Influence of Modification Chain Extender on Synthesizing Polyurea

In this paper, the modification amine chain extenders were prepared for prolonging gel time of spray polyurea elastomer. A new chain estender called diacetyl hexamethyene-diamine can be got as a white acicular crystal by synthesizing hexamethylene-diamine under having acetic acid and phosphoric. Its characterizations and structure were confirmed by kjeldahl nitrogen and infrared spectra and ~1H-NMR. Polyureas are synthesized using 4,4’-diphenyl diisocyanate and amine terminated poly (oxypropylene) with the new chain extender. The effects of chain extenders on characteristics of polyureas were studied. The gel time is greatly changed from 11s to 52s when diacetyl hexamethylene-diamine is used as chain extender instead of hexamethylene-diamine, and the tensile strength is also greatly increased.