Effects of core material, operating temperature and time on microencapsulation by in situ polymerization method

Microencapsulation of glass beads was carried out by the in situ polymerization method. Glass beads were chosen as the core material because their size distribution was narrow and their surface was easily changed to be hydrophobic. Melamine and formaldehyde were used as membrane materials of the capsule. The respective effects of amount and size of core material, hydrophobic core surface, addition time of core material, reaction temperature, and time of encapsulation process on microcapsules were investigated systematically. The membrane thickness of microcapsules decreased with larger amounts and larger diameters of core material, while a smoother membrane was obtained with a hydrophobic surface of the core material. It became clear that the membrane growth of capsules was almost finished within 15 min after the addition of initiator; however, it did not progress up to 10 min after the initiator addition at low temperature.