Explosibility of Polyamide and Polyester Fibers
The current research is aimed at investigating the explosion behavior of hazardous materials in relation to aspects of particulate size. The materials of study are flocculent (fibrous) polyamide 6.6 (nylon) and polyester (polyethylene terephthalate). These materials may be termed nontraditional dusts due to their cylindrical shape which necessitates consideration of both particle diameter and length. The experimental work undertaken is divided into two main parts. The first deals with the determination of deflagration parameters for polyamide 6.6 (dtex 3.3) for different lengths: 0.3 mm, 0.5 mm, 0.75 mm, 0.9 mm and 1 mm; the second involves a study of the deflagration behavior of polyester and polyamide 6.6 samples, each having a length of 0.5 mm and two different values of dtex, namely 1.7 and 3.3. (Dtex or decitex is a unit of measure for the linear density of fibers. It is equivalent to the mass in grams per 10,000 m of a single filament, and can be converted to a particle diameter.) The explosibility parameters investigated for both flocculent materials include maximum explosion pressure (Pmax), size-normalized maximum rate of pressure rise (KSt), minimum explosible concentration (MEC), minimum ignition energy (MIE) and minimum ignition temperature (MIT). ASTM protocols were followed using standard dust explosibility test equipment (Siwek 20-L explosion chamber, MIKE 3 apparatus and BAM oven). Both qualitative and quantitative analyses were undertaken as indicated by the following examples. Qualitative observation of the post-explosion residue for polyamide 6.6 indicated a complex interwoven structure, whereas the polyester residue showed a shiny, melt-type appearance. Quantitatively, the highest values of Pmax and KSt were obtained at the shortest length and finest dtex for a given material. For a given length, polyester displayed a greater difference in Pmax and KSt at different values of dtex than polyamide 6.6. Long ignition delay times were observed in the BAM oven (MIT measurements) for polyester, and video framing of explosions in the MIKE 3 apparatus (MIE measurements) enabled observation of secondary ignitions caused by flame propagation after the initial ignition occurring at the spark electrodes.
Minimum ignition energy of nylon fibres
Abstract The aim of this paper is to provide new experimental data on the minimum ignition energy (MIE) of clouds of fibres dispersed in the air. Nylon fibres from an Italian flock manufacturer (diameter between 10 and 27.4 μm, length between 600 and 1800 μm) were collected and tested in a modified Hartmann tube in order to measure the MIE. The instrument is equipped with a capacitive triggering system. The ignition energy ranged between 4 mJ and 4 J, and the delay time between dispersion and ignition could be set at a range between 30 and 180 ms. Two levels of energy were identified, named E 1 and E 2 , for each fibre dimension, according to Cesana and Siwek [2001. Operating Instructions for the Mike 3 Minimum Ignition Energy , Adolf Kuhner AG, Switzerland ASTM Committee E-27.05 (2001)] and ASTM [2002. E 2019-99 Standard Test Method for minimum Ignition Energy of a Dust Could in air , Annual Book of ASTM Standards 2002 (pp. 769–776). USA: ASTM International.]. E 2 is the lowest energy value at which ignition occurs at least once in ten successive tests, and E 1 is the highest energy value at which no ignition is observed in at least ten successive tests. A third energy level, named E 3 , was identified as the value at which explosion occurred in five consecutive tests. The probability of ignition between E 1 and E 3 was measured as a function of the spark energy at a given fibre concentration. The influence of the diameter and of the length of the fibres on the MIE was observed separately.
Industrial inorganic pigments
General Chemical and Physical Properties Behavior of Pigments in Binders White Pigments Titanium Dioxide Zinc Sulfide Colored Pigments Oxides and Hydroxides Cadmium Pigments Bismuth Pigments Ultramarine Pigments Iron Blue Pigments Carbon Black Properties Production Processes Specialty Pigments Magnetic Pigments Anticorrosive Pigments Luster Pigments Transparent Pigments.