Simple Explanation of PVC Terminology

Guangzhou XiongXing Plastic Product Co., Ltd. is the largest plastic factory in China, founded in 1995. Our customers sometimes do not understand the professional vocabulary of the PVC industry. Today, we will briefly popularize some of the professional terms of PVC raw materials.　

　

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). Relative density, also known as density ratio, refers to the ratio of the density of the substance to the density of the reference substance under their respective specified conditions. It means the mass of a certain volume of substance at temperature t1 and the mass of an equal volume of reference substance at temperature t2. Ratio. The commonly used reference substance is distilled water, and it is expressed by Dt1/t2 or t1/t2, which is a dimensionless quantity.　　

 

Melting point and Freezing point：The temperature at which a substance transforms between liquid and solid under air pressure is called the melting point or freezing point. This is due to the fact that the regular arrangement of atoms or ions in the solid is activated due to the rise in temperature and the thermal movement becomes disorderly, forming an irregular arrangement of liquids. The opposite process is solidification. The temperature at which a liquid becomes a solid is often called the freezing point. The difference from the melting point is that it emits heat instead of absorbing heat. In fact, the melting point and freezing point of the substance are the same.　　

 

Melting range：It refers to the temperature range from the beginning of the melting of the substance to the complete melting as measured by the capillary method.

　　

Crystal point：It refers to the phase transition temperature at which the liquid changes from liquid to solid during the cooling process.

　　

Pour point：One of the indicators indicating the nature of liquid petroleum products. It means that the sample is cooled to the temperature at which it starts to stop flowing under standard conditions, that is, the lowest temperature at which the sample can be poured when it is cooled.

　　

Boiling point：The temperature at which a liquid is heated to boil and become a gas. In other words, the temperature at which the liquid and its vapor are in equilibrium. Generally speaking, the lower the boiling point, the greater the volatility.

　　

Boiling range：Under standard conditions (1013.25hPa, 0℃), the distilled volume within the temperature range specified by the product standard.

　　

Sublimation：A phenomenon in which a solid (crystalline) substance is directly transformed into a gaseous state without passing through a liquid state. Such as ice, iodine, sulfur, naphthalene, camphor, mercuric chloride, etc. can all be sublimated at different temperatures.

　　

Vaporizing velocity: Evaporation refers to the vaporization phenomenon that occurs on the surface of a liquid. The evaporation rate is also called the volatilization rate. Generally judged by the boiling point of the solvent, the fundamental factor that determines the evaporation rate is the vapor pressure of the solvent at that temperature, followed by the molecular weight of the solvent.

　　

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

 

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

　　

Refractive index：The refractive index is a physical quantity that represents the ratio of the speed of light in two different (isotropic) media. The speed of light varies from medium to medium. When light enters another transparent medium with a different density from one transparent medium, it changes in the direction of progress due to the change in 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 speed of light when passing through a vacuum and when passing through a medium, is the refractive index. Generally expressed refractive index n refers to the value of light entering any medium from air. The refractive index usually referred to is measured at t°C using sodium yellow light (D line), so it is expressed by ntD, if measured at 20°C, it is n20D.

　　

Flashing point：Flash point, also known as ignition flash point, represents one of the indicators of the properties of flammable liquids. It refers to the lowest temperature at which the flammable liquid is heated to the minimum temperature when the mixture of vapor pressure and air on the liquid surface contacts the flame to cause a flash fire. The flash is usually a light blue spark, which will go out at a flash and cannot continue to burn. Flashover is often a precursor to a fire. There are open cup method and closed cup method for measuring flash point. Generally, the former is used to measure high flash point liquids, and the latter is used to measure low flash point liquids.

　　

Ignition point：The ignition point is also known as the ignition point, which represents one of the indicators of the properties of flammable liquids. It refers to the lowest temperature at which the flammable liquid is heated to the surface of the vapor and air mixture and the flame immediately catches fire and can 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 ignition point and flash point.

　　

Spontaneous ignition point：The lowest temperature at which a combustible substance can cause a fire without contact with an open flame is called the spontaneous ignition point. The lower the self-ignition point, the greater the risk of fire. The spontaneous ignition point of the same substance varies with pressure, concentration, heat dissipation and other conditions and test methods.

