Investigation of the functionality of white soft paraffin with regards to ointments

• Main Author: Bentley, Phillip John
• Other Authors: Murray, Brent S. ; Kapur, Nikil
• Published: University of Leeds 2017
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.733575

Within the pharmaceutical industry, paraffin products are used as functional ingredients to produce ointment products, suitable for consumer end use. Paraffin wax is a complex material, itself describes an entire group of alkanes ranging from C10 to C60. It was the aim of this project to characterise the paraffin constituent components (oils and waxes) and their combinations (creating white soft paraffin (WSP)). Using a wide range of instrumental characterisation such as cone penetration, viscosity, oscillation rheology and cross polar optical microscopy; thermal characterisation: differential scanning calorimetry: and chemical characterisation: solubility parameters and Raman spectroscopy, the functionality of WSP products will be examined. Finally using WSP blends and constituent components, long term stability was tested as well as overload process testing on model WSP blends. Waxes with high congeal points were found to have greater penetration forces and viscosities (MWM = 281.62 N, MWH = 273.67 N), model WSP blends containing different wax materials showed similar penetration values corresponding to wax forces (WSP9, a combination of PWH and MWH = 29.92 N). Similarities in waxes and WSP blends seen in penetration and rheology are not seen in DSC thermographs, loss of energy from wax components within the WSP blends were evident (PWL; 295.08 mJ + MWM; 134.58 mJ ≠ WSP5; 23.42 mJ). The progression of solubility parameters saw that there were similarities in expected WSP blends and correlation between wax components, indicating that miscibility has a role to play in WSP production. Processing testing and microscopic analysis showed that long term storage crystals decrease in size affecting the packing density, reducing penetration forces and G’ stiffness in samples, ultimately indicating the need for greater wax ratio mixes to be developed for consumer end use suitability.