Assessment of polyethylene stability using the standardized OIT procedure by DSC method

摘要

The standardized procedure for determination of oxidation induction time(OIT)using the differential scanning calorimetry(DSC)method has been described.A Perkin-Elmer DSC7 instrument was used and it was calibrated with indium and tin certified reference materials(CRMs).Measured values of melting temperature were consistent with the certified values within ±0.3 °C.The procedure was validated using commercially available PE samples.Relative standard deviation(RSD)values were calculated and compared with the published data.The values obtained were lower than those quoted in literature for particular PE grades.Then chemically modified(grafted)PE matrices and composites with a flame retardant filler were investigated.OIT values were measured at various temperatures and the optimum measurement temperature for modified PE composites was determined.It was equal to 220 deg C as compared with 200 deg C for unmodified PE.Thus,it has been found that the thermal stability of investigated composites in thermooxi-dative degradation conditions is higher than that of unmodified PE material.