　　

Explosive limits：Combustible gas, vapor of combustible liquid or dust of combustible solid mixed with air or oxygen to reach a certain concentration range at a certain temperature and pressure, it will explode when it encounters a fire source. This certain concentration range is called the 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 minimum concentration at which steam or dust mixes with air and reaches a certain concentration range, which will burn or explode when encountering a fire source is called the lower explosion limit, and the highest concentration is called the upper explosion limit.The explosion limit is usually expressed as the volume percentage of the vapor in the mixture, expressed in% (vol), and the dust is expressed in mg/m3 concentration. If the concentration is lower than the lower explosion limit, although the open flame will not explode or burn, because the air accounts for a large proportion at this time, the concentration of combustible vapor and dust is not high; if the concentration is higher than the upper explosion limit, there will be a lot of combustible substances, but lack The combustion-supporting oxygen will not explode even if it encounters an open flame without air supplement. Flammable solvents have a certain explosion range, and the wider the explosion range, the greater the danger.

　　

Viscosity: Viscosity is the internal frictional resistance of a fluid (liquid or gas) in the flow, and its size is determined by factors such as substance type, temperature, and concentration. It is generally the abbreviation for dynamic viscosity, and its unit is Pa·s or mPa·s (milliPa·s). Viscosity is divided into dynamic viscosity, kinematic viscosity, and relative viscosity. The three are different and cannot be confused.Viscosity can also be measured with Viscosity Cup-4or Viscosity Cup-1, and its unit is second (s).

 

                           Viscosity Cup-1

 

　　

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 the GB 1232 standard, the rotation (Mooney) viscosity is represented by the symbol Z100℃ 1+4. Among them, Z——rotational viscosity value; 1——preheating time is 1min; 4——rotation time is 4min; 100℃——test temperature is 100℃, and ML100℃ 1+4 is used to express Mooney viscosity.

　　

Solubility：At a certain temperature and pressure, the maximum amount of a substance dissolved in a given amount of solvent is called solubility. The solubility of a solid or liquid substance is generally expressed in grams of the substance that can be dissolved in 100g of solvent. The solubility of a gas solute is usually expressed in milliliters of gas dissolved in a liter of solvent.

　　

Solubility parameter：The solubility parameter is a measure of intermolecular forces. The effect of bringing molecules together is called cohesive energy. The cohesive energy per unit volume is called cohesive energy density (CED), and the square root of CED 1/2 is defined as the solubility parameter, and the code is δ or SP.

　　

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 molecular force. The unit of surface tension is N/m. The size of the surface tension is related to the nature, purity and temperature of the liquid. The surface tension multiplied by the surface area is the surface energy. The greater the surface tension, the greater the surface area and the greater the surface energy.

　　

Specific heat capacity：When the temperature of each kilogram of material increases by 1K, the heat required to absorb is called the specific heat capacity, and the unit is kJ/(kg·K). In the case of constant pressure, the heat absorbed when the temperature increases by 1K is called the specific heat capacity at constant pressure.

　　

Thermal conductivity：Thermal conductivity used to be called thermal conductivity or thermal conductivity, which reflects the thermal conductivity of materials. That is, take two parallel planes with a distance of 1cm and an area of 1cm2 within the object perpendicular to the direction of heat conduction. If the temperature difference between the two planes is 1K, the heat conducted from one plane to the other in ls is defined as the substance The thermal conductivity of the unit is W/(m·K).　　

 

Water content：The water contained in the substance, but does not include crystal water and associated water. It is usually expressed as the percentage of the original mass of the sample and the mass of the sample after loss of water.

　　

Water absorption：It is a measure of the water absorption of a substance. Refers to the mass percentage increase by immersing a substance in water for a certain period of time at a certain temperature.

　　

The percentage of Ash：The percentage of ashes is also called residue on ignition, which refers to the residues of oxides and salts formed by the mineral components after evaporation and ignition, expressed as a percentage.　　

 

Needle penetration: The 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, the needle connecting rod and the additional weight is 100±0.1g, the temperature is 25°C, and the time is 5s. The greater the penetration, the softer, that is, the smaller the consistency; otherwise, the harder, that is, the greater the consistency.

　　

Hardness：Hardness is the resistance of a material to external forces such as imprints and scratches. According to different test methods, there are Shore hardness, Brinell hardness, Rockwell hardness, Mohs hardness, Barcol hardness, Vichers hardness and so on. The value of hardness 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. The 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.

