Low temperature brittle impact tester for epoxy plastics

Low temperature brittle impact tester for epoxy plasticsBefore starting the rubber low-temperature brittleness testing machine, it is necessary to ensure that the grounding wire is properly connected to ensure safety; The power plug must be securely plugged in to prevent it from loosening and causing an instant shutdown that could burn out the compressor. In case of power outage or malfunction causing shutdown, the interval between restarts must be greater than 30 minutes; When the room temperature exceeds 25 ℃, the restart time must be greater than 60 minutes. If the compressor fails to start, works intermittently, or suddenly stops after a period of operation, please shut it down immediately. First, check the power supply voltage or configure an AC voltage regulator to reach the normal operating voltage value of this instrument. Secondly, attention should be paid to the ambient temperature. It is recommended to use this instrument at an ambient temperature below 25 ℃, as the high ambient temperature can cause the pressure in the compressor system to be too high. If the power grid capacity is insufficient or the low voltage is too low, it will be difficult to start at this time, and the interval between two startups will be much longer. The sample of the rubber low-temperature brittleness testing machine installed in the cooling tank should be wiped clean, and foreign objects such as iron filings should not be brought into the cooling tank to avoid blocking the circulation pipeline. Before reuse, the quality of the cooling medium in the slot should be checked to ensure it reaches a distance of 10-15mm from the cooling slot. If the actual temperature is low, please pay attention to the changes in the volume of the cooling medium caused by temperature and replenish the cooling medium in a timely manner. After each use, the cooling medium should be released. The cooling medium of the rubber low-temperature brittleness testing machine should be replaced regularly to minimize the content of impurities and water, otherwise poor circulation will affect the refrigeration effect and temperature accuracy. When pressing the "power" switch, be sure to fill the cooling tank with cooling medium and do not remove the temperature sensor from the cooling tank.

One small air compressor with a pressure of 2.5P or above (if there is a gas source in the factory, it is not necessary). The air pressure on our machine has been adjusted, so do not adjust it yourself. AC220V power socket. Ethanol (7-8 bottles), with a volume of 3-5cm from the wellhead, can be poured into the cold well to complete the preparation work.

The operation steps are as follows:

1. Pour alcohol into the cold well.

2. Connect the air source (the pressure of the machine itself has been adjusted and must not be adjusted).

3. Connect the power, turn on the switch, perform cooling and testing. front

4. Speak up

5. This standard is modified using ISO974:2000 "Determination of Brittle Temperature of Plastics by Impact Method" (English version).

6. This standard has been revised based on ISO 974:2000.

7. The main technical differences between this standard and ISO974:2000 are as follows:

8. An explanation of the two test methods in this standard has been added (Chapter 1):

9. Added normative references (Chapter 2);

10. The international standards referenced in ISO 974:2000 are replaced by corresponding Chinese standards (Chapter 2);

11. - Added B-type testing machine (similar to A-type testing machine in ASTMD746:2007) (5.2);

12. - Added provisions for "measuring tools" and "stopwatches" (5.7, 5.8);

13. - Added B-type specimen (same as Type I specimen in ASTMD7462007) (6.3);

14. Add a chapter on "Precision" (Chapter 10);

15. The experimental report has added the phrase 'indicate the experimental method used' (Chapter 11).

16. For ease of use, the following editorial modifications have been made to this standard:

17. Replace the comma with a decimal point

18. This standard replaces GB/T 5470-1985 "Determination of Impact Brittle Temperature of Plastics".

19. The main differences between this standard and GB/T 5470-1985 are as follows:

20. - Added explanations for the two test methods in this standard (Chapter 1);

