Some terms of the most popular epoxy resin raw mat

2022-08-07
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Brief explanation of some terms of epoxy resin raw materials

in the quality index of raw materials, we often encounter some terms. An accurate understanding of its meaning will help us better master the properties of raw materials. Here are some common terms

(1) density and relative density density refers to the mass contained in the unit volume of a substance. In short, it is the ratio of mass to volume. Its unit is million grams/m3 (mg/m3) or kilograms/m3 (kg/m3) or grams/cm3 (g/cm3). The relative density, also known as the ratio of density, refers to the ratio between the density of a substance and the density of a reference substance under their respective specified conditions, or the mass of a certain volume of substance at T1 temperature and the mass of an equal volume of reference substance at T2. Mass ratio at temperature. The commonly used reference material is distilled water, which is expressed by dt1/t2 or t1/t2, and is a dimensionless quantity

(2) melting point and freezing point the temperature at which a substance reaches equilibrium between liquid and solid state under its vapor pressure is called the melting point or freezing point. This is a phenomenon that the regular arrangement of atoms or ions in a solid is activated due to the temperature rise and the thermal movement becomes disordered, forming an irregularly arranged liquid. The opposite process is solidification. For Angang, Shagang Yongxing, Yaxin, Fengbao, Xinpu and Huixin, which are long process enterprises including sintering, ironmaking, steelmaking and rolling, the temperature when the liquid becomes solid is often called the freezing point or freezing point. The difference from the melting point is that it emits heat rather than absorbs heat. In fact, the melting point and freezing point of a substance are the same

(3) melting range refers to the temperature range measured by capillary method from the beginning of melting to the whole melting of the substance

(4) crystal point refers to the phase change temperature at which the liquid changes from liquid to solid during cooling

(5) pour point refers to one of the indicators of the properties of liquid petroleum products. It refers to the temperature at which the sample is cooled to stop flowing under standard conditions, that is, the lowest temperature at which the sample can be poured when it is cooled

(6) boiling point the temperature at which a liquid boils and becomes a gas when heated. Or the temperature at which a liquid and its vapor are in equilibrium. Generally speaking, the lower the boiling point, the greater the volatility

(7) boiling range is the distillation volume within the temperature range specified in the product standard under the standard state (1013.25hpa, 0 ℃)

(8) sublimation refers to the phenomenon that solid (crystalline) substances directly change into gaseous state without going through liquid state. Such as ice, iodine, sulfur, naphthalene, camphor, mercuric chloride, etc. can be sublimated at different temperatures

(9) evaporation velocity refers to the gasification phenomenon on the liquid surface. Evaporation rate is also called evaporation rate, which is generally judged by the boiling point of the solvent. The fundamental factor determining the evaporation rate is the vapor pressure of the solvent at this temperature, followed by the molecular weight of the solvent

(10) vapor pressure is the abbreviation of saturated vapor pressure. At a certain temperature, the liquid and its vapor reach equilibrium. At this time, the equilibrium pressure changes only due to the nature and temperature of the liquid, which is called the saturated vapor pressure of the liquid at this temperature

(11) azeotrope the constant boiling point mixture formed by two (or several) liquids is called azeotropic mixture, which refers to the mixed solution in the equilibrium state when the composition of gas phase and liquid phase are identical. The corresponding temperature is called azeotropic temperature or azeotropic point

(12) refractive index is a physical quantity indicating the ratio of light speed in two different (isotropic) media. The speed of light varies with different media. When light enters another transparent medium with different density from one transparent medium, it changes in its direction due to the change of speed, so it is called refraction. The ratio of the sine of the incident angle of light to the sine of the refraction angle, or the ratio of the velocity of light passing through a vacuum to that of a medium, is the refractive index. Generally, the refractive index n refers to the value of light entering any medium from air. Generally, the refractive index refers to sodium yellow light (D line) measured at TC, so it is expressed by NTD. If measured at 20 ℃, it is n20d

(13) flash point is also called flash point, which is one of the indicators indicating the properties of flammable liquids. It refers to the lowest temperature when the mixture of vapor pressure and air heated to the liquid surface of flammable liquid contacts with the flame to cause flash fire. The flash is usually a light blue spark, which is extinguished immediately after flashing and cannot continue to burn. Flashover is often the precursor of fire. There are open cup method and closed cup method to determine the flash point. Generally, the former is used to determine the high flash point liquid, and the latter is used to determine the low flash point liquid

(14) ignition point, also known as ignition point, is one of the indicators indicating the properties of flammable liquids. It refers to the lowest temperature at which the mixture of steam and air heated to the surface of flammable liquid can ignite immediately after contacting with the flame and continue to burn. The ignition point of flammable liquid is 1 ~ 5 ℃ higher than the flash point. The lower the flash point, the smaller the difference between the ignition point and the flash point

(15) spontaneous ignition point is the lowest temperature at which combustible substances can cause ignition without contacting open fire, which is called the spontaneous ignition point. The lower the spontaneous combustion point is, the greater the market concentration of fire hazard will be. The spontaneous ignition point of the same substance varies with the pressure, concentration, heat dissipation and other conditions and test methods

