Methyl methacrylate flame retardancy

Price, D., Pyrah, K., Hull, T. R., Milnes, G. J., Wooley, W. D., Ebdon, J. R., Hunt, B. J., and Konkel, C. S., Ignition temperatures and pyrolysis of a flame-retardant methyl methacrylate copolymer containing diethyl(methacryloyloxymethyl)-phosphonate units, Polym. Int., 2000, 49, 1164-1168. 

Pentaerythritol is used in self-extinguishing, non dripping, flame-retardant compositions with a variety of polymers, including olefins, vinyl acetate and alcohols, methyl methacrylate, and urethanes. Phosphoms compounds are added to the formulation of these materials. When exposed to fire, a thick foam is produced, forming a fire-resistant barrier (see Elame retardants) (84—86). 

In poly(ethylene terephthalate) (14—16) and poly(methyl methacrylate) (17—19), the mechanism of action of phosphoms flame retardants is at least partly attributable to a decrease in the amount of combustible volatiles and a corresponding increase in nonvolatile residue (char). In poly(methyl methacrylate), the phosphoms flame retardant appears to cause an initial cross-linking through anhydride linkages (19). 

A detailed understanding of the course of a reaction between a polymer and an additive will permit one to use that information to design new flame retardants. The reaction between poly(methyl methacrylate), PMMA, and red phosphorus is described and that information used to determine that CIRh(PPh3)3 should be used as a flame retardant. The results of this investigation are then used to choose the next additive. A recurring theme is the efficacy of cross-linking as a means to impart an increased thermal stability. 

Methyl methacrylate (MMA), 16 227 Alfrey-Price parameters, 7 617t azeotropic mixtures with, 16 236t block copolymer synthesis, 7 647t C-2 routes to, 16 252-254 C-3 routes to, 16 246—252 C-4 routes to, 16 254—257 carbon monoxide in production of, 5 6 chain-transfer constants for, 16 284t comonomer with acrylonitrile, 1 451t cumene as feedstock, 8 156 in flame-retardant resin formulation,... 

Methyl methacrylate is often used in combination with styrene to improve light transmission and uv stability in flame-retardant glazing applications. Phosphate ester (triethyl phosphate) additives are also included to supplement flame-retardant efficiency benzophenone uv stabilizers are required to prevent yellowing of these uv-sensitive resins. 

D. Price, K. Pyrah, T.R. Huh, G.J. Milnes, J.R. Ebdon, BJ. Hunt, P. Joseph, and C.S. Konkel, Flame retarding poly(methyl methacrylate) with phosphorus-containing compounds Comparison of an additive with a reactive approach. Polym. Degrad. Stab., 74,441 447 (2001). 

Ebdon, J. R Hunt, B. J., Joseph, P Konkel, C. S Price,D Pyrah, K Hull,T. R Milnes, G. J., Hill, S.B Lindsay, C. I., McCluskey, J., and Robinson, I., Thermal degradation and flame retardance in copolymers of methyl methacrylate with diethyl(methacryloyloxymethyl)phosphonate, Polym. Degrad. Stab., 2000, 70, 425 136. 

Banks, M., Ebdon, J. R., and Johnson, M., The flame-retardant effect of diethylvinyl phosphonate in copolymers with styrene, methyl methacrylate, acrylonitrile and acrylamide, Polymer, 1994, 35, 3470-3473. 

The reactive approach has been employed recently to prepare various polymeric systems.34 35 Silicon-containing polystyrenes and poly(methyl methacrylate)s (PMMAs) copolymers have been prepared by free radical polymerization. The LOI data indicated that a marginal improvement in flame retardancy has been observed compared to the parent homopolymers. The authors speculated that the nature of the silicon-containing group has an effect on the flame-retardant mechanism.34... 

Zhu, J., Start, R, Mauritz, K. A., and Wilkie, C. A. Thermal stability and flame retardancy of poly(methyl methacrylate)-clay nanocomposites, Polym. Degrad. Stab. (2002), 77, 253-258. 

