LINA Machinery Industrial Co.,Ltd

HomeNewsOverview of the molding properties and performance of rubber

Overview of the molding properties and performance of rubber

2019-04-28
[Rubber Technology Network - Processing Technology]

The molding properties and performance of rubber depend mainly on the internal structure of the rubber.

(1) The molecular structure of rubber is also a polymer compound, and the relative molecular mass can reach several hundred thousand. The molecular size of the polymer compound is not fixed, and the so-called relative molecular mass refers to its average relative molecular mass. The relative molecular mass has a great influence on the rubber strength. Generally, the molecular strength is only a certain degree to a certain extent, and the aging resistance of the polymer decreases with the increase of the polymerization degree (the index for measuring the molecular size of the polymer). However, the rubber will break the rubber molecules during the mastication process, and the relative molecular mass will become smaller, which can increase the plasticity and improve the processing conditions.

From the geometric shape of the rubber molecular chain, it can be divided into three types: linear type, branched type and crosslinked type (also called body type). Different geometries with completely different physical properties. Rubber is very flexible because the carbon atoms in the C-C chain of the rubber molecule can rotate around the chemical bond.

(2) Aggregation state of rubber The state in which rubber molecules are gathered together is called an aggregate state. Aggregation states can be divided into three states: solid, liquid, and gas. Rubber has liquid properties because the molecular segments of rubber can move relatively freely like low molecular liquids. Rubber has the property of being solid, because the molecular chain cannot be relatively displaced from the viewpoint of the entire macromolecular chain, and can maintain a certain shape and a large strength. Rubber also has the property of gas, such as the modulus of elasticity increases with the increase of temperature, and heat is generated when stretching, as if the gas is compressed, the heat is converted by energy.

(3) The viscoelastic rubber of rubber has good elasticity. In addition, it also has certain characteristics of obvious viscous liquid. It is mainly manifested in the fact that after the rubber is applied, its deformation is linear with time as the viscous liquid. development of. Therefore, rubber is considered to be a viscoelastic material, resulting in a series of viscoelastic phenomena such as creep, stress relaxation, and internal friction.

(4) Although the rheological rubber of rubber has high elasticity, it needs to be deformed in a flowing state during molding processing such as mastication, kneading, pressing or calendering, and therefore the molding process necessarily involves the fluidity of the rubber. Viscosity is an important parameter to characterize liquid fluidity. The viscosity of rubber is different from that of plastic. Plastic can greatly reduce the viscosity of the melt by increasing the temperature. The viscosity of rubber is little affected by temperature, which depends mainly on the relative molecular mass. Reducing the relative molecular mass can reduce the viscosity and elasticity, which will be beneficial to the molding process of rubber.

(5) Vulcanization of rubber Under the heating condition, the raw rubber in the rubber compound reacts with the vulcanized sulphur, and the cross-linking process of the macromolecule of the rubber from the linear structure to the three-dimensional network structure is called vulcanization, and the vulcanized rubber Known as cooked glue. After vulcanization, the physical, mechanical properties and other properties of the rubber compound are significantly improved.

The change in rubber properties during vulcanization is a result of changes in the molecular structure. The unvulcanized raw rubber is a linear structural macromolecule whose molecular chain has the independence of motion and exhibits large plasticity, high elongation, and solubility. The vulcanized rubber macromolecules form a transverse network between the molecular chains to form a spatial network structure. Therefore, in addition to the secondary valence bond between the molecules, there is a main valence bond at the junction of the molecules, so the ratio of the cooked rubber Raw rubber has high tensile strength, small elongation and high elasticity. Vulcanization is the last processing step in the production of rubber products.

With the development of cattle production, the concept of vulcanization has also made new progress. Vulcanizing agents and high temperature are no longer necessary conditions for vulcanization. Some special rubber compounds can be vulcanized at lower temperatures or even at room temperature. The vulcanizing agent is not added to the material, but is crosslinked by a physical method such as gamma irradiation.


Reprint, please keep, rubber technology network, rubber industry information, technology, service portal!
Related Products List

Home

Product

Whatsapp

About Us

Inquiry

We will contact you immediately

Fill in more information so that we can get in touch with you faster

Privacy statement: Your privacy is very important to Us. Our company promises not to disclose your personal information to any external company with out your explicit permission.

Send