| 摘要 |
A cross-linked urea-formaldehyde polymer matrix is formed by catalyzing, using a buffered acid as the catalyst, an aqueous mixture of a urea-formaldehyde concentrate, urea-form-aldehyde resin, and powdered urea. The resulting thermoset polymer which possesses, in part, a cyclic structure, is of unusual hardness and has utility, with or without fillers, as a molding or casting material possessing controllable shrinkage characteristics because of uniform molecular structure and formula versatility. |
