Thermal and optical properties of electron beam irradiated cellulose triacetate

Cellulose triacetate (CTA) is a polymer which is widely used in a variety of applications in the field of radiation dosimetry. In the present work, CTA samples were irradiated by electron beam in the dose range 10-200 kGy. The modifications in the electron irradiated CIA samples as a function of dose have been studied through different characterization techniques such as thermogravimetric analysis, differential thermal analysis and color-difference studies. The electron irradiation in the dose range 80-200 kGy led to a more compact structure of CTA polymer, which resulted in an improvement in its thermal stability with an increase in activation energy of thermal decomposition. Also, the variation of melting temperatures with the electron dose has been determined using differential thermal analysis (I)TA). The CTA polymer is characterized by the appearance of one endothermic peak due to melting. The results showed that the irradiation in the dose range 10-80 kGy causes defects generation that splits the crystals depressing the melting temperature, while at higher doses (80-200 kGy), the thickness of crystalline structures (lamellae) is increased, thus the melting temperature increased. In addition, the transmission of these samples in the wavelength range 200-2500 nm, as well as any color changes, was studied. The color intensity Delta E{*} was greatly increased with increasing the electron beam dose, and accompanied with a significant increase in the blue color component. (C) 2008 Elsevier B.V. All rights reserved.