Study by thermal analysis of composites prepared from silica gel, furfuryl alcohol and acetaldehyde

Composites from furfuryl alcohol, acetaldehyde and silica gel were prepared with trifluoracetic acid as a catalyst. The composites were studied by TGA and DSC. The TGA results showed three main losses of weight, the first of which was ascribed to water. The percentage of polymer in the composites reached a limit value, independently of the ratio of furfuryl alcohol/acetaldehyde used. The layer of polymer that covers the silica was not completely cross-linked. The composites contain soluble oligomers with (M) over bar (n) < 580 g mol(-1), that could be extracted with THF. The soluble fraction of composites prepared from mixtures of furfurylic alcohol and acetaldehyde decreased as the proportion of the acetaldehyde increased. The DSC of the samples indicated a T-g between -8 and -15degreesC that disappeared after an extraction with THF. The DSC of the oligomers removed showed a possible T-g at 13degreesC and an exothermic peak between 70 and 170degreesC which corresponded to an enthalpy of 326.1 J g(-1). (C) 2003 Society of Chemical Industry.