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 (Q_eq), 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.

Keywords:

• Superabsorbent
• surface cross-linking
• gel strength
• AUL
• diol compounds