Engineering and Technology Journal

Thick composite films were prepared employing hand – layup method . A definite quantity of PMMA ( 98%wt ) , fixed content ( 2% wt ) of rutile titanium dioxide TiO2 , gamma alumina ( ᵞ- Al2O3 ) and Zirconia powder ( ZrO2 ) , were added to polymer solution gradually and separately. Optical constants were obtained of the prepared samples using spectrometer (UV- VIS). The prepared composite samples were thermally characterized by differential scanning calorimeter ( DSC ). We notice increasing value of glass temperature and differential heat capacity ( ∆Cp ) for composites compared with pure PMMA .

The optical reflection, transmission, and UV/VIS- absorption spectra had been recorded in the wavelength(200-500nm) for PM-355 before and after irradiation with γ-ray irradiation by using 60Co-dose within range of(30-160Mrad) at normal conditions. The absorption spectra of irradiated samples showed radiation induced absorption changes by photodegradation. There was an increment in absorption proportional with irradiation dose. The optical constants (α,Kex,n,εi,εr,Eg,) were calculated for all samples. The effect of irradiation on the optical constants of the PM-355 before and after irradiation had been investigated.

In this paper, azo dye polymer materials was synthesis from P-toludine with Novolac by Fox method. The optical properties of an azo dye polymer film with thickness 10µm have been investigated by the transmittance and absorbance spectra in the wavelength range (300-900 nm). The linear optical parameters such as refractive index (n) , extinction coefficient (k) , absorption coefficient (α) , real and imaginary parts of dielectric constant were calculated. The optical energy gap was estimated from the absorption coefficient using Taue,s procedure. The oscillator energy (E0), dispersion energy(Ed) and the static refractive index (no) have been determined by the Wemple-DiDomenico method.

The present work was carried out to investigate the silver concentration Effect (Ag %)othe optical and the electrical properties of the polymethyl methacrylate (PMMA). The samples were casted as films from the photopolymer (PMMA) stated above and the reason. The optical constant (α,k,n, εr, and εi)for the photopolymer (PMMA),and Ag/PMMA composites at different concentration were investigated. It was seen that there was nonlinear relationship between the optical constants and the concentration ratio, which was attributed to their incompatibility. These results were confirmed with optical micrographs. It was found that there was increasing of carrier concentration with Ag ratio which Ag/PMMA composites at different concentration. These prepared polymer systems were analyzes spectrophotometically. It was found that an increasing in the absorption spectra with increasing of the silver concentration in Ag/PMMA composites, which was attributed to the increasing in localized states. The results proved that its energy gap was for 13%Ag/PMMA (4.85eV), which was the lowest of all polymer system involved due to previous was caused decreasing in the mobility. The results showed that the best conductivity was at 9%Ag ratio, and the lowest receptivity.

The aim of the present work is concerned with the study of the optical
constants of the PMMA/PC blend at different concentrations.
The samples are casted as films from the PMMA and PC homopolymers and
blend. These polymer systems are evaluated spectrophotometically. The
absorption spectra of homopolymers and PMMA/PC blends at different
concertation showed absorption changes in the wavelength range, which depends
on the polymer type, and the concentration of the polymer blends. It was found
that 50% ratio from these polymers showed higher absorption values in
comparison with the homopolymers, besides, the absorption spectroscopy of the
polymer blends did not always effect the similar information obtained from the
spectroscopy of the homopolymers .A phenomenon was attributed to immiscibility
or phase separation as associated with the blends formation. The results of the
optical constant proved that 50%ratio was the best, which was attributed to the
lowest energy gap (2.5 eV). Morphological investigations for the
casted polymer systems were introduced.

Anew mathematical procedure depends on the evolutionary algorithm has been proposed to estimate the optical constants (refractive index, extinction coefficient and thickness) of unknown deposited material on a defined substrate. The transmittance and reflectance experimental data are taken for two materials (Sc2O2 and Rh) with two different thicknesses for the wavelengths range (400-850 nm). The resulting optical constants and the theoretical transmittance and reflectance spectra are very close to the experimental data.

In this study, thin films of ZnTe were deposited on glass substrates using
vacuum evaporation technique. The optical measurements on the deposited films
were performed to determine the transmission spectrum and the absorption spectra
as a function of incident wavelength. As well, optical parameters, such as
extinction coefficient, value and type of energy gap, type of the dominant
absorption processes, real and complex refractive index as functions of incident
photon energy, were determined. This study may present better understanding for
the optical properties of ZnTe thin films and their devices in order to enhance their
characteristics and improve their efficiencies.