?-ray-induced degradation in ethylene?propylene copolymer

Abstract

SYNOPSISThe stabilization of polypropylene-disposable medical syringes against the y-ray-induced degradation has been the subject of active research during the last decade due to the largescale use of y-irradiation for sterilization purposes. Ethylene-propylene (EP) copolymers have been suggested as suitable alternatives to polypropylene for these purposes. In this article, we investigated the effect of irradiation dose and postirradiation time on the melt index and mechanical properties of an EP copolymer. We also determined the chemical changes occurring during irradiation and storage using IR spectroscopy and have made an attempt to co-relate the changes in chemical structure to the changes in mechanical properties and melt index measurements.

Structure and mechanical properties of isotactic polypropylene and iPP/talc blends functionalized by electron beam irradiation

“…For example, the G break value for radiation chain scission is 0.21–0.10, and the G c1 value for radiation crosslinking is 0.14–0.069 17. That is, during iPP irradiation, chain scission will predominate 19. When irradiated in air or oxygen, iPP mainly undergoes chain scission due to the chain oxidation reaction 20.…”

Modification induced by alpha particle irradiationin Makrofol polycarbonate

“…However, at increased energies, active sites or branching points created by scission may lead to intermolecular crosslinking. Methods to access the extent of radiation‐induced changes in polymeric materials include mechanical testing (tensile strength, % elongation at break, compression testing, tear strength, puncture resistance), and physicochemical testing, i.e., thermal testing (measurement of changes in sealability or crystallinity), colorimetry (measurement of changes in color), IR spectroscopy (measurement of structural changes), and rheological testing (i.e., measurement of changes in molecular weight) 7–13. Also, the study of the color change in irradiated polymers is an important technique that has been used to assess physical and chemical changes in polymers.…”

The Effect of Disinfection Methods on the Mechanical Properties of Thermoplastic Recyclates

“…These tests allow the measurement of parameters sensitive to changes in the molecular structure or morphology. [3][4][5][6][11][12][13][14][15][16][17][18][19][20][21][22][23]25,26] Examination Methods…”

“…Results and Discussion [11,12] In PP chain segments are split off due to chain scission whereas PE is cross-linked by radiation disinfection. But PP and PE recyclates disinfected with electron beam or gamma radiation can still be reprocessed.…”

“…As a result the melt mass-flow rate (MFR) of PP increases and the elongation at break is significantly reduced. [11][12][13][14][15] The impact strength of PP irradiated in air also decreases and the shear modulus may show a drop due to the building of branches. [16][17][18] PE undergoes predominantly cross-linking.…”