1. Department of Materials Science; Faculty of Science, Kasetsart University; 50 Ngam Wong Wan Road, Ladyao Chatuchak Bangkok 10900 Thailand
2. Center of Radiation Processing for Polymer Modification and Nanotechnology (CRPN), Department of Materials Science, Faculty of Science, Kasetsart University; 50 Ngam Wong Wan Road, Ladyao Chatuchak Bangkok 10900 Thailand
3. Thailand Institute of Nuclear Technology, Ministry of Science and Technology; Saimoon Onkharak Nakhon-Nayok 26120 Thailand
4. Department of Physics; Faculty of Science, Kasetsart University; 50 Ngam Wong Wan Road, Ladyao Chatuchak Bangkok 10900 Thailand