Enhanced Two-Step Microencapsulation Using Melamine-Formaldehyde Resin.

Alič, Branko; Šebenik, Urška; Krajnc, Matjaž

A novel microencapsulation process using melamine-formaldehyde (MF) resin as the shell material has been developed, involving two distinct steps. In the first step, a gradual increase in pH facilitated the deposition of MF resin with a low degree of polymerization onto the microcapsule surface. This adjustment slowed the polymerization rate, promoting the formation of smooth and homogeneous MF shells. Throughout this step, the pH value was rosen multiple times to achieve thicker shells. In the second step, a rapid and continuous lowering of the pH value furthered MF polycondensation, enhancing the polymerization degree and crosslinking density of the MF shells. This step aimed to increase the thermal stability of the shells. The shell thicknes and morphology were examined by SEM microscopy. Thermogravimetric results demonstrated that the produced microcapsules exhibited exceptional thermal stability. Significant weight loss was observed only above 350 °C, corresponding to the thermal degradation of the methylene bridges in the MF shell.

MICROENCAPSULATION; MELAMINE-formaldehyde resins; POLYCONDENSATION; THERMOGRAVIMETRY; SCANNING electron microscopy

Materials & Technologies / Materiali in Tehnologije, 2024, Vol 58, Issue 4, p18

1580-2949

Academic Journal

10.17222/mit.2024.1316