PVC-O pipe, the Chinese name is biaxially oriented polyvinyl chloride, the latest evolutionary form of PVC-O pipe pipe. By using a special orientation process to manufacture the pipe (biaxial stretching technology), the UPVC(M) pipe produced by the extrusion method is used for the axial direction. Stretching and radial stretching, so that the long-chain PVC molecules in the pipe biaxially arranged in order to obtain high strength, high toughness, high impact resistance, crack resistance of the new PVC pipe.
Tensile orientation mechanism of polymer materials
The stretching orientation process of polymer materials is the process of the molecules arranged from disordered to ordered under the action of external force under the condition of temperature between the glass transition temperature and the melting temperature (usually near the softening point). Biaxial stretching is a process in which a material is biaxially stretched to make the strength perpendicular to the the stretched surface of the biaxial stretching that superimposed on the strength of the stretched surface direction, thereby increasing the strength of the material in the direction of the stretched surface.
Ratio and stretching rate
Stretching orientation, in the simplest sense, is to straighten the curled molecular chains and align them in the direction of stretching. Increasing the stretching ratio appropriately increases the degree of molecular orientation and increases the strength of the material. However, excessively increasing the stretching ratio will lead to material damage, In plain terms, the molecular chain of the material is broken and the material is destroyed. In addition, if the stretching temperature is unreasonable, the stretching rate is inaccurate, and the molecular chain will relax during the stretching process, that is, the molecular chain has enough time and ability to return to the original curling state during the stretching process. The degree of orientation is reduced. Therefore, in order to obtain a more ideal degree of orientation, it is necessary to formulate a reasonable stretching temperature and a relatively high stretching rate in accordance with scientific formulas, and the temperature of the drawn material is promptly reduced to below the glass transition temperature. GPM has a complete set of production technology and standardized production processes.
Product Performance Comparison of PVC-O pipe, UPVC(M) and PE
Mechanical properties - impact resistance
PVC-O pipe has better impact resistance than UPVC(M). Especially at lower temperatures, conventional UPVC is brittle below 5°C, and PVC-O does not show this problem. At lower temperatures, the impact resistance of PVC-O pipe is even higher than UPVC at normal operating conditions (temperature > 20oC)。
There is also a difference between PVC-O pipe and PE. "Time" is a crucial factor in this difference: how to "long-term" resist the effects of crack propagation. Since PVC-O has a layered structure, cracks that occur are hardly propagated through the pipe wall, and cracks can be prevented from cracking. Therefore, PVC-O pipe has higher impact resistance. Although some “expensive” PE products that specifically resist cracking have appeared on the market, PE materials still suffer from slow crack growth. Especially the difference in slow crack growth, results in the PVC-O pipe has a lower requirement for backfill material during excavation trench construction (impact resistance is better).
Excellent impact resistance, PVC-O pipe tube can be used in very low temperature environment of -20 °C, excellent anti- point load performance, can be used for non-excavation construction applications.
PVC-O pipe 50 years of long-term life strength up to 50MPA, is twice to the ordinary UPVC(M), is 5 times to the ordinary PE pipe. The PVC-O pipe wall thickness is greatly reduced in application, and then the cost is reduced.
Mechanical property—PVC-O compares to UPVC（M）, has lower bending resistance and higher stretching resistance.
Compared with UPVC and PE pipes, PVC-O pipes have more excellent tensile properties.
PVC-O has much lower carbon emissions than PE and UPVC(M)
Compared to PE and UPVC, PVC-O pipes with the same nominal outside diameter use less material. PVC-O/UPVC uses only 43% non-renewable petroleum fuel, while PE is close to 100%. PE has a much lower carbon footprint than DI, but PVC-O has an advantage (carbon emissions are 35% lower than PE).