Investigation Of γ-ray Irradiation Effects On Poly(chloro-p-xylylene) Film

Poly(chloro-p-xylylene) (PC) film has excellent properties in gas and moisture barring. It also has good properties of mechanics, optics, dielectric, bio-compatibility and corrosion resistance. Therefore, it has been widely applied in many fields, such as semiconductors, integrate circuits, MEMS technology, sensors, medical apparatus, artifact conservation and resistance of moisture. PC film has been used as coating for conserving lithium hydride(LiH), a common used material in nuclear weapon systems, from moisture. Because LiH parts are in contact with many radioactive materials in nuclear weapon system, the radioactive resistance ability of PC film is very important to ensure properties of LiH parts.In this study, effects of gamma-ray(⁶⁰Co) radiation on surface appearance, molecular structures, thermal properties, moisture and gas permeabilities of PC film and LiH-base coated PC film, which were irradiated with dose rates of 100Gy/min and 33Gy/min in air and helium-atmosphere, were investigated using Atomic Force Microscope(AFM), Fourier Transform Infrared Spectroscopy(FTIR), Raman Spectrometer, Mass Spectrometer(MS), Thermal Analysis(TG, DTA). The moisture and gas permeabilities were also tested for all samples. The main conclusions are listed as follows.The surface appearance and molecular structures of PC films changed after γ-ray irradiation. The surface of the PC films became softer first and then harder with the irradiation dose increased, which maybe revealed that the amorphous components in the films crystallized. The pyrolyzed and the crystalline melting temperature of the films were also seen to decrease as the irradiation dose increased, which implied that the degradation of the films were more serious. But the crystalline degree and the glass-transition temperature of the irradiated films increased with the increase of the irradiation dose.The PC films were changed from transparent to opaque, and the color became yellowish ("yellowed" phenomena) after γ-ray irradiated. The degree of "yellowed" phenomena became larger with the irradiation dose increased. Pyrolysis GC-MS analysisrevealed that the "yellowed" product of PC film contained the unit ofbut not the a literature result.