Plastics can be seen everywhere in people's lives. Today, China Plastics Network - Jiuzhi Plastics Network takes everyone to understand the physical properties of plastics, as follows:
Specific gravity (density)
The specific gravity of plastic is the ratio of the weight of the weighing sample to the weight of the same volume of water at a certain temperature, the unit is g/cm3, and the liquid buoyancy method is commonly used as the measuring method.
Water absorption
The water absorption of plastic refers to the amount of water absorbed by the sample of the specified size when it is immersed in distilled water at a certain temperature (25±2) °C, after 24 hours; the size and shape of the sample are affected by the absorption of water, and the water absorption rate is expressed by weight. , often expressed in %.
Breathability
Gas permeability refers to the volume (cm3) of the gas permeated within 24 hours in a square meter of plastic film of a certain thickness, but the gas permeability and thin wax thickness, area, time, temperature , the air pressure difference and so on.
Moisture permeability
Moisture permeability refers to the transmission of water vapor to plastic film. The basic principle and definition are the same as the gas permeability.
transparency
The ratio of the luminous flux through the object to the luminous flux incident on the object is called the transmittance; the ratio of the scattered light in the direction of the incident light to all transmitted light, called haze or turbidity. The haze is usually translucent, And has a diffuse nature of the incident light.
Tensile Strength
Tensile strength means that the tensile load is applied along the longitudinal axis of the sample at a specified test temperature, humidity and tensile speed, and the maximum load at the time of failure of the sample is measured.
Compressive strength
Compressive strength is the strength at which a compressive load is applied to a specimen (for brittle materials) or yield (for non-brittle materials).
Bending strength
Bending strength refers to the strength of the specimen at the two fulcrums, applying a concentrated load to deform the specimen or until it breaks.
Impact strength
Impact strength refers to the Joule consumed per unit area when the specimen is broken by impact. For some plastics with high impact strength, a gap of a specified size is often opened in the middle of the specimen, which can reduce the need for it to break. joule.
Different test methods can be used for different test pieces: falling ball impact test and high speed tensile impact test.
Coefficient of friction
The friction coefficient refers to the ratio of frictional force to positive pressure. A positive pressure is applied to the sample to measure the dynamic and static ratio of the rigid motion of the specimen.
Wear
Abrasion refers to the mechanical destruction process in which the particles are continuously separated from the friction surface during the friction process, causing the size of the friction member to change continuously. It is also called wear or abrasion.
Fatigue strength
It refers to the strength of plastic damage under a static destructive force and a small amount of alternating circulation; the source of fatigue load is tensile, bending, torsion, impact and so on.
Creep
Creep is the characteristic that the plastic exhibits with time under the action of a fixed external force under a certain temperature and humidity condition. The characteristic of this deformation increases with increasing load, and decreases with the reduction of load. It is also gradually recovering. The sources of creep are tensile creep, compression creep, bending creep, etc.
Durable strength
Durable strength refers to the time function of the plastic's ability to withstand static loads for a long period of time. For example, the strength of the plastic before unloading is 1000 hours, and the load may be only between 50% and 70%.
Linear expansion coefficient
The coefficient of linear expansion refers to the number of centimeters of plastic per centimeter when the temperature rises by 1 degree Celsius. The coefficient of linear expansion of plastic is generally about ten times that of steel.
Specific heat
Specific heat refers to the unit of heat required when 1 gram of plastic rises harder than 1 degree Celsius.
Thermal Conductivity
The thermal conductivity refers to the unit of heat that a certain unit area and thickness of plastic can pass. The thermal conductivity of plastic is very small, only about one percent of steel, so it is a good thermal insulation material.
Heat resistance
The heat resistance of plastic is a characteristic that reflects the relationship between the temperature of the plastic part and the amount of deformation. The heat resistance is more important for temperature-related plastic parts.
Glass transition temperature
The temperature at which the plastic is reduced from the melt flowable temperature to the solid state is called the glass transition temperature. At this time, the molecular segment is substantially incapable of moving, and the internal rotation of the link is also fast and fast, and only a little movement between the atoms is stretched and ordinary. The elastic deformation, so the plastic at this time will have a lot of brittleness.
Embrittlement temperature
When pressure is applied to a plastic at a low temperature, it will break under a small deformation, and this temperature is the embrittlement temperature.
Decomposition temperature
The decomposition temperature refers to the temperature at which the macromolecular chain breaks when the plastic is heated, and is one of the indicators for identifying the heat resistance of the plastic; when the temperature of the melt exceeds the decomposition temperature, most of the melt will have a yellowish color, and the product The intensity will be greatly reduced
Melt Index
Melt Index (MFI) MI refers to the weight of the melt flowing through the orifice of the tester in a 10 minute period of the thermoplastic at a certain temperature and pressure, expressed in grams per 10 minutes.
Combustibility
The flammability of plastics is expressed by the ratio of the burning rate (the burning length of the sample during the burning time) to the burning weight loss rate (the percentage of the difference between the weights before and after the burning), from the ignition time to the spontaneous combustion time and the extinguishing time. Can be used as a reference for resistance to combustion.
Withstand voltage
Rapidly raise the voltage to a certain limit value, stay for a period of time, the plastic sample is broken down, and the voltage value at this time is said to be the withstand voltage that the sample can withstand.
Aging resistance
The aging resistance of plastics means that during the process of use, storage and processing, due to the external factors such as light, heat, oxygen, water, biology, stress, etc., the chemical structure is destroyed and the original excellent performance is degraded. Phenomenon. Studying the aging of plastics is to improve its stability and extend its service life.
Chemical resistance
The chemical resistance of plastics refers to whether the plastic is corroded in the chemical medium. The basis for the evaluation is usually the degree of change in weight, volume, strength, color, etc. of the plastic in the medium after a certain period of time.
Mold shrinkage
Molding shrinkage refers to the molded product that is demolded after cooling in the mold. It must shrink when the thermoplastic is smaller than the cavity size.
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Self Adhesive Fiberglass Geogrid
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Feicheng Lianyi Engineering Plastics Co., Ltd , https://www.lianyigeosynthetics.com