Cotton burning tests

POMOCO DB is not to be considered as "flame-proofing" nor "durable", but it has been found to enable fabrics such as rayon and cotton drapery materials to pass the 6-lnch burning tests before and after 5 dry-cleanings. 

In the Vertical Burning Test for Classifying Materials 94V-0, 94V-1, or 94V-2 of UL 94-1981, test specimens are 127 mm long, 12.7 mm wide with a maximum thickness of 12.7 mm. A set of 5 pecimens is conditioned in a normal atmosphere (23 °C, 50% R.H.) for 168 hours and another set in a circulating air oven at 70 °C for 168 hours followed by cooling in a desiccator for 4 hours. Each specimen is suspended vertically so that its lower end is 9.5 mm above the top of the burner tube and 305 mm above a horizontal layer of cotton wool 50 mm x 50 mm x 6 mm. The test flame is applied centrally under the lower end of the specimen or tilted to an angle up to 45 deg. if the material will drip (Fig. 3.53). The specimen is ignited for... 

Flammability The flammability of a plastic is most commonly characterised by the Underwriters Laboratory (UL 94) horizontal burning test. The test sample, a rectangular bar 127 mm long, is held horizontally, or at 45°, and clamped at one end. The burning speed of the bar is measured when exposed to a pilot flame. The bar is held 305 mm above the surface of a layer of surgical cotton. The thickness of the bar can be varied, but is quoted as part of the result, e.g. VO, 1.57. The commonly quoted ratings given to a material are ... 

Visual and Manual Tests. Synthetic fibers are generally mixed with other fibers to achieve a balance of properties. Acryhc staple may be blended with wool, cotton, polyester, rayon, and other synthetic fibers. Therefore, as a preliminary step, the yam or fabric must be separated into its constituent fibers. This immediately estabUshes whether the fiber is a continuous filament or staple product. Staple length, brightness, and breaking strength wet and dry are all usehil tests that can be done in a cursory examination. A more critical identification can be made by a set of simple manual procedures based on burning, staining, solubiUty, density deterrnination, and microscopical examination. 

One of the most stringent and most widely accepted test is UL 94 that concerns electrical devices. This test, which involves burning a specimen, is the one used for most flame-retardant plastics. In this test the best rating is UL 94 V-0, which identifies a flame with a duration of 0 to 5 s, an afterglow of 0 to 25 s, and the presence of no flaming drips to ignite a sample of dry, absorbent cotton located below the specimen. Tlie ratings go from V-0, V-l, V-2, and V-5 to HB, based on specific specimen thicknesses. 

Cold cure" or high resilience PU foams tended to liquify before igniting were developed and gave good results in standard tests such as BS 4735(25) (similar to the discontinued ASTM D1692) but could still burn when used with flammable fabrics in furniture (Table IV). However they have been used most successfully in the UK in combination with flame retarded cotton interliners and fabrics of low flammability e.g. wool, nylon, FR cotton etc. and formed the basis of public area furniture used in the UK since the early 1970 s (Table V). 

Cloths used to apply linseed oil to laboratory benches were not burned as directed, but dropped into a waste bin. A fire developed during a few hours and destroyed the laboratory. Tests showed that heating and ignition were rapid if a draught of warm air impinged on the oil-soaked cloth. Many other incidents involving ignition of autox-idisable materials dispersed on absorbent combustible fibrous materials have been recorded [1], Practical tests on the spontaneous combustion of cotton waste soaked in linseed oil and other paint materials had been reported 40 years previously [2],... 

Experiment 107. — (a) Carbon, (i) Recall or repeat the experiments which showed that carbon is a constituent of wood, cotton, bone, starch, sugar, illuminating gas, candle wax, meat, flour, bread, albumen. (2) Heat 2 or 3 cc. of turpentine in a porcelain or iron dish, and then set fire to it. Does it contain carbon Hold a bottle over the flame long enough to collect any product, and then test the contents for carbon dioxide does the observation verify the previous conclusion (3) Repeat with alcohol. Does it contain carbon Burn a small lump of camphor in a dish or on a block of wood. Does it contain carbon (4) Hold a bottle over a burning kerosene lamp long enough to collect any product, and test as in (2). Does kerosene contain carbon ... 

The preparation gun-cotton fuses is exactly the same as that of gun-cotton. They can be tested as described in the section on Nitrocellulose (p. 33). These fuses transmit fire faster than any other form, and are mostly used for firing laige set-pieces they burn very fast, and will fire a fuse-paper wrapped round them with absolute certainty they have the further advantage that they can be used in wet weather. 

The burn results for polymers 15 and 19 show that the polymers are inherently flame retardant with low base flammability (Table 4). The polymer dripped but did not ignite the cotton when it was subjected to the UL-94 flame test, and with the addition of 1 wt% PTFE, it did not drip. The PCFC results show that these polymers have a high heat release capacity when compared with the BPC carbonates and aryl ethers, but it is still significantly less than that of the base commodity polymers, such as polyethylene or polystyrene (Table 5). 

It is a feature of these tests with vertical specimens that a piece of surgical cotton is placed below the specimen to detect the formation of burning drips and that specimens are conditioned for 48 hours at 23 C. 50 o rh. and after for 168 burns at 70 C. 

Flammability Tests Burning wool smells like burnt horn, burning silk smells like burnt egg-white, and burning cellulose fiber smells like burnt paper. Polyamide and polyester fibers melt before they burn polyacrylonitrile fibers, upon burning, leave a residue of hard, black spherical particles. On heating the dry fibers in a test tube, wool, silk, and polyamides develop alkaline vapors, while cotton, bast fibers, and regenerated cellulose (rayon) develop acidic vapors (test with moistened universal indicator paper). 

In Canada, the flammability of mattresses is tested with a single glowing cigarette. The mattress passes the test if extension of carbonization is not more than 50 mm and no burning phenomenon is observed 10 min after the extinction of the cigarette. Experience shows that most cotton felt mattresses in Canada meet these requirements unless the cotton felt is in direct contact with the external cover. Since the thin (<150 g/m ) permanently attached ticking on the mattress is not susceptible to glowing, the above requirements are reasonable. ... 

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