| The aim of the present work is to optimise the governing parameters during pultrusion of fibre reinforced thermoset resins. This process is used with a variety of resin and fibre reinforcement to produce profiles ranging from simple to complex structural parts. In a pultrusion machine, the heated die is regarded as the heart of the process where the majority of the phenomenons leading to the resin-fibre consolidation took place. This consolidation results from the resin's morphological changes which generate pressure and resisting forces. From this consideration, the present work deals mainly with the study of thermal and chemical phenomenons occurring inside the pultruder die in order to control and expand the process knowledge.; The first aspect treated in this work concerns the cure kinetics of thermoset resins used in pultrusion process. From the results found in this part of the study, it is shown that the exothermic heat evolved during the cure reaction is completely independent from the heating rate of the dynamic run and the temperature of isothermal run. Consequently, this amount of heat is considered as an intrinsic property of a given resin formulation. The proposed method can be easily generalized to non-uniform time-temperature profiles as in the case of pultrusion process.; The cure kinetics was then used to study the temperature and conversion profiles of pultruded composites inside the die. Thermal and chemical phenomenons were expressed by appropriate three dimensional energy balance equation including transient, conduction and heat source terms. The numerical program is also tested by investigating the effect of pulling speed. In this case, the results show clearly that temperature gradient is more pronounced for slow pulling speed while the peak temperature increases and shifts toward the die exit with increasing pulling speed. These remarks are related to the residence time and rate of cure depending on the pulling speed and affecting by the way the progress of thermal and chemical phenomenons.; The last treated subject in this thesis concerns the size and location of the liquid, gelatinous and solid zones of the resin during the cure process inside the die. The obtained contour delimiting the liquid and gelatinous zones has a parabolic form and shows that the cure increases from the interface between the material and the die to the material centerline. Unlike this, the gel/solid contour has a complex geometrical form leading to a fast cure for the interface and the centerline than the remaining points on the material section. Moreover, increasing the pulling speed has a significant effect especially on the size of the liquid zone. (Abstract shortened by UMI.)... |
