Filled thermosetting resins used for adhesives, sealants, and coatings are two‐phase systems whose rheological behavior is determined by the properties of both phases as well as by the interactions between the matrix and the filler. The chemorheological changes during the crosslinking of an epoxy system (EPON 828 with curing agent Y from Shell Chemical Co.) were investigated. The influence of an untreated silica filler on the reaction kinetics and the Rheological behavior of the system were also analyzed. The concentration of the filler was varied between 0 and 17.25 vol%. The influence of the filler on the gel point was explained in terms of the accelerating effect of the filler on the reaction kinetics.

Nonisothermal differential scanning calorimetry (DSC) measurements were used to estimate the kinetic parameters for the curing reaction of a commercial unsaturated polyester resin. The reaction rate expression was derived from a mechanistic kinetic model based on the concept of free radical polymerization, accounting also for the diffusion controlled reaction. The total heat of reaction was evaluated in experiments run at very low scan speeds and using high amount of initiator. The kinetic parameters were found to show no dependency on the heating rate nor on the initiator concentration. Dynamic DSC measurements provide reliable kinetic data over a broad range of temperatures that is mostly significant for process simulations.

A mechanistic kinetic model based on the concept of free radical polymerization and corrected for diffusion controlled reactions was used to describe the curing behavior of an unsaturated polyester resin. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry (DSC) scans using a multiple regression technique. The presence of kaolinite or fiber glass in the system does not affect the progression of the reaction. The results obtained from the kinetic studies were used to simulate the influence of system composition on temperature and conversion profiles inside a pultrusion die. The results of the simulations show that kaolinite and fiber glass act as heat sinks for the composite system reducing the peak exotherm and delaying curing progression.

Dicyclopentadiene (DCPD) based liquid engineered resins are emerging among the newest commercial reaction injection molding (RIM) systems. Since the filling stage is coupled with chemical reaction, an understanding of the chemorheological changes is critical for establishing moldability criteria. An adiabatic reactive viscometry technique which involves the simultaneous measurement of viscosity and temperature changes was used to investigate the chemorheological changes during the adiabatic copolymerization of a DCPD based RIM system. The influence of impingement mixing conditions and initial material temperature on the reaction kinetics, rheology, as well as the resulting final physical properties of the system were investigated. The “apparent gel time” under adiabatic conditions is estimated from the intersection of the tangents to the initial and final portions of the viscosity curve. An autocatalytic kinetic model with an Arrhenius rate constant was used to model the reaction kinetics.

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