Assessing Effect of the Migration of A Paraffin Wax on the Surface Free Energy of Natural Rubber

Abstract

Abstract The effect of the migration of paraffin wax on the surface free energy of natural rubber (NR) was investigated. The rubber was mixed with the wax and then stored at ambient temperature for up to 168 hrs before its surface free energy was measured using contact angle measurement. Static secondary ion mass spectrometry was also used to provide a chemical fingerprint of the rubber surfaces. The surface free energy decreased as a function of storage time because of the migration of the wax to the rubber surface. The highest rate of reduction was recorded up to 3 hrs and thereafter, the surface free energy decreased at a much slower rate, reaching a plateau after 48 hrs in storage. In total, the surface free energy reduced by approximately 46% as a result of the migration of the wax to the rubber surface. The reduction in surface free energy could adversely affect ability of the rubber to stick to itself and to other dissimilar elastomers.