21. Added a chapter on "Normative References" (Chapter 2);

22. Added a B-type testing machine (similar to the A-type testing machine in ASTMD746:2007) (5.2);

23. The reading microscope (3.6 of GB/T 5470-1985) has been removed from the instrument;

24. Requirements for the casing and mixer have been added (5.5 and 5.6);

25. Added Type B specimen (same as Type I specimen in ASTMD746:2007) (6.3);

26. Cancel the incision specimen (see 4.4 of GB/T5470-1985);

27. Added a chapter on "Precision" (Chapter 10);

28. The experimental report has added the phrase "indicate the test method used" (Chapter 11).

29. This standard was proposed by the China Petroleum and Chemical Industry Association.

30. This standard is under the jurisdiction of the National Plastic Standardization Technical Committee (SAC/TC 15)

31. Drafting unit for wood standards: Resin Application Research Institute of Sinopec Beijing Yanshan Branch,

32. Participating drafting units of this standard: National Synthetic Resin Quality Supervision and Inspection Center, National Chemical Building Materials Testing Center (Material Testing)

33. Department), National Petrochemical Organic Raw Material Synthetic Resin Quality Inspection Center, Guangzhou Jinfa Technology Co., Ltd.

34. The main drafters of this standard are Zheng Huiqin, Yang Lili, Wang Xiaoli, Gao Xueyan, Wu Yanjin, Zhao Shuzhi, Yu Yang, Wang Jiandong, Wang Chaoxian

35. Li Jianjun and Wang Zhenjiang.

36. The previous versions of the standards replaced by this standard are GB/T 5470-1985. Characteristics and Applications:

The low-temperature brittle impact testing machine is used to measure the high temperature at which a sample of a material fails under specified conditions due to impact, known as the brittle temperature. It can be used to compare and evaluate the performance of plastics and other elastic materials under low-temperature conditions. It can determine the brittleness temperature and low-temperature performance of vulcanized rubber with different rubber materials or formulations. Therefore, it is applicable in the quality inspection of scientific research materials and their products, as well as in the control of production processes. This instrument is designed according to the GB1682 national standard, and its technical indicators meet the requirements of national standards such as HG 2-162-1965 Plastic Low Temperature Impact Compression Test Method and GB5470-2008 Plastic Impact Brittle Temperature Test Method.
Technical Specifications

1. Temperature control range: room temperature to -70 ℃ (room temperature ≤ 25 ℃)

2. Constant temperature accuracy: ± 0.3 ℃

3. Cooling rate: 0 ℃ to -30 ℃, approximately 2.5 ℃/min

-30 ℃ to -40 ℃, approximately 2.5 ℃/min

-40 ℃ to -70 ℃, approximately 2.0 ℃/min

4. Dimensions: 900 × 500 × 800mm (length × width × height)

5. Effective workspace in the studio: 260 x 170 x 150mm (length x width x height)

6. Number of samples that can be loaded: 1

7. Digital timer: 0 seconds to 99 minutes, resolution of 1 second

8. Cooling medium: ethanol or other non freezing liquid

9. Mixing motor: 8W

10. Working power supply: 220V~240V, 50Hz, 1.5kW

11. Working temperature ≤ 25 ℃

structural principle

1. Lifting gripper

The lifting gripper consists of a cylinder with a gripper and a cylinder seat.

The distance from the impacted part of the specimen to the lower end of the gripper is 11.0 ± 0.5mm.

2 Impact devices

The impact device consists of an impactor and an impact cylinder.

3 impactors

The shape and size of the impactor head are as shown in the actual product. The weight of the impactor is 200 ± 20g, and its working stroke is 40 ± 1mm. In the reset state of the impact cylinder, the distance from the end of the impactor to the specimen is 25 ± 1mm.