(16) explosive limits when combustible gas, vapor of combustible liquid or dust of combustible solid are mixed with air or oxygen to reach a certain concentration range under a certain temperature and pressure, they will explode when they encounter a fire source. This certain concentration range is called explosion limit or combustion limit. If the composition of the mixture is not within this certain range, no matter how much energy is supplied, it will not catch fire. The lowest concentration of steam or dust mixed with air and reaching a certain concentration range, which will burn or explode in case of fire source is called the lower explosion limit; The maximum concentration is called the upper explosive limit. Explosion this experiment adopts C language programming. The limit is usually expressed by the volume percentage of steam in the mixture, i.e.% (vol); Dust is expressed in mg/m3 concentration. If the concentration is lower than the lower explosion limit, the open fire will not cause explosion or combustion, because the air accounts for a large proportion at this time, and the concentration of combustible vapor and dust is not high; If the concentration is higher than the upper limit of explosion, there will be a large number of combustible substances, but there is a lack of combustion supporting oxygen. Without air supplement, even in case of open fire, it will not explode for a while. Flammable solvents have a certain explosion range. The wider the explosion range, the greater the risk

(17) viscosity refers to the internal friction resistance generated by the fluid (liquid or gas) in the flow, and its size is determined by the type, temperature, concentration and other factors of the material. It is generally the abbreviation of dynamic viscosity, and its unit is pa · s or millipa · s. Viscosity is divided into dynamic viscosity, kinematic viscosity and relative viscosity, which are different and cannot be confused. Viscosity can also be measured with tu-4 or Tu-1 cup, and its unit is seconds (s)

(18) Mooney viscosity Mooney viscosity, also known as rotational Mooney viscosity, is a value measured with a Mooney viscometer, which basically reflects the degree of polymerization and molecular weight of synthetic rubber. According to GB 1232 standard, the rotational (Mooney) viscosity is represented by the symbol Z100 ℃ 1+4. Where Z - rotational viscosity value; 1 - preheating time: 1min; 4 - rotation time is 4min; 100 ℃ - the test temperature is 100 ℃. Traditionally, ml100 ℃ 1+4 is used to represent Mooney viscosity

(19) solubility the maximum amount of a substance dissolved in a certain amount of a given solvent at a certain temperature and pressure is called solubility. The solubility of solid or liquid substances is generally expressed in grams of substances that can be dissolved in 100g solvent. The solubility of gaseous solutes is usually expressed in milliliters of dissolved gas per liter of solvent

(20) solubility parameter is also called solubility parameter, which is a measure of intermolecular force. The action energy that brings molecules together is called cohesive energy. The cohesive energy per unit volume is called cohesive energy density (CED), and the square root of CED (CED) 1/2 is defined as the solubility parameter, code as δ Or sp

(21) surface tension and surface energy the attraction of the molecules inside the liquid makes the molecules on the surface under an inward force, which makes the liquid minimize its surface area and form a force parallel to the surface, which is called surface tension. In other words, it is the mutual traction force per unit length between two adjacent parts of the liquid surface, which is a manifestation of the molecular force. The unit of surface tension is n/m. The magnitude of surface tension is related to the nature, purity and temperature of the liquid. The surface energy is the surface tension multiplied by the surface area. The greater the surface tension, the larger the surface area, and the greater the surface energy

(22) specific heat capacity the heat required to be absorbed when the temperature of each kilogram of substance increases by 1K is called the specific heat capacity, and the unit is kJ/(kg · K). Under the condition of constant pressure, the heat absorbed when the temperature rises by 1K is called the specific heat capacity at constant pressure

(23) thermal conductivity in the past, thermal conductivity was called thermal conductivity or thermal conductivity, reflecting the thermal conductivity of materials. That is, two parallel planes with an area of 1cm2 and a distance of 1cm are taken in the interior of the object perpendicular to the heat conduction direction. If the temperature difference between the two planes is 1K, the heat transmitted from one plane to the other in LS is specified as the thermal conductivity of the material, and its unit is w/(m · K)

(24) water content the water contained in the material, but excluding the consumption of plastic bags, is still very large crystal water and connective water. It is usually expressed as the percentage of the original mass of the sample and the mass of the sample after water loss

(25) water absorption is a measure of the degree of water absorption of a substance. It refers to the mass percentage increased by soaking the substance in water for a certain time at a certain temperature

(26) ash (ash) ash, also known as burning residue, refers to the residue of oxides and salts formed by its mineral components after evaporation and burning, expressed in percentage

(27) needle penetration is expressed by the depth of the standard needle vertically penetrating the asphalt sample under certain load, time and temperature conditions, and the unit is 1/10mm. Unless otherwise specified, the combined weight of the standard needle, needle connecting rod and additional weight is 100 ± 0.1g, the temperature is 25 ℃, and the time is 5S. The greater the penetration, the softer it is, that is, the smaller the consistency; Otherwise, it means that the harder it is, the greater the consistency

(28) hardness hardness refers to the resistance of a material to external forces such as impression and scratch. According to different test methods, there are shore hardness, Brinell hardness, Rockwell hardness, Mohs hardness, Barcol hardness, vichers hardness, etc. The hardness value is related to the type of hardness tester. Among the commonly used hardness testers, the shore hardness tester has a simple structure and is suitable for production inspection. Shore hardness tester can be divided into type A, type C and type D. type A is used to measure soft rubber, and type C and D are used to measure semi-hard and hard rubber

(29) aniline point (A.P.) aniline point is the lowest temperature at which equal volume petroleum alkanes and aniline are mutually dissolved, which is used to indicate the content of alkane saturated hydrocarbons. The higher the aniline point is, the more alkanes are; The lower the aniline point, the more aromatic hydrocarbon content

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