On the Abrasion of Plastics

Abstract

The formula on the abrasion of plastics has been derived from the scratch hardness test as follows;
V=β.P.l.η……(1)
where V is the total abrasion volume, β abrasion coefficient and represented by the term, (α/4H_ccotθ/2·n²), P vertical load on the abrasion surface, l abrasion distance, and η abrasion efficiency. And H_c is the scratch hardness number, α, cotθ/2 and n² are the constants peculiar to each material and determined by the figure of scratched groove.
It has been proved that the formula (1) nearly corresponds to the results of the actual abrasion test which was carried out by using ASTM type's abrasion tester for several plastics, such as phenolic, polyester, acrylic, polystyrene, polycarbonate and nylon.
Generally, hardness number H_c of thermosetting plastics is greater than that of thermoplastic material, but the values of the above constants, such as α, cot θ/2 and n², for the thermosetting plastics are so greater than those for thermoplastic material, that the value of abrasion coefficient β for thermosetting plastic becomes greater than that for thermoplastic material.
The effect of the grain size of abrasive Al₂O₃ on the abrasion efficiency, and of the relative speed between the surface of test piece and abrasive on the abrasion efficiency are also experimentally discussed respectively.