Preparation and characterization of melamine-urea-formaldehyde microcapsules containing linseed oil using polyvinylpyrrolidone as emulsifier

Microcapsules containing linseed oil with melamine-urea-formaldehyde (MUF) shell was fabricated by in-situ polymerization of a n oil-in-water emulsion using polyvinylpyrrolidone as a stabilizer for the dispersion properties. The effects of agitation rate, molecular weight of PVP and its concentration on microencapsulation process were investigated using SEM and optical microscopes. Chemical structure and thermal stability of microcapsules were studied using Fourier transform infrared (FTIR), d ifferential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). By increasing the molecular weight of PVP and concentration, the microencapsulation yield and surface morphology were improved with an increase in stirring rate, surface morphology improved and the average particle sizes decreased. The prepared microcapsules provide better thermal stability than urea-formaldehyde microcapsules containing linseed oil. Mean diameter of prepared microcapsules ranged from 34 µm to 346 µm in various synthesis parameters with high linseed oil load up to 90.3%.