High-strength hydraulic-pressure-resistant polyethylene pipe and preparation method thereof

Abstract

The invention discloses a high-strength hydraulic-pressure-resistant polyethylene pipe. Conventional polyethylene and micro-crosslinked polyethylene are mixed and then molten and extruded under the rotation of a mandrel or / and a mouth model in a polymer tube rotary extrusion device; a prepared extruded pipe is 10.8 to 16.12MPa in annular strength under the condition of 20 DEG C static hydraulic pressure, and is 5.52 to 7.15MPa in annular strength under the test condition of 80 DEG C static hydraulic pressure; the time to failure at 100 to 200 percent of the standard time to failure is 100 to 200 hours, and the time to failure at 120 percent and 130 percent of standard pressure is 100 to 400 hours. The small amount of micro-crosslinked polyethylene is added in the conventional polyethylene,and thus the relaxation time of a polyethylene molecular chain in a molten state is prolonged greatly, so that an orientation structure in the polyethylene pipe prepared by rotary extrusion is effectively cooled and molded before relaxation, and more deviated axially-arranged shish-kebab with larger deviation angles are formed, thereby greatly improving the annular strength and static hydraulic pressure resistance of the polyethylene pipe.

Description

technical field [0001] The invention belongs to the technical field of polyethylene pipes and their preparation, and in particular relates to a high-strength hydrostatic-resistant polyethylene pipe and a preparation method thereof. Background technique [0002] Polymer pipes, especially polyethylene pipes, have excellent comprehensive properties, such as low density, low flow resistance, corrosion resistance, easy installation, easy connection, etc., and are widely used in the fields of gas transmission, water transmission, and agricultural irrigation. At present, my country's polymer pipe processing has become one of the country's important pillar industries. In 2015, my country's polymer pipe production exceeded 13 million tons, becoming the country with the largest polymer pipe production in the world. 9% growth rate is growing. [0003] There are some inherent defects in polyethylene pipes produced by traditional extrusion methods: after the melt flows through the shunt ...

AI Technical Summary

Problems solved by technology

[0003] There are some inherent defects in polyethylene pipes produced by traditional extrusion methods: after the melt flows through the shunt shuttle, weld marks will be formed on the formed pipe, and these weld marks will become weak points under high fluid pressure, causing the pipe to undergo circumferential damage; Due to the structure of the conventional melt extrusion device, the extrusion direction and stretching direction of the material are both along the axial direction, and the molecular chains in the pipe are also oriented along the axial direction, so that the polymer pipe has high axial strength and low hoop strength. ;The spray cooling device used can only spray and cool the outer wall of the polymer pipe, resulting in uneven cooling rate of the inner and outer walls of the pipe, resulting in a large internal stress inside the PE pipe, which is easy to cause internal defects in the polymer pipe and reduce its mechanical properties. strength

Obviously, such performance cannot fully meet the actual use requirements of polyethylene pipes

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