Optical, structural, thermal and physical properties of polymethylmethacrylate and polysulfone nanocomposites

Transparent polymers, such as polymethylmethacrylate (PMMA) and polysulfone (PSF), contain absorbing chromophores as a part of their structure. The chromophoric groups are able to absorb UV energy and involved in the photochemical degradation reactions leading to the formation of hydroperoxides and chain scission. Superb properties of environmentally friendly cellulose esters encourage us to use them as an inhibitor for photochemical interaction in addition to the high-formation ability. Moreover, the absorption peak of indium oxide nanoparticles (nano-In₂O3) at round 280 nm. contribute to curb the photochemical interaction in the polymer matrix. The present thesis aims to improve PMMA and PSF in order to protect themselves and covered surfaces from the impact of UV radiation by using three environmentally friendly cellulose esters and the nano- In2O3. Two sets of transparent nano-composites based on PMMA and PSF were prepared separately with cellulose acetate butyrate (CAB), cellulose acetate propionate (CAP) and cellulose acetate phthalate (CAT) added with nano-In₂O₃ using a twin screw extruder in various percentage concentrations. The preparation process was divided into two stages; the first was preparing transparent samples from PMMA and PSF separately with CAB, CAP and CAT. The second was adding nano-In₂O₃ to selected blend concentrations. Scans over UV and visible spectra for all highly transparent samples were made from 220 nm. to 800 nm. using a spectrophotometer. The results showed that the absorbance peak in the ultraviolet region for pure PMMA at 226 nm and for pure PSF at 268 nm, whilst the transmittance peak in the visible range for pure PMMA at 798 nm and for PSF at 712 nm. The results also showed that the increase in CAB, CAP and CAT percentage concentrations in blends reduce UV rays’ absorbance while maintaining a high transmittance. The selection of specific concentrations PMMA/10%CAB, PMMA/10%CAP, PMMA/1%CAT, PSF/0.2%CAB, PSF/0.2% CAP and PSF/0.1% CAT represents less absorbance value within UV damage threshold for PMMA and PSF. The effect of nano-In₂O₃ percentage concentrations on the absorbance and transmittance spectrum for PMMA and PSF was done using a spectrophotometer. The results demonstrated that PMMA/0.05%/nano-In₂O₃ and PSF/0.02%/nano-In₂O₃ have maximum UV absorbance with high transmittance. Morphological and structural characterizations of selected samples were studied by means of Scanning Electron Microscopy (SEM) and Differential Scanning Calorimetry (DSC). The SEM results showed single phase for PMMA blends and composite surfaces, while PSF blends surfaces showed a size reduction in all blend and composite samples. The DSC results indicated that all samples are miscible. The thermogravimetry analysis (TGA) was used to characterize thermal behavior of the samples. The results indicated that pure PMMA degraded in three steps while pure PSF degraded in two steps. The TGA analyses also indicated that all CAB, CAP and CAT blends with PMMA and PSF have good thermal stability and adding nano-In₂O₃ maintained the thermal stability for all samples. The dynamic mechanical Analysis (DMA) showed that the storage modulus and loss modulus of PMMA significantly increased by the incorporation of nano-In₂O₃. Finally, the samples PMMA/10%CAB/0.05% In₂O₃ and PSF/0.2%CAP/0.02% In₂O₃ are the best overall properties in this work.

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