Resin characterization

Abstract

Currently, thermosetting adhesives are characterized by physical andchemical features such as viscosity, solids content, pH, and molecular distribution, and their reaction in simple gel tests. Synthesis of a new resin for a particular application is usually accompanied by a series of empirical laboratory and plant trials. The purpose of the research outlined in this paper was to develop techniques that could be used to characterize thermosetting resins by their time-dependent reaction to the environmental conditions--temperature and moisture--that influence both cure and bonding. Resin-impregnated glass cloth samples were exposed to controlled temperatures and humidities for increasing periods. Development of mechanical stiffness in the resin was monitored using a dynamic mechanical analyzer. Chemical advancement was determined using a differential scanning calorimeter. Chemicalmechanical relations expressed as percentage of cure were useful in comparing the reactivity of different resins. Lap-shear tests of flake pairs bonded under the same conditions used to determine resin cure will provide data on the rate of strength development. By recovering and testing resin cure and flake- bonding specimens from hot-pressed boards, the selective response under controlled conditions can be compared with that under actual operating conditions. Changes in molecular descriptions of newly synthesized resins, obtained using nuclear magnetic resonance and infrared analysis, can then be used to predict the performance of the resins in specific applications.

Citation

Geimer, Robert L.; Follensbee, Robert A.; Christiansen, Alfred W.; Koutsky, James A.; Myers, George E. 1990. Resin characterization. Proceedings of the 24th WSU International particleboard/composite materials symposium; 1990 April 3-5; Pullman, WA. Pullman, WA: Washington State University; 1990: Pages 65-83.