The Linear Growth Rates of Pentaerythritol Crystals


The linear growth rates of the (101) faces of single crystals of Pentaerythritol (Pe) in aqueous solutions have been measured as a function of temperature (10-50°C), and concentration difference (0.25 x 10° acs 2.60 x 10-2 KgPe/Kg Solution) under stagnant conditions in a batch cell. The effect on growth rate of the two main by-product impurities of Pe manufacture, di-Pe and a Formal, and several other impurities has been determined over a range of working conditions. It was found that the growth rate of the pure material varied with time and also from crystal to crystal. Due to the purification method used in preparing the solutions an impurity (X) was removed which resulted in these growth rates being at least two orders of magnitude greater than those previously reported. The pure material growth rate was kinetically controlled having a parabolic law over most of the range of conditions studied with an activation energy of 8.47 Kcal/mol. The effect of di-Pe was generally that it caused a slight reduction in the growth rate except at certain critical concentrations where the effect was an increase by up to a factor of two. The effect of the Formal was that it drastically reduced the crystal growth rate virtually to zero, when in concentrations greater than the order of 0.001 mass fraction. Of the other added impurities, only Formaldehyde, Sodium hydroxide, and 1,1,1,trimethylolethane had significant effects in reducing the growth rate. In the absence of (X) and Formal, Pe crystals were found to exhibit (110) and (001) faces in addition to the usually reported (101) faces. The phenomenon of secondary nucleation appears to be related to the magnitude of the crystal growth rate under the conditions investigated. It appears that (X) may be 1,1,1,trimethylolethane or similar compound.

Divisions: College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
Additional Information: Copyright © Rehmatullah, 1973. S. Rehmatullah asserts their moral right to be identified as the author of this thesis. This copy of the thesis has been supplied on condition that anyone who consults it is understood to recognise that its copyright rests with its author and that no quotation from the thesis and no information derived from it may be published without appropriate permission or acknowledgement. If you have discovered material in Aston Publications Explorer which is unlawful e.g. breaches copyright, (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please read our Takedown Policy and contact the service immediately.
Institution: Aston University
Uncontrolled Keywords: linear growth rates,pentaerythritol crystals
Last Modified: 08 Dec 2023 08:03
Date Deposited: 21 Nov 2010 10:14
Completed Date: 1973
Authors: Rehmatullah, Sikandar

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