Curing starch based adhesives: microwave or conventional

The field of microwave material processing is inherently multidisciplinary linking electromagnetism and material science. There are a variety of manufacturing industries utilising microwave power as heating drying source, several cases incorporating hybrid-heating technologies in processes such as paper, rubber, polymers, foodstuff and brick. In reference to starch based adhesive bonding, microwave processing produced improved adhesive joint properties due to the incorporations of dielectric heating methodologies. Relative to the ageing steam heated hot plate, which has been plagued with inconstancies such as; operational efficiency, economics of scale, factory floor requirements and throughput, the science of microwave curing of wheat base starch adhesive is based on the relationship between the interaction of electromagnetic energy and the dielectric properties of the materials. Microwave heating possesses some unique characteristics, which are not found in other types of heating. In volumetric heating, heat is generated principally in the product and not on the kiln walls or atmosphere. Hence the heat losses from the oven walls to the surroundings are much lower and results in reduced running costs. The objective of this article is to establish a comparative material characterisation between microwave and conventionally cured wheat base starch adhesives, also to provide a bonding strength analysis. All references made to microwave heating also apply to microwave curing.