Ash: when the polymer is burned at high temperature, a series of physical and chemical changes occur. Finally, the organic components volatilize and escape, while the inorganic components (mainly inorganic salts and oxides) remain. These residues are called ash. In the general modified products, the ash content is silica, calcium carbonate, talc powder, glass fiber, titanium dioxide and other inorganic minerals.
Test method: calcination method (burning organic matter and treating its residue at high temperature until constant weight), burning in muffle furnace at 600 ℃ for 10min, and weighing its residue.
Ash content is expressed as mass percentage: (m1-m0) × 100/M
M represents the weight of the pattern, M1 ash and the weight of the cup, and M0 the weight of the cup
Objective: to determine the content of inorganic substances in plastics as a basis for judging the authenticity of materials and the performance of materials. For example, in plastics with glass fiber, the rigidity of plastic materials increases and the heat resistance increases, but the toughness decreases. On the contrary, the toughness increases and the rigid heat resistance decreases.
Moisture: water contained in an object.
Test principle: it is mainly divided into infrared rapid moisture determination and halogen rapid moisture determination
Infrared moisture test principle: infrared heating weightlessness is to use the thermal effect and strong penetration ability of infrared heating object to quickly evaporate the moisture of the measured object and lose weight. Through the data of the initial mass of the object and the mass of the object after evaporating the moisture, the moisture content of the measured object at a specific temperature can be obtained.
Halogen rapid moisture determination:
Test calculation formula: Let G be the weight of the sample before drying, and G be the weight of the sample after drying; L is the water content of the sample, and R is the drying of the sample; LR is the sample moisture regain 'or is the sample wet weight rate, so
Test purpose: moisture content is an important factor affecting the processing technology, product appearance and product characteristics of resins such as polyamide (PA) and polycarbonate (PC). In the process of injection molding, if plastic particles with excessive moisture content are used for production, some processing problems will occur and eventually affect the quality of finished products, such as surface cracking, reflection, reduction of mechanical properties such as impact resistance and tensile strength, etc.
Melt index test:
Melt index: a numerical value indicating the fluidity of plastic materials during processing.
Test method: first let the plastic particles melt into plastic fluid under a certain time (10 minutes), a certain temperature and pressure (different material standards), and then pass through the weight or volume of a diameter circular pipe. MFI: fluid quality; MVR: fluid volume.
Meaning: it indicates the processing fluidity of the plastic material. The greater the value, the better the fluidity. On the contrary, the worse the fluidity; Microscopically, the larger the melt index, the smaller the viscosity and molecular weight. On the contrary, the greater the viscosity and molecular weight of the plastic.
Tensile / bending test:
Tensile test: determine the basic physical properties of polymer materials. After applying stress to the materials, measure the deformation and calculate the stress. The stress-strain curve is the most common method. Fix the two ends of the spline with tools, and apply the tensile load in the axial direction until the stress and distortion when damaged.
Elastic modulus: e = (F / s) / (DL / L) (in the elastic deformation stage of materials, the stress and stress become a positive proportional relationship) "elastic modulus" is a physical quantity describing the elasticity of materials, which is a general term, including "Young's modulus", "shear modulus", "bulk modulus", etc.
Significance of elastic modulus: elastic modulus is an important performance parameter of engineering materials. From a macro point of view, elastic modulus is a measure of the ability of an object to resist elastic deformation. From a micro point of view, it is the reaction of bonding strength between atoms, ions or molecules.
Variation of tensile pattern of different plastics
Strength: the maximum capacity of a material to resist plastic deformation or damage under load.
Yield strength: the resistance of a material to significant plastic deformation.
Tensile strength: the maximum tensile stress borne by the specimen until fracture in the tensile test.
Tensile stress: the tensile load borne by the sample on the unit initial cross section within the measurement gauge.
Tensile breaking stress: σ ｔ－ ε T the stress at fracture on the curve.
Tensile yield stress: σ ｔ－ ε T the stress at the yield point on the curve.
Elongation at break: the ratio of the increase in the distance between markings to the initial gauge distance when the sample is broken.
Yield point: σ ｔ－ ε On t curve σ T does not follow ε Tinitial point of increase.
Definition: when the pendulum strikes the middle of the simply supported beam sample, the sample is impacted and broken. The impact energy consumed per unit area or unit width is the impact strength.
Significance: impact toughness describes the toughness or fracture resistance of polymer materials under high-speed impact. Generally speaking, impact toughness includes two aspects: deformation capacity after impact and carrying fracture capacity. The former is generally expressed by elongation at break, while the latter is generally expressed by impact strength.
Thermal deformation temperature test:
Heat deflection temperature: the temperature corresponding to the specified deformation when a certain load is applied to the polymer material or polymer and the temperature rises at a certain speed.
Test principle: the plastic sample is placed on the support with a span of 100mm, placed in a suitable liquid heat transfer medium, and a specific static bending load is applied at the midpoint of the two supports. Under the condition of constant temperature rise, when the bending deformation of the sample reaches the specified value.
Test purpose: for polymers in glassy or crystalline state, with the increase of temperature, the motion energy of atoms and molecules increases, and the ability of deformation caused by directional movement under the action of external force increases, that is, the modulus of materials resisting external force decreases with the increase of temperature, and the deformation of plastics under fixed load increases with the increase of temperature.
Vicat softening temperature test:
Test principle: put the plastic strip in the liquid heat transfer medium. Under certain load and constant temperature rise conditions, the temperature when the sample is pressed into 1mm by a 1 mm2 pressure needle.
Significance: Vicat softening temperature is one of the indexes to evaluate the heat resistance of materials and reflect the physical and mechanical properties of products under heating conditions. The Vicat softening temperature of materials can not be directly used to evaluate the actual service temperature of materials, but can be used to guide the quality control of materials. The higher the Vicat softening temperature, the better the dimensional stability of the material when heated, the smaller the thermal deformation, that is, the better the heat-resistant deformation ability, the greater the rigidity and the higher the modulus.
Thermal aging test:
Test principle: put the plastic sample into the thermal aging test chamber under given conditions (temperature, wind speed, air exchange rate, etc.) to undergo the accelerated aging effect of heating and oxygen.
Objective: to detect the changes of properties before and after exposure and evaluate the heat aging resistance of plastics.
Plastic viscosity: refers to the mutual friction coefficient between macromolecules when plastic melts and flows. It is a reflection of the melt fluidity of plastics, that is, the greater the viscosity, the stronger the melt viscosity, the worse the fluidity and the more difficult it is to process. At the same time, it is also an evaluation method of polymer molecular weight. The viscosity of plastics is inversely proportional to the melt index of plastics. The viscosity of plastics varies with the characteristics of plastics, external temperature, pressure and other conditions.
Combustion performance: refers to all physical and chemical changes that occur when a material burns and meets fire. This performance is measured by the ignitability and flame propagation, heating, smoke, carbonization, weight loss, and the generation of toxic products on the material surface.
Test methods: mainly aerobic index combustion performance test, horizontal combustion performance test, vertical combustion performance test and glow wire flammability index test. The flame retardancy of materials directly affects the use of materials.
Test principle: fix one end of the rectangular strip on the horizontal or vertical fixture, and expose the other end to the specified test flame. Evaluate the horizontal combustion behavior of the sample by measuring the linear combustion rate; The combustion performance of plastics was evaluated by measuring the remaining fireworks and residual flame time, combustion range and particle drop.
Significance of test: under the specified conditions, the combustion performance of different materials is of great significance to the application range of materials, manufacturing process and combustion characteristics.
Contact Person: Ms. Victoria Li
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