The Properties of Pipes Produced under the Conditions of Spiral Flow

Deberdeev, R. Ya.; Zuev, B. M.; Bezruk, L.I.; Bortnikov, V. G.; Кузнецов, Е. В.; Vinogradov, G. V.

doi:10.1080/00914037408072352

Cited by 13 publications

(4 citation statements)

References 2 publications

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“…Hence, it is of great importance to adjust the orientation of molecular chains or GFs and prepare pipes with improved hoop strength. Up till now, many efforts have been devoted to achieve this goal, among which rotation extrusion has attracted much attention because of its simple equipment and easy implementation.…”

Section: Introductionmentioning

confidence: 99%

The influence of hoop shear field on the structure and performances of glass fiber reinforced three‐layer polypropylene random copolymer pipe

Deng

Jin

Zhao

et al. 2018

J of Applied Polymer Sci

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Three-layer pipe has many advantages over single layer one, especially for the pipe of glass fiber (GF) reinforced materials. But the hoop strength of the pipe produced via convention extrusion is poor because GFs orient along axial direction. In this work, a self-designed rotation extrusion system was adopted to extrude GF reinforced three-layer polypropylene random copolymer (PPR) pipe, in which a hoop shear field was applied to the polymer matrix and fibers in the middle layer. The structure and performance of pipes were investigated via scanning electronic microscope (SEM) and synchrotron two-dimensional wide-angel X-ray diffraction (2D-WAXD). Due to the hoop shear field, the orientation of GFs in middle layer deviated from axial direction. As a result, PPR pipes with enhanced hoop tensile strength were obtained. Because of the three-layer structure and the production process, the molecular chains of middle layer did not emerge distinct orientation after rotation shear, as shown in 2D-WAXD and SEM experimental results. This three-layer pipe rotation extrusion system offers a novel method for the modification of pipes in manufacture industry.

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Section: Introductionmentioning

confidence: 99%

The influence of hoop shear field on the structure and performances of glass fiber reinforced three‐layer polypropylene random copolymer pipe

Deng

Jin

Zhao

et al. 2018

J of Applied Polymer Sci

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show abstract

“…1,2 However, in the convention extrusion of PE pipes, due to the strong axial drag force of traction device, the molecules orient along the axial direction and subsequently the formed shish-kebab crystals also parallel to the axial direction, 3,4 so the axial performance of the pipe is much higher than the hoop. 10,12 However, the previous studies focused on mandrel rotation extrusion where the inner layer of the pipe rotated together with the mandrel while the outer layer remained stationary, so the hoop stress imposed by the mandrel rotation was gradually decreased from the inner to the outer layer. 5 Up to now, many efforts have been devoted to improving PE pipe's resistance to SCG and many technologies also have been developed, such as the solid deformation processing, 6 die-drawing, 7 vibration extrusion, 8 rotation extrusion, [9][10][11] etc.…”

Section: Introductionmentioning

confidence: 99%

Control of rotation extrusion over shish‐kebab crystal alignment in polyethylene pipe and its effect on the pipe's crack resistance

Nie

Wang

2012

J of Applied Polymer Sci

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A self-designed rotation extrusion system was adopted to extrude polyethylene (PE) pipe. The experimental results showed that when the mandrel and die rotated in the same directions during the PE pipe extrusion, apart from the axial stress, all polymer melts in PE pipes were also subjected to the hoop stress so that the formed shish-kebab crystal in the whole pipe deviated from the axial direction greatly, which was further fixed by the double cooling on both inner and outer walls. As a result, the PE pipe with better resistance to slow crack growth was prepared. As compared to the PE pipe produced by the convention extrusion, the crack initiation time of the PE pipe manufactured by the novel method increased from 27 to 174 h, by 544%.

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“…Therefore, it is expected that increasing the molecular orientation in the hoop direction may improve the PE pipe's performance. Up to now, many approaches are available to change the molecular orientation in the plastic pipe to prepare the high‐performance PE pipe, such as the solid deformation processing [7], die‐drawing [8], vibration extrusion [9], rotation extrusion [10–12], etc.…”

Section: Introductionmentioning

confidence: 99%

Morphology and property of polyethylene pipe extruded at the low mandrel rotation

Nie

Wang

Bai

2010

Polymer Engineering & Sci

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During the rotation extrusion of polyethylene (PE) pipes, with the rotating mandrel, compressed air as a cooling medium was introduced through their interior to achieve the quick cooling of the inner wall. The experimental results showed that the hoop stress exerted by mandrel rotation could promote the molecular orientation in the hoop direction; moreover, the introduction of compressed air could quicken its inner wall's cooling rate so as to slow down the relaxation of the oriented molecule and to reserve the orientation structure. Therefore, the hoop orientation degree increased with the increasing inner wall's cooling rate. As a result, the performance of the PE pipe was greatly enhanced. The hoop tensile strength of the PE pipe produced by the novel extrusion method increased from original 24.1 MPa up to 35 MPa; the pipe's crack initiation time increased from 27 to 60 h and the crack growth rate slowed down.

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The Properties of Pipes Produced under the Conditions of Spiral Flow

Cited by 13 publications

References 2 publications

The influence of hoop shear field on the structure and performances of glass fiber reinforced three‐layer polypropylene random copolymer pipe

The influence of hoop shear field on the structure and performances of glass fiber reinforced three‐layer polypropylene random copolymer pipe

Control of rotation extrusion over shish‐kebab crystal alignment in polyethylene pipe and its effect on the pipe's crack resistance

Morphology and property of polyethylene pipe extruded at the low mandrel rotation

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