Hořlavost materiálů běžných pracovních oděvů

Abstract

The submitted bachelor’s thesis deals with the flammability of materials commonly used in workwear. Three flammability properties are tested. The first is the oxygen index, tested according to the standard ČSN EN ISO 4589-2 – Plastics – Determination of burning behavior by oxygen index – Part 2: Test at ambient temperature. The oxygen index is the lowest concentration of oxygen in a mixture with nitrogen at which the material burns under conditions defined by the standard. The second property is the ease of surface ignition, tested according to ČSN EN 6940 – Textiles – Flammability – Determination of ease of ignition of vertically oriented test specimens. This test determines the average ignition time of a vertically oriented specimen, rounded to whole seconds. The final property is the rate of flame spread over the surface, tested according to ČSN EN ISO 6941 – Textiles – Flammability – Measurement of flame spread on vertically oriented test specimens. This test measures the time elapsed from the application of a flame to the surface until three threads placed on the specimen surface are severed. The specimens are tested in both the longitudinal and transverse directions of the cut. The result is not the flame spread rate itself, but the time value, which is suitable for comparison with other samples tested by the same method. The thesis compares experimental results of these properties between a selected workwear textile composed of 100% cotton and a selected denim fabric composed of 61% cotton and 39% polyester. It also compares these properties for textiles contaminated with simulated sweat, prepared as a saline solution containing chemically pure sodium chloride per liter of distilled water, and with a stain of technical ethanol with a volume of 150 microliters. The first part addresses the issue of flammability testing. It explains the principles of the selected tests and provides background on the issue of fabric contamination. Subsequent sections describe the methodology according to technical standards, including sample dimensions and testing procedures. The equipment used is also described, including its components and the locations where the apparatus was situated during testing. The properties of the selected textiles are then presented, including their exact composition, sources, and areal density. The precise method by which the textiles were contaminated with the saline solution and technical ethanol is also detailed. A complete overview of all sample sets, including their dimensions, materials, and treatments, is provided. In the practical part, the procedural specifications are first introduced, including exact deviations from the standards, and hypotheses of the test results are established based on literature review. This is followed by a presentation of experimental results and their evaluation, including whether the stated hypotheses were confirmed. The final section begins with a clear summary of all results and their discussion. This is followed by recommendations for employers, suggesting suitable workwear materials based on laboratory results with the aim of improving user safety. Finally, a conclusion is provided, addressing the obtained results, fulfillment of the objectives, and possibilities for further research. The bachelor’s thesis focuses on the experimental determination of selected flammability properties, their evaluation, and subsequent recommendations for users based on these findings.