Abstract: The moisture permeability of medical dressings has an important impact on the cleaning and healing of wounds, and is an important aspect to measure its performance. In this paper, the Labthink W3/031 water vapor transmission rate tester is used as the testing equipment. The water vapor transmission rate of the foamed polymer medical dressing sample is tested by the inverted cup method. The principle, parameters and application range of the equipment are tested. The test process is briefly described to provide a reference for the monitoring of the moisture permeability of medical dressings.
Key words: medical dressing, water vapor transmission rate, moisture permeability, water vapor transmission rate tester, weighing method, inverted cup method, cup method
Meaning
Medical dressings are medical materials that can be used to cover skin lesions such as sores, wounds, and the like. Most of the early medical dressings are made of natural gauze material, which has high permeability, easy adhesion to the wound, and external microorganisms easily pass through infection wounds. It is easy to make the wound dehydrated and difficult to heal, and consume natural resources. Therefore, in order to solve the above problems, natural gauze is gradually replaced by polymer materials such as polymembrane, foamed polymer, and hydrocolloid. These dressings are freely permeable to gases such as oxygen and water vapor, and particulate matter and microorganisms in the environment. The inability to pass, while having good moisturizing properties, can make the wound moist and not easily adhered, and prevent cross-infection, accelerate wound healing, and save the cost of changing dressing.
Medical dressings should have high water vapor transmission properties, so that the skin has good moisture retention. The moisture permeability of the medical dressing can be verified by the inverted cup method on the water vapor barrier of the dressing and the skin contact side, which is usually measured by the water vapor transmission index. If the water vapor permeation amount is high, the moisture retention of the dressing is indicated. better. Therefore, medical dressing-related manufacturers should strengthen the monitoring of water vapor permeability of products to prevent the water vapor permeation of products from being too low, which makes the wound difficult to heal.
Figure 1 Medical dressing and its way of covering the skin
2. Test samples
A sample of a foamed polymer medical dressing provided by a pharmaceutical company.
3. Detection basis
Due to the relevant test standards for the domestic cupping test, the relevant GB 1038-1988 only gives the weight gain method based on the principle of desiccant moisture absorption, which cannot be used for the inverted cup test of direct contact of distilled water with samples, so this test Refer to the relevant American standard ASTM E96-2015 "Material Vapor Transmission Test Method".
4, test equipment
Jinan Languang Electromechanical Technology Co., Ltd. independently developed the W3/031 water vapor transmission rate tester.
Figure 2 W3/031 water vapor transmission rate tester
4.1 Test principle
W3/031 adopts the principle of wetting cup weighing method. Under certain temperature, the specific humidity difference is formed on both sides of the sample. The water vapor passes through the sample in the moisture permeable cup and enters the dry side. The amount of change in the weight of the moisture permeable cup over time is determined by parameters such as the amount of water vapor permeation of the sample.
4.2 Scope of application
(1) This equipment is suitable for testing the water vapor transmission rate (rate) of packaging materials such as plastic film, sheet, paper, cardboard and textiles, and non-woven fabrics.
Film material: Suitable for water vapor transmission rate (rate) test of various plastic film, paper-plastic composite film, geomembrane, aluminized film, aluminum foil, waterproof and breathable film;
Sheet type: Suitable for water vapor transmission rate (rate) test of various medical dressings, engineering plastics, rubber, building materials (waterproof materials for construction), thermal insulation materials, etc., such as PP sheet, PVC sheet, PVDC Sheet, nylon sheet, etc.;
Suitable for water vapor transmission rate (rate) testing of textiles, non-woven fabrics, etc.;
It is also suitable for water vapor transmission rate (rate) test of liquid crystal display film, solar back panel, sterile protective film, beauty mask and other materials;
(2) This equipment can meet a number of national and international standards, such as ASTM E96, YY/T 0148, GB 1037, GB/T 16928, ASTM D1653, TAPPI T464, ISO 2528, DIN 53122-1, JIS Z0208, YBB 00092003 .
4.3 Equipment parameters
Test range: 0.1 ~ 10,000 g / m2 · 24h (conventional range);
Number of samples: 1 ~ 3 pieces (data are independent);
Test accuracy: 0.01 g/m2? 24h;
Resolution: 0.0001 g;
Test temperature range: 15 °C ~ 55 °C, temperature control accuracy ± 0.1 °C;
Test humidity range: 10% RH ~ 98% RH (standard 90% RH), humidity control accuracy ± 1% RH;
Purge wind speed: 0.5 ~ 2.5 m / s (non-standard optional);
Test area: 33 cm2;
Sample thickness: ≤ 3 mm (other thicknesses can be customized);
With the LystemTM laboratory data sharing system, test data and device information can be reported simply by setting up and operating, making it easy to centralize and systematically manage laboratory test data.
5. Test process
(1) Three samples of 74 mm in diameter were cut from the sample using a sampler for testing.
(2) Place the samples on the three moisture permeable cups, and then place the moisture permeable cup upside down to ensure that the distilled water in the cup is in full contact with the sample.
(3) Place the three moisture permeable cups in the inner bracket of the instrument and close the glass sealing door.
(4) Set the sample name, sample thickness, test temperature (38 ° C), test humidity (90% RH) and other parameters.
(5) Start the air supply and click the “Start Test†option.
(6) After the test is over, the instrument automatically calculates and displays the test results.
6. Test results
The water vapor permeation amount on the inner side of the foamed polymer medical dressing sample tested in this test was: 1203.64 g/m2? 24h, 1159.87 g/m2? 24h, 1266.75 g/m2? 24h. Refer to YY/T 0148-2006 "General Requirements for Medical Tapes" for adhesive tape (such as water vapor vapour-coated film dressing). The water vapor permeation per 24 hours should be no less than 500 g/m2·24h. The dressing has good water permeability.
7. Conclusion
W3/031 Water Vapor Transmission Rate Tester is a professional testing equipment for water vapor barrier monitoring. It has high test accuracy and good repeatability of test results, which can truly reflect the water resistance or water permeability of materials. Labthink has been committed to providing professional testing services and equipment to customers around the world, providing customers with a large number of packaging material performance data references. At the same time, to provide customers with reliable technical solutions. For more information on related test instruments, you can log in to view specific information. Labthink is looking forward to enhancing technical exchanges and cooperation with users in various industries.
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