How much do you know about rubber vulcanizers?
Feb 13, 2023
It can be seen from the curing process, the rubber is in the vulcanization, its physical mechanical properties or comprehensive properties to the best value, pre-sulfur or sulfur phase of the rubber properties are not good.
The shortest time needed to reach the positive vulcanization state is the theoretical positive vulcanization time, also known as the positive vulcanization point. The normal vulcanization is a stage, in the normal vulcanization stage, the rubber's physical and mechanical properties maintain the highest value, but the rubber's performance index often can not reach the best value at the same time, therefore, accurate determination and selection of positive curing point becomes the decisive factor for determining curing conditions and obtaining the best product performance.
According to the curing chemical kinetics principle, the curing state should be the maximum crosslinking density of the compound, and the curing time should be determined by the time it takes for the compound to reach the maximum crosslinking density.In practical application, the optimum point is selected according to some main performance indexes (proportional to the crosslinking density) , and the positive curing time is determined.
The vulcanizer can continuously measure the parameters related to the processability and vulcanization performance, including initial viscosity, minimum viscosity, scorch time, vulcanization rate, positive vulcanization time and activation energy.
In fact, the measurement of Vulcanizator recorded the value of torque to reflect the size of the torque to the degree of vulcanization of rubber, the basic principle of measurement is based on elastic statistics theory,
*In the equation:G-Shear die,MPa;
ρ-Cross-linking density,mol/mL;
R-Gas constant，Pa·L/(mol·K);
T-Absolute temperature,K.
That is, the shear die G of the compound is proportional to the cross-linking density ρ.There is a linear relationship between G and torque M.
According to the analysis of the force exerted on the rubber compound in the mould of vulcanizer, when the rotor swings at ± 3 ° angle, a certain force is applied to the rubber compound to cause its deformation.
At the same time, the compound will produce shear force, tensile force, torque, etc. , these combined forces on the rotor will produce torque M, hinder the movement of the rotor. With the vulcanization of the compound, its G gradually increased, rotor swing in the case of fixed strain, the required torque M will be proportional to increase.
To sum up, the stress change of the compound with time measured by Vulcanizator (the Vulcanizator is reflected by torque reading) can indicate the change of the shear mold, thus reflecting the cross-linking process of vulcanization.
