Morphology and phase compositions of different starch-gelatin blends were investigated by various microscopes： optical, SEM and synchrotron FTIR microscopy. A high amylose （80%） corn starch, grafted with hydroxypropyl to enhance flexibilty and hydrophilicity, and plasticized by poly（ethylene glycol） （PEG）, was used in this work. SEM revealed that the surface became smoother after adding PEG. Optical microscopy observation revealed that compatibility between gelatin and starch was improved by adding PEG. An FTIR beam focused on a 5 ~tm x 5 ~tm detection area by the micro-spectroscope was used to map chemical composition. The ratio of areas of the saccharide bands （1180-953 cm-1） and the amide I and II bands （1750-1483 cm-1） was used to monitor the relative distributions of the two components in the blends. The FTIR maps indicated that gelatin constituted the continuous phase up to 80% of starch content. All of the FTIR spectra showed contributions from both starch and gelatin absorptions, therefore indicating that complete demixing with pure starch and gelatin domains did not occur. The PEG improved the compatibility of the gelatin-starch blends.
Cassava starch-based superabsorbent polymer was successfully synthesized using a new technology that based on modification of a Haake twin-roll mixer as reactor. The cassava starch was first gelatinized then modified by grafting under external shear stress in the reactor. The torque and temperature curves as a function of time can reflect the variations in the reactor and also offer some information about the copolymerization reaction. The advantages of this system include starch modification can be carried out （l） with high starch concentration, （2） under controlled ticne and （3） smaller amount of sample （60 g） required. The technology provides useful guides for reactive extrusion. The starch grafted composites were characterized by Fourier transform infrared spectroscopy （FTIR）, nuclear magnetic resonance （NMR） and thermal gravimetric analysis （TGA）. The TGA was also used for determining the percentage of grafting ratio. The results show that the cassava starch has been successfully grafted with acrylamide then crosslinked by N,N＇-methylene-bisacrylamide using this reactor. The ultimate water absorbent capacity of the cassava-based superabsorbent polymer impacted by various pH values illustrated that the acid and basic solutions inhibit the ability of imbibing water. Additionally, gel properties of the cassava-based superabsorbent polymer were investigated. It can be concluded that the structure of cassava gel is stable, while the three dimensional network of cassava-based superabsorbent polymer is rigid but its structure could not resist external force effectively and everlastingly since G＇ was decreased with increasing amplitude.
