| Carbon membrane supporter (CMS) is prepared from phenol-formaldehyde resin(PFR) cured by hexamethylenetetramine (HMTA). Different conditions, includingHMTA content, particle size of curable PFR, residence time, heating rate, and protectivegas flow rate, are tested to study their effects on pore size distribution and mean poreradius of CMS. The microstructures CMS of are observed by Scanning electronmicroscopy (SEM). The variable regularity during the formation of CMS, including themechanisms for curing thermoplastic PFR and carbonizing PFR tube, are studied bythermo gravimetric analysis (TGA), gas chromatography (GC), Fourier transforminfrared spectroscopy (FT-IR) and ultimate analysis.The main results are summarized as follows:a) Pore size distribution of CMS is dependent on HMTA content, which determines the extent of thermoplastic PFR curing.b) Particle size of curable PFR has an effect on pore size distribution of CMS. The smaller of the curable PFR particle size, the smaller the mean radius of CMS is.c) Pore size distribution of CMS is observed to have a strong dependence on carbonization residence time and heating rate, whereas shows a little dependence on protective gas flow rate. l-2h of carbonization residence time and l-3癈/min heating rate are suitable conditions for getting a good CMS.d) According to the results of TGA and FTIR, the pyrolysis of HMTA occurs from 150 to 210 . Curing of thermoplastic PFR and HMTA begins from 25 and almost completes at 150癈. The HMTA is decomposed to NH3 and CH2O, and then CH2O reacts with active point on thermoplastic PFR.e) The pores of CMS are mainly formed from 250 to 650 . During carbonization, when 250-370 , besides pyrolysis of methyl cellulose, PFR begins pyrolysing; when370-800 , the pyrolysis of PFR is quickened. At the same time, gases including H2, CH CO, CO2 and C2 are released from PFR tube, which then turns to be porous CMS with rich carbon. Methylcellulose makes pores for CMS partially while felting PFR. |
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