Thermal properties of polysaccharide aerogels

Polysaccharide aerogels are an advanced class of materials and recently the subject of much research. Most studies are based on their applications in the pharmaceutical field, yet some novel research proposes these materials as thermal insulators. In this study, polysaccharide aerogels (high-methoxyl pectin, low-methoxyl pectin, alginate, guar and xanthan) were prepared with alcohol-induced gelation and later supercritical drying, and nitrogen adsorption was used to determine their surface area and pore volume. Their thermal behaviour was analysed by DSC and TG, and their thermal conductivity was determined by DSC. Since polysaccharide aerogels produced by the alcohol gelation method consist entirely of pure polysaccharide, their thermal behaviour is very similar to that of pure polysaccharides. Aerogels are highly hygroscopic materials; thus, the initial dehydration step was present in all samples. The thermal conductivity measurements obtained varied between the different polysaccharides used for aerogel production. Low-methoxyl pectin provided the lowest thermal conductivity and guar the highest among our samples. The thermal conductivities were in the range of insulating materials, especially for low-methoxyl pectin aerogel, for which the conductivity was 21 mW m(-1) K-1. The optimization of process parameters was tested later on with alginate, and it was observed that methanol-induced gelation forms more porous structures with lower thermal conductivity than the other forms tested. The lowest conductivity measured for alginate aerogel was 42 mW m(-1) K-1.