Analysis of the crosslinking process of a phenolic resin by thermal scanning rheometry

Abstract

ABSTRACT:The curing reaction of a phenolic resin (resole type) carried out in the absence of an initiator was studied by thermal scanning rheometry under isothermal conditions at temperatures from 70 to 105°C. The same curing reaction was studied in the presence of an acid as a catalyst in the temperature range of 50 -80°C. The gel time, which was defined by several criteria, was found to be a good parameter to determine the apparent activation energy of this process. An empirical model was used to predict the change in complex viscosity with time until the gel time was reached. If first-order kinetics were assumed, the apparent kinetic constant of the curing reaction could be obtained. Furthermore, the effect that the addition of water and free phenol had on the curing process of this type of resin was studied.

Regeneration and utilization of waste phenolic formaldehyde resin: A performance investigation

“…Similar TOX concentration dependence on the intensities of OH, CO stretching, and CH 2 bending bands was found for the reaction‐injected series with higher RPF 10 concentrations, whereas the critical TOX concentration associated with the near disappearance of these bands increased from 0.75 to 1.0 and 1.5 phr, as their RPF 10 concentrations increased from 15 to 20 and 22.5 wt %, respectively [see Figure (d,g,j)]. This gradual disappearance in the FTIR bands associated with CH 2 OH functional groups is most likely attributed to the crosslinking reaction occurred between OH, CH 2 OH or CHO groups of PF and RPF and the CHO groups of TOX . Based on the above FTIR results, possible reaction mechanism during the reactive injection process of PF/RPF w /TOX is presented in Scheme .…”

Reaction Kinetics of Polyurethane Formation Using a Commercial Oligomeric Diisocyanate Resin Studied by Calorimetric and Rheological Methods

“…The degree of conversion at the gel point can be considered as constant for thermosetting systems,23, 35, 50 allowing for a direct relationship between the gel time ( t gel ) and the apparent curing constant K c :35, 51 …”

Sigmoidal Chemorheological Models of Chip‐Underfill Materials Offer Alternative Predictions of Combined Cure and Flow

“…The kinetics of conversion for reactive resins and their dependence on an activation energy has often been evaluated by curing at different temperatures and establishing the activation energy. [4][5][6][7][8] A recent review related conversion to the capacity for molecular diffusion for several common polymerization Prior rheology results on chip-underfill epoxy resins have been re-analyzed by a sigmoidal model that contains three variable physical parameters, including the terminal cured viscosity of the gel, an induction or dwell time and a time factor associated with the speed of conversion as viscosity undergoes large dynamic changes during rapid crosslinking. The analyses were conducted with resins that were originally cured between 150 and 180 8C and show obvious non-linearity, even on a semi-log plot of dynamic viscosity.…”