Polyurea

(or polycarbamide), a linear polymer that contains carbamide groups, —HN—CO—NH—, in the main chain of the macromolecule.

Polyureas are produced by the reaction of diamines with compounds of various classes (for example, diisocyanates, phosgene, and urea and its derivatives). An industrial method has been developed for the production of polyureas of the general formula [—(CH₂)₉NHCONH—]_n from urea and 1,9-diamino nonane.

Polyureas are crystalline white substances with molecular weight 7,000–90,000, density 1.03–1.25 g/cm³ at 20°C, and melting point 245 °C. They are soluble in cresol, formic and sulfuric acids, dimethylformamide, and methylpyrrolidone and are characterized by high resistance to water (water absorption in 24 hr, 0.05–1.70 percent). Polyureas are similar to other polyamides in their strength and other mechanical properties (tensile strength, 66 meganewtons per sq m, or 660 kilograms-force per sq cm).

Polyureas are used to form fibers (produced in Japan under the trade name Urilon), which are used in the production of fishing nets and knitwear. They are also suitable for the production of tubes, rods, films, and lacquers.