Polymers and Pigments Department, National Research Centre, 33 El Bohouth St. Dokki, Giza, P. 0. 12622, Egypt;
Spectroscopy Department, Physics Division, National Research Centre, 33 El Bohouth St. Dokki, Giza, P. 0. 12622, Egypt;
Polymers and Pigments Department, National Research Centre, 33 El Bohouth St. Dokki, Giza, P. 0. 12622, Egypt;