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The so-called embrittlement temperature (brittle temperature) refers to a measurement of the mechanical behavior of plastics at low temperatures. In the case of a hammer with certain energy, the temperature of the specimen when the crack probability reaches 50%, namely the embrittlement temperature.
It can also be understood as the boundary point of glass state and high elastic state, below the brittle temperature, the loss activity of the molecule chain is in a rigid fixed state, the fracture of the force is brittle fracture and the elongation is almost zero. In the gb∕t 5470-2008 "Plastic impact embrittlement Temperature test method" You can know that plastic in a variety of uses under the condition of withstanding or not under the impact of low-temperature bending. The orientation, the history of heat, the force exerted on the material when the impact is applied, especially the velocity of the force will affect the brittleness of the polymer. The embrittlement temperature can be used to predict the low-temperature behavior of plastic materials when the applied deformation conditions are similar to those stipulated in the test method.
The embrittlement temperature test is used to measure the loss toughness of polymers with a "glassy" temperature. The minimum installation temperature of the cable is inseparable from the low-temperature embrittlement temperature of the PVC cable material. However, there is no authoritative report yet on the corresponding relationship. In general, the probability of cracking of impact specimen is zero when the embrittlement temperature is 5 ℃. Theoretically speaking, if the impact of the installation is less than the test impact of the case can be constructed.
But it involves a variety of cable models and construction code and the practice of testing data support. If you want to really understand the relationship between the installation temperature and the low-temperature embrittlement temperature of the material, is a relatively large research topic, from materials, cables, construction (or imitation construction) and other aspects of sampling test, systematically find the critical point of destruction, which requires a lot of financial and material resources and human support.
Conversely, once made clear, to the enterprise is a very big feedback. If it is true that there is no authoritative data support, the gb/t12706 standard is higher than the sheath embrittlement temperature of 20 ℃ as the basis for a given installation of the laying temperature. Although with a difference of 20 ℃ for installation and laying temperature is not so accurate, very safe margin is very large, but will not be due to the construction temperature and crack quality problems. The difference of 15 ℃ is also possible to install the installation temperature, but the cable model and construction must be strictly controlled.