Melamine as a wall material and 37% formaldehyde as a
crosslinking agent were purchased from Junsei Chemicals (Japan).
Thyme oil as a core material was obtained from French Korean
Aromatics (Korea). SLS and T80 as emulsifiers were purchased
from Junsei Chemicals (Japan). P127 as a emulsifier and poly(vinyl
alcohol) (PVA) as a protective colloid were purchased from Sigma-
Aldrich Co (Korea). All reagents used in this work were of chemical
grade.