Effect of bubbles on the surface of sample on the measurement of plastic particle density tester

Plastic particle density tester to measure the density of plastic particles, the most widely used in rubber, plastic and other industries, but in the measurement often encounter small bubbles on the surface of the sample, many people do not care about such a phenomenon, in fact, attached to the surface of the bubble on the sample density measurement results is quite large.
Why emphasize the effect of air bubbles on the density of plastic particles?
1. Measuring the density of plastic particles, accumulated experience for a long time.
2. Because the measurement plastic is the product of the petrochemical industry, the surface of the particles are all with oil composition.
Because of the surface tension of water, it is easy to attach bubbles.
3. Plastic particles in the process of mixing melting → production strip → cut into particles about 0.3cm×0.8cm, easy to make plastic particles exist pores, easy to attach bubbles.
It causes poor reproducibility when testing plastic particles.
4. Air bubbles attached to plastic particles.
According to the research report:
· A bubble with a diameter of Φ0.5mm will cause a buoyancy of less than 0.0001g;
· A bubble with a diameter of 1mm will generate a buoyancy force of 0.005g;
· A bubble with diameter of 2mm will generate a buoyancy force of about 4.200g.
How to reduce the bubbles attached to the surface of the sample when measuring with a plastic particle density tester?
Need to understand the principle of bubble generation, as long as we need to measure the sample in the sink before dipping in absolute alcohol, dissolve its surface oil, can be very effective removal of surface bubbles