PTFE products are a special variety of plastics, which are quite different from other plastics. According to the industry standards of the Ministry of Light Industry, the PTFE products produced must meet the index requirements, and we have listed the definition of 13 main testing indicators of PTFE products for reference.
1.The linear expansion coefficient indicates the degree of expansion or contraction of the material, and refers to the expansion ratio of the finished PTFE plastic product under a certain pressure, when the temperature increases1, and is expressed as the linear expansion coefficient 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 as 1 or 1 K in units. The linear expansion coefficient is formulated as =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), that is, (0.).01-0.012)%, PTFE has a linear expansion coefficient of 10 20 times that of iron, which is larger than most plastics.
2.Thermal conductivity: Also known as thermal conductivity, it reflects the heat conductivity of a substance. It is defined as taking two parallel planes with an area of 1 meter apart and an area of 1 square meter perpendicular to the direction of thermal conductivity in the object, and 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·open-1 (w·m-1·k-1). It is a reference index for studying the thermal insulation of the target product when designing a product.
3.The tensile strain at break is the tensile strain corresponding to the tensile fracture stress when the PTFE product specimen does not yield under the action of tensile load, and is the ratio of the difference between the length and the original length of the sample material when it has just undergone plastic shape and the original length, which is expressed as a 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 rate of change of the length), and is the ratio of the difference between the length and the original length at the time of tension break to the original length, expressed as a percentage (%).
7.Electrical strength: a parameter that indicates the breakdown of the equipment insulation under a certain rated voltage, and indicates the degree of insulation of the product withstand voltage. It means that under certain conditions, the ratio of the breakdown voltage to the thickness of the broken down sample is the electrical strength of the product.
8.Breakdown voltage: The voltage at the time of breakdown of the specimen is the highest voltage before being subjected to breakdown. That is, the specimen does not break down at this voltage. Breakdown is usually caused by a partial discharge in the gas or liquid medium surrounding the specimen and electrodes, and destroys the specimen at the edge of the smaller electrode (or two electrodes of equal diameter).
9.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 this substance. kilogram meters or 1 gram cubic centimeter 10 10 kg m PTFE plastic products are typically tested by impregnation, liquid pycnometer and titration.
10.The withstand voltage is the withstand voltage of the sample before the power frequency AC voltage rises between the electrodes and rises to the breakdown voltage of the sample.
11.Nominal strain at break refers to the tensile strain corresponding to the breaking stress when the tensile specimen breaks without yielding using the specified specimen size, 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 of the difference between the length of the treated sample and the original size of the pipe (100 1) in the oven for 3 hours, and the difference between the length of the treated sample and the original size and the ratio of the original size to the original size for 3 hours.
13.Dielectric strength is a measure of the electrical strength of a material when it acts as an insulator. It is defined as the maximum voltage per unit thickness of the specimen when it is broken down, measured in volts per unit of thickness. That is, the ratio of the breakdown voltage to the thickness of the sample, and the breakdown voltage refers to GB T14081-2006 was tested in kilovolts per millimeter (kv mm).