Product

Contact us

TEL:0531-85809007 Jinan Hengpin Electromechanical Technology Co. Ltd.
ADDRESS:Jinan City Industrial Park
TEL:0531-85806007
FAX:0531-85806007
EMAIL:jnhengpin@163.com

Technical Support

Your current location:home>>Technical Support>>

Tensile testing standards and testing methods for plastics
Add time:2016-03-27 Views:2585
(a) tensile test
Plastic tensile tensile testing standard and testing method of share mastery of plastic tensile test method, to understand the basic structure and the working principle of a plastic tensile test machine, and through the tensile should stress strain curve and the test data to analyze the static tensile mechanical properties, on the tensile strength, yield strength, elongation at break and elastic modulus evaluated.
(two) tensile test principle
In the specified test temperature, humidity and strain rate by the plastic sample in the direction of the longitudinal axis tensile load applied, make samples produce deformation until the destruction of the material. Record the maximum load and the corresponding sample damage when the distance between the changes of the marking. (in microprocessor electronic tensile machine, as long as the input of the relevant data and sample size and other requirements, in the tensile process, sensor to force value is passed to the computer, computer through processing, automatic recording of stress strain data of the whole process and the stress-strain curve and the test data through the printer to print out).
(three) tensile test equipment and tensile test specimens
1 test equipment
(1) mechanical tensile testing machine
Special fixture suitable for each type of sample.
The movement speed of the fixture should be able to be multilevel or full speed regulation, in order to meet the needs of the standard method.
Test data indicated that the value should be 90% ~ 10% in each grade, but not less than 4% of the maximum load of the test, the value of the error should be within 1%.
2 tensile specimen
(1) standard methods for the shape and size of the sample to use four types of specimens.
(2) sample selection
Thermosetting molding material: I type.
Hard materials: type II (more than 170mm).
Hard, semi hard thermoplastic molding material: with type 2, thickness of D = (4 + 0.2) mm.
Soft plate, sheet: with type III, the thickness of d < =2mm.
Plastic film: with type IV.
(3) requirements for samples:
Sample surface should be smooth, no bubbles, cracks, delamination, no obvious defects such as impurities and processing damage, there are differences in the direction of the test piece should be sampled along the longitudinal direction.
The cardboard thickness d < 10mm, on the original thickness as the thickness of the specimen; when the thickness of D, 10mm, from the side of machining 10mm.
Test elastic modulus, with thickness of 4 ~ 10mm of type II or with a long 200mm, width 15mm of the strip sample.
The specimens of not less than 5.
(four) tensile test step
1 experimental conditions
(1) test speed (no load) A: (10 + 5) min / mm, B: (50 + 5) min / mm, mm (100 + 10) C: / min or (250 + 50) min / mm.
Thermosetting plastics, rigid thermoplastic, with A speed.
Elongation of hard, semi rigid thermoplastic plastics (such as PP, PA, etc.), using B speed.
C speed for soft plates, sheets and films. Relative elongation < 100% with (100 + 10) mm / min speed, relative elongation > 100% with (250 + 50) mm / min speed.
(2) determination of the modulus of 1 ~ 5mm / min of the tensile speed, the amount of deformation should be accurate to 0.01mm.
2 mechanical tensile testing machine as an example: according to the GBl039 - 92 standard method of regulating the test environment treatment of samples or GB/T1040 for room temperature.
(1) test environment temperature: thermoplastic plastics (25 + 2) C, thermosetting plastics (25 + 5). Humidity: relative humidity (65 + 5)%.
(2) sample pretreatment will be placed in a small environment, so that the surface as far as possible exposure to the environment. The sample treatment time of D with different thickness is as follows: the sample of d < 0.25mm is not less than O.25mm; 4H < d < 2mm specimen is not less than D; 8h > 2mm specimen is not less than 16h.
(3) measurement of the specimen's width and thickness of the molded specimens and plate specimen accurately to 0.05mm; sheet specimen thickness O.01mm; film thickness of the sample 0.O01mm; each specimen from marking the distance measurement of the third point, take arithmetic mean value.
(4) the test specimen is in elongation should be parallel part stretching for marking, the marking of the test results should not affect.
(5) clamp for clamping the samples to make the vertical axis of the sample in the direction of the centre and upper and lower clamp center line coincide, and proper tightness, can not make the sample in stress slippage or clip to tight in the nip at the damage to the specimen. Clamping thin film specimens for elastic sheet of rubber and the like in the fixture.
(6) according to the choice of speed, start the machine, tensile test.
(7) the elongation at break of the specimen after reading of the load and the distance between the gauge, or the load of the yield load. If the specimen fracture in the distance outside the site, then the test void, and take samples to do.
(8) to determine the modulus of the load and the corresponding deformation should be recorded, and the corresponding stress - strain curve.
More details please
Ji'nan Heng product official website: http://www.jnhpjd.com
Tel: 85809007