Effects of Homogeneous Low Energy Electron Beam Irradiation (HLEBI) on Water Absorption and Hydrolysis Suppression of High Strength Polycarbonate

Abstract

In order to evaluate effects of homogeneous low energy electron beam irradiation (HLEBI) on water absorption and hydrolysis suppression, the mass gain and loss of high strength polycarbonate (PC) dipped in boiling water after drying was obtained. Dipping for less than 5 © 10 3 s increased the mass gain ratio (C w ) for all PC samples, although remarkable mass gain could not be detected from 5 © 10 3 to 2 © 10 5 s. HLEBI with small dose from 0.04 to 0.13 MGy mostly suppressed the C w value for initial dipping time for less than 5 © 10 3 s. 0.04 MGy-HLEBI slightly enhanced the experimental saturated C w values at 10 4 s-dipping ( e C w ). Based on the Johnson-Mehl equation, the initial absorption index (n) for PC with and without HLEBE was approximately equal to 0.5, which was approximately equal to that of nylon6. Since esteratic sites attracted the water molecules in PC polymers, the water absorption can be explained. On the other hand, the small mass loss could be detected of PC dipped in boiling water for 10 5 s prior to drying, although that for 10 4 s could not be detected. HLEBI suppressed the mass loss, 40 +/¹ 20% smaller than that untreated, for PC dipped in boiling water for 2 © 10 5 s prior to drying. Since HLEBI probably cut off the >C=O bonds in aldehyde base in PC polymers. Based on the FT-IR (>C=O bonds) signals, the intensity of untreated PC polymer is more than 15.7% higher than that after 0.13 MGy irradiation. Thus, HLEBI suppressed the hydrolysis of PC.