(41e) Rheological Characterization of Phenol Formaldehyde Resol Resin

Resole resin is manufactured in Iraq as a substitute for imported furan. However, the main problem facing its production is the solidification of the final product in the reaction vessel or immediately after discharge. Moreover, factory manufactured Resole is highly viscous and has short shelf - life at ambient temperature for subsequent fabricating. Solution to this persisting problem will be profitable and reduces the cost involved in importing furan.

ChemCad Simulation software package is adapted in this study in order to design a simulation to the real Al-Jihad Phenol-Formaldehyde Resole Resin  Plant in Iraq. This software simulation program is used for the first time in such a study. The operation conditions employed in the real site is tested on this model in order to check its applicability, results obtained were in the form of overall mass balance, Stream flow simulation results, Stream properties and  Flow sheet summary. The simulation showed good behavior when modified manufacturing procedure was applied.

Viscometry, owing to its experimental simplicity is considered to be a suitable tool for a rapid and reliable characterization of polymer solutions in research and particularly in practice. Such rheological characterization is carried out experimentally in this work using a Fann VG meter Rotational Viscometer. This work attempts to carry out structure rheological analysis with resole dissolved in acetone, in order to come up with a solution to the problem of solidification of (PF) in the factory.

Results of rheological measurements are plotted as flow curves, namely Logή vs Logɣ. Three important parameters are obtained from the flow curves namely; zero shear viscosity (ηo), the onset of shear dependence (ɣc) and the inflection point (ɣ).  Of importance is the relationship between Logηo values and the corresponding values of LogM from which a Knick diagram may be obtained. From the plot two straight lines are seen to intersect at a certain point in a form of a break. The abscissa of the intersection point is called Mc (the critical molecular weight). Knick diagram offers important information concerning polymers dissolved in solvents at certain concentrations and at a fixed temperature indicating the existence of entanglement in the solution. Another important rheological character, exponent (a), this is derived from the slopes of the given flow curves. The exponent in the scaling law for ηo (M < Mc) is considerably increased above the theoretical value of 3.5. This could be explained by the assumption that instead of entanglement points, a rather stable entanglement region with no slippage at all is obtained. It may be said that the network polymer obtained from Resole is composed principally of Phenolic nuclei joined by Methylene groups.

From the intersection of Mc of both lines the mass of network strand me = Mc/2 is determined which is the most important figure for the structure rheological evaluation. The slope of the plot of LogMe vs LogC is one of the criteria that are required to determine the scaling exponent (X) which is a measure of the penetration hindrance. A scaling exponent of 0.23 is obtained which is below the value expected for a network with free penetration. Therefore partial penetration is expected.