Nylon hot melt wire elongation test

Nylon hot melt wire elongation test

As a high-performance engineering material, nylon hot melt wire is widely used in textiles, 3D printing, composite materials and other fields. Its elongation at break is an important indicator to measure the maximum deformation that the material can withstand during the stretching process, which is crucial to ensure the reliability and safety of the product in practical applications.

1. The importance of nylon hot melt wire elongation test
Nylon hot melt wire achieves material connection through molten bonding at high temperature, and its elongation at break directly affects the quality and service life of the final product. If the elongation at break of the hot melt wire does not meet the standard, it may lead to defects such as insufficient bonding strength, delamination, shrinkage deformation, etc., which seriously affect the reliability and safety of the product. Therefore, elongation at break test of nylon hot melt wire is a necessary means to ensure the consistency of material performance and process stability.

2. Standards and methods for elongation at break test of nylon hot melt wire

(I) International standards
At present, the elongation at break test of nylon hot melt wire is mainly based on the following international standards:
ASTM D638: Standard test method for tensile properties of plastics, suitable for quantitative evaluation of breaking strength and elongation.
ISO 527-2: Test method for tensile properties of textiles, applicable to the determination of maximum force and elongation.
GB/T 3923.1: Test method for tensile properties of textiles, applicable to the determination of maximum force and elongation.
ASTM D5035: Test for breaking strength and elongation of textiles (strip method), applicable to woven and non-woven fabrics.
(II) Test method
The elongation at break of nylon hot-melt yarn is usually tested by the strip method, and the specific steps are as follows:
Sampling: Randomly select a sufficient number of specimens from the nylon hot-melt yarn to ensure the representativeness and uniformity of the specimens.
Humidification: Humidify the specimens in a standard environment (temperature 21±1℃, relative humidity 65±2%) until the weight change of the specimen does not exceed 0.1%.
Sample preparation: Cut the specimen into a specified width (such as 25mm or 50mm), and ensure that the length direction of the specimen is parallel to the test direction.
Instrument preparation: Use a standard tensile strength machine (such as CRE, CRL or CRT type), set the effective distance between the two clamps to 75±1mm, and the test speed to 300±10mm/min.
Test process: Clamp the sample in the tensile strength machine, start the instrument until the sample breaks, and record the breaking strength and elongation.
Data processing: Calculate the average value of the breaking strength and elongation, and discard abnormal data (such as data where the sample slips or breaks near the clamp).

3. Selection and use of test equipment
(I) Tensile strength machine
Tensile strength machine is a key equipment for testing the elongation at break of nylon hot melt wire. Common types include:
CRE (Constant rate of elongation tester): Suitable for most test scenarios and can provide a stable test speed.
CRL (Constant load uniform acceleration tester): Suitable for tests that require precise control of load.
CRT (Constant rate of traction tester): Suitable for tests that need to simulate actual use scenarios.
(II) Fixtures
The selection of fixtures is crucial to the accuracy of test results. The fixture should have the following characteristics:
Flatness: The fixture surface should be flat to prevent damage to the specimen.
Parallelism: The front and rear fixtures should be parallel, and the center of the upper and lower fixtures should be consistent with the force direction.
Pad: Adding pads to the fixture can prevent the specimen from slipping and improve the reliability of the test.
(III) Auxiliary equipment
Humidification equipment: used to control the temperature and humidity of the test environment to ensure that the specimen is tested under standard conditions.
Standard fabric: used to verify the performance of the instrument and ensure the accuracy of the test results.

4. Analysis and application of test results
(I) Calculation of elongation at break
Elongation at break refers to the ratio of the increase in length of the specimen during the stretching process to its original length, usually expressed as a percentage. The calculation formula is:
Elongation at break (%) = (length at break of original length − original length) × 100
(II) Evaluation criteria for test results
Depending on different application scenarios, the elongation at break of nylon hot melt wire has different evaluation criteria:
Textile grade: The elongation at break is usually between 20%-50%.
3D printing grade: The elongation at break is usually between 30% and 60%.
General standard: The elongation at break should not be less than 20% to ensure the reliability and safety of the material in practical applications.
(III) Precautions in practical applications
Material properties: The elongation at break of nylon hot melt wire is affected by its molecular structure, processing technology and environmental conditions. Before testing, the characteristics of the material should be fully understood to select appropriate test parameters.
Test environment: The temperature and humidity of the test environment have a significant impact on the test results. The test should be carried out under a standard environment and ensure that the sample is fully humidified.
Data processing: Abnormal data may appear during the test, such as sample sliding or breaking near the chuck. These data should be discarded and resampled for retesting.

5. Case analysis
(I) Textile application
In the textile industry, nylon hot melt wire is used for bonding seamless clothing and functional fabrics. The test results of elongation at break directly affect the elasticity and comfort of clothing. For example, when a brand tested its nylon hot melt wire, it was found that the elongation at break was between 30% and 40%, which met the textile grade standard and could meet the production requirements of seamless clothing.
(II) 3D printing application
In the field of 3D printing, the elongation at break of nylon hot melt wire directly affects the printing accuracy and finished product strength. A 3D printing company tested its nylon hot melt wire and found that the elongation at break was between 35% and 50%, which met the 3D printing grade standard and could effectively reduce the delamination and fracture phenomenon during the printing process.

6. Conclusion
The elongation at break test of nylon hot melt wire is a key link to ensure the consistency of material performance and process stability. By following international standards, selecting appropriate test equipment and methods, and rationally processing test data, the elongation at break of nylon hot melt wire can be accurately evaluated.