Functional rubber
Functional rubber is a new type of material in elastomers. In addition to the unique elasticity of rubber, it also has different special functions. This special function is obtained by physical and chemical methods such as synthesis, blending, grafting and compounding. These special functions involve many aspects, such as ultra-high strength in mechanical properties, ultra-low hardness; thermal sensitivity related to thermals; electrical superconductivity; optical photosensitivity, lithography, optical storage; and biomimetic bionic functions. Wait.
Functional approach
In order to achieve a specific function, the following different approaches are required.
(1) by chemical synthesis and modification
1) Synthetic chemical synthesis to obtain the desired function. For example, a metallocene catalyst system can be used to synthesize an elastomeric polyolefin having a damping effect that greatly exceeds that of butyl rubber.
2) Chemical modification Halogenation, hydroxylation, cyclization and other methods are used to modify the original elastomer to obtain an elastomer which is easy to stick, easy to blend, oil resistant and heat resistant. For example, 1,2-polybutadiene is a functional rubber, which is unique in that it has excellent gas permeability and moisture permeability and is an ideal food preservation material.
3) Coupling modification Introducing a group with high activation degree into the rubber, and introducing a hydroxyl group at both ends, can be solidified by means of moisture in the atmosphere, thereby greatly simplifying the process. Another example is the reaction of a silane coupling agent with a polyester or polyether having an isocyanate end group to form a sealant for a large number of applications in construction engineering.
(2) Through the control of structure and shape
1) Controlling the vulcanization structure Consciously controlling the crosslinked structure and morphology is another major way to achieve rubber functionalization. The sulfur/accelerator system is generally used in various types of products, and its advantage is that the product has high mechanical properties, but the disadvantage is that it is easy to return to the original and the heat resistance is poor. The peroxide cross-linking has good heat resistance and aging resistance, but the physical properties are relatively poor. If the advantages of these two vulcanization systems are combined, they can play a “complementary” role. For example, a composite vulcanization system consisting of 0.48 parts of sulfur, 1.3 parts of DCP and 0.5 part of accelerator NS enhances the control of the vulcanization structure for some reason, and can produce a functional rubber with balanced performance in all aspects, which can satisfy high mechanics. Performance, high environmental resistance and heavy requirements.
2) Controlling the vulcanization form of rubber from the form of vulcanization is also one of the ways to prepare functional rubber. The general trend is to tilt towards dynamic vulcanization. Specifically, two or more thermodynamically incompatible polymers are used to form a heterogeneous multiphase body.
