Surface cross-linked SAPs with improved swollen gel strength using diol compounds

Abstract

In this study, to improve swollen gel strength, surface cross-linking of acrylic-based superabsorbent polymers (SAPs) was performed by diol compounds (i.e., 1,2-ethanediol, 1,3-propanediol and 1,4-butanediol) as external cross-linking agents. A two-step surface treatment procedure was conducted on dried SAP particles and effective parameters (i.e., distilled water/acetone ratio, concentration and type of surface cross-linking agent, curing time and temperature) were optimized to accomplish SAPs having maximum swollen gel strength and suitable free swelling capacity. Attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopy, rheological and thermal analysis, free swelling capacity (Qeq), absorbency under load (AUL) and gel content measurement were employed for products evaluation. According to the results, the gel content was increased by 20%, storage modulus was improved three-fold in surface-treated samples when compared with untreated samples and AUL was improved up to 26 g/g in comparison with untreated samples (13 g/g). So, the current SAPs can have potential to use in hygienic application due to high AUL and swollen gel strength.