3.4 Freezing medium: Industrial ethanol Figure 2

The spring of the impact device is compressed, and the distance from the end of the impactor to the specimen is 25 ± 1 mm

4.2.2 Impact spring

The impact spring should meet the following technical requirements:

a. Free state: diameter of 19mm, length of 85-90 mm;

b. Compressed state: Length of 40 ± 1mm, load of 11-12kgf (108-118N)

4.3 Low temperature thermometer plastic

Determination of Brittle Temperature by Impact Method

This standard specifies the method for determining the temperature at which non rigid plastics undergo brittle fracture under specific impact conditions at standard ambient temperature. press

There are two methods based on the different types of testing machines and specimens, namely

A method using an A-type testing machine and A-type specimens;

A B-method using a B-type testing machine and B-type specimens.

This standard uses statistical methods to determine the brittleness temperature. Due to the need to calculate the brittleness temperature based on statistics, sufficient samples need to be prepared

Product. Statistical techniques have been used to measure the embrittlement temperature as defined in section 3.1.

This standard determines the embrittlement temperature when the sample damage rate is 50%. This standard is useful for developing material specifications without the need to measure materials

Low usage temperature of the material. When used for material specifications, the measurement accuracy of the measured values shall not exceed ± 5 ℃.

Normative reference documents

The clauses in the following documents become clauses of this standard through the reference surface of this standard. Any referenced document with a date shall be followed by all subsequent references

The amendment form (excluding errata) or revised version is not applicable to this standard. However, all parties who have reached an agreement based on this standard are encouraged to study it

Can new versions of these files be used. Any referenced document without a date shall apply to the new version of this standard.

GB/T 2918-1998 Standard Environment for Condition Adjustment and Testing of Plastic Test Specimens (idt ISO 2911997)

GB/T 11547-2008 Determination of resistance of plastics to liquid chemical reagents (ISO175:1999, MOD)

ASTM D746:2007 Determination of Brittle Temperature by Impact Method for Materials and Elastomers

The following terms and definitions apply to this standard.

Brittleness temperature

The temperature at which the sample breakage rate is 50% under the specified test conditions.

Test speed

The relative velocity between the punch of the testing machine and the specimen fixed in the fixture.

The principle is to immerse the sample fixed in a cantilever beam in a precisely controlled heat transfer medium in the fixture, adjust the state according to the specified time, and then regulate it accordingly

A fixed speed single swing punch impacts the sample. Test a sufficient number of samples and use statistical theory to calculate the embrittlement temperature. When 50% of the sample is damaged

The temperature is the embrittlement temperature. GB/T5470-2008

There should be no significant difference in the values obtained from the two measurements when it takes effect (see GB/T 11547-2008).

5.5 Box body

Has adiabatic properties.

5.6 Blender

Enable the thermal conductive medium to circulate uniformly.

5.7 Measuring Tools

The accuracy is 0.1mm, used to measure the width and thickness of the sample.

5.8 Stopwatch

6 samples

6.1 Overview

For many polymers, the test results largely depend on the conditions and methods of sample preparation and specimen preparation. Unless otherwise specified,

Sample preparation should be carried out in accordance with relevant product regulations, and then cut from the sample. Clean knives and reduce or eliminate accidental gaps will both be necessary

To a lower brittleness temperature.

It is important to prepare the sample using the same method. Use a blade or other sharp tool to cut the sample smoothly each time. Not recommended for manual operation

Cut the sample with a punching knife, although this may produce satisfactory samples. Recommend using an automatic punching machine. Regardless of the method used, regularly check and

Maintaining the punching knife is very important. To obtain reliable test results, a sharp punch should be used to prepare the sample.

The condition of the punching tool can be determined by observing the rupture point on any series of damaged samples. When the broken spline is removed from the fixture of the testing instrument

When falling up and down, it is easy to collect these samples and observe whether they have a tendency to rupture at or near the same point

The momentum. If the rupture point consistently appears at the same location, it indicates that the position of the punch has been passivated, has a notch, or is bent.

