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Journal of Adhesion Science and Technology 

 3

While the physical nature, including density and molecular arrangements are dependent
on the casting conditions of the samples; all samples are taken from the same source. The
irradiation of PC/PBT polymeric samples was carried out with Co-60 Gamma source at
Atomic Energy Authority, Cairo, Egypt. The polymer samples were irradiated with different
doses ranging from 200 to 1950 kGy under the same conditions with dose rate 3.5 kGy/h.
The UV–vis absorbance spectra of pristine and irradiated samples were investigated by
UV–vis spectroscopy. The spectra were performed in the wavelength region of 190–1100 nm
using JASCO V-630 double-beam spectrophotometer with resolution of 0.1 nm.
XRD patterns measurements of the pristine and irradiated samples were detected with
Philips powder diffractometer-type PW-1373 goniometer. The X-ray wavelength was
1.5405 Å. The X-ray patterns were recorded at room temperature in the 2θ range of 4–70°
with a scanning speed of 2°/min.
The chemical structure and bonds were investigated by FTIR spectroscopy in the wavenumber range 400–4000 cm−1 using Nicolet 6700 FTIR spectrometer. The accuracy was
±4 cm−1.
Surface wettability, surface free energy, and work of adhesion were estimated by contact
angle measurements for three different liquids (distilled water, glycerol, and formamide).
Micro-syringe was used to put three drops for each liquid on the sample surface and the
average of three measurements of the contact angle was calculated and used.

3.  Results and discussion
3.1.  UV–vis spectra analysis
UV–vis absorbance spectra for pristine and gamma irradiated PC/PBT polymer samples
at different doses are shown in Figure 1. It is clear from Figure 1 that there are many alterations in the UV–vis spectra of irradiated sample compared to the pristine one. One can
notice that two regions of high absorption were observed, one centered around 290 nm
(from 270 to 330 nm) and the other belongs to the band gap absorption. We deem that the

Figure 1. UV–vis spectra of gamma-irradiated PC/PBT blend.