Thermal Studies on Granular Maize Starch and its Graft Copolymers with Vinyl Monomers

Abstract

The graft copolymers of pure granular maize starch with acrylamide, methacrylamide, acrylic acid and methacrylonitrile were synthesized using ceric ammonium nitrate as an initiator. The formation of graft copolymer was confirmed by gravimetric measurement, acid hydrolysis and IR spectroscopy. The thermal analysis of the pure granular maize starch and graft copolymers was carried out using thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), differential thermal analysis (DTA) and isothermal analysis. In order to determine the mechanism of decomposition of these polymers, the isothermal analysis was coupled with IR spectroscopy. The activation energies at every stage of decomposition for all the polymer samples were determined from their primary thermograms. The glass transition temperatures (Tg) for pure granular maize starch and all the graft copolymers have been reported. Except starch‐graft‐acrylic acid, all other graft copolymers showed enhanced thermal stability over pure starch. Tg of pure starch was observed as 91°C. All the graft copolymers showed lower values of Tg with a minimum of 57°C for starch‐graft‐methacrylonitrile. DTA studies indicated a delayed oxidative degradation of graft copolymers.

Cellular architecture and its relationship with mechanical properties in expanded extrudates containing apple pomace

“…At low moisture contents (17.5 and 20% MC) addition of apple pomace suppressed the T s . In corn flour, the amorphous portion of starch is the main fraction that undergoes glass transition, at a T g of approximately 71.5-91°C in the moisture range of 10 to 55% (Athawale & Lele, 2000;Slade & Levine, 1988). It is likely that compaction was also related to the plasticization of this portion in the corn flour-apple pomace blends, since cell wall materials from fruit and vegetables do not have a detectable T g in this temperature range (Aguilera, Cuadros, & del Valle, 1998).…”

Single and multi-step carboxymethylation of water yam (Dioscorea alata) starch: Synthesis and characterization

“…The derivatogram indicates that maximum decomposition occurred at the range 259-354 • C. At 500 • C, 99.49% of the native starch was decomposed. Similarly, three-step thermogram, wherein the major weight loss (75.5%) occurred in the second stage (233-386 • C) was reported for maize starch [31,32]. Representative carboxymethylated alata starch showed four decomposition stages with 9.86%, 36.57%, 3.04% and 23.07% progressively.…”

Removal of Cu2+Ions from Aqueous Solutions by Starch-Graft-Acrylic Acid Hydrogels

“…Starch has been the raw material of industrial and academic studies for many years, due to its low cost and biodegradability [1] . Chemical modification of starch via oxidation, hydrolysis, esterification, etherification, and grafting have been extensively studied [2] .…”