Supplementary MaterialsAs something to your authors and readers, this journal provides supporting information supplied by the authors. whereas the mechanism of foaming was elucidated by a combination of thermal and rheological analyses. A preliminary screening of conditions was conducted to identify the parameters controlling this foaming process. A foam was produced in a controlled way with open and/or closed cells with cell diameters between 0.2 and 3.5?mm. Humins foams were characterized by Raman spectroscopy, FTIR, SEM, nitrogen adsorption, pycnometry, and mechanical tests. The results show that, based on humins, it is possible to obtain porous materials with controlled architectures and a range of parameters that can be tailored, depending on the foreseen applications. to double bonds (the less energetic stereoisomer). Observed changes in the region 850C760?cm?1 may correspond to ring rearrangements and hydroxyls loss owing to reactions of condensation through nucleophilic attack. Raman spectra of F300 and F900 foams are compared in Physique?8. The spectrum of F300 is usually typical of a carbonaceous material BAY 63-2521 cost in the carbonization regime (and not in BAY 63-2521 cost the graphitization regime), since it presents the basic G and D bands at 1360?cm?1 and 1590?cm?1, respectively, but with a wide contour and with G being a lot more intense than D.56 The D band (1360?cm?1) is well known in complex carbon\based materials and is associated with a breathing mode of A1g symmetry of the carbon rings. In highly disordered carbons, another broad band, less intense and centered around 1180?cm?1 overlaps the D band, as also seen here by a shoulder at about 1200?cm?1. This is characteristic of soot or coal chars,57, 58, 59 but the interpretation of this signal is still under investigation.60, 61 The G band (1590?cm?1), instead, corresponds to a Raman active vibrational 2E2g mode of graphite single crystals, and can be associated with the degree of metallicity of the structure. Open in a separate window Physique 8 Raman spectra of humins foams BAY 63-2521 cost F300 and F900. These two peaks were also detected for F900, with the D band slightly shifted to 1345?cm?1, which is perhaps due to the effect of the sp2/sp3 carbon peripheral polyenes. The Raman peak intensity height ratio and compressive stress of humins foams. thead valign=”top” th valign=”top” rowspan=”1″ colspan=”1″ Sample /th th valign=”top” rowspan=”1″ colspan=”1″ em E /em ?[MPa] /th th valign=”top” rowspan=”1″ colspan=”1″ em /em ?[MPa] /th /thead F1800.600.006F2500.520.011F90012.230.123 Open in a separate window Although these properties remain limited, humins foams might find applications where mechanical resistance is not critical, for instance, in most energy and environmental applications for which materials are used in the form of powders. Getting foams is indeed a very convenient preliminary step before the surface area and the narrow porosity can be developed further. Highly porous carbons derived from humins foams might be quite relevant as catalyst supports, adsorbents, or electrode materials. More demanding applications such as core materials for (thermal or acoustic) insulating panels would require some changes in the formulation and/or the thermal treatment, but are out the scope of the present paper. For instance, much tougher foams were already obtained by reinforcing them with natural fibers.48 Conclusions As byproducts from the industrial acid\catalyzed dehydration of sugars, humins proved to be excellent precursors for producing new rigid porous components. Their intrinsic personal\foaming and car\combination\linking capability above 180?C, without the pretreatment, was highlighted. The underpinning system of humins foaming was defined as a combined mix of phenomena: melting at 120?C, discharge of volatiles (mainly H2O, CH3OH, CO, and CO2) over 140?C, car\combination\linking over 170?C, and gelation in about 186?C. From this true point, bubbles had been stabilized in the thermoset humins\structured resin, resulting in the cellular framework of the ultimate material. Car\combination\linking can be done by the current presence of many reactive air moieties such as for example carbonyls and hydroxyls, which may be involved with aldol condensation, along with reactions of rearrangements and furan condensation. Certainly, FTIR demonstrated that \OH groupings had been steadily dropped when raising the foams planning temperatures, whereas CO groups were more and more involved in the conjugated systems. New peaks appeared with temperature, associated with furanic rearrangement and aromatization. Humins foams could be obtained with high control of morphology and cell sizes by adjusting the parameters used during their preparation process. Foams prepared at low temperatures Rabbit polyclonal to TNFRSF13B (between 180 and 250?C) were quite homogeneous in terms of size and shape of the cells, the latter being mainly closed. Foams prepared at higher temperatures (350C900?C) were gradually less homogeneous, with a more open porosity, until only a reticulated structure remained. Higher temperatures of treatment increased the surface area and produced a secondary porosity, and could be converted into true vitreous carbon foams at 900?C under inert atmosphere. In addition, pyrolysis considerably improved the mechanical properties of the materials, and opened the routes towards environmental and energy applications, such as catalyst supports, absorbents, or electrode materials. This will be the subject of forthcoming.