Properties of plastics
DATE：2022/7/11 8:40:16 / READ： / SOURCE：This station
Properties of plastics
Density the density of plastic refers to the mass per unit volume at a certain temperature. Plastic extrusion molding technician manualThe test method of plastic density is as follows. Coating equipment www.handern com
① Preparatory work
a. Select clean, crack free, bubble free plastic products (tubes, plates, rods) with a mass of no more than 30g.
b. Analytical balance (accuracy not less than 0.001g). c. Metal wire with diameter less than 0.13MM.
d. The impregnation solution is distilled water or kerosene (the density of the tested object is less than 1g/cm ³ Kerosene is selected as the impregnating solution), and the temperature is (23.0+0.5) ℃.
② Test method use a balance to test the quality of products suspended in the impregnation solution and in the air with metal wires. According to the actual measurement of the mass of the tested object in the air and the impregnation solution and the density value of the impregnation solution, the density of the tested product sample can be calculated.
That is, PP shares (G-G) g-g1 coating equipment www.handern com
Where, the density of impregnating solution at standard temperature, g/cm;
G-mass of sample and wire in air, G; G -- mass of sample and wire in impregnation solution, G; G -- mass of metal wire in air, G. ③ Inspection and test precautions
a. This test method is not suitable for film and foamed plastic products. b. There shall be no impurities and bubbles in the impregnation solution. c. Pay attention to prevent the influence of static electricity. Coating equipment www.handern com
d. Pay attention to the stability of the working environment and the temperature of the impregnation solution. The standard is (23+2) ℃. e. After the test sample is immersed in liquid, the distance between the upper end and the liquid level shall not be less than 10mm. Coating equipment www.handern com
(2) Water absorption the water absorption of plastic refers to the amount of water absorbed by the plastic sample after soaking it in distilled water for 24 hours at 23 ℃. The ratio of water absorption to sample mass is water absorption.
(3) Transparency is represented by transparency. Transmittance refers to the percentage ratio (%) of the luminous flux passing through the measured object and the luminous flux emitted on the measured object, which is measured on the photometer,
(4) Friction is the force generated by the friction coefficient preventing the movement of two contacts. The ratio of the friction force to the pressure between the two contact surfaces is the friction coefficient. The friction coefficient of plastics is not only related to surface roughness and cleanliness, but also to the pressure on the contact surface, moving speed, temperature and humidity.
(5) Tensile strength the tensile strength of plastic refers to the maximum tensile force borne by the specimen along its longitudinal (axial) tensile load until the specimen breaks under the specified standard (test temperature, humidity and tensile speed) test conditions, that is, the tensile strength of this plastic. The calculation formula of tensile strength is: in the first product formula -- tensile strength, PA; P -- maximum tensile load of sample, N; B -- sample width, m; D -- sample thickness, M. The tensile strength of plastics shall be tested according to gb/t1040-92 standard
(6) Tensile modulus of elasticity tensile modulus of elasticity is a physical quantity that indicates the rigidity of a material and whether it is easy to be stretched and deformed. The higher this value is, the greater its rigidity is and the less easy it is to deform. Coating equipment www.handern com
(7) Elongation refers to the length change rate of a material when it is damaged by tensile fracture (that is, the ratio of the elongation value at tensile fracture to the initial length value), indicating the toughness of the material. For plastic products, the greater the elongation, the softer it is.
(8) Bending strength the strength when the specimen is placed horizontally on two fulcrums and a concentrated load is applied between the two fulcrums to deform the specimen until it breaks is the bending strength. Coating equipment www.handern com
(9) The ratio of the bending stress of the specimen to the corresponding strain within the proportional limit is called the bending elastic modulus of the material. It is a physical quantity that indicates whether plastic products are easy to bend and deform. Coating equipment www.handern com
(10) Compressive strength and compressive elastic modulus apply compressive load to both ends of the standard specimen under the condition of standard specimen until the maximum compressive stress at the time of failure is the compressive strength of the material. The ratio of the compressive stress of the specimen to the corresponding strain within the proportional limit is called the compressive elastic modulus of the material. The toughness of the impact material indicates the impact strength, which indicates the ability of the material to resist fracture failure due to plastic deformation and energy absorption under rapid load. It is expressed by the energy consumed per unit fracture area, and the unit is kj/m.
(12) Fatigue strength fatigue strength refers to the ultimate strength of plastic under the action of alternating periodic stress.
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