Note that for splines using automatic cutting, see Bestelink, P.N. and Turner, S; Low temperature impact test method for polyethylene, ASTMBulletinGB/T5470--2000

6.3B type specimen

The sample is 31.75 mm ± 6.35 mm in length, 6.35 mm ± 0.51 mm in width, and 1.91 mm ± 0.13mm in thickness. The specific dimensions and status can be adjusted

According to the material standards, adjust the state of the sample. If there are no regulations and the relevant parties have not reached a consensus, follow GB/T2918-

Select appropriate state regulation conditions in 1998.

operation steps

When determining the brittleness temperature of a material, it is recommended to conduct the test under the temperature conditions where the expected decoration reaches a 50% damage rate. At this temperature

Use at least 10 samples for testing. If all the samples are damaged, raise the temperature of the bath by 10 ℃ and retest with a new sample;

If all the samples are not damaged, lower the temperature of the bath by 10 ℃ and retest with a new sample; If the approximate brittleness temperature is not known,

The starting temperature can be arbitrarily selected.

Prepare the bath before the experiment and adjust the instrument to the starting temperature. If using dry ice to cool the bath, place an appropriate amount of powdered dry ice in an insulated box

Then slowly add the thermal conductive medium until the liquid level is at a height of 30 mm~50 mm from the top. If the instrument is equipped with liquid nitrogen or thousand

The ball cooling system and automatic temperature control device should be operated according to the instructions provided by the instrument manufacturer.

8.3 Tighten the sample in the fixture and fix the fixture on the testing machine (see Figure 3).

Note that when the clamping force of the fixture is too high, it may cause pre stress on certain materials, leading to premature failure during testing. The clamping of the sample can be controlled by using a torque wrench

Apply the same small tillage force to each sample.

8.4 Lower the fixture into the heat transfer medium. If dry ice is used as a coolant, it can be maintained at a constant temperature by adding a small amount of dry ice at the appropriate time. if

The instrument is equipped with a liquid nitrogen or dry ice cooling system and an automatic control device, and should be operated in accordance with the settings and control methods provided by the instrument manufacturer.

When using liquid medium, record the temperature for 3 minutes ± 0.5 minutes and impact the sample once; When using gas medium, it takes 20 minutes

Record the temperature for 0.5 minutes and perform one impact on the sample.

B. 6. Remove the fixture from the testing instrument and take out each sample from the fixture. Check each sample one by one to determine if it is damaged. so-called

Breaking the load means that the sample is divided into two or more parts, or visible cracks are visible on the sample. If the sample is not separated, it can be

Bend the specimen to 90 ℃ along the bending direction caused by the impact, and then inspect the cracks in the bent part. Record the number of damaged samples and tests

Temperature.

Note: The temperature at which the sample is bent should be higher than the temperature at which the sample is impacted.

Increase or decrease the bath temperature in increments of 2 ℃ or 5 ℃, repeat the above steps until the low temperature without sample damage is measured

When the temperature is high and all the samples are damaged, new samples are used for each test.

8.7 Conduct tests at four or more temperature points within the range of 10% -90% damage (when using the graphical method given in 9.1 to determine Tu,

Excluding temperature points at 0% and 100% break simulation.

9 results indicate

The embrittlement temperature T „ can be represented by any of the following methods:,

9.1 Graphic Method

Mark the points on the probability map where the test temperature and corresponding percentage of damage are measured at any given temperature, and draw an ideal line through these points

Straight line. The temperature indicated by the point where the line intersects with a 50% probability is the cell temperature. An example of using graphical method to determine the embrittlement temperature Ts is shown in Figure 7

9.2 Calculation Method

Calculate the brittleness temperature of the material according to equation (1),

No.231,68(1958)。

Type A specimen

The sample is 20.00 mm ± 0.25 mm long, 2.50 mm ± 0.05 mm wide, and 2.00 mm ± 0.10 mm thick. The specific dimensions are shown in Figure 6

(a)。 The sample can be easily cut into the specified size from a long strip sample with a width of 20.00 mm ± 0.25 mm and the required thickness. good

The method is to use an automatic punching machine.

