Investigation of Surface Free Energy for PTFE Polymer by Bipolar Argon Plasma Treatment

The low ion energy argon plasma was used for surface modification of Poly tetra fluoroethylene (PTFE) polymer. The plasma was generated between two plane metal electrode by using 50 kHz bipolar power supply. The plasma treated surface was characterized by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The surface free energy (SFE) of plasma treated surface was calculated from contact angle measurement. SFE increases from 33.39 mJ/m2 to 41.40 mJ/m2 with the increase in plasma treatment time and the corresponding contact angle changed from 76? to 60?. XPS study shows that F/C ratio change from 1.8 (untreated) to 1.3 (treated) and O/C ratio changes from 0.094 (untreated) to 0.148 (treated). The XPS analysis shows that both F1s and the C1s spectra for PTFE are marginally modified by plasma treatment. AFM study shows that the average surface roughness (Ra) increased from 8.5 nm to 22.8 nm after plasma treatment. Vicker’s micro hardness of the film increases upon plasma treatment. The increase in SFE after plasma treatment is attributed to the functionalization of the polymer surface with hydrophilic groups as supported from the above observations.

2-22 Elastic Scattering Studies of Light Proton-rich

The elastic scattering is an important probe to study the properties of a nucleus. An accurate measurement ofthe elastic scattering differential cross section is very important to determine the optical potential parameters andthe so-called one quarter angle (q1=4). Also, the optical potential parameters of stable nuclei and unstable nucleiare found to be different. 8B, the binding energy of the last proton is only 0.137 MeV, is a well-known protonhalonucleus even there are still some arguments. Many investigations have been done for 8B by measuring thetotal reaction cross sections, breakup cross section and inelastic scattering differential cross section. However, theexperimental data of elastic scattering of 8B and other light proton-rich nuclei on heavy target are few. Therefore, aseries of experiments have been carried out for such nuclei at the Radioactive Ion Beam Line in Lanzhou (RIBLL).

New empirical formula for(γ, n) reaction cross section near GDR peak for elements with Z ≥ 60

A new empirical formula has been developed that describes the（7,n nuclear reaction cross sections for isotopes with Z ≥ 60.The results were supported by calculations using TALYS-1.6 and EMPIRE-3.2.2 nuclear modular codes.The energy region for incident photon energy has been selected near the giant dipole resonance（GDR peak energy.The evaluated empirical data were compared with available data in the experimental data library EXFOR.The data produced using TALYS-1.6 and EMPIRE-3.2.2 are in good agreement with experimental data.We have tested and presented the reproducibility of the present new empirical formula.We observe the reproducibility of the new empirical formula near the GDR peak energy is in good agreement with the experimental data and shows a remarkable dependency on key nuclei properties：the neutron,proton and atomic number of the nuclei.The behavior of nuclei near the GDR peak energy and the dependency of the GDR peak on the isotopic nature are predicted.An effort has been made to explain the deformation of the GDR peak in（γ,n nuclear reaction cross sections for some isotopes,which could not be reproduced with TALYS-1.6 and EMPIRE-3.2.2.The evaluated data have been presented for the isotopes ^180W,^183W,^202Pb,^203Pb,^204Pb,^205Pb,^231Pa,^232U,^237U and ^239Pu,for which there are no previous measurements.

Correlation between quarter-point angle and nuclear radius

The correlation between quarter-point angle of elastic scattering and nuclear matter radius is studied systematically.Various phenomenological formulae with parameters for nuclear radius are adopted and compared by fitting the experimental data of quarter point angle extracted from nuclear elastic scattering reaction systems.A parameterized formula related to binding energy is recommended,which gives a good reproduction of nuclear matter radii of halo nuclei.It indicates that the quarter-point angle of elastic scattering is quite sensitive to the nuclear matter radius and can be used to extract the nuclear matter radius.