Cassava starch‐graft‐polymethacrylamide copolymers as flocculants and textile sizing agents

Abstract

Cassava starch‐graft‐polymethacrylamide (PMAM) copolymers were synthesized by a free‐radical‐initiated polymerization reaction, and the products were tested for their efficiency as flocculants and textile sizing agents. The highest percentages of grafting and monomer conversion were 79.9 and 78.0%, respectively. The grafted starches were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction analysis, scanning electron microscopy, differential scanning calorimetry, and thermogravimetric analysis. The average molecular weight of PMAM chains in the grafted starches ranged from 15.9 to 30.8 × 105 g/mol. The grafted starches exhibited a higher peak viscosity and paste stability in comparison to the native starch (NS). Dynamic mechanical analysis showed that grafting provided fairly shear‐stable hydrogels, and the highest storage modulus obtained was 17,900 Pa compared to 1879 Pa for NS. The flocculation studies demonstrated the superiority of starch‐g‐PMAM over cassava starch and PMAM as an efficient flocculant. The tensile strength of cotton yarns sized with the starch‐grafted copolymer was significantly higher (104 MPa) compared to that sized with NS (34 MPa). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39810.

Free-Radical Graft Polymerization onto Starch as a Tool to Tune Properties in Relation to Potential Applications. A Review

“…Some of the synthesized products were subjected to flocculation tests, where the product made with 0.88 g/L CAN performed best. The relation of flocculation performance to graft spacing is not straight-forward here since all of the products tested had relatively high N AGU values [15].…”

“…The usual method is to hydrolyze all of the starch, both amylose end amylopectin, either by the use of strong acid in molar excess [1,10] or by enzymatic degradation [15]. It is not a problem if one or a few sugar groups remain in the synthesized chains as their contribution to the total weight of the molecules will not be more than 0.2-0.3%, which is within experimental error margins.…”

“…When the grafts are isolated, Gel Permeation Chromatography (GPC) can be applied to determine both the average molecular weight and the weight distribution. Before the advent of GPC, but also in more recent publications of Nair and Jyothi [15], a calibrated viscosity measurement was used to determine molecular weights [16].…”

“…In addition, the molecular weight of the grafts increases with monomer dosage, most certainly if compared at the same level of initiator. Nair and Jyothi [15], Case 3 in Table 4, present a recent elaborate study on the effect of reaction variables when pre-gelatinized starch is also grafted with acrylamide with Cerium Ammonium Nitrate (CAN), a much used but relative slow reacting initiator [1,2]. From the data represented in Table 4, it can be seen that again, initiator dosage has a large effect on the graft spacing, but the effect is a little mixed up with the influence of monomer concentration-a situation that is inevitably associated to the use of an experimental design method.…”

Polymeric flocculant based on cassava starch grafted polydiallyldimethylammonium chloride: Flocculation behavior and mechanism

“…Cassava starch has recently been receiving considerable interest in grafting with various monomers because of its low cost, availability, renewability, and biocompatibility [12]. Grafting is the most frequently attempted method in imparting desirable properties to cassava starch without sacrificing its biodegradable nature [13].…”