PhD student University of Alberta Edmonton, Alberta, Canada
Adsorbents with high surface area, thermal stability and microwave absorption ability are highly desired for cyclic adsorption and microwave regeneration processes. However, most polymeric adsorbents are transparent to microwaves. Herein, porous hypercrosslinked polymers of HCP-BCMB (4, 4´-bis ((chloromethyl)-1, 1´ -biphenyl- benzyl chloride)) with different carbon black (CB) contents were synthesized via the Friedel-Crafts reaction. CB was selected as the filler due to its low cost and high dielectric loss and was embedded inside the polymer structure during polymerization. Thermo-gravimetric analysis, dielectric property measurement, Bruner–Emmett-Teller (BET) analysis and gravimetric sorption analysis were used to characterize the thermal stability, microwave absorption ability, specific surface area, and adsorption performance of composites, respectively. CB-containing composites showed enhanced thermal stability at high temperature and a large increase (up to 2100%) in the dielectric loss factor. When the CB is dispersed well, the large surface area of the CB aggregates acts as the electrode surfaces of numerous tiny capacitors. This network of CB aggregates within the polymer matrix creates a large dielectric constant and loss factor. As a result, microwave heating rates increased by 18 times compared to polymer without CB. BET surface area analysis demonstrated that CB presence in the polymer structure decreases the surface area and total pore volume by 10 and 6 %, respectively at the highest CB load. Besides, toluene adsorption isotherms showed less than 5 % drop in adsorption capacity with increase in the CB content. This work indicates that CB fillers can effectively enhance microwave absorption properties of polymeric adsorbents without sacrificing their adsorption ability and thermal stability.
