| 摘要 |
<p>Polyurethane resins of higher than desired molecular weight with or without gel fractions which comprise insoluble material due to crosslinking or excessive degree of polymerization are treated in the solid state with a liquid or gaseous primary or secondary amina under thermal conditions which cause aminolysis of both linear linkages and crosslinkages. By this procedure, the average molecular weights of the products can be reduced to acceptable levels. Also, if the product contains gel fractions, these too can be reduced to negligible levels. The procedure is applicable to both polyether and polyester urethanes and is effective to provide improved polymer characteristics for thermoplastic processing and solution applications.</p> |
