Superabsorbent hydrogels of poly(sodium acrylate) with crude and exfoliated vermiculites

Abstract

Novel superabsorbent hydrogels of poly(sodium acrylate) [poly(SA)] with crude vermiculite (CVMT) and exfoliated vermiculite (EVMT) were synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Both types of hybrids are more stable materials than poly(SA) and their thermal stability increases as the clay content increases. The equilibrium water absorbency for each hybrid type varies with the clay content, showing a maximum at 15 wt % and 20 wt % for EVMT and CVMT, respectively. The equilibrium water absorbency is higher for the hybrids than for poly(SA) at clay contents close to their maxima. The swelling kinetics obey a Voigt-based equation. The water desorption kinetics showed the existence of free water and bound water within the polymeric matrix. All of the superabsorbent materials investigated retained the water absorption capacity after repeating five wet-dry cycles.

Microwave-assisted one-step synthesis and characterization of a slow release nitrogen fertilizer with inorganic and organic composites

“…In addition, the inclusion of Bent created a resistant path through the polymer matrix, thus, a transient protective barrier was present. 22,23 The NaAlg-g-p(AA-co-AM)/ Bent/urea thermogram displayed a slightly lower thermal resistance property than NaAlg-g-p(AA-co-AM)/Bent, but a higher thermal resistance property than urea. This phenomenon occurred because the mass percentage of Bent in the composite decreased as urea was added, and as a result, the decomposition rate was slightly increased.…”

New Semi-IPN Hydrogels Based on Cellulose for Biomedical Application

“…Out of the three polymers, namely, CMP, poly (SA), and PEG, present in the hydrogel, the highest content is of poly (SA) and so its thermal stability is expected to govern the overall stability of the thermogram. It can be seen that below 350 ∘ C there is weight loss of almost 31%, which is attributable to the loss of water molecules bound to the polar groups of polymeric constituents, and decarboxylation of -COO groups associated with poly (SA) chains [20]. Beyond 350 ∘ C, the weight loss of polymer continues up to 433 ∘ C due to presence of small amount of PEG in the sample.…”

Biocatalysis for Biobased Chemicals

“…Resins of poly(sodium acrylate) are used as water-absorbent materials for cleaning surfaces, in water and oil conditioning, personal care products, and disposable materials for medical applications [177]. …”

“…Enzyme-catalyzed vinyl polymerizations have been demonstrated in recent years with significant control of polymer molecular weight and yield depending on reaction conditions [ 149 ]. Resins of poly(sodium acrylate) are used as water-absorbent materials for cleaning surfaces, in water and oil conditioning, personal care products, and disposable materials for medical applications [ 177 ].…”