Innovative Application of Biopolymer Keratin as a Filler of Synthetic Acrylonitrile-Butadiene Rubber NBR

Table 3

The influence of keratin on the rheometric properties of NBR mixes.

Parameters	Symbol
	Standard	Sample I	Sample II
𝐿𝐿—minimal of torque moment [dNm]	14,7	12,7	13,9
Δ𝐿—the decrease of torque moment
Δ𝐿=𝐿HR−𝐿𝐿[dNm]	67,0	69,4	70,8
𝜏0,9—time of vulcanization [min]	15	9	7
𝜏0,2—scorch time [min]	3,5	2,9	2,8
𝑎𝑓—filler activity [—]	—	0,72	1,13

(Δ𝐿/Δ𝐿₀)−1=𝑎_𝑓∗(𝑚_𝑓/𝑚_𝑟)
where
 Δ𝐿—the increase of torque moment of mixes with protein
 Δ𝐿₀—the increase of torque moment of mixes without protein
𝑚_𝑓—the weight parts of filler
𝑚_𝑟—the weight parts of rubber.