HDPE pipes has been used for nearly half a century. From the first water pipes to gas and other fields; initially low-density polyethylene (LDPE) was used, then high-density polyethylene (HDPE) and medium-density polyethylene (MDPE).
are widely used in municipal engineering. High-density polyethylene HDPE raw materials came out in 1956. Due to the insufficient technical level of plastic products at that time, there was no mature HDPE plastic products, and it was not widely used until later. PE has excellent resistance to most household and industrial chemicals. PE tube is a translucent packaging material with high crystallinity, white powder or granular, non-toxic, tasteless, and high hardness.
The first generation of HDPE pipes grade resin comonomer content is very low, in order to improve performance, it must be compensated by increasing the molecular weight.
The second-generation resin is the current PE80 material, and the comonomer content is increased on the basis of the first-generation resin. The main disadvantage is that if the ESCR performance is further improved, the pressure resistance of the material will be greatly lost, thereby reducing the pressure level of the extruded tube using this material. On the other hand, if the pressure level is to be further increased, the possibility of brittle failure will increase before 50 years (required life) at 20°C, which is difficult to achieve.
The third generation resin is PE100 which appeared in the late 1980s. PE100 has a bimodal molecular weight distribution, and the comonomer is preferentially located on the longer molecular chain, which makes the third-generation HDPE pipes resin have higher density or rigidity, 20°C, 50 years of creep resistance; while maintaining better Good ESCR performance.