The evaluation and selection of core materials for microencapsulation: A case study with fragrances

Abstract This work focuses on the universal applicability of microencapsulation on core materials. From this point, nine different fragrance oils were selected as core materials, and the corresponding melamine resin shell microcapsules were prepared by a uniform process. According to characterization results, the microencapsulation shows good universality for most core materials, but their encapsulation efficiency ( E %, 17.28%‐88.26%), particle size distribution ( D 50 , 9.65‐33.82 μm) and optical micro‐morphology are significantly different. By analysing the influence of the interfacial tension ( F ), relative dielectric constant ( ε ), viscosity ( τ ), density ( ρ ) and refractive index ( n ) of the core materials on encapsulation, it was found that the F determines whether the core material is suitable, and f ≥ 1 is the basic condition for the core material to have the value of microencapsulation. Besides, the ε and n both can be used as auxiliary criteria, τ and ρ also influence the microencapsulation process. Based on these data, a “Dimensionless encapsulation number” was tentatively established, and the mathematical relation between it and corresponding E % was constructed, which could be applied as a semi‐empirical formula in practical work.