Jean-Luc Bailleul

Optimization of thick rubber part curing cycles

Thick rubber part moulding is a process, during which coupling between heat and chemical kinetic equations is strong. Automatic tooling control, therefore, is the guarantee of achieving proper curing within the mould. This article initially presents a detailed method for curing optimization. With this aim in view, the optimum temperature cycle for the desired curing state is examined. The use, here, of the conjugate gradient method implies to determine the solution of both adjoin and sensitivity equations. A sensitivity study is also conducted in order to improve the kinetic model. Finally, some optimization examples are discussed.

Recycling By Solvolysis Thermosetting Composite Materials Of Sustainable Surface Transport

A solvolysis process is studied to degrade an unsaturated polyester resin based on DCPD (dicyclopentadiene) and crosslinked with styrene, as the matrix of a composite material reinforced with long glass fibers. The study presented here investigates in particular the hydrolysis in conditions below the critical point of water (T<374°u2009C and P<221bar) in a batch reactor. Process window and parameter influences were studied by a Design of Experiments (DOE) approach (1). A tar‐like substance issued from thermal degradations is formed in greater or lesser quantities depending on the operating conditions, and coats the fibers. The appearance of the composite samples and the degree of conversion for the degradation at 250°u2009C lead us to make a parallel with osmosis phenomena to explain the initiation mechanism of the degradation.

Numerical natural rubber curing simulation, obtaining a controlled gradient of the state of cure in a thick‐section part

Although numerical simulation has proved to be a useful tool to predict the rubber vulcanization process, few applications in the process control have been reported. Because the end‐use rubber properties depend on the state of cure distribution in the parts thickness, the prediction of the optimal distribution remains a challenge for the rubber industry. The analysis of the vulcanization process requires the determination of the thermal behavior of the material and the cure kinetics. A nonisothermal vulcanization model with nonisothermal induction time is used in this numerical study. Numerical results are obtained for natural rubber (NR) thick‐section part curing. A controlled gradient of the state of cure in the part thickness is obtained by a curing process that consists not only in mold heating phase, but also a forced convection mold cooling phase in order to stop the vulcanization process and to control the vulcanization distribution. The mold design that allows this control is described. In the hea...

Heat transfer analysis during the hydrothermal degradation of an epoxy resin using differential scanning calorimetry (DSC)

AbstractnIn the present work, an epoxy-amine-cured resin is subjected to hydrothermal degradation, in high-temperature and high-pressure water. The thermal behaviour of the epoxy-amine-cured resin, during the hydrothermal degradation, was characterized, by differential scanning calorimetry using high-pressure and high-temperature crucibles. The study is performed by heating samples from ambient temperature to a bearing temperature between 335 and 390xa0°C. Operating pressure at these bearing temperatures can exceed 400xa0bar. The complete degradation of the resin can be achieved at 335xa0°C, but only for nonzero resident times (IE, maintaining the heating at the bearing temperature), regardless of the bearing temperature. At a specific temperature level, an exothermic heat flux is observed, when heating both water only (system 1) and waterxa0+xa0resin (system 2). We have shown that this exothermic heat flux is due to a phase transition.