　　

Aniline point(A．P．)：The aniline point is the lowest temperature at which an equal volume of petroleum alkanes and aniline dissolve each other, and is used to indicate the content of paraffinic saturated hydrocarbons. The level of the aniline point is related to the chemical composition. The higher the aniline point, the more alkane content; the lower the aniline point, the more aromatic hydrocarbon content.

　　

Volume resistivity:Also called volume resistance and volume resistivity, it is an important index to characterize the electrical properties of dielectrics or insulating materials. It represents the resistance of 1cm3 dielectric to leakage current, and the unit is Ω·m or Ω·cm. The larger the volume resistivity, the better the insulation performance.　

　

Oil absorption:The quantity of oil required when the surface of a certain mass of filler particles is completely wetted by oil.

　　

Acid value：It represents an indicator of organic matter, which is the number of milligrams of potassium hydroxide (KOH) required to neutralize the free acid in the non-volatile matter of 1g of organic matter, that is, mgKOH/g.

　　

Hydroxyl value：The number of milligrams of potassium hydroxide (KOH) equivalent to the hydroxyl group in 1g sample is expressed in mgKOH/g.

　　

Iodine value：An indicator of the degree of unsaturation of organic substances. It is the mass percentage of iodine that can be absorbed by 1g sample. The higher the degree of unsaturation, the greater the iodine value.

　　

Epoxy value：The epoxy value refers to the equivalent number of epoxy groups contained in 100 g of epoxy resin, that is, the larger the epoxy value, the lower the molecular weight and the lower the viscosity.

　　

Epoxy equivalent：The epoxy equivalent represents the molecular weight of the resin corresponding to each epoxy group.

　　

HLB value：HLB is the abbreviation of Hydrophile-Lipophile-Balance, which is used to measure the relative strength of the polar group and non-polar group in the surfactant molecule. If the polar group is stronger, its HLB value is greater and its hydrophilicity is stronger; if the non-polar group is longer, its HLB value is smaller and its hydrophilicity is worse.

　　

Critical micell concentration: Critical micell concentration is abbreviated as CMC. The concentration range where the nature of the emulsifier solution changes is called the critical micelle concentration of the emulsifier. After the emulsion system reaches the critical micelle concentration, many emulsifier molecules gather to form micelles. The unit of CMC is mol/L.

　　

Degree Baum′e：The value given by the Baume meter, which uses a special indexing method in the glass tube float meter, is called the Baume degree, and the symbol is °B′e. Used to indirectly give the density of a liquid.

　　

Solid content：The solid content is also called the non-volatile content and the total solid content (TS), which represents the ratio of the mass of the residue to the mass of the sample after heating the sample at a certain temperature, expressed as a percentage.

　　

Surface-active agent: A substance whose surface active agent can significantly change the surface tension of the liquid or the two-phase interfacial tension. In other words, it can be strongly adsorbed on the surface of other substances or aggregated on the surface of the solution to reduce the surface tension of liquids or solids.

　　

Relative humidity: A method of expressing humidity is the ratio of absolute humidity to saturated absolute humidity under the same conditions (same temperature and pressure), that is, under the same conditions, the actual water vapor in the air (or other gas) The ratio of mass to saturated water vapor mass. Generally expressed as a percentage.　

　

Apparent density：It was once called bulk density, false density, and apparent density, which represents the mass of matter per unit volume (including voids).

　　

Isomer：The phenomenon that compounds have the same molecular formula but different structures and properties is called isomerism. Compounds that can undergo isomerism are called isomers, or isomers for short.

　　

Relative molecular mass：The abbreviated molecular weight refers to the ratio of the average mass of a molecule or specific unit of a substance to the atomic mass of the nuclide 10 6 C (1/12), and the symbol is Mr.

　　

Number average molecular weight：Polymers are composed of homologous mixtures with the same chemical composition but varying degrees of polymerization, that is, a mixture of polymers with different molecular chain lengths. The average molecular weight is usually used to characterize the size of the molecule. According to the statistical average of the number of molecules, it is called the number average molecular weight, and the symbol is (ˉMn).

　　

Degree of polymerization：The number of chain links that make up the molecular chain of a polymer is called the degree of polymerization, and the code is n or DP, which can be used as a measure of the molecular weight of the polymer.

