Method for measuring and testing melting and sagging properties of polyethylene

The invention discloses a method for measuring and testing melting and sagging properties of polyethylene. The method includes steps of prefabricating and processing different raw materials to obtain dumbbell-shaped sheets, guaranteeing the dimensional consistency of specimens, arranging marked lines at an end of each specimen, measuring distances LO among the marked lines and recording the distances LO; perpendicularly suspending the specimens in high-low temperature test chambers at constant temperatures, keeping the specimens in the high-low temperature test chambers for a certain period of time, melting the specimens, allowing the specimens to naturally sag and using portions, above the corresponding marked lines, of the end of each specimen as fixture clamping portions; steadily taking the specimens out of the high-low temperature test chambers; measuring distances LO among the marked lines of the specimens after the specimens are completely cooled, and computing dimensional change percentages of the spe