Evaluation of “Payne effect” in radiation-induced modification of chlorobutyl rubber

Abstract

The major effect of high energy photon, such as gamma rays, in organic polymers is the generation of free radicals, causing changes in electrical, optical and mechanical properties. This work aims to the study of a controlled degradation of a chlorobutyl rubber compound after irradiation at: 25, 100 and 200kGy doses. Effects of irradiation on a rubber compound were investigated via DMA (Dynamic Mechanical Analysis) tests using the so-called Payne effect, which is directly related to the dynamic properties of the vulcanized rubber. The test begins in a low strain excitation upwards to a maximum programmed strain, and then downwards to a minimum strain at room temperature. The dependency of the material related to the strain amplitude is illustrated by Payne effect. Material behavior presents a non linear evolution on both modulus and Tan when increasing the strain (Payne effect). A difference on G′ and tangent δ values at low strain can be observed between the sweeping ways up and down. The difference between new and irradiated material at 25kGy dose material is not very significant. Nevertheless, the chain scission for higher irradiation doses (≥25kGy) is verified, as observed by Payne effect. Another interest in strain sweep is to facilitate the detection of strong breaking in materials linkage at high strain amplitude as illustrated by Mullins effect.