Relationship between PVC cable temperature and cable laying temperature

SAN PEDRO, Belize - March 23, 2021 - PRLog -- The brittleness temperature is a measure of the mechanical behavior of plastics at low temperature. When the impact hammer with certain energy is used to impact the specimen, the temperature when the cracking probability of the sample reaches 50%, i.e. the brittleness temperature. It can also be understood as the dividing point between the glass state and the high elastic state, which is lower than the embrittlement temperature, the molecular chain segment loses its activity and is in a rigid and fixed state. The fracture under stress is brittle fracture, and the elongation is almost zero.

According to GB / T 5470-2008 test method for impact embrittlement temperature of plastics, it can be known that plastics need to be bent at low temperature with or without impact in various applications. The brittleness of polymer is affected by orientation, thermal history, the force exerted on the material during impact, especially the speed of force application. When the applied deformation conditions are similar to those specified in the test method, the embrittlement temperature can be used to predict the low-temperature behavior of plastic materials. The brittleness temperature test is used to measure the temperature at which a polymer loses its toughness in a "glassy" state.

The relationship between the minimum installation temperature of cable and the low temperature embrittlement temperature of PVC cable material is definitely inseparable. However, there is no authoritative report on the corresponding relationship. Generally speaking, when the brittleness temperature is higher than 5 ℃, the cracking probability of impact specimen is zero. Theoretically speaking, if the impact force of installation and laying is less than the test impact force, it can be constructed. However, it involves various cable models and construction specifications as well as the support of practical test data.

If we want to really understand the relationship between the installation and laying temperature and the low temperature embrittlement temperature of materials, it is a relatively large research topic. We need to take samples from materials, cables, construction (or imitation construction) and other links to systematically find out the critical point of failure, which requires a lot of financial and material resources and human resources. On the other hand, once it is clear, it will be a great feedback to the enterprise.

If there is no authoritative data support, the installation and laying temperature shall be given according to GB / T12706 standard, which is 20 ℃ higher than the sheath embrittlement temperature. Although the installation temperature difference of 20 ℃ is not so accurate and the safety margin is very large, the cracking quality problem will not occur due to the construction temperature. The difference of 15 ℃ is acceptable for installation and laying temperature, but the cable type and construction must be strictly controlled.

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