Chemical Modification of Partially Hydrogenated Vegetable Oil to Improve its Functional Properties for Candles

Abstract

Partially hydrogenated vegetable oil (PHVO) has recently been used to make vegetable oil-based candles. However, its use is limited primarily to container candles because of its inherent physical properties, such as brittleness when a hard material is produced, and greasiness when it is soft by low degree of hydrogenation. Such material lacks the most desired cohesiveness and elasticity compared to the commercial petroleum paraffin and beeswax. To improve the cohesiveness and thermal properties of PHVO, epoxidation, ring-opening reaction, and esterification were conducted to introduce new functional groups into the fatty acyl chain of PHVO. These newly synthesized derivatives or waxes were also mixed with the fully hydrogenated soybean oil (FHSO) or PHVO base materials. Hardness and cohesiveness of the new waxes and the mixtures were measured with a texture analyzer. Their thermal properties were analyzed with a differential scanning calorimetry (DSC). It was found that the introduction of hydroxyl (OH) group significantly improved the cohesiveness of PHVO. The melting range of PHVO also increased after the reactions. However, the hardness of the new wax was lower than those of commercial paraffin wax or beeswax. For wax mixtures, the hardness of dihydroxy wax was significantly improved by the addition of FHSO, however, the cohesiveness was negatively affected by the amount of FHSO added. Both the melting and the crystallization ranges were widened by mixing the derivatives with the base materials.