AbstractMicroencapsulation of aqueous materials by the technique of organic phase separation using copoly(vinyl chloridevinyl alcoholvinyl acetate) (91:3:6 by weight) resulted in microcapusules which were isolable as a free‐flowing powder and were storable after drying. Using a dye marker in the core, the dried microcapsules were found to release the core contents through the spherical wall membrane in the presence of an exogenous aqueous medium. A technique was found for conveniently coating the dried microcapsules onto filter paper, and the partial constituents of an indicator system were encapsulated and coated onto filter paper pretreated with the complementary color‐forming constituents. The rate of color development in the wetted paper‐microcapsule system was used to assess the relative rate of release of the microcapsule core contents. Crosslinking of the poly(vinyl chloride) copolymer prior to encapsulation resulted in an attenuation of release of the microcapsule core con
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