In-situ Dielectrometry Monitoring Of Adhesives Cure Behavior During Wood-based Panel Hot-pressing Process

The cure behavior of thermoset adhesives affects directly the glue bond strength during wood-based panel hot-pressing. The large-scale manufacturing enterprise can not be quick response to market changes as the higher cost for product transformation and the longer time for hot-pressing process certification are mainly due to the traditional research approach for thermoset adhesives curing. The in-situ monitoring of adhesive cure behavior during wood-based panel hot-pressing is a suitable microdielectrometry analytical method for real time monitoring the adhesives cure behavior under real-world scenarios.A prototype apparatus for in-situ microdielectrometry monitoring of adhesive cure behavior during wood-based panel hot-pressing and a number of heat resistant and high conductivity interdigital fringing electrical field sensors are developed initially in China by importing and assimilating the technical solutions be of Professor Wang Siqun and Dr. Sernek. The monitoring apparatus eliminates the stray capacities with three terminal measuring approaches. It generates the excitation signal and measures the adhesives dielectric properties in fringing electrical field by domestic Tonghui TH2826digital bridge LCR meter. It measures the temperature of mats and adhesives with thermometer. The self-developed monitoring software shows visually the changes of dielectric losses and temperature for adhesives curing during the wood-based panel hot-pressing process after integrating the data-out of LCR meter and thermometer.The monitoring experiment for plywood hot-pressing with imported sensor demonstrated the effectiveness of the self-developed monitoring apparatus. The self-developed sensor and apparatus are as well as imported in terms of technical performance has been confirmed by the contrast experiments for measuring the dielectric properties of distilled water with analysis level with sensor and monitoring the plywood hot-pressing process.The monitoring experiment for wood-based panel hot-pressing process demonstrated that the best monitoring results are at10kHz excitation frequency with the self-developed apparatus and the thickness of the veneers is minimal impact on monitoring results and the monitoring system can effectively monitor the cure behavior of PF and UF resin during hot-pressing and the monitoring method is also effective for MDF.There had been demonstration and extension activities for in-situ monitoring technology of adhesive cure behavior during wood-based panel hot-pressing over the study period, including two universities and a large-scale enterprise. The effect of the activities is good and they all have expressed the desire for further cooperation. It shows that the technology has good application prospects.