Radiation Graft Co-polymerization of Methacrylic Acid (MAA) onto Sago Starch Films

Abstract

In this work, the factors that may affect the gamma radiation-induced grafting of methacrylic acid monomer (MAA) onto sago starch films were investigated. The graft copolymers were characterized by tensile mechanical testing, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and infrared spectroscopy. The results showed that the highest grafting yield was obtained within the irradiation dosage level of 10–20 kGy and by using monomer concentration range of 15–20 wt%. The highest tensile mechanical properties were observed for sago starch films having 66% graft yield of MAA. The DSC thermograms indicated a decrease in the gelatinization temperature (temperature at which the disruption of the molecular orders in the starch granules occurs) of sago starch as a result of grafting. This behavior was explained on the basis that radiation grafting prevents the retrograddation process of starch (starch re-crystallization). On the other hand, the IR spectra indicate an increase in the intensity of the absorption band due to C˭O stretching, confirming the occurrence of grafted chains of MAA.

Keywords:

• Radiation grafting
• Starch films
• MAA monomer
• Thermal and mechanical properties
• IR spectroscopy

Notes

The samples are dried in a vacuum oven for 72 h at 52°C, just before carrying out the measurements.