Study On Orientation Structure And Mechanical Properties Of UHMWPE/HDPE Extruded-stretched Sheets

This experiment focuses on the research of the morphology and mechanical propoties of the relatively low molecular HDPE and HDPE with small amount of UHMWPE under the action of tensile.lt is found that under some processing conditionS，UHMWPE can induce the oriention crystalline structure significantly.The work and main result are summarized as follows:1. When drawing the HDPE sheets at different tempreture and drawing rate. The results showed:under the same drawing rate, with the decreasing of drawing tempreture, the degree of oriention and the crystallinity of HDPE sheets increases.However, under the same drawing tempreture, with the decreasing of drawing rate, the degree of oriention increases and then decreases.2. Compared to the pure material system (HDPE), When the drawing tempreture is high(210℃,190℃), the effect of UHMWPE to induce the oriention crystalline structure is significant. However when the drawing tempreture is low(170℃), the whole degree of oriention is much less than pure HDPE under the same experiment conditions.3. Tension tests of sample at environment tempreture of100℃show that after adding UHMWPE, the mechanical properties of the stretching sheets under higher melting tempreture(210℃,190℃) were improved significantly however the mechanical properties of the stretching sheets under lower melting tempreture(170℃) were decreased when compared to the pure HDPE, this result match the degree of orientation from above. So we can conclude that the formation of orientation is the key factor to improve the mechanical propoties of samples.This work vertify the oriention induced effect of the long molecular chains of UHMWPE and found that the disentanglement and orientation of the macromolecule is the key actor of the orientation induced crystallization which can promote the mechanical propoties on the orientation direction.