PPR Polypropylene is short for Random, chemical name was called Random copolymerization Polypropylene, which is usually said Ⅲ type Polypropylene. It is composed of propene monomer and a small amount of ethylene monomer (3%-5%), which are randomly copolymerized under the action of heating, pressure and catalyst.

Temperature - deformation curve of amorphous polymers As a high polymer, PP-Polypropylene, its toughness is greatly affected by temperature and loading speed. When the temperature is higher than the vitrification transition temperature, it also shows a ductility fracture after impact failure, while when it is lower than the vitrification transition temperature, it also shows a brittle fracture. When the temperature is lower than the vitrification transition temperature, the impact force required for brittle fracture of polymer materials will be greatly reduced. It is worth mentioning that the vitrification transition temperature of different materials is not the same, and PPR material this temperature is relatively high, so its low temperature resistance performance is relatively poor, which is the reason why PPR water pipe is not impact resistant at low temperature. The composition of PPR is given priority to with acrylic monomers, the introduction of a small amount of ethylene monomer (polyethylene PE low glass transition temperature of the polypropylene PP) has taken a hit against performance has improved, but the introduction of the vinyl will influence on the performance of the PPR high temperature resistant, for home use water pipe, and must have a high temperature of hot water resistance, so it is a contradiction, on the technology itself is a bad problem.

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It is absolutely a mistake to judge the quality of PPR water pipe by cracking, because we know that cold brittleness is the inherent property of PPR water pipe raw material, and its quality can not be judged by whether it can be broken.So the question is, are those indestructible pipes good? What we can conclude is that the broken pipe must not be authentic PPR pipe, we know the low temperature toughness of PE is stronger than PPR, if it is the use of PE pipe pretending to be PPR pipe, the pipe must be resistant to damage, but PE pipe is not able to transfer hot water, generally only do cold water pipe use, detailed can refer to the national standard "GB/T13663-2000". On the other hand, it is worth warning that, in order to blindly improve the low temperature toughness of PPR pipe, we can not know what materials are added inside the pipe. So a pipe that doesn't break is not necessarily a good pipe. 。

As for how to prevent the cold brittle fracture of PPR pipe, in fact, the national standard GB/T50349-2005 has already made clear requirements. In the specific operation process, attention should be paid to: PPR pipe is strictly forbidden to be thrown, dropped, rolled or dragged in the process of handling. The position of the pipe should be marked after dark application, so as not to damage the pipe after secondary decoration. Pipe requirements stored in warehouse and simple huts, and stacking height can't more than 1.5 m; Pipeline before cutting, such as found that stress caused by the external force factors white phenomenon of pipe material, should avoid to use; The pipe after installation in the directly buried and straight tunnel must test before apply. The test pressure of the cold water pipe is 1.5 times of the working pressure of the system, but shall not be less than 0.9mpa; The test pressure of the hot water pipe is 2 times of the working pressure, but not less than 1.2mpa. Cold brittleness is the inherent material characteristic of PPR, which is unavoidable, which is why outdoor installation of PPR pipe should be equipped with insulation sleeve. After we understand its principle, we should pay attention to avoid the PPR pipeline damage caused by cold brittleness and violent construction.