Multi‐scale study of the structuration of candle blends with a high content of vegetable fats to replace paraffins: Effect of 12‐hydroxystearic acid content

Abstract

AbstractThe aim is to replace mineral waxes with vegetable fats as an organogel for candle manufacturing while keeping the same texture. The physico‐chemical characteristics of renewable vegetable raw materials differ from those of mineral waxes and consequently the structure of the blends in which they are used is modified. Their properties are measured at different scales using FT‐IR analysis, polarized light microscopy, calorimetry and rheology. The addition of 12‐hydroxystearic acid (12‐HSA) promotes the creation of hydrogen bonds within the rapeseed oil that makes possible its incorporation to form an organogel. The addition of 12‐HSA also results in a modification of the crystal microstructure of blends made of 90% vegetable raw materials. Hence, the crystal lattice is denser and the crystal size is reduced compared to blends including mineral waxes. At a macroscopic scale, the physical properties of blends with 12‐HSA are modified compared to the reference one, mainly made of mineral waxes. A modification of crystallization and melting temperatures as measured by differential scanning calorimetry as well as the rheological behavior and the hardness assessed by penetrometer are observed. This results in a higher stability against exudation for blends with a high content of 12‐HSA. Mineral waxes can thus be substituted in the formulation of candles by renewable materials for the use of organogel, via the incorporation of an organogelator, 12‐HSA.