A new approach to optimize compression of paraffin materials: influence of particles size and shape

The work described in this paper investigates the behaviour of paraffin material under pressure. Compressibility has been widely described in the literature but the behaviour of paraffin materials under compression is not well known. This study intends to highlight the influence of particle size and shape of paraffin material on their compressibility. This is of major interest for the candle industry. Indeed, one of the main forming processes is pressing of paraffin powder. For this purpose, particle size and shape were characterized according to a digital image analysis approach and compressibility was measured by compressing the paraffin into a mould using a texture analyser. Results show that compression at low pressure (0.2 MPa) is governed by the average circularity and mean diameter of the paraffin particles while compression at higher pressure seems to be governed by the uniformity of the dispersion of particle size. It helps the selection of the particle size and shape category to be used to promote candles formation and production. This study also provides a tool to assess plasticity of paraffin by using the mean yield pressure.