Plastic people must master 28 plastic application performance parameters
physical properties
1. Specific gravity: The specific gravity of plastic is the ratio of the density of the sample to the density of water under certain temperature conditions.
2. Water absorption: the specified size of the sample immersed in water at a certain temperature, after 24 hours of absorption of water, the size and shape will be affected by water absorption.
3. Air permeability: a certain thickness of plastic film under an atmospheric pressure, a square meter area in 24 hours of air permeability.
4. Moisture permeability: water vapor through the plastic film.
5. Transparency: transmittance, the ratio of the luminous flux through the object and the luminous flux emitted to the object.
6. Fog or turbidity: The ratio of astigmatism to all transmitted light in the direction of the incident light. Fog is usually opaque but diffused to incoming light.
mechanical properties
1. Tensile strength: The tensile force is applied to the sample at the specified test temperature, humidity, and tensile speed, and the maximum load of failure is determined.
2. The compression strength: places compression force on the samples, to burst (brittle) or give in.
3. Bending strength: The strength of the sample when it is placed on two fulcrums and a concentrated load is applied to deform or break the sample.
4. Impact strength: joules consumed per unit area when the sample is broken by impact.
5. Friction coefficient: the ratio of friction force to positive pressure.
6. Abrasion: plastic size change of mechanical failure process in the process of friction, wear, abrasive wear)
7. Hardness: plastic resistance to other hard objects pressed into the performance. (Rockwell, Shaw).
8. Fatigue: The plastic is destroyed in a static destruction with a small amount of alternating cycles.
9. Creep: under fixed temperature and humidity conditions, under the continuous action of fixed external force, the plastic will show creep characteristics with time, which increases with the load, decreases with the load, and the deformation is gradually restored. (tensile creep, compressive creep, bending creep, etc.)
10. Lasting strength: The ability of plastic to withstand static load for a long time is determined by a high and low time function
use performance
1. Linear expansion coefficient: the number of mm per 1mm of plastic elongation per 1 degree of temperature increase. It is generally ten times that of steel.
2. Specific heat: The unit of heat required to raise the temperature of 1 gram of plastic by 1 degree.
3. The coefficient of thermal conductivity: a unit area and thickness of the plastic can through thermal units, 1% for steel
4. Heat resistance: the relationship between temperature and deformation.
5. Glass transition temperature: the temperature at which the plastic can flow from melting to solid state, with great brittleness.
6. Embrittlement temperature: When the pressure is applied to the plastic at a certain low temperature, it will be destroyed under a small deformation.
7. Melting index: thermoplastic at a certain temperature and pressure, melt in 10 minutes through the test hole outflow of plastic weight.
8. Combustion resistance: It is expressed by the combustion rate (the burning length of the sample during the combustion time) and the combustion weight loss rate (the difference between the weight before and after the combustion).
9. Voltage resistance: quickly rise the voltage to the specified value, a certain period of time the sample is not broken down.
10. Aging resistance: plastic in the use, storage, processing process due to the role of light, heat, oxygen, biology, stress and other external factors, causing chemical structure damage and the original excellent performance of the phenomenon of decline.
11. Chemical resistance: Whether the plastic is corroded in the chemical medium. (Weight, volume, strength, color, etc.)
12. Molding shrinkage: the shrinkage phenomenon of the molded product after the plastic is formed in the mold and demoulded after cooling.