Plastic density and relative density

Tensile load to continue on the injection molding processing, most of the thermoplastic material will have larger deformation. High elongation of materials, such as elastomer, deformation can be up to 800% 1000%. Plastic during tensile elongation, because he has a degree of elasticity, the higher the polymer relative molecular mass, molecular chain is smooth, good, the greater the elasticity of plastic, the elongation. High strength and high elongation of the material, has the very good toughness, is the ideal impact resistant material.

plastic is the material of low density, plastic has low density properties and various varieties of plastic density difference, because the quality is the quality of the individual molecules per unit volume and the function of the degree of packing. No heavy atoms in the hydrocarbon molecules, so amorphous polymer density of hydrocarbons is commonly 0. 86 - 1. 05, some big molecules of atoms, the quality of the unit volume is larger. If polymer crystallization, high degree of molecular packing, molecular density is high, such as teflon.

tensile properties when material by the tensile load is shown by the mechanical behavior. Materials under the action of tensile load, the internal stress resistance to deformation, and the resulting strain. Initial stage of the relationship between stress and strain is proportional to the general, the ratio of tensile modulus of elasticity. Elastic modulus is measured materials when subjected to external forces, to prevent the scale of the deformation ability. If a tensile load is large enough, more than the elastic limit of material, flexible material yield will appear. Yield is the tensile strength, yield stress at the time of the corresponding strain for the yield percentage elongation, a lot of stress on the engineering design of general yield stress.

polyethylene for manufacturing method is different, its branching degree, degree of crystallization have bigger difference, so there is a difference between low density polyethylene and high density polyethylene. Density is one of the important properties of the polymer, the change of the density directly affects all performance parameters of the polymer. High density of polymer, the molecules together closely, molecular inter-atomic forces is larger, so the strength, stiffness, hardness and heat resistance of polymer is relatively high, and depends on the molecular chain movement on performance, such as flexibility, elongation at break and impact strength is relatively low. Density also affect other properties of the polymer, such as permeability.

using the properties of low density polymer, has been widely used in many ways. On the premise of meet the material design performance, people more willing to use low density of the material. Material strength and modulus and the ratio of the density, respectively the than strength or modulus. The higher than the strength of the material, create part is, the smaller the weight of the same material than the higher modulus, the more rigid parts. Due to the polymer matrix and composite materials of reinforced material, even because of high than some than strength and modulus of metal material, and in the car such as traffic vehicle and aerospace industries widely used.

mechanical properties is the ability of material to resist the external force damage. When polymer processing becomes a product, when using this ability depends on the chemical structure of the material itself, the structure of the injection molding processing factors of material and components, design and use conditions. In addition, the influence of stress types and stress on the material is also very important. Relative density is the density of the material and the ratio of the density of water, is a dimensionless number. Density and relative density was used for testing the quality of the parts and calculate the cost of the product.

in the high quality of inertia and the application of seismic body body, and hope to have a weight of daily necessities. Such as adornment, senior containers of cosmetics, high content of metal and inorganic powder material can be filled into the matrix components, in order to improve the relative density of the material, on the other hand, you can also use the foaming agent, polymer as porous foamed plastics, reduce the relative density, according to the need, foam density control in 0. - 0. 005g/m³ 。

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