DYNAMIC-MECHANICAL PROPERTIES OF THERMOSETTING RESIN ADHESIVES .2. UREA RESIN

The mechanical curing process of urea formaldehyde (UF) resin treated under several conditions was studied using dynamic mechanical analysis (DMA). The following results were obtained: (1) the curing process of liquid UF resin with catalyst proceeds through a two-stage curing pro cess with increasing oven temperature. However, the curing process of UF resin was greatly affected by the presence or absence of water and a catalyst. (2) The cured states of preheated resins by hot-platen hea ting and steam-injection heating were observed. In addition, a mechani cal curing index was calculated to reveal the mechanical curing behavi ors under each heating condition. It has become apparent that the curi ng of UF resin proceeds with increasing heating time under hot-platen heating. However, it was found that UF resin immediately cured to some degree, and then dilution and/or decomposition took place under steam -injection heating.