Study On Polyethylene Micro Crosslinking Technology And Its Application In New Product Development

With the development of national economy,polyolefin materials have replaced many traditional materials,but there are still performance limitations.The micro crosslinking modification of polyolefin materials has received much attention since it can produce crosslinking structure to improve molecular structure and the performance of polyolefin products.The control of its crosslinking degree can maintain good processing performance so that it can be recycled for processing and utilization.In this paper,high-density polyethylene(HDPE)with low degree of crosslinking was prepared by peroxide crosslinking reaction in a twin-screw extruder.In this paper,the effect of peroxide content on the properties and structure of HDPE was studied.The results show that both degradation and cross-linking reactions are involved in the polyethylene reaction process.With the addition of low peroxide content,the weight average molecular weight of polyethylene decreases,the molecular weight distribution narrows,the melt index increases,the crystallinity increases,and the mechanical properties decrease.When the content of crosslinking agent is higher than a certain degree,the system shows the characteristics of crosslinking reaction.The weight average molecular weight becomes larger,the high molecular weight part increases,the molecular weight distribution becomes wider,the melt index becomes smaller,the crystallinity becomes smaller,and the mechanical properties improve.Secondly,the effect of antioxidant content on the micro crosslinking reaction was studied.Antioxidant can alleviate the degradation of HDPE in the process of hot processing.However,the crosslinking reaction will be delayed and the degree of crosslinking will be reduced when the amount of antioxidant is large.At last,the influence of crosslinking aids on the micro crosslinking reaction was studied.After adding crosslinking aids,the system needed less peroxide,the weight average molecular weight increased,the crosslinking reaction dominated the system,the crystallinity of HDPE decreased due to the change of structure,the storage modulus were significantly improved under low-frequency shear,and the mechanical properties were improved.The optimal ratio of crosslinking agent and crosslinking agent is 1:1.