Instrument Type A Testing Machine

The testing machine consists of a sample fixture, a punch, and mechanical connecting components. Proper installation of these components ensures that the punch can operate at a relatively constant level

Impact the sample at high speed. Figure 1 shows the dimensional relationship between the punch and fixture components of the A-type testing machine, and Figure 2 shows the protrusion of the A-type sample with the sample installed

Figure 3 shows a detailed description of the punch and sample fixture of the A-type testing machine.

Use low-temperature thermometers with small divisions not exceeding 1 ℃, or thermocouples, resistance thermometers, etc., to measure the temperature of the freezing medium. temperature

Calculated as an internal standard semi immersion, it is advisable to use a tail length of 150mm and a immersion depth of 75.mm

Freezing medium

The freezing medium is composed of a suitable heat transfer medium and refrigerant.

Heat transfer medium

At the experimental temperature, liquids that can maintain flow without any additional impact on the sample can be used as heat transfer media. This type of heat transfer medium is usually used

Ethanol, in addition to acetone, siloxane liquids, and so on.

Refrigerant

Dry ice or liquid nitrogen can be selected as needed.

sample

Specifications

The length of the sample is 25.0 ± 0.5 mm, the width is 6.0 ± 0.5 mm, and the thickness is 2.0 ± 0.3 mm

requirement

The surface of the sample should be smooth, free of foreign impurities and damage. The finished product should be polished and planted to the corresponding size.

Laboratory temperature

The laboratory temperature should comply with the relevant provisions of GB2941

Test steps

Test preparation: Press the lifting clamp and place the low-temperature thermometer so that the temperature bulb of the thermometer is at the same horizontal position as the lower end of the clamp.

This measuring instrument uses a compressor for direct cooling No need for cooling circulating water.

Instructions: Connect the power supply, and the temperature controller and timer display lights will turn on.

Inject freezing medium (usually industrial ethanol) into the cold well, and the injection amount should ensure that the distance from the lower end of the clamp to the liquid level is 75 ± 10mm.

Clamp the sample vertically onto the gripper. The clamp should not be too tight or too loose to prevent deformation or detachment of the sample. After reaching the test temperature, press the start button and the testing machine will automatically start working (press the gripper to start freezing the sample, and at the same time, start the timing control switch or press the stopwatch to time. The sample freezing time is specified as 3.0 ± 0.5min. During the freezing period of the sample, the temperature fluctuation of the freezing medium shall not exceed ± 1 ℃. Remove the sample, bend it 180 ° in the direction of impact, and carefully observe for any damage.

After the sample is impacted (each sample is only allowed to be impacted once), if damage occurs, the temperature of the freezing medium should be increased. Otherwise, the temperature should be lowered and the test should continue.

Temperature adjustment method: a. Press the set button to enter the setting state of the temperature controller

b、 Press the "<" key to move to the desired position

c、 Press the "∧" key to adjust the temperature

d、 Press the 'set' key to confirm

Through repeated experiments, determine the low temperature at which at least two samples remain intact and the high temperature at which at least one sample fails. If the difference between these two results is no more than 1 ℃, the experiment is considered complete.

Test Standard

Specifications

The length of the sample is 25.0 ± 0.5mm, the width is 6.0 ± 0.5mm, and the thickness is 2.0 ± 0.3mm.

requirement

The surface of the sample should be smooth, free of foreign impurities and damage. The finished product should be polished and cut to the corresponding size.

Precautions

The cylinder pressure has been adjusted before leaving the factory and cannot be changed arbitrarily.

Rubber, vulcanized - Determination of low-temperature brittleness - Single specimen method

GB/T 1682-94

Rubber , vulcanized--Determination of low-temperature

Replace GB1682-82

brittleness(single test piece method)

Scope and purpose of application

1.1 This method is applicable for determining the brittleness temperature of vulcanized rubber on a single specimen brittleness testing machine.

