Polymeric Shell with Low Permeability

摘要

A polymeric shell with low permeability was manufactured via a combined process including both an interfacial polymerization and an in-situ condensation. A polyisocyanate, tolylene diisocyanate (TDI) or 1,6-hexamethylenediisocyanate (HDI), was added in the core compositions as a reactive monomer for the formation of both polyurethane wall and polyurea wall. PPG-2,000, a polypropylene glycol, was employed as another reactive monomer to form the polyurethane wall. Melamine-formaldehyde precondensate was prepared and used as the raw material for the aminoplast wall formation. The polymeric shell thus consists of three walls, which includes a polyurethane inner wall, a polyurea middle wall and an aminoplast outer wall. The triple-walled shell has proven to possess low permeability and then wrap the paraffin compounds tightly.