Medical Dressings Water Vapor Permeability Test

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To prevent microbe invading open wound, keep moisture and help wound rapid healing, medical dressings are applied. Medical dressing’s applications require it to have good microbes barrier properties and water vapor permeability. As the development of Pathological and Physiological Study on Wound Healing, types of medical dressings are extended from traditional cotton gauze to Synthetic fibers, polymembranes, foamed polymers, hydrocolloids, alginates etc. Wound moisture and effusion pearmeability is always a focus in medical dressing studies. This paper introduces a method for testing medical dressing water vapor permeability.

Specimen

A medical wound dressing with antibacterial function is used as the specimen in this test.

Test principle

This paper assesses specimen’s water vapor permeability by measuring its water vapor transmission rate. The test conforms to YY/T 0471.2-2004 Test methods for primary wound dressing Part 2: Moisture vapor transmission rate of permeability film dressings. Test condition 37℃、80%RH, test 6 specimens and take the average of the results.

Testing instrument

The testing instrument used in this test is W3/060 Water Vapor Transmission Rate Test System, developed and produced by Labthink Instruments.

4.1 Test principle

Cup method calculates material water vapor transmission rate by measuring the weight changes in test cups. Fill the test cup with stilled water, seal the test cup with the specimen to form separate environment inside and outside the test cup. Control the humidity in the test chamber in order to create humidity difference between the two sides of the specimen, water vapor permeate from the high humidity side through the specimen to the low humidity side, the weight of the test cup increase when dry cup method is used, in wet cup method test the weight of the test cup decreases. Monitor the weight change over time and calculate and analyze the Water Vapor Transmission Rate. Cup method is subdivided into upright cup method and inverted cup method, in upright cup method test specimen contact water vapor, in inverted cup method specimen contact directly with water.

Test procedure

This test adopts upright cup method to test specimen permeability to water vapor.

Cut 6 specimens with diameter of 74mm.

Fill the 6 test cups stilled water, seal the specimens to the cups and clamp tight.

Put 6 test cups to the rack in the instrument and close the test chamber cover, set the parameters such as specimen name, temperature, humidity, test mode and etc, click start to start the test.

The instrument displays 6 test results when the test is completed.

Test result

The water vapor transmission rate of the rested medical dressing is 1004.1584 g/(m²·24h).

Conclusion

Water vapor permeability is a key performance index of medical dressings. This paper described a test of medical dressing water vapor transmission rate with testing instrument W3/060 Water Vapor Transmission Rate Test System. The test procedure was simple and efficient while the result was accurate and reliable. Labthink Instruments Co., Ltd, is dedicated to providing customers with packaging testing solutions and helping the manufacturers to reach their goals of quality and safety assurance through improvement of packaging testing techniques and development of high-end packaging testing instruments. For more information please visit www.labthink.com.