Effect Of Grease On Candle Performance

Vegetable oil is drawing attention as a renewable alternative to paraffin wax for use incandles. However vegetable oil candles suffer from several problems, especially greasy,cracking and blooming. This project is to study the effect of lipid physicochemical propertieson the functionalities of candle. It consists of three parts,(1) the functionalities oftriglyceride-based candles;(2) the influence of emulsifier and stearic acid for candles;(3) theeffect of triglyceride, emulsifier and stearic acid on candles.Triglyceride-based candle was prepared by hydrogenation, fractionation and oil blending.The crystallization behavior and functionalities of candle were investigated. The conclusionsincluded:(1) Hydrogenated palm stearins (ST) were carried out at different degrees. Theresults showed that at the initial stage of hydrogenation, the slip melting point was reducedbecause the formation of elaidic acid inhibited the transformation to the β form. Withincreasing the hydrogenation degree, the conversion of oleic acid and elaidic acid to saturatedfatty acids increased, and led to the slip melting point increased. Crystallization peak becamesharper and crystal size became bigger. At the same time, grease disappeared but crackingappeared. Therefore, products hydrogenated within15~20min were considered suitable forthe candle production.(2) Hard ST, as a fractionation product of palm stearin, contained mostof saturated triglycerides. It has higher melting point and SFC than palm stearin and largercrystal size. However, the candle made from hard ST was cracked, bloomed and appeareduneven surface.(3) Binary mixtures of palm stearin and fully hydrogenated palm stearin(FHST) were studied. It was found with the addition of fully hydrogenated palm stearin, slipmelting point decreased at the initial stage as a result of eutectic. After that, slip melting pointincreased, crystal size became bigger, and grease disappeared but cracking appeared. The bestbasic formula was ST/FHST7/3.The influence of emulsifier:(1) Investigated influence of monoglyceride(MAG)concentration on crystallization behavior and functionalities of binary mixture of ST/FHST7/3. It found that when the adding concentration was above7%, SFC developed, rod-like crystal appeared, and crystallization range became wider. As a result, adding7%MAGsample had no greasy appearance, but cracked annularly. Adding more than20%MAG hadno crack. Taking the cost into account, adding7%MAG was the best choice.(2) ChoosingMAG, MAG-DAG, Q-1810S, Q-185S, PGMS90, and CRYSTALLIZER400, investigated theinfluence of different emulsifiers. It found that PGMS90reduced SFC greatly at eachtemperature while others did not. CRYSTALLIZER400, Q-1810S, Q-185S and MAG formeddensely packed crystal network, while PGMS90and MAG-DAG formed separated largecrystal particles, and showed grease. Large bloomed crystal particles were found inside thecandles with Q-1810S and PGMS90, which cracked seriously. Overall, Q-185S,CRYSTALLIZER400and MAG were more suitable as crystal modifier.The influence of stearic acid (SA) on binary mixture of ST/FHST7/3was studied. Itfound that crystallization range became wider after adding stearic acid. Candles with stearicacid had no crack but heavily bloomed. Candle with20%SA had no smooth appearance.10%SA was the suitable concentration.Ternary mixtures of triglycerides (ST/FHST7/3), emulsifiers (Q-185S,CRYSTALLIZER400, MAG) and stearic acid was chosen as candle material in a ratio of83:7:10. Their characteristics were investigated as candle material. It was found the crystalmorphology of ternary mixture was similar. Small densely packed crystals were formed. Forthe emulsifier, samples with CRYSTALLIZER400and Q-185S had sharper crystal peak.Their hardness was significantly higher than sample with MAG. Three candles all had goodappearance, but the former two cracked when drilled hole to put candlewick. TAG-MAG-SAis the better formula.Correlation between candle appearance and crystalline characters were concluded:(1) Greasy was related to both SFC and crystal morphology. Candle had no grease tendencywhen SFC was high or small densely packed crystal formed.(2) Cracking was based on crystallization characteristic (DSC measurement) and influencedby internal character. If crystallization peak was sharp, large non-uniform crystal particlesformed inside candle. It was easy to crack. (3) β form crystal was more easier to lead bloom, but XRD detection not always had goodcorrelation with bloom as observed with naked eyes.