Vicat Softening Temperature

1. What is Vicat softening temperature?

Vicat softening temperature test is a method for measuring Vicat softening temperature of thermoplastic pipes and fittings. It is suitable for thermoplastic plastic materials that can measure the temperature when the pipe begins to soften rapidly, and is not suitable for crystalline or semi-crystalline polymer materials.

2. How to test Vicat Softening temperature?

Put the sample in a liquid medium or a heating box, and measure the temperature of the standard pressure needle when it is pressed into the sample cut from the pipe or pipe fitting for 1mm under the action of （50±1）N force under the condition of constant temperature rise.

3. Standards to determine Vicat Softening temperature

Standards to determine Vicat softening point include ASTM D 1525 and ISO 306, ISO2507 & GB/T 8802-2001 Determination of Vicat Softening Temperature of Thermoplastic Pipes and Fittings

4. Specimen Size:

4.1 Pipes

Cut from the pipe along the axial direction, with the length  about 50mm and width 10 mm ~ 20 mm.

4.2 Pipe fittings

The sample should be an arc-shaped segment cut from the socket, socket or cylinder of the pipe fitting, and the sample should be cut from the part where there is no clamping line or injection point. See Table 2 for detailed dimensions:

Table 2 Sample Size of Pipe Fittings

4.3 Sample preparation

4.3.1 If the wall thickness is greater than 6mm, the pipe or key surface shall be processed by appropriate methods to reduce the wall thickness to 4mm.

4.3.2 If the socket of pipe fittings is threaded, the threaded part should be turned off to make its surface smooth.

4.3.3 Samples with wall thickness ranging from 2.4 mm to 6.0 mm (including 6mm) can be directly tested.

4.3.4 If the wall thickness of pipes and fittings is less than 2.4mm, two arc-shaped pipe sections can be superimposed together to make the total thickness not less than 2.4 mm.. As a cushion, the sample of the lower pipe section should be flattened first, and the upper arc pipe section should remain unchanged.

4.3.5 Number of samples: two samples are used for each test.

4.4 Pretreatment

4.4.1 Pretreat the sample at a temperature 50℃ lower than the expected Vicat softening temperature (VST) for at least 5 minutes.

4.4.2 For ABS and ASA samples, they should be dried in an oven at the temperature of (90 2)℃ for 2h, and then cooled for (15 1) min at the temperature of (23 2)℃ and the relative humidity of (50 5)%. Then press 7.1 for processing.

5.  Test steps

5.1 Adjust the temperature of the heating bath to 50℃ lower than the softening temperature of the sample and keep it constant.

5.2 Place the concave surface of the sample upward and horizontally under the pressure pin of the unloaded metal rod. The contact surface between the sample and the instrument base should be flat. For samples with a thickness less than 2.4mm, the end of the pressing needle should be placed on the concave surface of the non-flattened sample, and the flattened sample should be placed below it. The end of the pressure needle is not less than 3mm from the edge of the sample.

5.3 Place the sample in the heating bath, position the needle for 5min, add the required mass to the load plate, so that the total axial pressure on the sample is (50 1) N, and adjust the reading of the dial indicator to zero.

5.4 Raise the temperature at a constant speed of (50 5)℃/h to raise the bath temperature. The agitator should be started during the whole test.

5.5 When the needle is pressed into the sample (1±0.01)mm, record the temperature at this time, which is the Vicat softening temperature (VST) of the sample.

6. Expression of results

The arithmetic average of Vicat softening temperature of two samples is the Vicat softening temperature (VST) of the tested sample, and the unit is expressed in℃. If the difference between the results of two samples is greater than 2℃, no less than two samples should be taken again for testing.

7. Test report

The test report shall include the following contents:

a)        This standard number;

b)        Name, specification and batch number of the sample;

c)        Preparation method, size and pretreatment conditions of samples, and whether the samples are superimposed;

d)        Heat transfer medium used in the heating tank;

e)        Initial temperature, heating rate and applied load;

f)         Arithmetic average of Vicat softening temperature of each sample and Vicat softening temperature of two samples, unit:℃;

g)        Special changes in the appearance of the sample during or after the test;

h)        Any operation details not included in this standard that may affect the results;

i)         Tester and date.

8. Vicat softening temperature index of common products

Table 3 Vicat softening temperature index of common products

Above is detail information of vicat softening temperature. ERA company conducts Vicat softening point tests on pipes and fittings made of different materials to ensure that the products fall within the standard range. Please watch the Vicat softening point testing video for CPVC fittings below.

Vicat softening temperature test for cpvc fittings

Vicat softening point testing is a fundamental aspect of pipe and fitting quality assessment. ERA diligently selects batches of pipes every 8 hours and meticulously records the results to guarantee that all manufactured pipes meet the necessary quality standards. This proactive approach underscores our dedication to delivering consistently high-quality products.

Understanding the Significance of Vicat Softening Temperature in Thermoplastic Pipes and Fittings

Introduction:

Thermoplastic pipes and fittings play a pivotal role in various industries, offering versatility and durability. One critical property that defines their performance is the Vicat softening temperature. This article delves into the importance of the Vicat softening temperature, the testing procedure, relevant standards, specimen sizes, and the overall significance in ensuring the quality and reliability of thermoplastic pipes and fittings.

