Effect of melt index instrument extruded strips on polypropylene oxidation induction time
Using a differential scanning calorimeter,the oxidation induction time of three different types of polypro-pylene particles and melt index extruded strips were measured under the same conditions,verifying that the oxida-tion induction time measured by the strips was smaller than that of polypropylene particles.This is because the ma-terial extruded by the melt index meter has undergone partial oxidation at 230 ℃.Compared with the corresponding polypropylene particles,the material has consumed some of the antioxidants in the original particles during the measurement of melt index.In addition,the strip is still in a high-temperature molten state afterflowing out of the mold and is directly exposed to the air,which is more likely to cause oxidation of antioxidants.Therefore,the an-tioxidant performance of the index strip itself decreases,resulting in a shorter oxidation induction time measured by the strip.Therefore,in actual production,directly using polypropylene particles for measurement can more accu-rately reflect the antioxidant performance of polypropylene products,or the manufacturer and user can jointly negoti-ate and determine the temperature conditions and sample morphology of the test to avoid deviation in results caused by different test forms.
Differential scanning calorimeterPolypropyleneOxidation induction time
万方数据
维普
