Synthesis and characterization of (poly (N-vinyl formamide)—pregelled starch—graft copolymer

Graft copolymerization of poly(vinyl acetate) onto starch using KMnO4-H2SO4 redox system

“…Swelling power ( Figure 2) and solubility (Figure 3) of all samples increased as the temperature increased. Similar increases in swelling power and solubility of native starch with increase in temperature were reported by Mostafa et al [12]. The increase in swelling power with temperature is a result of an increase in mobility of starch molecules, which facilitated percolation of water and subsequent increase in swelling and solubility.…”

Starch‐graft copolymers of N‐vinylformamide and acrylamide modified with montmorillonite manufactured by reactive extrusion

“…Lower water absorption (ca. 2.1 g/g) of (unsaponified) S‐g‐ NVF copolymer (starch:NVF weight ratio 100 : 50) was found by Mostafa et al11…”

“…Generally, for both types of starch graft copolymers based on AAm and NVF adsorption of cadmium cation is higher than Fe 3+ . This can be explained by the differences between the metal ions characteristics, i.e., relative atomic size; ability of metal ion to interact with the polymer, metal ion charge density and reactivity of the metal ion 11. The preliminary adsorption tests correlate with the results on adsorption of Cd 2+ and Fe 3+ on montmorillonites/bentonites (cadmium cation sorption in a wide range: 7.3–32.7 mg/g and Fe 3+ 12–28.9 mg/g), depending on the aluminosilicate clay type and experimental conditions) presented by other authors 22, 24.…”

“…Besides AAm, N ‐vinylformamide (NVF) is being more often used for (co)polymerization reactions as it is considered to be more environmentally safe. Mostafa et al described pregelled starch graft copolymerization with NVF (starch/monomer weight ratio 100 : 12.5–200) by conventional batch process using redox initiating system (bromate/cyclohexanone) 11. The materials obtained at 40°C (120 min, pH 6, 50 wt % NVF) exhibited 90–310% degree of swelling and 9.5–47.5% solubility in water.…”

Free radical induced grafting of acrylonitrile on pre-treated rice straw for enhancing its durability and flame retardancy

“…The graft yield percentage based on nitrogen content of polyacrylonitrile (25.41 wt%) can be also calculated to estimate the grafting efficiency more accurately using the following expression [35]:$\text{Graft yield}false(\%false)=\frac{100false(N\%\times 0.05306false)}{100-false(N\%\times 0.05306false)}\times 100$where 0.05 is the molecular weight of acrylonitrile divided by 1000.…”