1. Vicat Softening Temperature Defined:

The Vicat softening temperature is a key parameter used to assess the thermal behavior of thermoplastic materials, specifically in pipes and fittings. It signifies the temperature at which these materials begin to soften rapidly, impacting their structural integrity and performance. Notably, this property is not applicable to crystalline or semi-crystalline polymer materials.

2. Testing Procedure:

The Vicat softening temperature test involves placing a sample cut from the thermoplastic pipe or fitting into a liquid medium or heating box. A standard pressure needle is then pressed into the sample under a constant force, with the temperature recorded when the needle penetrates the material by 1mm. This procedure helps determine the material's response to heat, providing valuable insights into its usability and limitations.

3. Standards Governing Vicat Softening Temperature:

Accurate testing is essential, and several standards guide the determination of Vicat softening temperature. Prominent among these are ASTM D 1525, ISO 306, ISO 2507, and GB/T 8802-2001. Adhering to these standards ensures consistency and reliability in assessing the thermal properties of thermoplastic pipes and fittings.

4. Specimen Size and Preparation:

The size and preparation of specimens are crucial aspects of the Vicat softening temperature test. For pipes, samples are cut along the axial direction with specific dimensions. Pipe fittings require an arc-shaped segment, ensuring representation of different sections. Special attention is given to sample preparation, including adjustments for wall thickness and pretreatment conditions to achieve accurate results.

5. Test Steps:

The Vicat softening temperature test involves precise steps to ensure reliable outcomes. These steps include adjusting the temperature of the heating bath, placing the sample correctly, applying a specific load, and raising the temperature at a constant rate. Monitoring the needle's penetration and recording the temperature at this point determine the Vicat softening temperature of the material.

6. Expression of Results:

Results are expressed as the arithmetic average of the Vicat softening temperature from two samples. If the difference between the results exceeds 2℃, additional tests are recommended. This stringent approach ensures the accuracy of the assessment and provides a comprehensive understanding of the material's thermal characteristics.

7. Test Report:

A detailed test report is essential for transparency and traceability. The report includes the standard number, sample specifications, preparation methods, heat transfer medium used, initial temperature, heating rate, applied load, and the arithmetic average of the Vicat softening temperature. Any deviations from the standard procedure or unexpected observations are documented to provide a comprehensive overview.

8. Vicat Softening Temperature Index of Common Products:

Understanding the required reference values for the Vicat softening temperature is crucial for assessing product quality. The table provides an index for common products such as PVC-C pipes for cold and hot water, PVC-U pipes for water supply, PVC-M pipes for water supply, and various fittings. These reference values ensure that products meet the necessary standards for their intended applications.

9. ERA's Commitment to Quality:

The article concludes by highlighting the commitment of ERA (the company mentioned in the information) to quality assurance through Vicat softening point testing. The company conducts regular tests on pipes and fittings made of different materials to ensure they fall within the standard range. The proactive approach of selecting batches every 8 hours underscores ERA's dedication to consistently delivering high-quality thermoplastic pipes and fittings.

10. Conclusion:

In conclusion, the Vicat softening temperature is a critical parameter in assessing the thermal properties of thermoplastic pipes and fittings. The testing procedure, adherence to standards, specimen size considerations, and the expression of results all contribute to a comprehensive understanding of the material's behavior under heat. Manufacturers, like ERA, play a crucial role in maintaining quality standards, ensuring that thermoplastic pipes and fittings meet the necessary requirements for diverse industrial applications.

Vicat softening temperature refers to the temperature at which a standard indenter with a cross-sectional area of 1 mm2 penetrates a thermoplastic to a depth of 1 mm under a certain load condition when the temperature rises at a constant rate.

This temperature reflects the expected softening point of the material when used in a heating device, that is, the heat resistance of the material under heat and stress. The Vicat softening temperature test is only applicable to thermoplastic hard or semi-rigid plastics. The Vicat softening temperature or heat deformation temperature needs to be tested when the material is stressed and heated during use.

The Vicat softening temperature is measured when the force-bearing area is as small as a needle tip, and the thermal deformation temperature is measured when the force-bearing area is large. ① Principle: The softening of materials is essentially a glass transition. Below the glass transition point, the material is in a rigid state. Above the glass transition point, the material is in a softened state. The same degree of softening can be specified by inserting a standard indenter with a cross-sectional area of 1 mm2 into the thermoplastic to a depth of 1 mm, so that Conveniently compare different materials under the same test conditions

② Test conditions: (test environment 23±2℃, 50±5%RH) two loads (10N and 50N) and two heating rate conditions (50℃/h and 120℃/h), there are four combinations of two Conditions: 1. 10N, 50℃/h; 2. 10N, 120℃/h; 3. 50N, 50℃/h; 4. 50N, 120℃/h. to

③ Size requirements: The product material must be uniform, the bottom surface should be a square with a side length of 10mm or a circle with a diameter of 10mm, the upper and lower surfaces should be parallel, and the thickness should be 3-6.5mm

④ Standards: ISO306:2004, GB/T1633-2000 and ASTM D1525-2009 ISO is consistent with GB/T, but there are two differences from ASTM D. First, ASTM D has added regulations that fluid powders can be used as heat transfer media; second, the loading times of the two are different. ISO puts the sample into the medium first, loads the weight after 5 minutes, and then clears the dial indicator.