Templated Synthesis Of Phenol-formaldehyde Resin Based Carbon Foams And Their Applications

Carbon foams are lightweight materials with high mechanical strength, low thermalexpansion coefficient, adjustable thermal conductivity and large external surface area withopen cell structure, which make them suitable materials for energy absorption, catalystsupports, electrode materials and filters etc. In this thesis, carbon foams named CF-1, CF-3,CF-4, CF-5, have been reported using polyurethane foam (PU) as templates and resin-1,resin-2as well as resin-L as the carbon precursors. In addition, CF-2has been synthesizedusing PU foam pretreatment by NaOH as templates. The applications of the carbon foamsused as optically transparent electrode materials and adsorbent have been investigated. Themain results are summarized as follows:1. CF-1has been obtained using resin-1as carbon sources and its structures have beencompared before and after modification of polyurethane foam. The results show that the foamtemplates with high open cell can be obtained after60min pretreatment by50oC10wt%NaOH,which lead to the formation of CF-2with the pore size distribution centered at540μm.2. CF-3has been improved synthesized using polyurethane foam as templates andphenol-formaldehyde resin as carbon sources by impregnation, solidification andcarbonization process. During this process, alkali solution is used as both the catalyst of resinand the open-cell agent of the polyurethane foam, which saves the pretreatment of thetemplate by alkali. The obtained carbon foams have the pore size distribution centered at400~600μm, which is used to measure the electrochemistry behaviors. The results show thatthe carbon foam electrode displays obvious oxidation and deoxidization peaks whenimpregnated into the iron-phenanthroline complex solution, and the absorbance valuedecreases with the increase of the potential at the wavelengths of510nm.3. CF-5has been synthesized used lignin partially substituted the phenol component ofthe phenol-formaldehyde resins as carbon sources, and the obtained carbon foams have beenused in the oil/water separation. The replacement of25%phenol with crude lignin leads to theformation of resin-L in an alkaline medium. The resultant carbon foams exhibit openmacropores with the size about400~600μm and their bulk density can be tailored in the rangeof20.6~29.4mg cm-3. The carbon foam can efficiently separate oil from water, demonstrating high absorption capacities of12to41times its own weight for a wide range of oils/organicsolvents.