الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 211 |  |  |
| | | from | 211 | | |
Abstract
Nanocomposites based on cellulose acetate (CA), starch -cellulose acetate (ST-CA) matrix reinforced with clay, and starch -polyvinyl (ST-PVA) reinforced with zinc oxide (ZnO) nano- particles were prepared by solvent-casting technique using gamma irradiation.
The structure, morphology and thermal properties of the nanocomposite films were investigated by FTIR, XRD, SEM, TGA and DSC.
The nanocomposite films based on CA matrix reinforced with clay were prepared using DMF as solvent in the presence of polyethylene glycol (PEG) as plasticizer and irradiated with 10 kGy in order to improve their properties. The effect of clay and PEG contents on mechanical properties, oxygen and water permeability were studied. The results indicated significant changes in the opacity index, mechanical properties, water and oxygen permeability with respect to clay and PEG contents. The prepared nanocomposites showed intercalation of polymer inside the clay structure that caused a reduction of water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) compared to pure cellulose acetate.
Co-solvent of H2O/DMF with composition 50/50wt% was used in the preparation of starch-cellulose acetate /clay (ST-CA/Clay) nanocomposite films. XRD analysis indicated that the clay sheets are exfoliated and uniformly dispersed in the polymer matrix. TGA analysis of ST-CA nanocomposite films that contain 3wt% clay showed that the exfoliated silicate layers increase the polymer thermal stability. The good dispersion of the nanoclay particles into ST-CA nanocomposite film should promote a protective barrier against the carbon chain decomposition, shifting the onset temperature (To) and maximum degradation temperature (Tmax) to upper values. The introduction of CA as hydrophobic polymer on starch increases the resistance of starch biofilm towards water and hence decreases both its solubility and WVTR. It was found that as the content of clay increases the WVTR and OTR decreases for all prepared ST-CA nanocomposite, films with different compositions.
Bio-active nanocomposite films based starch-poly (vinyl alcohol)/ zinc oxide (ST-PVA/ZnO) have been prepared with different ZnO ratios and different copolymer compositions. The prepared nanocomposite structure was ascertained by FTIR and XRD studies. The FTIR study confirmed the creation of hydrogen bonds between the ST and PVA and electrostatic interaction between ST-PVA and ZnO. The barrier properties of the ST-PVA/ZnO nanocomposite films were studied to find that the WVTR decreases with increasing PVA content and addition of 0.5wt% of ZnO significantly decreases the OTR. The antibacterial activity of the nanocomposite film increased with increasing ZnO content.