In order to meet the extensive severity and retreadability during service life of the carcass of a tire, the suitability of HAF black has been explored in laboratory scale.
Since aggregate size or surface area is the primary determinant of reinforcement, a black with larger aggregate size than HAF black was developed based on attaining a level of reinforcement without affecting important tire properties like tensile strength and tear resistance, etc.
The tint for all the HAF blacks is almost in an identical range, showing their uniformity in aggregate size.
In the present study, it varies from 58 to 84 mg/gm for different HAF blacks; and for N660 it is 36.2 mg/gm.
Nitrogen surface areas of the HAF blacks varied from 69 to 77 [m.sup.2]/gm.
As expected, the modulus of HAF blacks (irrespective of IAN value) was higher compared to the N660 grade, irrespective of the formulation used.
Table 1 - filler properties Filler BET Primary Characterization [m.sup.2]/g particle diameter (nm) Seast(*) KH 93 24 HAF black
Seast 6 117 22 ISAF black Seast 9 142 19 SAF black Ultrasil VN-2G(**) 125 20 precipitated silica Ultrasil VN-3G 175 17 precipitated silica Nipsil AQ(***) 200 16 precipitated silica