The morphology of irradiated isotactic polypropylene

Abstract

ABSTRACT:The research in this article explores the response of semicrystalline isotactic polypropylene to gamma radiation in air, and relates the morphological changes of the polymer to corresponding changes in mechanical properties. The effect of the initial morphology of the polymer on its response to irradiation is considered using infrared spectroscopy (FTIR), small-and wide-angle X-ray scattering, dynamic mechanical thermal analysis (DMTA), and mechanical testing. The extent of chain scission and crosslinking is dependent on the dose but not the initial starting morphology. These chemical changes cause the crystallinity to increase slightly, and the glass transition temperature to rise by a few degrees in all samples, but the overall morphology is only subtly changed. In contrast, a major deterioration in mechanical properties is caused. The effects of the irradiation observed under these conditions are similar in each material and the ultimate properties determined by the properties seen in the original material.

Sterilization by Gamma Irradiation

“…The extent of chain scission and crosslinking of PP is dependent on the -irradiation dose but not the initial starting morphology (Zhang and Cameron 1999). Using WAXD (Wide angle X-ray diffraction) and DSC (Differential scanning calorimetry) techniques, Alariqi et al (2006) found change in the degree of crystallinity, which caused by -irradiation, depends on the -irradiation dose ( see Table 6) and Kostoski and Stojanovic (1995) found the increase in crystallinity of oriented isotactic polypropylene with low absorbed doses of -radiation, up to 200 kGy.…”

Gamma Radiation as a Novel Technology for Development of New Generation Concrete

“…The ductile-brittle transition rises dramatically with irradiation, while the glass transition shows only a small increase. This observation is explained by irradiation, through chain scission and cross-linking, having a dominant effect on large-scale plastic deformation and a lesser effect on the deformation which relies on the amorphous phase alone [Zhang & Cameron, 1999].…”

“…Research concerning to the micro-mechanical deformation mechanisms of irradiated and non-irradiated isotactic polypropylene (iPP), studied as a function of temperature above the glass transition has been reported [Zhang & Cameron, 1999]. Several deformation mechanisms were identified and included lamellar separation, shear, stable and unstable fibrillated deformation and cavitation.…”

“…Post irradiation ageing may occur as free radicals formed during irradiation react after the irradiation has ceased [Carlsson & Chmela, 1990;Carlsson et al, 1985]. Studies on isotactic polypropylene indicate that irradiation at 50 kGy in air causes slight increment of the crystallinity and the glass transition temperature to rise by a few degrees [Zhang & Cameron, 1999]. The changes to the dimensions of the lamellar architecture are small.…”

Stress–strain and thermo-gravimetric analysis of Co-60 gamma-irradiated polypropylene and polyimide

“…This requires a thorough understanding of the effects of radiation on variety of polymers. A literature survey indicates that most of the work on the radiation effects on polymers focuses on a single macromolecule, leaving no scope for comparison, otherwise in a few reports the polymers with same class are compared (4)(5)(6)(7)(8)(9)(10)(11)(12). To the best of our knowledge, no report is found which focuses on the comparative studies on macromolecules belonging to quite different classes, but irradiated with the same radiation and under identical conditions.…”