Recycling of waste products can involve a wide range, and rubber sheet is not an exception, considered included in the classification of recycling. This is actually in the oxygen heat, mechanical force, oxygen and chemical regeneration agent under the combined effect of waste rubber under the regeneration of the nature of the degradation reaction occurs, and vulcanized rubber crosslinked network structure is destroyed. , So that the plasticity of waste rubber to a certain degree of recovery in order to restore the purpose of regeneration.
The main factors affecting the regeneration of vulcanized rubber are four aspects: thermal oxygen, mechanical force, softener and regenerating activator.
1, the role of thermal oxygen
Heat causes the molecular motion to intensify, leading to the molecular chain fracture. At about 80 ℃, thermal cracking is obvious, to about 150 ℃, thermal cracking speed, and then every 10 ℃ increase in thermal cracking rate of about 1 times faster. The cleavage of free radicals remains at the end of the cleavable molecule, presenting an unstable state. If such molecules meet the ability to have recombination at their ends, the cleavage rate will gradually decrease with increasing free radical concentration if no other material is present. The presence of oxygen allows the free end groups to react with oxygen, generating hydroperoxides and the like. While the hydroperoxide itself can aggravate the rubber mesh structure damage, greatly speeding up the regeneration rate.
2, the action of mechanical force
Mechanical force can make the mesh structure of vulcanizates, occurred in C - C key or C - S keys, and the mechanical action of grinding and can make the rubber molecules in association with the carbon black particle surface disposal.All these faults are mostly occur at relatively low temperatures, the degree of fracture is closely related to the temperature.
3, the role of the softener
Softener is low molecular substances, easy in vulcanizates mesh, swelling effect, make the mesh structure relaxation, thereby increasing the oxidation of osmosis, is beneficial to the oxidation of mesh structure fracture, and can reduce the possibility of new structured, accelerate the regeneration process.Because this kind of material is dissolved in rubber and itself has certain viscosity, thus can improve the plasticity and viscosity of reclaimed rubber. Softener dosage for 10-20, commonly used varieties with coal tar, pine tar, rosin, tall oil, double pentene etc.
4, the action of regeneration as activator
Hereinafter referred to as activator, break down of free radicals.This is also a free radical acceptor or accelerated thermal oxidation speed, the effect of rubber radical generated in stable thermal oxidation, and organization, again. So regeneration activator at the same time also can cause the degradation of sulfur and double sulphur keys, in order to improve their in the crosslinking degree of damage, so as to achieve regeneration as soon as possible. And reclaimed activator can bring obvious effects. Usually with aromatic thiol disulfide, such as activator, activator, activator, 463, 420, 901 activator 6810, amines, metal oxide and phenylhydrazine, etc.