TY - JOUR
T1 - Process variable optimization in the manufacture of resorcinol–formaldehyde gel materials
AU - Prostredný, Martin
AU - Abduljalil, Mohammed G. M.
AU - Mulheran, Paul A.
AU - Fletcher, Ashleigh J.
PY - 2018/4/17
Y1 - 2018/4/17
N2 - Influence of process parameters of resorcinol-formaldehyde xerogel manufacture on final gel structure was studied, including solids content, preparation/drying temperature, solvent exchange, and drying method. Xerogels produced using a range of solids content between 10 to 40w/v% shows improved textural character up to 30w/v% with a subsequent decrease. Preparation/drying temperature shows a minimal threshold temperature of 55 °C is required to obtain a viable gel structure, with minimal impact on gel properties for further thermal increase. Improving the solvent exchange method by splitting the same amount of acetone used in this phase over the period of solvent exchange, rather than in a single application, shows an increase in total pore volume and average pore diameter, suggesting less shrinkage occurring during drying when using the improved method. Finally, comparing samples dried under vacuum and at ambient pressure, there seems to be less shrinkage when using vacuum drying compared to ambient drying, but these changes are insubstantial. Therefore, of the process parameters investigated, improved solvent exchange seems the most significant, and it is recommended that, economically, gels are produced using a solids content of 20w/v% at a temperature in excess of 55 °C, with regular solvent replenishment in the exchange step followed by ambient drying.
AB - Influence of process parameters of resorcinol-formaldehyde xerogel manufacture on final gel structure was studied, including solids content, preparation/drying temperature, solvent exchange, and drying method. Xerogels produced using a range of solids content between 10 to 40w/v% shows improved textural character up to 30w/v% with a subsequent decrease. Preparation/drying temperature shows a minimal threshold temperature of 55 °C is required to obtain a viable gel structure, with minimal impact on gel properties for further thermal increase. Improving the solvent exchange method by splitting the same amount of acetone used in this phase over the period of solvent exchange, rather than in a single application, shows an increase in total pore volume and average pore diameter, suggesting less shrinkage occurring during drying when using the improved method. Finally, comparing samples dried under vacuum and at ambient pressure, there seems to be less shrinkage when using vacuum drying compared to ambient drying, but these changes are insubstantial. Therefore, of the process parameters investigated, improved solvent exchange seems the most significant, and it is recommended that, economically, gels are produced using a solids content of 20w/v% at a temperature in excess of 55 °C, with regular solvent replenishment in the exchange step followed by ambient drying.
KW - xerogel
KW - BET
KW - BJH
KW - temperature
KW - solids content
KW - drying
KW - solvent exchange
UR - http://www.mdpi.com/journal/gels
U2 - 10.3390/gels4020036
DO - 10.3390/gels4020036
M3 - Article
SN - 2310-2861
VL - 4
JO - Gels
JF - Gels
IS - 2
M1 - 36
ER -