Rheological and thermal properties of saponified cassava starch‐g‐poly(acrylamide) superabsorbent polymers varying in grafting parameters and absorbency |
| |
Authors: | Prabha C. Parvathy Alummoottil. N. Jyothi |
| |
Affiliation: | Division of Crop Utilization, Central Tuber Crops Research Institute, Sreekariyam, Thiruvananthapuram, Kerala, India |
| |
Abstract: | Cassava starch‐graft‐poly(acrylamide) superabsorbent polymers (SAPs) with varying absorbencies were synthesized. Weight average molecular weight (Mw) of the hydrolyzed starch‐graft‐copolymers ranged from 1.6 × 106 to 2.8 × 106 g/mol, the largest being shown by the sample with highest percentage grafting. The storage (G′) and loss modulus (G″) of hydrogels were determined as a function of frequency. G″ was larger than G′ for the hydrogels with higher absorbencies and exhibited a liquid‐like behavior. However, hydrogels with lower absorbencies showed a reverse viscoelastic behavior. The viscosity of hydrogels determined using a Brookfield viscometer at different shear rates was found to be larger for the hydrogels with higher absorbencies. The melting temperature (Tm) and enthalpy change of fusion (ΔHf) of the SAPs ranged from 149.7 to 177.7°C and 65 to 494.9 J/g, respectively and showed a positive correlation with grafting parameters and Mw. Heavy metal ion removal capacity of hydrogel followed the order Cu2+ > Pb2+ > Zn2+. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40368. |
| |
Keywords: | biomaterials biopolymers & renewable polymers copolymers differential scanning calorimetry (DSC) glass transition |
|
|