Algal extracts – The appropriate stabilizers for radiation processed UHMWPE

Abstract

The present paper presents the stabilization effects of commercially available algal extracts of Chlorella vulgaris, Spirulina platensis and Ascophyllum nodosum added in UHMWPE matrices at the concentration of 2 wt%. The chemiluminescence assay reveals the high efficiency of active antioxidant components in γ-radiated materials after their exposure at 25 and 100 kGy in respect with pristine polymer. The main kinetic parameters depicting the progress of degradation, as well as the stabilization efficiency: onset oxidation temperature, oxidation induction time and oxidation rate are taken into consideration for the evaluation of protective activities. While the unirradiated neat ultra-high molecular weight polyethylene (UHMWPE) is degraded four times faster than the stabilized samples, all the modified polymer samples keep their exceptional oxidation resistance after the γ-exposure even at 100 kGy. The application of technological dose of 100 kGy maintains constantly oxidation endurance even at high operation temperature exceeding 200 °C. The extension of antioxidant features over the large dose range recommends the tested algal extracts safety usage compounds for the protection of various classes of polymer applied working in several conditions such as UV exposure during food handling, γ-sterilization, outdoor corrosion protection and insulation, sealing products for the security of fluid loops as functional units in nuclear power plants. The reported antioxidant evidences for the stability improvement of UHMWPE may be generally applied for all polymer formulations based on the oxidation protectors provided by nature.