Divann D. Robertson

Stellenbosch University | SUN · Department of Chemistry and Polymer Science

The mechanism of performance of hydrocarbon waxes used as external lubricants in typical PVC pipe formulations is not completely understood or defined. This study will benefit pipe manufacturers to tailor PVC processing conditions and wax addition levels to enhance the value of waxes with different molecular architectures in Sn-stabilized PVC formu...

In this study, three chemically similar but morphologically different high melting hydrocarbon waxes having similar DSC peak melting temperatures were analysed, and the influence of their molecular architectures on hot melt adhesive (HMA) performance, was evaluated. Selected waxes included each of the following types: Fischer Tropsch wax (FT), by-p...

Lubrication is one of the most important parameters in unplasticized polyvinyl chloride (uPVC) processing apart from the PVC resin and processing equipment. Lubricants are used in specific ratios to ensure effective fusion of PVC particles. The exact mechanism on how these lubricants interact is not yet fully understood. A widely accepted theory is...

A detailed study was conducted on seven different waxes used in hot melt adhesive formulations together with conventional resins and tackifiers, to characterize the waxes and investigate the effects of wax structure and morphology on the thermal behaviour and basic properties of the resultant hot melt adhesive formulations (HMAs). The waxes selecte...

Surfactin-loaded polyvinyl alcohol (PVA) nanofibers were spun using gravity electrospinning. Scanning electron microscopy (SEM) images showed that nanofibers spun with surfactin are free from bead formation and uniform in diameter. The average nanofiber diameters were decreased (273 ± 39 nm, 259 ± 39 nm and 217 ± 33 nm) with increasing levels of su...

Hyaluronic acid nanofibers (HA/PDLLA) were prepared by coating electrospun poly(D,L-lactide) (PDLLA) with different concentrations of HA. Highest concentration of HA deposited onto PDLLA nanofibers (17% per weight) were obtained by coating with 0.3% (w/v) HA. Coating with 0.5% (w/v) and 0.1% (w/v) HA yielded a deposit of 3.8% and 3% per weight, res...

For the first time, the solution crystallization and dissolution behaviour of polyolefins in a variety of solvents was investigated by using a recently developed crystallization based analysis technique - solution crystallization analysis by laser light scattering (SCALLS). SCALLS results provide clear evidence that crystallization and dissolution...