　　

Molecular weight distribution：Due to the different sizes of polymers, in addition to the statistical properties of molecular weight, there is also polydispersity, that is, molecular weight distribution. The same average molecular weight will have different molecular weight distributions and show different properties.

　　

Homopolymer: A polymer composed of repeating chain links from the same monomer, called a homopolymer.

　　

Copolymer: A polymer formed by the polymerization of two or more monomers or monomers and polymers, called copolymers. It is divided into block copolymers, random copolymers, regular copolymers, graft copolymers and so on.

　　

Graft copolymer：A copolymer in which certain atoms of the polymer main chain are connected with side chains of polymer segments that are different in chemical structure from the main chain, called graft copolymers, such as grafted chloroprene rubber and SBS grafted copolymers .

　　

Prepolymer：A polymer with a lower molecular weight (below 1500) with a degree of polymerization between the monomer and the final polymer, also known as oligomers, oligomers (Oligmer), is a polymer composed of a few chain segments, Such as dimers, trimers, tetramers, or mixtures of these oligomers.

　　

Glass transition temperature：The approximate midpoint of the narrow temperature range at which an amorphous or semi-crystalline polymer changes from a viscous fluid state or a highly elastic state to a glass state (or vice versa) is called the glass transition temperature. It is usually expressed as Tg, which is an indicator of heat resistance.

　　

Brittle temperature：A measure of polymer low-temperature performance. When a hammer with a certain energy impacts a sample, the temperature at which the probability of cracking of the sample reaches 50% is called the embrittlement temperature, also called the brittle break point.

　　

Heat deflection temperature under load: A measure of the heat resistance of a polymer. It is measured by immersing a polymer sample in a suitable heat transfer medium with a constant temperature rise under the action of a simply supported beam static bending load. The temperature at which the bending deformation of the sample reaches the specified value is the thermal deformation temperature, referred to as HDT.

　　

Minimum filming temperature：The lowest temperature at which the synthetic emulsion system forms a continuous film is called the minimum film-forming temperature, or MFT for short.

　　

Softening point: A certain load is applied to the polymer sample in a certain form and heated to the temperature at which the deformation of the sample reaches the specified value according to the specified heating rate, which is the softening point.

　　

Marten’s test: A method to evaluate the tendency of materials to deform at high temperatures. In the heating furnace, the sample is subjected to a certain bending stress and heated at a certain rate. The temperature at which the heated free end of the sample produces a specified amount of deflection is called the Martin temperature.

　　

Vicat softening point test: A method to evaluate the tendency of high temperature deformation of thermoplastics. Under the condition of constant heating, a flat thimble with a specified load and a cross-sectional area of 1mm2 is placed on the sample. The temperature when the flat thimble penetrates the sample 1mm is the measured Vicat softening temperature.

 

Melt index：The melt index is abbreviated as MI, which is an index reflecting the flow characteristics and molecular weight of the thermoplastic resin melt. Under a certain temperature and load, the melt will pass through the standard capillary in 10 minutes, expressed in g/10min.

　　

Stress relaxation：The phenomenon that the deformation is fixed and the stress decays with the extension of the action time is called stress relaxation.

　　

Creep：When the stress remains constant, the phenomenon that the deformation changes with time is called creep.

　　

Shrinkage ration: defined as the percentage of the ratio of the shrinkage to the size before shrinking, and the shrinkage is the difference between the size before and after shrinking.

　　

Internal stress：In the absence of external force, the internal stress of the adhesive layer (material) due to defects, temperature changes, and solvent effects.

　　

Tensile strength: Tensile strength is the maximum tensile stress when the sample is stretched to break. This commonly used term used to be very inconsistent. It was called tearing force, tearing strength, tensile strength, and tensile strength, as well as strength and strength. According to the GB 6039-85 standard, it is uniformly called the tensile strength, and the unit is MPa.

　　

Shear strength: Shear strength refers to the maximum load that can withstand a unit bonding area parallel to the bonding area. The commonly used unit is MPa.

　　

Peel strength: Peel strength refers to the maximum breaking load that can be withstood per unit width. It is a measure of the line's force-bearing capacity, and the unit is kN/m.

　　

Specific strength: The ratio of the material's tensile strength to its density is called the specific strength.

　　

Elongation: The increase in length of the specimen under tensile force, expressed as a percentage of the original length.

