Thermal management and core-shell construction produced super-low residual monomer and rapid absorbing SAP for hygiene goods

Minimized residual monomer is an essential requirement for mature industry products, particularly in ones such as superabsorbent polymers (SAPs), whose component is constituted sodium polyacrylic acid (PAA-Na). In this study, ternary compounded initiator (V-44, V-50, APS) was used to initiate the polymerisation reaction and effectively control the heat of polymerisation to release rate, which can be of paramount importance to achieve desired swelling and residual monomers performance of PAA-Na used in normal saline. For this purpose, solution polymerizations of acrylic acid (AA) at 75 % neutralization and over range of nominal temperatures of 50, 60, 70, 80 and 90 ℃ initiated by thermal initiator were carried out and the residual monomers, swelling ratio as well as mechanical properties were measured by means of high performance liquid chromatograph and extended rheometer. A star-shaped surface crosslinker was used to vary surface crosslinking density of SPAs, which strongly affected its absorbing rate. Finally, PAA-Na with quickly absorbing rate was used in personal care products and address the issue of skin irritation brought on by AA residues monomers.