Synthesis, and Investigation of Swelling Behavior Natural Based Superabsorbent Composites with High Thermal Resistance

In the present paper, attention is paid to synthesis and investigation swelling behavior of a superabsorbent hydrogel composite based on Pectin (Pec) and polyacrylonitrile (PAN) in the presence Kaolin powder. The physical mixture of Pec, Kaolin and PAN were hydrolyzed by NaOH solution to yield H-Pec-poly (sodium acrylate-co-acrylamide)/Kaolin superabsorbent hydrogel composite. A proposed mechanism for hydrogel formation was suggested and the structure of the product was established using FTIR and SEM spectroscopies respectively. According to FTIR, all the nitrile groups were converted to carboxylate and carboxamide groups. H-pectin-g-PAN/Kaolin composite was also characterized by DSC and TGA thermal methods. Both modified pectin exhibited enhanced thermal stability over pectin. On the other hand, the Pec-poly (sodium acrylate-co-acrylamide) hydrogel composite exhibited a pH-responsiveness character so that a swelling-deswelling pulsatile behavior was recorded at pHs 3 and 8. This abrupt swelling behavior was explained based on variety of pHdependent interactions of functional groups incorporated in the gel network by an external pH modulation. The results clearly suggested that the natural-bsae hydrogel composite may be a potential polymeric carrier for drug delivery in the intestinal tract.