Effect of PVA-Boric Acid Strengthening Agents on the Properties of Foam-formed Sheets

Foam forming technology is a sheet or mold forming process that uses liquid foam instead of water, allowing for high consistency forming, improved dewatering, enhanced formation, and the production of low density materials.However, foam-formed sheet generally has lower strength compared to water-based sheet.Therefore, to increase the applicability of foam forming technology, methods to improve sheet strength need to be developed.In this study, the effects of the chemical addition sequence of SDS, PVA, and crosslinkers, as well as the PVA-to-crosslinker ratio and the amount of PVA or PVA-boric acid on the physical properties of foamformed sheets, were investigated.The results indicate that the optimum chemical addition sequence involves first generating fiber foam with SDS, followed by the sequential addition of PVA and borate.The most effective PVA-to-crosslinker ratio was determined to be 95:5, with boric acid selected as the optimal crosslinker.Increasing the dosage of PVA or PVA-boric acid resulted in an increase in bulk but a decrease in tensile strength in foam-formed sheets.However, the combination of PVA and boric acid improved tensile strength by 25-35% compared to PVA alone at the same dosage level.In addition, at equivalent bulk levels, the tensile strength of the PVA-boric acid system remained higher than that of PVA alone.These results suggest that the combined use of PVA and boric acid as strength additives can simultaneously improve the bulk and tensile strength of foam-formed sheets, enabling the development of low density materials with improved mechanical properties.