Preparation of rubber nanocomposites

To use nanomaterials in rubber suction cup processing, the first problem encountered is how to make the nano-scale powder material smoothly enter the rubber and evenly disperse, because only the composite of rubber/nano material can exert the nano-effect. It is well known that all nano-powder particles have a diameter of less than 100 nm, and the rubber maintains a high-viscosity fluid state even during rubber mixing.

Therefore, it is not easy to let the nano-powder smoothly enter the rubber and evenly disperse. Moreover, due to the strong surface effect of nanomaterials, the tendency of self-aggregation is serious, which easily leads to agglomeration and agglomeration. The difficulty of evenly spreading it is not small. At present, the commonly used composite routes can be roughly divided into four types, namely, a blending method, an in-situ polymerization method, a sol-gel method, and an interlayer intercalation method.

(1) Blending method

The blending method can be achieved by three methods.

The first type is mechanical blending (dry blending), also known as melt blending. The rubber blending machine commonly used in rubber plants can be used. The tantalum compound is in a viscous state and the nano material is directly blended with the rubber compound. The advantage of this method is that the rubber factory can complete the compounding by itself, but the disadvantage is that it is difficult to achieve uniform dispersion of the nano material. Two-stage blending can be improved.

At present, as an innovative measure, the nanopowder is first pre-dispersed into a masterbatch, and then added to the main material (rubber) for secondary dispersion, and the effect is good. It is also possible to adopt a method of adding a dispersing agent, that is, first coating the dispersing agent on the surface of the nano material, and then blending, and also having a certain effect.

The second type is solution blending, adding nano-powder in the rubber solution, stirring uniformly, removing the solvent and drying to obtain a composite. The disadvantage of this method is that it is easy to pollute the environment.

The third is emulsion blending, replacing the solution with a latex, and the other steps are the same as the second. Emulsion blending has two advantages, namely no pollution caused by solvents, and is suitable for insoluble gels. In order to speed up the compounding, ultrasonic waves can be used to accelerate the blending process. When the energy of the ultrasonic wave reaches a certain impact level, a “cavitation” effect is generated. The expansion and blasting of the cavitation bubble form a shock wave with a velocity of 110 m/s in the reaction zone and cause local high temperature and high pressure to accelerate the composite process and obtain rapid Three effects of high efficiency and energy saving.

(2) In-situ polymerization

In-situ polymerization is also known as in-situ polymerization. The nanoparticles were added to the monomer solution, dispersed by means of ultrasonic shock, and then polymerized. The difficulty of this method is that it starts from the polymerization of monomers, has many processes, is not difficult, and brings problems such as pollution of the environment and solvent recovery.

(3) Sol-gel method

The sol-gel method, also known as the precursor method, dissolves the precursor of the dispersion (for example, a metal oxide or a metal inorganic salt) by mixing with a monomer or a polymer. Through the hydrolysis and condensation of the precursor, a dispersed phase is formed, at which time the particle size distribution and its dispersion in the matrix are controlled. The disadvantage of this law is that the fore body is expensive and toxic. In addition, during the drying of the solvent, shrinkage stress is generated after the small molecules of the solvent are volatilized, which easily causes the composite to be brittle.

(3) Interlayer insertion method

Interlayer insertion method is only applicable to materials with a lamellar structure (such as clay, montmorillonite, etc.), and the interlamellar spacing needs to meet the requirements of nanomaterials, preferably between. The contact surface should be treated with organic matter to impart a certain activity to promote the reaction between the host and the guest with the inorganic nanomaterial, and the inorganic material is modified into a composite material whose surface is modified by the organic material, so that the affinity with the rubber can be greatly improved. For example, adding 20 parts of nano-materials to rubber, the addition of nano-light calcium carbonate can increase the airtightness by 18.4%, the addition of nano-clay can increase by 24%, and the use of intercalated clay can increase by 58%.