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Retardant fillers oxygen index

Recent advances in the application of ultrafine talc for enhanced mechanical and thermal properties have been studied [12]. A particularly important use is of finely divided filler in TPO as a flame-retardant additive. In a representative formulation, 37 parts of E-plastomer, Ml 2.0, density 0.92, 60 parts of amorphous EPR, and 4 parts of fine carbon black were dry blended, kneaded at 180°C, pelletized, and press molded into test pieces, which showed oxygen index 32 versus 31 in the absence of a filler. The oxygen index is a measure of flame retardancy. [Pg.179]

There is evidence to show that the particle size of the filler also plays a significant role in flammability resistance. For example, below a certain particle size (about 1-2 pm), in many tests, including oxygen index, aluminum hydroxide shows enhanced fire-retarding performance,34 which may be associated with the rate of filler decomposition and/or with the formation of a more stable ash. However, it has been found that the particle size effect is absent, or less evident, in the cone calorimeter test.35 Similarly, particle size reduction has been shown to enhance fire retardancy in magnesium hydroxide-filled PP in this case, samples were characterized by the UL94 test.36 This raises the question as to whether further reductions in particle size to the nanoscale will lead to an additional increase in flammability performance, and perhaps enable filler overall levels to be significantly reduced. This aspect is considered in a later section. [Pg.170]

Filler-polymer interactions have also been observed in EVA copolymer yielding differences in fire retarding effectiveness between ATH and MH.42 In EVA with 30% vinyl acetate content, magnesium hydroxide had an oxygen index of 46%, whereas aluminum hydroxide gave a value of... [Pg.171]

An investigation was carried out into the fire retardant behaviour of zinc hydroxystannate-coated fillers (alumina trihydrate and magnesium hydroxide) in PVC and EVA cable formulations. Measurements were made of the limiting oxygen index, peak rate of heat release and smoke parameter and the data for unfilled and filled formulations compared. X-ray photoelectron spectroscopy and diffuse reflectance infrared Fourier-transform spectroscopy were used to study the filler-coating interaction. 16 refs. [Pg.44]

Polycarbonate exhibits a relatively high oxygen index of 26. It may be further flame retarded by the addition of flame-retardant additives, including tetrabromo-BPA polymer, oligomer, or other bromi-nated additives, alkali metal salts,polytetra-fluoroethylene, phosphorus-containing additives, or silicones.Glass fillers or other inert fillers may also provide improved performance in Underwriters Laboratories (UL) flame testing. [Pg.2280]

The sueeess of graphite in this applications shows that filler with plate like struetures should be considered when intumescent materials are being formulated. Reeent developments in intumescent paints show that performanee ean be improved if a layer of organic material is inserted between the layers of the plate like filler. The degradation of this material in the enclosed space increases the expansion rate and the retention of gas inside the degrading material. Based on this prinei-ple any plate like filler has the potential to be useful in an intumescent applieation. The eomposition of filler is also important. When clay was used as a filler in fire retardant applieations, it was found that some of its components interfere with the action of carbonization catalysts and detract from the overall performance of the system in terms of limiting oxygen index. ... [Pg.289]

Several fillers are involved in modification of flame-retarding properties of semi-rigid and flexible PVC. Figure 3.17 shows a typical result of increased addition of flame-retarding filler. The limiting oxygen index increases with increased addition of filler but Figure 3.18 shows that the efficiency of flame retardant decreases with its concentration increase. [Pg.55]

Alumina trihydrate exerts its considerable flame-retarding effect only at a high proportion, i.e. when incorporated as a filler. For this reason, its application is essentially suitable in conventional filled compounds like polyesters, epoxy resins and PVC cable compounds, etc. " . The oxygen index of a polyester resin is plotted in Figure 5.4 against the proportion of this flame-retardant additive. [Pg.377]

Inert fillers (such as quartz flour, alumina, kaolin, talc, etc.) have a flame-retardant effect in as much as they reduce the flammable proportion in the formulation. Their usually very small influence appears as a slight increase in the oxygen index, while the horizontal and the vertical flame spread rates remain constant even at a high load of these non-inflammable inert fillers. The incorporation of glass fibres may even enhance the flammability when compared to that of the original resin. [Pg.381]

The chlorine content of rigid PVC can be enhanced up to approximately 70 per cent by chlorination, when its oxygen index may be as high as 60 per cent. The characteristics of chlorinated PVC (CPVC) are rather different from those of PVC itself — in practical terms, it is a different plastic material. Rigid PVC can be flame-retarded by inert fillers and by alumina trihydrate. In practice, the flammability parameters of rigid PVC are generally not worth improving since its inherent characteristics meet the usual requirements. [Pg.390]

Polyamides are less combustible plastics due to their chemical composition. Unfilled and unmodified PA 6 and PA 66 are rated V-2 according to UL 94, with an oxygen index of about 25 per cent without any added agents. One peculiarity is that glass fibres, mineral fillers, and some additives (such as the impact modifiers) actually enhance the flammability of polyamides they are rated only HB when not flame-retarded. A drawback of polyamides is dripping during the combustion. [Pg.392]

Rychly and Pavlinec have developed a method for analysing thermo-gravimetric data for multi-step processes obtained under non-isothermal conditions to provide kinetic data for each step [38]. Rychly and co-workers have applied this and other methods to a detailed study of the flame retardant effects of fillers [36]. In addition to the oxygen index, they used an ignition test based on an adapted thermal analysis method to assess flammability. [Pg.287]

They also observed that carbon retention and subsequent oxidation could be very important and was particularly noticeable with magnesium hydroxide in polypropylene leading to a sharp exotherm of the type already illustrated in Figure 6.11. They also claimed that this could lead to greater heat feedback in the oxygen index test, thus reducing fire retardant filler effects. [Pg.289]

Limiting oxygen index (LOI) is the parameter most frequently used to characterize the improvements in fire retardancy. " " " " " Table 12.2 gives a summary of data obtained for various fillers. The data in Table 12.2 show that even the addition of very common and inexpensive fillers such as calcium carbonate or talc increases the LOI value. From the data presented, Sb203 and Mg(OH)2 are the most efficient in increasing LOI. [Pg.396]

When other fillers such as barium sulfate, calcium carbonate and glass fiber were incorporated into flame-retardant PP systems, similar results were obtained, i.e. addition of fillers led to poor flame-retardancy in UL94 and oxygen index tests. The degree of decrease in flame-retardanry was dependent on the types of fillers incorporated, which might be due to filler size, shape, and chemical properties of the fillers. [Pg.917]

The flaming behavior of flame-retardant PP based composites was affected by addition of fillers. Larger size of talc and higher content of talc led to improved flame-retardancy in UL94 and oxygen index tests. [Pg.917]


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See also in sourсe #XX -- [ Pg.277 , Pg.279 , Pg.280 ]




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