Prediction of Non-Isothermal Polymer Penetration into Porous Layers

Understanding the dynamic fluid flow in a porous mediaconsideringtemperature changes is of general interest over a wide range of applicationssuch as flow in porous catalytic reactors, flow in packed distillationcolumns, and hot melt adhesive flow into paper and wood. The penetrationof a hot melt adhesive into a paper substrate is important to quantifyto optimize adhesion and improve quality control. There has been noattempt in the literature to quantify adhesive penetration and topropose a model of the process that links process and material parameters.A model, based on Darcy's law, is developed that accounts fortemperature differences between the adhesive and the paper, the adhesiveand paper properties, and the time and pressure of compression. Anenergy balance is used to estimate the temperature and viscosity ofthe adhesive in the pore space. The model also accounts for differentlayers of pore space and for the limited supply of adhesive. Experimentswere conducted to quantify penetration depth and final bond strengthof a hot melt adhesive that is pressed into well-characterized paperboardand coated paperboard under different conditions of temperature andpressure. The model agreed within 20% of experimental results fordifferent papers, press pressures, and paper temperatures. The permeabilityof the coating layer was found to be a key parameter in controllingthe penetration degree. For uncoated samples, the paper temperaturewas a key parameter that influenced penetration depth.