary blend composites was investigated. The morphological study using scanning electron microscopy, transmission electron microscopy, three-dimensional tomography, and differential scanning calorimetry indicated that the intercalated silicate layers were located in the interphase region between N6 and EVOH in the N6/EVOH/masterbatch composite and core–shell particles were formed, with EVOH as the core. On the other hand, the intercalated silicate layers were well distributed in the blend matrix of the N6/EVOH/organoclay composite, and it was difficult to differentiate between two phases. Finally, the different morphological developments were correlated with the melt-state rheological properties of the composites to evaluate the processing and product performance. The results showed that the masterbatch played an important role in establishing the compatibility of N6 and EVOH, and it could impede the gel formation that would benefit processing and product development.

Polylactide/butylated-starch/nanoclay (70/25.5/4.5 wt%) composites were prepared by melt blending with nanoclays of varying hydrophobicity. Electron microscopy studies indicated that the interphase boundary interaction was highest in the clay with intermediate hydrophobicity but decreased with clays of higher or lower hydrophobicity. Conventional and modulated differential scanning calorimetry studies showed that, in the case of composites, the change in the ratio of rigid and mobile amorphous fractions depends on the hydrophobicity of clays used for the preparation of blend composites. The mobile amorphous fraction related to the polylactide phase decreases in the case of intermediate hydrophobic clay compared with less and more hydrophobic clays or neat blend samples. Avrami bulk crystallization analysis and polarized optical microscopic observation demonstrated that hydrophobic clays hindered the crystallization of the PLA phase into the formation of disc-shaped spherulites. On the basis of obtained results, we propose a general understanding on how the morphology and thermal properties of the blend composites are related to the hydrophobicity of the nanoclays.

In this article, a combined experimental and theoretical approach has been proposed to establish a relationship between the required shear force and the degree of delamination of clay tactoids during the melt-processing of polymer nanocomposites. Polypropylene (PP) was selected as a model polymer, and nanocomposites of PP with organically modified clay were prepared by a master batch dilution technique in a twin-screw extruder. The effect of PP throughput during the dilution of the master batch on the dispersion and orientation of clay platelets were studied in detail. Powder X-ray diffraction, small and wide angle X-ray scattering and high resolution transmission electron microscopy were used to study the structure and morphology of the obtained nanocomposites. The results showed that a lower feeding rate led to the orientation of clay platelets almost in the direction of extrusion. The adhesive force and the interaction energy between the clay platelets were theoretically calculated using the Hamaker approach. The analysis showed that the peeling mechanism is a practical explanation for the delamination of clay platelets during melt extrusion and that the dimensions of the clay platelet tactoids play an important role in the peeling due to the shear stress.