The effect of plasticization by water on the mechanical properties of additive-free poly(vinyl butyral) (PVB) was investigated. PVB is hygroscopic and the amount of absorbed water was measured in various environmental conditions. Two kinds of interactions with hydrophilic sites was demonstrated. The thermal and thermomechanical studies (differential scanning calorimetry and dynamic mechanical thermal analysis) showed that water decreases the glass transition temperature thus acting as a plasticizer. This gives the material larger deformation capability and increased toughness. Surprisingly, the modulus remains high and this was explained by a structure consisting in two phases with different levels of plasticization, reflected by a double peak of relaxation associated to multiple phases with different glass transition temperature. Atomic force microscopy measurements on samples with high level of hydration shows evidence of nanometric hydrated domains acting as an elastomeric phase and thus inducing toughening of the material.

This work focuses on the extrusion foaming under CO2 of commercial TPV and how the process influences the final morphology of the foam. Moreover, numerical modelling of the cell growth of the extrusion foaming is developed. The results show how a precise control on the saturation pressure, die geometry, temperature and nucleation can provide a homogeneous foam having a low density (<500 kg/m3). This work demonstrates that an optimum of CO2 content must be determined to control the coalescence phenomenon that appears for high levels of CO2. This is explained by longer residence times in the die (time of growth under confinement) and an early nucleation (expansion on the die destabilizes the polymer flow). Finally, this work proposes a model to predict the influence of CO2 on the flow (plasticizing effect) and a global model to simulate the extrusion process and foaming inside and outside the die. For well-chosen nucleation parameters, the model predicts the final mean radius of the cell foam as well as final foam density.

The use of reactions between polycarbonate (PC) and polystyrene-block-poly(ethylene-butylene)-block-polystyrenegrafted-maleic anhydride (SEBS-g-MAH) is a convenient way to create SEBS-g-PC. Grafting was realized by reactive extrusion at three temperatures using SnOct 2 or TBD catalysts. SEC analyses showed the apparition of a double distribution when the TBD was used. The mean residence time widely increased when this catalyst was used, and the rheological curves depicted a percolation effect of the SEBS nodules in the PC matrix. No explicit evolution was found with the use of SnOct 2 . The thermal analyses showed the disappearance of the PC phase transition temperature. The Van Gurp-Palmen plots confirmed the efficiency of the TBD catalyst and that 260 C was the optimal reactive extrusion temperature.