Evaluation of Some Conducting Polymers as Novel Antioxidants for Rubber Vulcanizates

Table 4

Rheometric characteristics and physico-mechanical properties of SBR vulcanizates containing the prepared homopolymers and copolymers.

Property	Formulation no.
	1′	2′	3′	4′	5′	6′	7′	8′	9′
Rheometric characteristics at 152±1°C
Minimum torque, 𝑀𝐿, dN·m	13	12	12	11	11	11	11	11	12
Maximum torque, 𝑀𝐻, dN·m	65	69	65	74	72	79.5	71.5	69	69
Optimum cure time, 𝑡𝑐90, min	25	22.5	24	18	18	17	19	21	23
Scorch time, 𝑡𝑠2, min	5.5	5.0	6.0	4.0	4.0	3.0	4.5	5.5	5.5
Cure rate index, CRT, min^−1	5.13	5.71	5.56	7.14	7.14	7.14	6.9	6.45	5.71
Physicomechanical properties at the optimum cure time
Stress at yield, 𝜎𝐵, Pa	15.28	17.2	17.58	24.4	22.35	26.12	21.8	19.5	18.86
Stress at rupture, 𝜎𝑅, MPa	15.01	16.34	17.06	23.83	21.4	25.8	20.2	18.47	17.2
Strain at yield, 𝜀𝐵, %	325	368	370	451	430	480	423	410	380
Strain at rupture, 𝜀𝑅, %	338	372	375	460	444	483	420	417	383
Equilibrium swelling, Q%	335	318	283	240	251	234	259	268	275