This valuable book is devoted to problems of the synthesis, vulcanization, modification, and study of structure and properties of highly filled sealants based on polysulfide oligomers (PSO). The book summarizes information concerning chemistry, synthesis technology, structure, and properties of liquid thiokols and thiokol-containing polyesters. It also presents a literary survey on chemism and mechanisms for liquid thiokols vulcanization involving oxidants or through polyaddition. The book describes formulation principles of sealants, their properties, and application areas.