Research on the Test of Moisture Permeability of Medical Protective Clothing

Human body heat is emitted by radiation, conduction, convection and evaporation pathways in a static state, and the amount of perspiration per day is 700 ~ I 200 per adult; when goods are transported outdoors at 32 35 ℃, they will emit 200 ~ 2 per day. 000 perspiration, this is the sense of sweating. About 87.5% of the human body’s heat is discharged through the skin. Therefore, the clothing with the largest skin contact area plays a vital role in the heat dissipation of the human body. If the moisture permeability of the clothing is 500 g/( m2 · 24) above, it can maintain the comfort of wearing I-medical protective clothing is a special functional clothing. The most basic condition for clothing is to meet the physiological needs of people. If this condition is not met, the functional Fortunately, during the SARS period, the medical staff in the isolation area wore multi-layer protective clothing and performed various operations with the air conditioner turned off. As a result, some medical staff suffered from chest tightness, shortness of breath, and a lot of sweating, leading to collapse and fainting. Most protective products have poor moisture permeability and wearing comfort, so moisture permeability has become the focus of attention and research focus. This article will focus on the research and analysis of medical protective clothing fabric structure, moisture permeability and related test standards. 1 Fabric moisture permeability test 1.1 Test method The standard test method for fabric moisture permeability is generally the test of the fabric water vapor transmission rate and the test of the evaporation heat transfer resistance. Two major researchers commonly use water vapor resistance to evaluate human sweat from the surface of the body through the fabric to the environment. The transfer ability should include the sweating hot plate method and the sweating dummy method, and the fabric and clothing manufacturers tend to use the vapor-permeable cup method, that is, under a fixed temperature, a certain humidity and a fixed wind speed, the fabric will pass through the fabric in a unit of time. The water vapor per unit area, which is the more familiar moisture permeability, is used to evaluate the moisture permeability of the fabric. 1.2 The test standard moisture permeability is an index closely related to the wearing comfort of protective equipment]. The moisture vapor permeability test methods often used in medical protective equipment in the world mainly include the American standard ASTM E96, the Japanese standard JIS 1099, the international standard ISO 2528, the British standard BS3424 and the Chinese national standard GB/T 12704 1991. They all have the same standards. The test conditions, therefore, the test value is sometimes very large. It can be seen through comparison. Although all countries use the same standard to test the temperature permeability of fabrics, the applicable objects of the national standards are different. The ASTM standard is the most widely applicable and can be used for any sheet. Because of the wide range of test conditions, sample size ranges and test time intervals, ASTM standards require that the selected standard test conditions and the use environment of the material are close to the relative humidity specified by the B method in the Chinese standard. It is difficult to control during testing. Moreover, it does not conform to the actual use conditions of the fabric. The Japanese standard is equivalent to the scope of the Chinese standard. They are all textile products, so the test method is very close, but there is no inverted cup method in the test method in China. 2 Experimental part 2.1 Materials In order to have an understanding of the moisture permeability of protective clothing fabrics, a protective polytetrafluoroethylene (PfFE) laminated fabric was developed, and other types of medical protective clothing fabric laminated fabrics can be collected according to the end use Need to adopt different design structures and composite layers. The sample specifications are shown in the table. The fabric is a developed polytetrafluoroethylene (PfFE) multifunctional protective clothing fabric, and the material is a layer composite sample, although the hand feels slightly hard , But it can improve abrasion resistance;'The fabric is polyurethane (PU) coated fabric; the emblem and fabric are thermoplastic polyurethane (TPU coated non-woven fabrics) with different areal densities, and the areal density is 50 83 g/m2. ; 10 The fabric is a disposable protective high-density polyethylene non-woven fabric. These medical protective clothing non-oily particles (NaCl granular gel (075 µm)) generally have a rapid efficiency above 95 (GB/T 2-2003) The requirement is not less than 70. 2.2 Instruments and methods Test instruments: KYKY-28008 scanning electron microscope; LFY-216A moisture meter; JD400-3 electronic balance (precision 0.001 method: moisture permeability comparison test and moisture permeability test under multi-layer wear GB/ T 12704-91 method-desiccant method (positive cup) and GB/T 12704-91 method-evaporation method (positive cup) test method and refer to the American standard ASTM E96 and Japanese standard JIS. 'Test conditions (temperature) (38 ±) ℃ relative humidity 50 ± 2)% moisture permeability calculation formula: WVT u003d 24 ml A? T where WVT is the moisture permeability per square meter per day (g/( ~ 2 ·24 h)); The common name is the same experimental combination (g); the experimental time (h); the actual experimental area (open) each time the test sample is not less than one piece, the relative error is less than 10%.
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