1.2 The brittle temperature measured by this method is the characteristic temperature of vulcanized rubber and does not represent the lower limit of the working temperature of vulcanized rubber and its products benefit

The brittleness temperature can be used to compare the low-temperature performance of different rubber materials or formulations of vulcanized rubber Therefore, whether in scientific research or rubber

The quality inspection and production process control of adhesive materials and their products have certain practical value.

Reference standards

GB2941 Standard temperature, humidity, and time for environmental conditioning and testing of rubber specimens

GB/T 15256 Determination of low-temperature brittleness of vulcanized rubber Multi sample method

Define brittle temperature (single specimen method); Under certain conditions, the high temperature at which the specimen is damaged by impact.

Brittle fracture: including the appearance of fractures, cracks, and visible micropores in the specimen.

Test equipment

This equipment consists of a workbench, a lifting clamp, an impact device, a low-temperature thermometer, a low-temperature bottle for holding the freezing medium, a stirrer, and other parts.

Lift gripper

The lifting gripper consists of a lifting rod with a gripper and a lifting spring.

The distance from the impacted part of the specimen to the lower end of the gripper is 11.0 ± 0.5mm, as shown in Figure 1. Inject heat transfer medium (usually industrial ethanol) into the low-temperature bottle, and the injection amount should ensure that the distance from the lower end of the clamp to the liquid level is 75 ±

10mm.

Slowly stir and add refrigerant (usually dry ice) to the heat transfer medium, and adjust to the desired temperature.

Lift the lifting gripper and clamp the sample vertically onto the gripper (as shown in Figure 1). The clamp should not be too tight or too loose to prevent deformation or detachment of the sample

Falling.

Press the gripper to start freezing the sample, and at the same time, activate the timing control switch (or press the stopwatch) for timing. The freezing time for the sample is specified as

3.0 ± 1min. During the freezing period of the sample, the temperature fluctuation of the freezing medium shall not exceed ± 1 ℃ When the temperature control needs to be reset, you can press the SET setting button. When the temperature indicator window shows SO, you can set it. Press the shift button to select the setting position, and then press the add or subtract button to set the number as needed. After setting, press the SET setting button again to enter the automatic temperature control state.

Lift the lifting gripper and allow the impactor to impact the specimen within half a second.

Remove the sample and bend it 180 degrees in the direction of impact, carefully observing for any damage.

After the sample is impacted (each sample is only allowed to be impacted once), if damage occurs, the temperature of the freezing medium should be increased, otherwise its temperature should be reduced

Degree, continue with the experiment.

Through repeated experiments, determine the low temperature at which at least two samples do not fail and the high temperature at which at least one sample fails, such as these two

When the difference in results is no more than 1 ℃, the experiment ends.

The high temperature at which the test results and the processed sample fail is the brittle temperature of the test sample (single sample method)

The temperature value should be accurate to 1 ℃

Test Report

The test report should include the following contents:

a. Test method standards;

b. Brittle temperature (single specimen method);

c. Sample damage situation;

d. The heat transfer medium and refrigerant used.

It is recommended to actively adopt the GB/T 15256 method for the determination of rubber brittleness temperature in product standards. The GB/T1682 method is currently being used for

Conduct comparative experiments between GB/T 15256 and GB/T1682 methods, accumulate data, and convert to GB/T 15256 method.

Low temperature brittle impact tester for epoxy plastics

1. Inject freezing medium (usually industrial ethanol) into the cold well, and the injection amount should ensure that the distance from the lower end of the clamp to the liquid level is 75 ± 10mm.

2. Connect the power, and the temperature controller and timer display lights will turn on. Press the mixing and cooling switch, set the required temperature value according to the test requirements, and then the compressor starts cooling. When the temperature drops to the required temperature value, the machine will have a music reminder.

3. Clamp the sample vertically onto the gripper. The clamp should not be too tight or too loose to prevent deformation or detachment of the sample.