Robust thermally insulating carbon-gehlenite composite foams from newspaper waste and sucrose by filter-pressing

Carbon Foams by Solid State Foaming of Short Vermicelli Bonded by Phenol-Formaldehyde for Thermal Insulation and Electromagnetic Interference Shielding

“…The EMI shields work by a combination of reflection and absorption mechanisms. − EMI shielding materials in the porous form are preferred over their dense counterparts as the pores improve the impedance matching leading to the easy penetration of EM waves into the material and enhances the EM absorption due to the availability of more surface. The waves that penetrate the shielding material undergo multiple internal reflections within the pores leading to enhanced absorption. ,, Recently, carbon-based foams are attracting renewed interest as EMI shields over their metallic counterparts because they are lightweight, noncorroding, inexpensive, and easy to fabricate. A typical graph showing the shielding effectiveness as a function of the frequency of a carbon foam produced from vermicelli and a 90 vol % PF solution measured in the X band region of microwave spectra is shown in Figure a.…”

“…The waves that penetrate the shielding material undergo multiple internal reflections within the pores leading to enhanced absorption. 20,21,58 Recently, carbon-based foams are attracting renewed interest as EMI shields over their metallic counterparts because they are lightweight, noncorroding, inexpensive, the effect of porosity, pore size, and pore interconnectivity on EMI shielding effectiveness using a series of reticulated and cellular vitreous carbon foams. 16,59 They observed decreases in the contribution of reflection with an increase in porosity due to the enhancement of impedance matching.…”

“…Carbon foam monoliths are also reported from biomasses such as cotton, paper waste, sawdust, and rice husk by employing a filter-pressing method. 20,21 Solid-state foaming is a relatively new method for the preparation of microcellular polymer foams. 22−25 Unlike the conventional foaming of molten polymers or polymer resins, in solid state foaming, the polymer remains in the solid form throughout the foaming process.…”

“…In most cases, foaming requires a surfactant and blowing agent, which are harmful to the environment. Carbon foam monoliths are also reported from biomasses such as cotton, paper waste, sawdust, and rice husk by employing a filter-pressing method. , …”