　　

Swelling: A phenomenon in which a polymer absorbs solvent molecules and expands in volume, which is called swelling. Swelling is divided into limited swelling and infinite swelling. Infinite swelling is dissolution.

　　

Emulsion: In the presence of an emulsifier, the phenomenon of dispersing an insoluble liquid in another liquid is called emulsification.

　　

Gelatinization: The phenomenon that starch-like substances and water become viscous translucent gels or pastes at a certain temperature.

　　

Compatibility: When two or more substances are mixed, the ability to not repel the separation phenomenon.

　　

Mastication: Mastication, also known as mastication and rolling, refers to the transformation of raw rubber from a strong elastic state to a soft and plastic state under the action of mechanical force, heat and oxygen, which means that it increases its plasticity (fluidity). The process of) is called mastication, and the essence of mastication is to reduce molecular weight, reduce viscosity, and reduce viscous flow temperature. The masticated raw rubber is called masticated rubber.

　　

Milling: Mixing is the process of mixing plasticized rubber or raw rubber with a certain degree of plasticity and various compounding agents through mechanical action to make them uniformly mixed. The quality of the rubber compound obtained after mixing has a great influence on the performance of the formulated adhesive.

　　

Valcanization: Vulcanization is a process in which rubber, sulfur, accelerators, etc., under certain temperature and pressure, cause the rubber macromolecular chain to undergo a cross-linking reaction, that is, the process of converting plastic rubber into elastic rubber or hard rubber. Broadly speaking, vulcanization refers to the process in which rubber macromolecules are transformed from linear to network structure through cross-linking after chemical or physical treatment of the rubber material, thereby improving the physical and mechanical properties and chemical properties of the rubber.

　　

Crosslinking: refers to the chemical bonding between the main chains of linear polymer molecules.

　　

Scorching: Scorching refers to the early vulcanization of rubber compounds during processing. In order to avoid the danger of scorching, a scorch inhibitor can be added, such as sodium acetate added during the mixing of neoprene.

　　

Oil resistance: The ability of a material to resist swelling, dissolution, cracking, deformation, or degradation of physical properties caused by oil.

　　

Solvent resistance: The ability to resist swelling, dissolution, cracking or deformation caused by solvents.

　　

Chemical resistance: The ability to withstand acids, alkalis, salts, solvents and other chemical substances.

　　

Water resistance: The ability of a material to maintain its physical and chemical properties after being acted on by water or moisture.

　　

Flame resistance: The ability of a material to resist burning when it comes into contact with a flame or hinder the continued burning when it leaves the flame.

　　

Weatherability: The material's resistance to exposure to sunlight, heat, cold, wind and rain.

　　

Permanence: Durability is also called stability and service life. That is, under the combined action of external environmental factors, the ability to maintain its performance for a long time.

　　

Aging: In the process of processing, storage and use, due to the action of external factors (heat, light, oxygen, water, radiation, mechanical force and chemical medium, etc.), a series of physical or chemical changes occur to cross-link the polymer materials It becomes brittle, cracked and sticky, discolored and cracked, rough blistering, surface chalking, delamination and peeling, performance gradually deteriorates, and even loss of mechanical properties can not be used. This phenomenon is called aging.

　　

Lethal dose: The lethal dose is an important data to measure the toxicity of poisons. To some animals (such as rats, rabbits, etc.) orally or inject the poison, the dose that can kill half of the animals is called the half-lethal dose, abbreviated as LD50, expressed in mg/kg. The lower the LD50, the greater the toxicity, and the LD50 exceeding 5000 mg/kg can be regarded as non-toxic.

　　

Maxium allowable concentration：In order to prevent acute or chronic personal poisoning caused by chemical substances, all countries have stipulated the value that the toxic vapor or dust contained in the air in the workplace should not exceed, called the maximum allowable concentration, or MAC for short, usually expressed in mg/m3 or ppm . Conversion relationship between ppm and mg/m3: mg/m3=ppm× (22.45 is 25℃, 1mol gas volume at 101.3kPa).　　

Storage life: The longest period of time that materials with changing properties can maintain their usable performance when stored under certain conditions.

　　

Penetration ratio: the ratio of the penetration of the sample after the evaporation loss to the original penetration is multiplied by 100 and the percentage obtained.