Session: 17-01: Poster Presentations

Paper Number: 169960

169960 - Non-Evaporative Drying Using Thermo-Responsive Polymers 

Abstract: 

The drying process is crucial in various industries, including food processing, paper manufacturing, and textiles. Traditional evaporative drying process relies on heating to remove the water by overcoming the enthalpy of vaporization, leading to high energy costs and increased carbon emissions. In contrast, non-evaporative drying technologies offer a more energy-efficient and sustainable alternative by removing water without phase change of water from liquid to vapor. Techniques such as mechanical dewatering, superabsorbent materials, and solvent-assisted drying can significantly reduce energy consumption by bypassing the latent heat requirement. As such, non-evaporative drying minimizes thermal damage to materials, accelerates processing times, and reduces the carbon footprint of industrial drying operations.

In this work, we developed a non-evaporative drying method using thermo-responsive polymers and demonstrated its feasibility for drying paper products. We synthesized a thermo-responsive copolymer, P(NIPAM-g-PEGMA), by graft-copolymerizing hydrophilic macromonomer poly(ethylene glycol) methyl ether methacrylate (PEGMA) with N-isopropylacrylamide (NIPAM). Below its lower critical solution temperature (LCST) of 37 °C, the polymer remains hydrophilic, absorbing water from paper. Above the LCST, it becomes hydrophobic, releasing the absorbed water in liquid form. We optimized the polymer composition by varying the monomer ratio, water content, and crosslinker (N,N'-Methylenebisacrylamide, MBAA) concentration to enhance its thermochemical and mechanical properties. The optimized polymer, composed of 12 wt.% PEGMA, 0.25 wt.% MBAA, and 50 wt.% water, exhibited a high water absorption capacity of 8 g water/g polymer below the LCST. Above the LCST, it retained only 0.3 g/g of water. In addition, it demonstrated a fracture tensile strength of 230 kPa and an elastic modulus of 80 kPa, providing sufficient mechanical stability.

In paper drying tests, each square meter of the optimized polymer demonstrated the ability to absorb 30 grams of water from the wet paper web within 5 minutes when operating below its LCST. Upon heating to ~50 °C, the polymer released one-third of the absorbed water in liquid form within 5 minutes, effectively regenerating itself for subsequent reuse. In contrast to thermal evaporative drying (>100 °C), our developed thermo-responsive polymer has the potential to reduce thermal energy consumption by 40% and CO₂ emissions by 35%, providing a promising solution for industries seeking to enhance efficiency and sustainability in drying processes.

Presenting Author: Leshi Feng University of Texas at Dallas

Presenting Author Biography: Leshi Feng is a PhD student in Mechanical Engineering at the University of Texas at Dallas. Her research focuses on the development and application of thermo-responsive polymers, with a particular emphasis on non-evaporative drying methods.