Flame retardancy of polypropylene

Chen, Y.H. and Wang, Q. 2007. Reaction of melamine phosphate with pentaerythritol and its products for flame retardation of polypropylene. Polym. Adv. Technol. 18 587-600. 

Weil, E.D., Lewin, M., and Lin, H.S., Enhanced flame retardancy of polypropylene with magnesium hydroxide, melamine and novolac, J. Fire Sci., 16, 383-404, January, 1998. 

Chiu, S.H. and Wang, W.K., Dynamic flame retardancy of polypropylene filled with ammonium polyphosphate, pentaerythritol and melamine additives, Polymer, 39, 1951-1955, 1998. 

Lewin, M. and Endo, M. 2003. Catalysis of intumescent flame retardancy of polypropylene by metallic compounds. Polymers for Advanced Technologies 14 3-11. 

Lewin, M. Endo, M In Intumescent systems for flame retarding of polypropylene, Fire and Polymers, Nelson, G. ed., ACS Symp., 1995, 599, 91-116. 

Tkac, A. Radical process in polymer burning and its retardation. II. An ESR study of flame retardation of polypropylene. /. Polym. Sci. Polym. Chem. Ed., 19, 1495 (1981)... 

Endo, M. Lewin, M. Flame retardancy of polypropylene by phosphorns-based additives, in Proceedings of the 4th Conference on Recent Advances in Flame Retardancy of Polymeric Materials, Stamford, CT, 1993. 

Flame retardation of polypropylene can be done by the application of chlorine and bromine derivatives with and without Sb203 as a synergist and phosphorus compounds as well as inert fibers. Bromine compounds are much more effective for PP than chlorine compounds and aliphatic compounds are more effective than aromatic ones. 

Related esters of this alcohol are disclosed by Ak2o as useflil flame retardants for polypropylene, particularly in combination with ammonium polyphosphate (90). 

There is only perhaps one significant case where low concentrations of an antioxidant shows flame-retardant behavior, in the case of certain hindered amine stabilizers (HAS) that at the normally used concentrations (<1 wt%), offer low levels of flame retardancy in polypropylene and show synergy with bromine-containing flame retardants.78 80... 

To improve the fire retardancy of polypropylene, beyond the UL 94 V-2 level, it is necessary to use blends of aromatic bromine fire retardants with antimony trioxide as a synergist. The usual loading is between 35% and 40% fire retardant however, the additional cost may prohibit commercialization. Moreover, the presence of aromatic bromine increases the photooxidation of polypropylene67 69 inactivating hindered amines. To reduce the cost without losing in efficacy the combination of brominated flame-retardant/antimony trioxide system with magnesium hydroxide... 

Liu, Y. and Wang, Q. 2008. Reactive extrusion to synthesize intumescent flame retardant with a solid acid as catalyst and the flame retardancy of the products in polypropylene. J. Appl. Polym. Sci. 107 14—20. 

The effects of metal-containing POSS on the combustion behavior of polypropylene have been investigated.46 Metal-POSS was prepared from incompletely condensed structures by reaction with organometallic compounds. The dimeric and oligomeric of Al and Zn-isobutyl silsesquiox-ane (POSS) have been evaluated as potential flame retardants for polypropylene, and the results were compared with PP/octaisobutyl POSS. The cone calorimeter data (Table 8.2) revealed that... 

Marosi, G., Anna, P., Balogh, I., Bertalan, G., Tohl, A., and Maatoug, M. A. 1997. Thermoanalytical study of nucleating effects in polypropylene composites. 3. Intumescent flame retardant containing polypropylene. Journal of Thermal Analysis 48 717-26. 

Oligomeric bromine-containing ethers on the basis of tetrahromoxylene dihaUdes and tetrahromohi-sphenol-A (molecular weight between 3,000 and 7,000) are useful flame retardants for polypropylene, polystyrene, and ABS. 

Natural fiber-reinforced polyolefins are commonly apphed to automotive and constmction applications. The most abundantly used additive is fire retardant. Flammability is an important factor that often limits the application of composites to a specified field. Magnesium hydroxide is the most common flame retardant material used in the constmction industry. This filler responds well to surface modifiers and decomposes by an endofliermic reaction that releases water at temperatures close to the polymer degradation temperature as show in Eq. 6.1. Rothon et al. [78] studied the effects of magnesium hydroxide on polypropylene as a flame retarder of 60 % by weight. The smdy found less heat emission at 100 kWm after 6 min of fire exposure compared to filled PP without Mg(OH)2 at 500 kWm. ... 

The flame-retarding of HDPE and PP is not so complex. 4.25 phr. of Saytex BN 451 and 2 phr. of antimony trioxide yield the rating V-2 for polypropylene. 6 per cent of octabromodiphenyl oxide and 3.5 per cent of antimony trioxide in 90.5 per cent of HDPE is rated B2 according to DIN 4102 (cf. Section 3.2.1) while the flammability of a compound with 9 per cent of decabromodiphenyl oxide and 4 per cent of antimony trioxide to 87 per cent of HDPE is rated B1. For reaching the classification V-0, a rather high portion of flame-retardants should be admixed, for example 30 phr of decabromodiphenyl oxide and/or BT 93 is recommended with 10 phr. of antimony trioxide to polypropylene. Masterbatches with these flame-retardants facilitate processing (cf. Table 5.15). The same systems are also used for polyolefin elastomers (such as EPDM) . 

Work in Russia has shown that the use of elemental silicon plus tin chloride can enhance the flame retardancy of both polypropylene and polyamide 66 compounds. Silicon tetrahalides are formed in the gas phase of combustion and inhibit the chain reactions that develop in a fire. These silicon halides do not act like halogen hydrocarbons in the atmosphere so there is no likelihood of contributing to ozone depletion. 

FIGURE 1.1 Dependence of total flaming time of polypropylene measured in a UL-94 test on bromine content for an aliphatic brominated flame retardant and an aromatic brominated flame retardant. (From Ref. 23, cop)Tight 2001, Routledge/Taylor Francis Group, with permission.)... 

Prins, A.-M. Douma-, C. Kaspa-sma, J. Glow wire and V-2 paformance of bromi-nated flame retardants in polypropylene, in Flame Retardants 2000. Interseienee Communications, London, 2000, pp. 77-85. 

Physical and chemical mapping using AFM and ToF-SIMS are appropriate means for studying surfaces of flame retarded materials. Various interactions may take place between ammonium polyphosphate (APP), pentaerythritol (PER) and tetraethoxy-silane (TES). Whereas the reaction between APP and PER has been described [820], no direct reaction could be found between APP and TES. Marosi et al. [821] have reported imaging ToF-SIMS of APP-PER-ME-TES intumescent flame retarded (IFR) polypropylene. The image prepared on the basis of SiOjc ions proved the existence of a silicone layer between polymer and solid APP particles covered by PER. 

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