La rhéologie à hauts taux de cisaillement pour deux polymères, le PEHD semi-cristallin et le PMMA amorphe a été étudiée. Des outils de rhéométrie classique, un rhéomètre plan-plan en mode dynamique, et un rhéomètre capillaire, ont été utilisés dans des conditions extrêmes (avec des filières pour la rhéométrie capillaire de diamètres allant jusqu'à 0,3 mm) mais les dépouillements de ces résultats ont été fait suivant les hypothèses conventionnelles en négligeant les instabilités et les phénomènes physiques qui interviennent lors de ces écoulements.Nous avons par la suite développé un modèle mathématique de l'écoulement dans un capillaire pour rendre compte de l'importance des différents phénomènes physiques qui peuvent avoir lieu dans des écoulements extrêmes, à savoir l'échauffement et la piezodépendance de la viscosité, la compressibilité et le glissement à la paroi. Les résultats du modèle développé ont été comparés avec les résultats expérimentaux.Nous avons aidé au développement d'une presse de microinjection originale et nous l'avons testée avec un moule de plaque instrumenté d'épaisseur allant jusqu'à 0,2 mm. Nous avons montré qu'il était possible de réaliser des pièces de qualité ce qui est avéré par des mesures de pression, vitesse et de température bien reproductibles. Nous avons exploité les données rhéologiques expérimentales dans la modélisation de la phase de remplissage avec le logiciel de calcul Rem3D. Des corrélations entre les mesures expérimentales et les calculs ont été réalisées en comparant l'évolution des pressions dans le système d'alimentation et dans l'empreinte. / Rheology at high shear rate for both polymers, semi-crystalline HDPE and amorphous PMMA was studied. Classical rheometry tools, plane-plane dynamic mode rheometer and capillary rheometer, were used in extreme conditions (with channels diameters for capillary rheometry up to 0.3 mm). However, analyses of these results were made following conventional assumptions neglecting instabilities and physical phenomena involved in these flows.We then developed a mathematical model of a capillary flow in to reflect the importance of different physical phenomena that can occur in extreme flows, namely heating, pressure dependency of viscosity, compressibility and the wall slip. The results of the developed model were compared with experimental results.We helped develop a press microinjection original and we tested it with instrumented plate mold with thickness up to 0.2 mm. We have shown that it is possible to make quality parts which are proven by well reproducible pressure, speed and temperature measurements. We used the experimental rheological data in filling phase modeling with the calculation software Rem3D. Correlations between experimental measurements and calculations were carried out by comparing the pressure in the filling system and the cavity.

Applications of Hot Melt Extrusion (HME) in pharmaceuticals have become increasingly popular over the years but nonetheless a few obstacles still remain before wide scale implementation. In many instances these improvements are related to both processing and product performance. It is observed that HME process optimisation is majorly focused on the active pharmaceutical ingredient's (API) properties. Characterising polymeric properties for their suitability in HME should be equally studied since the impact of excipients on both product and process performance is just as vital. In this work, two well-established cellulose ester derivatives: Hydroxy Propyl Methyl Cellulose Acetate Succinate (HPMCAS) and Hydroxy Propyl Methyl Cellulose Phthalate (HPMCP) are studied for their HME suitability. Their thermal, thermodynamic, rheological, thermo-chemical and degradation kinetic properties were evaluated with model plasticisers and APIs. It was found the thermal properties of HPMCP are severely compromised whereas HPMCAS is more stable in the processing zone of 150 to 200 °C. Thermodynamic properties revealed that both polymers share an important solubility parameter range (20-30 MPa P1/2P) where the majority of plasticisers and BCS class II APIs lie. Thus, greater miscibility/solubility can be expected. Further, the processability of these two polymers investigated by rheometric measurements showed HPMCAS possesses better flow properties than HPMCP because HPMCP forms a weak network of chain interactions at a molecular level. However, adding plasticisers such as PEG and TEC the flow properties of HPMCP can be tailored. The study also showed that plasticisers have a major influence on thermo-chemical and kinetic properties of polymers. For instance, PEG reduced polymer degradation with reversal in kinetic parameters whereas blends of CA produced detrimental effects and increased polymer degradation with reduction in onset degradation temperatures. Further, both polymers are observed to be chemically reactive with the APIs containing free -OH, -SOR2RN- and -NH2 groups. Finally, these properties prove that suitability of HPMCP is highly debated for HME and demands great care in use while that of HPMCAS is relatively better than HPMCP in many instances.

Applications of Hot Melt Extrusion (HME) in pharmaceuticals have become increasingly popular over the years but nonetheless a few obstacles still remain before wide scale implementation. In many instances these improvements are related to both processing and product performance. It is observed that HME process optimisation is majorly focused on the active pharmaceutical ingredient's (API) properties. Characterising polymeric properties for their suitability in HME should be equally studied since the impact of excipients on both product and process performance is just as vital. In this work, two well-established cellulose ester derivatives: Hydroxy Propyl Methyl Cellulose Acetate Succinate (HPMCAS) and Hydroxy Propyl Methyl Cellulose Phthalate (HPMCP) are studied for their HME suitability. Their thermal, thermodynamic, rheological, thermo-chemical and degradation kinetic properties were evaluated with model plasticisers and APIs. It was found the thermal properties of HPMCP are severely compromised whereas HPMCAS is more stable in the processing zone of 150 to 200 °C. Thermodynamic properties revealed that both polymers share an important solubility parameter range (20-30 MPa P1/2P) where the majority of plasticisers and BCS class II APIs lie. Thus, greater miscibility/solubility can be expected. Further, the processability of these two polymers investigated by rheometric measurements showed HPMCAS possesses better flow properties than HPMCP because HPMCP forms a weak network of chain interactions at a molecular level. However, adding plasticisers such as PEG and TEC the flow properties of HPMCP can be tailored. The study also showed that plasticisers have a major influence on thermo-chemical and kinetic properties of polymers. For instance, PEG reduced polymer degradation with reversal in kinetic parameters whereas blends of CA produced detrimental effects and increased polymer degradation with reduction in onset degradation temperatures. Further, both polymers are observed to be chemically reactive with the APIs containing free -OH, -SOR2RN- and -NH2 groups. Finally, these properties prove that suitability of HPMCP is highly debated for HME and demands great care in use while that of HPMCAS is relatively better than HPMCP in many instances.