PTFE, PFA, FEP, PVDF Fluoroplastic products industry experts
Interpretation of main detection indexes of PTFE products
Classification:
Industry dynamics
Author:
PTFE tube little sister
Source:
PTFE tube little sister
Release time:
2018-04-26
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PTFE products are a special variety of plastics, and other plastics are quite different. According to the industry standards of the Ministry of Light Industry, PTFE products produced must meet the requirements of the indicators. Below we list the definitions of 13 main detection indicators of PTFE products for reference.
1. The coefficient of linear expansion indicates the degree of expansion or contraction of the material, which refers to the expansion ratio of the finished PTFE plastic product at a temperature increase of 1 ℃ under a certain pressure, which is expressed as the coefficient of linear expansion relative to the unit length. This coefficient is one of the important indicators to understand the degree of change in the size of PTFE products with the increase of temperature, and is expressed in units of 1/℃ or 1/K. The linear expansion coefficient formula is α = ΔL/(L * ΔT), where ΔL is the change in the length of the object under the given temperature change ΔT, and L is the initial length. The linear expansion coefficient of PTFE is about 10-12*10-5/℃ (ambient temperature 25-250 ℃), I .e. (0.01-0.012)%, and the linear expansion coefficient of PTFE is 10-20 times that of iron, which is larger than most plastics.
2. Thermal conductivity: Also called thermal conductivity, it reflects the thermal conductivity of the material. It is defined as taking two parallel planes with a distance of 1 meter and an area of 1 square meter perpendicular to the heat conduction direction inside the object. If the temperature difference between the two planes is 1K, the heat conducted from one plane to the other within 1 second is defined as the thermal conductivity of the substance, and its unit is Watt-m-1-1(W m-1-K-1). It is a reference index for studying the thermal insulation of the target product when designing the product.
3. Tensile strain at break is the tensile strain corresponding to the tensile fracture stress when the PTFE product sample breaks without yielding under the action of tensile load. It is the ratio of the difference between the length of the sample material and the original length when it just becomes plastic and the original length to the original length, expressed in percentage (%).
5. Tensile strength: In the tensile specimen test, the critical value of the transition from uniform plastic deformation to local concentrated plastic deformation characterizes the resistance of the material to the maximum uniform plastic deformation, and is also the maximum bearing capacity of the plastic under static tensile conditions (Maximum tensile stress). The unit is MPa.,
6. Elongation at break: is the increment of the index from the original unit length (I. e. the change rate of the length), and is the ratio of the difference between the length and the original length at break to the original length, expressed as a percentage (%).
7. Electrical strength: a parameter that indicates the breakdown of equipment insulation under a certain rated voltage, indicating the degree of insulation of the product. Under certain conditions, the ratio of the breakdown voltage to the thickness of the sample is the electrical strength of the product.
8. Breakdown voltage: The voltage at which the test piece breaks down is the highest voltage before it is subjected to breakdown. That is, the sample does not break down at this voltage. Breakdown is usually caused by a partial discharge in a gas or liquid medium around the sample and the electrodes, and results in the destruction of the sample at the edge of the smaller electrode (or two electrodes of equal diameter).
9. Density The ratio of the mass of a substance to its volume, that is, the mass of a substance per unit volume, is called the density of the substance. Kg/m3 or 1g/cm3 1.0 × 10 ³ kg/m³ PTFE plastic products are usually tested by immersion method, liquid pycnometer method and titration method.
10. The withstand voltage is the withstand voltage of the sample between the electrodes, and the voltage before the power frequency AC voltage rises to breakdown is the withstand voltage of the sample.
11. Fracture nominal strain refers to the tensile strain corresponding to the fracture stress when the tensile specimen is not yielding and breaks, expressed as a dimensionless ratio or percentage.
12. The longitudinal dimensional change rate refers to the percentage of the difference between the length of the treated sample and the original size and the ratio of the original size to the original size of the cut-off pipe (100 ±1) placed in the oven (260±2 ℃) for 3 hours, taken out and placed at room temperature at 23±2 ℃ for 4 hours.
13. Dielectric strength is a measure of the electrical strength of a material as an insulator. It is defined as the maximum voltage per unit thickness when the sample is broken down, in volts per unit thickness. That is, the ratio of breakdown voltage to sample thickness. The breakdown voltage is tested with reference to GB/T1408.1-2006, and the dielectric strength is in kilovolts per millimeter (KV/mm).
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