TPE hardness test on the accuracy of the analysis
1. The influence of sample thickness
Shore A hardness value is determined by the pressure needle pressed into the depth of the sample is measured, and thus directly affect the thickness of the sample test results. Thick samples deformed under pressure, thinned portion under pressure, the hardness value increases. Therefore, the hardness value of a small sample thickness, hardness small sample thickness values.
2. Impact pressure needle length on the test results
Standards set forth in Shore A hardness of pressure needle pressure surface exposed height of 2.5mm, in the free state pointer should refer to zero. When on a smooth metal plate or glass pressure needle, the instrument pointer shall mean 100 degrees, if the indication is greater than or less than 100 degrees, the needle is exposed for crimp height is greater than or less than 2.5mm, or less than 2.5mm, this case should be stopped use, correction. When the pressure is high hardness value is greater than the height of the exposed needle 2.5mm measured.
3. Impact pressure needle end shape of the test results
Pressure needle ends Shore A hardness in long-term effect, lead to wear, geometry changes affect the test results, the end of the larger diameter of the wear and tear of the measured results are also large, this is because the unit area due to a difference in pressure. The small diameter pressure measured hardness value is too large, too small and vice versa.
4. Effect of temperature on the test results
Rubber is a polymer material, whose hardness varies with changes in the environment, high temperatures, the hardness value decreases. Different compounds of different degree of influence, such as the slow crystallization rate of natural rubber, the impact of temperature on smaller, and chloroprene rubber, styrene-butadiene rubber, etc. are significantly affected.
5. Affect the reading time
Shore A durometer readings when measuring a great time on the test results. Indenter and sample readings immediately after compression and stability after reading pointer, the results obtained vary greatly, the former high, which is low, the difference between them up to about 5-7 degrees, especially synthetic rubber test again more significant, primarily makes rubber after compression creep due. So when the sample data compression should be read immediately.
