The motivations of the present work are to investigate the exfoliation of montmorillonite within a linear low-density polyethylene matrix and to control its orientation during the cast extrusion process. The first part is focused on the exfoliation of the montmorillonite through the melt extrusion process. The accuracy and relevance of each method used to determine the exfoliation state of montmorillonite have been examined, thanks to X-ray diffraction, transmission electronic microscopy, and rheology. All these methods have presented limitations, but the combination of all leads to a better estimation of the exfoliation state. Finally, the orientation of the montmorillonite is quantified systematically by X-ray texture analysis and correlated with process parameters to discern which one is affecting their orientation. The results have demonstrated an enhancement of the “in-plane” orientation of the montmorillonite with the exfoliation, especially at high concentration and when combined with cast extrusion. Finally, in the multi-nano-layer polymer film configuration, the reduction of the individual layers 29 nm thickness leads to some orientation improvements. However, these improvements are almost at the same level as the concentration effect in a monolayer system. This work gives an overview of all the parameters needed to achieve a significant organo-modified montmorillonite “in-plane” orientation.

The present work aims to explore and enhance two important aspects in polymer blends: mixing efficiency and compatibilization, either separately or in a combined approach to target a potential application on the flexible plastic waste’s treatment. The major objective of this study is the optimization of the complex blend compatibilization generated after mechanical recycling using commercial compatibilizing agents. For this purpose, the first experiments were carried out using virgin model polymer’s blend based on the multilayer food packaging’s films compositions: LLDPE, EVOH, and an LLDPE grafted with maleic acid (LLDPE-g-MA) as commercial compatibilizer. The efficiency of these compatibilizing agents and the stability of the morphology were evaluated with different characterization techniques as tensile test, shear rheology, and SEM (scanning electron microscopy). The results obtained with the shear relaxation time experiments showed that the EVOH reaction with LLDPE-g-MA compatibilizer was promoted by higher screw speed extrusion and shorter residence times. These observations were then confirmed with the improvement of the mechanical properties and the finer morphology observed with SEM analysis.