Compatibility of poly(acrylic acid)/starch blends

Compatibility of poly(acrylic acid) (PAA) and corn starch blends was studied by various techniques. Blends were prepared by using solution mixing and casting method with the aid of glycerol as a plasticizer. The molecular level interactions between the blend components were analyzed with Fourier transform infrared spectroscopy (FTIR). Dynamic mechanical analysis (DMA) showed that the introduction of starch into PAA matrix contributed substantially to the increase of the storage modulus. Differential scanning calorimetry (DSC) studies revealed that the PAA/starch blends were partially miscible and had an amorphous structure. The thermal gravimetric analysis (TGA) confirmed that the blends had higher thermal stability than the individual polymers. Water uptake experiments showed that the degree of swelling was mainly dependent on the PAA content in the blend. X-ray diffraction (XRD) studies showed that the incorporation of the PAA into starch destructed its crystalline structure. The morphology of the blends was changed by varying the composition. Scanning electron microscopic (SEM) analysis showed that at higher loads of starch, the PAA was formed as layers around starch granules. Blends containing higher amount of starch showed more homogenous and compatible behaviors relative to those with lower starch contents.