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Abstract The effect of addition of four different stabilizers from N phenyl maleimide derivatives on the thermal stability of poly(vinyl chloride) (PVC) was investigated. It is found that Para ethyl carboxy N-phenyl maleimide (PEC-NPMI) :1dditive is the most effective ·stabilizer which improves the thermal· stability of pure PVC to a higher degree. The effect of addition of PEC-NPMI, with different concentrations, on the physical properties of PVC was studied. Thermogravim tri Analysis (TGA) in the temperature range from room temperature up to 600 °C and at a heating rate of 10 °C/min was performed on the PVC samples stabilized by different concentrations ofPEC-NPMI. Using the TGA and DTG thermo grams, values of activation energy of decomposition were calculated. The results indicated that the 0.01 gmPEC-NPMJJl gmPVC concentration has the maximum thermal stability and hence it could be suitable for dosimetric applications. Also the results of the Differential Thermal Analysis (DTA) from room temperature up to 400 °C at a heating rate of 10 °C/min showed that the O.Gl gmPEC NPMI/1 gmPVC sample has the maximum value of melting temperature. The Infrared spectra measured in the wavenumber range (0-4000cm- 1 showed that the concentration 0.01gmPEC-NPMI/1gmPVC has the maximum value of absorbance at different wavenumbers. This property suggests that this sample is most suitable for applications requiring PVC of high absorbance value in the IR region. On the other side, the ultravioiet spectra in the wavelength range (200 - 400 nm) showed that the sample with 0.01 gmPEC NPMI/1 gmPVC concentration has the minimun1 value of absorbance in the UV region. Refractive index measurements were performed on solution samples of different PEC-NPMl concentrations and the results showed that the PVC polymer sample stabilized by O.OlgmPEC-NPMI/lgmPVC has the maximum isotropic nature and thus this sample might be a suitable candidate for dosimetric applications. The X-ray diffraction measurements showed that the degre’=’ of ordering of the samples is dependent on_the PEC-NPMI concentration. Since the sample with the concentration ofO.Ol gmPEC NPMI/1 gmPVC showed the maximum thermal stability, maximum absorbance in the lR range and maximum isotropic nature, this sample was chosen to be a subject for further study to investigate the effect of laser radiation on it aiming to study the feasibility of further enhancement in its properties. Samples from the O.OlgmPEC-NPMVlgmPVC concentration were exposed to infrared laser radiation with energy fluences at levels between 0.95 and 8.53 J/cm2 ’Thennogravimetric Analysis was performed on all irradiated samples and the values of the activation energy of decomposition were calculated. The results showed that the thermal stability of the 0.01 gm PEC-NPMI I 1 gm PVC sample is reduced by the action of laser. The results of Differential Thermal Analysis (DTA) indicated that the irradiation with laser pulses up to 8.53 J/cm2 decreases the melting temperature of the samples and this is most suitable for applications requiring molding of thi.s polymer at lower temperatures. The results of the lR and UV spectra indicated that tlte PVC polymer sample stabilized by 0.01gmPEC NPMI/1gmPVC and irradiated with 4.27 J/cm2 has the maximum value of absorbance. This property suggests that this sample is most suitable for applications requiring PVC of high absorbance value in the lR and UV regions. The refractive index of irradiated samples showed an increase up to a maximum value around 4.27 J/cm2 followed by a decrease on increasing the laser energy fluence up to 8.53 J/cm2. The X-ray diffraction measurements showed that the irradiation up to 4.27 J/cm2 leads to an increase in the disordering character of the samples, then increasing the laser energy fluence up to 8.53 J/cm2 leads to an increase in the degree of ordering of the samples. from the above study, one can draw the conclusion that this study can be used to introduce the basis which may be used in constructing a simple sensor for laser radiation. I |