MaTestLab > Test Standards > ASTM D7191 Standard Test Method for Determination of Moisture in Plastics by Relative Humidity Sensor
Last updated 4th November 2024
ASTM D7191 Standard Test Method for Determination of Moisture in Plastics by Relative Humidity Sensor
The ASTM D7191 test method is employed for the quantitative detection of water in polymers down to 20 ppm. An airtight, sealed flow system is used for this test in order to protect the analyzer from contamination by atmospheric water, as sample temperatures in this test method can approach or exceed 250°C. Therefore, the analyzers need to be handled with care. Results of the ASTM D7191 test are stated in SI units as they are considered standard units. This test method is used as a control, acceptance, and assessment test. The ASTM D7191 method is also designed to obtain the boiling point distribution of other incompletely eluting samples, such as atmospheric residues and vacuum residues, as the sample components are resolved from the solvent. However, the ASTM D7191 test method is not suitable for the analysis of materials containing a heterogeneous component, such as polyesters and polyolefins.
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ASTM D7191 Introduction
ASTM D7191 is a commonly used technique for control, acceptance, or assessment tests. Moisture content significantly affects the physical characteristics of different polymers, including hydrolysis-induced deterioration and surface defects. While low moisture (combined with high temperature) results in solid-phase polymerization, high moisture concentrations cause hydrolysis-induced surface defects (splay or bubbling) or deterioration. As a result, the ASTM D7191 test technique has a wide range of uses in the plastics industry and accurately determines the moisture content of polymers.
Because of the inadequate separation of C4-C8 compounds in the presence of high concentrations of carbon disulfide caused by the use of thin-film capillary columns in the ASTM D7191 test technique, the boiling point distribution corresponding to this elution period is not trustworthy. Furthermore, an incorrect quantitative measurement of the boiling distribution in the C4-C8 area is caused by the quenching of the detector’s response to hydrocarbons eluting during carbon disulfide elution. MaTestLab in the USA is one of the best testing service providers, with an extensive network of well-equipped testing laboratories in the USA.
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Test Procedure of ASTM D7191
ASTM D7191 involves Relative Humidity Sensor in order to determine moisture content in plastics.
Test Setup and Execution
ASTM D7191 specifies that a sample is loaded into a glass vial and heated to evolve volatiles. Dry carrier gas flows into the vial, allowing high-boiling volatiles to condense on a hydrophobic filter. The filter’s hydrophobic properties measure moisture, which is integrated to measure the total mass of water in the sample. The moisture content is then divided by sample mass.
ASTM D7191 Equipment and Sample Preparation
Specimen Type
ASTM D7191 specifies that the specimen be taken in airtight containers made of glass or other qualified or suitable material, heated to remove moisture, and cooled to room temperature before determination.
Specimen Details
ASTM D7191 specifies that the specimen is taken in airtight containers made of glass or other qualified or suitable material and then heated to remove moisture and must cool to room temperature before determination.
Results of ASTM D7191 and Interpretation
The ASTM D7191 results provide significant details regarding the plastic’s moisture content. Moisture content is a critical parameter in plastics processing and manufacturing, and excessive moisture can adversely affect the material’s properties and processing characteristics.
Tests Relevant to ASTM D7191
The tests relevant to ASTM D7191 include ASTM D6980 (Standard Test Method for Determination of Moisture in Plastics by Loss in Weight) and ASTM D6869(Coulometric and Volumetric Determination of Moisture in Plastics Using the Karl Fischer Reaction).
Use of ASTM D7191 in Various Industries
This standard is very important in the automotive, aerospace, packaging, and electronics industries for exact moisture control in plastics. It ensures that parts such as interior trim and connectors have very strict moisture specifications that increase reliability and longevity.
Materials Commonly Tested with ASTM D7191
This method is used for such moisture-sensitive polymers as polyamides, polycarbonate, and PEEK absorbed in moisture that changes their structure and function.
Common Challenges and Troubleshooting in ASTM D7191 Testing
Sensor calibration, sample preparation, and environmental control are challenges in testing. Accurate moisture measurements can be ensured through proper calibration, strict laboratory conditions, standard sample sizes, and uniform environmental conditions for the results.
Safety and Best Practices in ASTM D7191 Testing
Samples handling is to be careful while doing testing, particularly with volatile compounds released by plastic materials. The operators must wear protective gloves, provide ventilation, calibrate the relative humidity sensor, and avoid direct contact for safety and accuracy.
Importance of ASTM D7191
It is a standard related to quality control about moisture content of plastics that directly determines the performance and durability of the material. Conformance to such a standard eliminates degradation, failure, and recalls in products in industries such as aerospace and medical devices. It assures better safety coupled with industrial dependability in the products.
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You can share your astm d7191 testing requirements with MaTestLab. MaTestLab has a vast network of material testing laboratories, spread across the USA and Canada. We support your all material testing needs ranging from specific astm d7191 test to various testing techniques.
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Please contact us for a detailed quote for your astm d7191 testing needs. Cost incurred to carry out different astm d7191 testing methodology depends on the type of raw material; number of samples, coupons, or specimens; test conditions, turn around time etc. Costs of some ASTM testing methods start from $100 and the final value depends upon the factors listed above. Please contact us for the best and latest prices.
How many samples are required for astm d7191?
The required number of samples or specimens should comply with the procedure given in the astm d7191 standard. However, the MaTestLab operations team can assist you for your special requirements once you share your testing details with us.
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MaTestLab has a vast testing laboratory network, hence we bring you the best testing facilities in a cost-effective way. We offer considerable discounts (15-20%) to our returning customers based on test volume and frequency.
How many days will it take to complete the astm d7191 test?
The turnaround time for astm d7191 test methodology depends upon the test procedure mentioned in the standard test document. However, we at MaTestLab understand your research requirements and hence try to get your test completed within the least possible time.
Where can I get the astm d7191 tested?
You can share your astm d7191 testing requirements with MaTestLab. MaTestLab has a vast network of material testing laboratories, spread across the USA and Canada. We support your all material testing needs ranging from specific astm d7191 test to various testing techniques.
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