We evaluated ice skid number of BPST and reinforcing properties of each 20 phr leather powder blended rubber compounds using E-SBR or NR65/BR35 for polymer to compare with S-SBR.
And we confirmed that this improvement of stopping distance index by 20phr leather powder blend is 10%, and almost the same degree with the improvement rate of ice skid number of BPST in laboratory.
Regarding a general rubber compound, ice skid number of BPST was analyzed by its complex modulus and the thickness of liquid like layer on ice for the factors of effective contact area, and its loss modulus for the factor of hysteresis loss.
So we tried to investigate some materials being able to improve the ice skid number of BPST, even if the liquid like layer exists on ice.
The 20phr leather powder blended rubber compound had the maximum ice skid number of BPST and improved it by 10% 7% compared with rubber compound at the temperature region from 0 [degree] C to -5 [degrees] C which has liquid like layer on ice and is most slippery state.
The just combination blend of leather powder and S-SBR showed the superior ice skid number of BPST and reinforcing properties.
The tread of S-SBR compound blended with 20phr leather powder showed the improvement of stopping distance index by 10% in an actual tire test on ice and this was almost the same degree with the improvement rate of ice skid number of BPST in laboratory.
5mm by freezing distilled water dynamically, repeating to slide the test piece of standard rubber compound using BPST at a temperature of -20 [degrees] C because of getting the smooth ice surface with strong and uniform crystal structure.
Skid resistances of rubber compounds were also measured on the smooth surface of PTFE by BPST at each temperature from 0 [degree] C to -20 [degrees] C to evaluate the skid resistance on dry condition.
We measured ice skid number and PTFE skid number of BPST to analyze each factors of effective contact area and hysteresis loss affecting the friction of a rubber compound on ice.
So, including the factors of E* of the rubber compound and the thickness of liquid like layer which changes depending on lowering temperature, we can propose equation (3) and equation (4) transformed from equation (2) for the factors affecting the ice skid number of BPST of the rubber compound.
3) BPST Ice - 1 = aFco(E*) + bFco(1/Lt) + cFh(E") + [W.