The concern with the faster curing compound is the scorch time
. The predicted results for the Mooney scorch test at 121[degrees]C shows that the faster curing case has a t5 that is 55% of the control.
The scorch time
([T.sub.s]), cure time ([T.sub.90]), maximum torque ([S.sub.max]), and minimum torque ([S.sub.min]) of the gum NR and RHF/NR composites were determined.
Several literature reports show that the reaction of nitroxides and its derivatives with carbon-centered radicals can be a novel way to increase the scorch time
and control the cure reactions by peroxide crosslinking , Although the scorch safety with DCP increases in the presence of TEMPO nitroxide, (DCP + TEMPO)-cured PDMS still suffers from the bad odor due to the faster decomposition of DCP at high temperatures.
(d) Scorch time
(tS5) which is a measure of the time at which vulcanization begins.
In addition, the product is designed to enable increased manufacturing rates at cable manufacturers, improving productivity due to an approximately 15% boost in scorch time
and 9% boost in cure level.
The cure characteristics which include the minimum torque ([M.sub.L]), maximum torque ([M.sub.H]), scorch time
([TS.sub.2]), optimum cure time ([T.sub.90]) and curing speed index (Vc) were determined using a rotorless rheometer (MR-C3 Beijing RADE Instrument Co.Ltd) at 160 [+ or -] 2 [degrees]C for 10 minutes.
In this present work, the effect of WFA loading on mooney scorch time
, swelling behavior, hardness and resilience of natural rubber is reported.
1 2 3 4 5 Rheometric characteristics at 142[degrees]C [+ or -] 1[degrees]C Minimum torque, [M.sub.L], dN 1.5 1 1 1 1.5 x m Maximum torque, [M.din.H], dN 64 66 66 70 68 x m Optimum cure time, 18 15 15 12 12 [t.sub.c90], min Scorch time
, [t.sub.s2], min 8 6.5 5 5 6 Cure rate index, CRT, 10 11.76 10 14.29 16.67 [min.sup.-1] Physicomechanical properties at the optimum cure time Stress at yield, 20.4 22.3 22 25.36 23.23 [[sigma].sub.B], MPa Stress at rupture, 19.3 21.2 21.8 25.11 23.11 [[sigma].sub.R], MPa Strain at yield, 496 530 525 645 539 [[epsilon].sub.B], % Strain at rupture, 503 540 530 647 541 [[epsilon].sub.R], % Equilibrium swelling, Q% 325 270 259 225 232 Property Formulation no.
The minimum and maximum torque, cure time, compression set, hardness, swelling index, swelling coefficient, mol percentage uptake of solvent increases with increasing the amount of reclaim rubber but tensile, strength, elongation at brake, rear strength, resilience, scorch time
and volume fraction of rubber vulcanizate decreases.
Oscillating disk rheometers can provide useful data points such as scorch time
, T90, and maximum torque.
The scorch index is the scorch time
consumed and is taken mostly as 50% reduction of scorch.
As such, these additives are usually characterized by a scorch time
, [t.sub.10%], defined as the time needed for a cure formulation to reach 10% of its ultimate storage modulus change.