Properties of Vulcanized Polyisoprene Rubber Composites Filled with Opalized White Tuff and Precipitated Silica

Table 2

Formulation of the composites based of NR/PS and NR/OWT characteristics.

Sample	Compounds (phr)^a
	NR/PSi	NR/OWT	ZnO	Stearic acid	Vulkacit DM^b	Vulkacit D^b	Sulfur
1	100/50	—	2.5	1.4	2.5	0.1	1.4
2	—	100/20	2.5	1.4	2.5	0.1	1.4
3	—	100/40	2.5	1.4	2.5	0.1	1.4
4	—	100/50	2.5	1.4	2.5	0.1	1.4
5	—	100/60	2.5	1.4	2.5	0.1	1.4

aParts per hundred; ^baccelerators Vulkacit DM-2-benzothiazol-2-yldisulfanylbenzothiazole, Vulkacit D-diphenyl guanidine.