Incorporation of modified clays into thermosetting resins, and particularly in epoxy35 or unsaturated polyester resins, in order to improve thermal stability or flame retardancy, has been reported.36 A thermogravimetric study of polyester-clay nanocomposites has shown that addition of nanoclays lowers the decomposition temperature and thermal stability of a standard resin up to 600°C. But, above this temperature, the trend is reversed in a region where a charring residue is formed. Char formation seems not as important as compared with other polymer-clay nanocomposite structures. Nazare et al.37 have studied the combination of APP and ammonium-modified MMT (Cloisite 10A, 15A, 25A, and 30B). The diluent used for polyester resin was methyl methacrylate (MMA). The... 

Whereas UL 94 delivers only a classification based on a pass-and-fail system, LOI can be used to rank and compare the flammability behavior of different materials. In Figure 15.2 the increasing LOI values are presented for different polymers as an example POM = poly(oxymethylene), PEO = poly(ethyl oxide), PMMA = poly(methyl methacrylate), PE = polyethylene), PP, ABS, PS, PET = polyethylene terephthalate), PVA = poly(vinyl alcohol), PBT, PA = poly(amide), PC, PPO = poly(phenylene oxide), PSU, PEEK = poly(ether ether ketone), PAEK = poly(aryl ether ketone), PES, PBI = poly(benzimidazole), PEI = poly(ether imide), PVC = poly(vinyl chloride), PBO = poly(aryl ether benzoxazole), PTFE. The higher the LOI, the better is the intrinsic flame retardancy. Apart from rigid PVC, nearly all commodity and technical polymers are flammable. Only a few high-performance polymers are self-extinguishing. Table 15.1 shows an example of how the LOI is used in the development of flame-retarded materials. The flame retardant red phosphorus (Pred) increases... 

Some other interesting copolymers having properties of PVC thermal stabUizers, like poly[Af-(a-benzothiazolonylmethyl)methacrylate-co-methyl methacrylate] [45], of flame retardants like a terpolymer of styrene, acrylonitrile and a polymerizable perbrominated phenol [76] or poly[4-methacryloyloxy-2,3,5,6-tetrabromobenzyldi-phenyl phosphonate-co-methyl methacrylate] [104] (93), bioddes, mostly copolymers of monomers containing tris(n-butyl tin) or triphenyl tin moieties and alkyl acrylates, methacrylates, vinyl acetate, acrylonitrile, styrene or A-vinylpyrrolidone [105], e.g. a terpolymer of styrene, MMA and tri(n-butyl tin) itaconate [106] (94),... 

Montmorillonite is an effective complex with the initiator in the polymerization of methyl methacrylate." It not only accelerates the polymerization but also improves such mechanical properties as hardness and compression strength. Pentabromobenzyl acrylate was mechano-polymerized in the presence of Mg(0H)2. The polymerization occurred at a reduced temperature and a flame retarded product was produced. 

Flame retardants are usually halogen-containing materials. 2,4,6-Tribromophenyl, pentabromopheuyl, and 2,3-dibromopropyl derivatives of acrylate and methacrylate esters can be readily polymerized or copolymerized with styrene, methyl methacrylate, and acrylonitrile to produce polymers with improved flame retardancy (Equation 5.20). 

Air velocity 25 mm/s ignition by pilot flame. A PVC B polyethylene C polypropylene D polystyrene E poly(methyl methacrylate) F flame-retarded polyester G unmodified polyester H amine-cured epoxy resin I carboxylic anhydride-cured epoxy resin J resin I filled with 60 phr. of AlgOg, K resin / filled with 60 phr. of Al(OH)g . beech-wood M fir-wood... 

Poly(methyl methacrylate) PMMA, flame-retarded Polyamide... 

Phosphoric acid is added to methyl methacrylate in the course of the polymerization as a flame-retardant. Other water-soluble compounds, such as dibasic and monobasic ammonium phosphates, have been applied for a long time, mainly as impregnating agents for wood, textile, and paper while ammonium polyphosphates are used in rigid polyurethane foams, polyesters, epoxy resins, and some reactive coatings. Their commercial names are also included in Table 5.6. 

Acrylate and methacrylate polymers are flame-retarded mainly by phosphorus compounds. Mixing monomeric methyl methacrylate with 8 per cent of phosphoric acid coupled with the initiator improves the flammability characteristics of the polymeric product. 

Some types of Sandoflam (Sandoz Huningue S. A.) flame-retardants are specifically recommended for poly(methyl methacrylate). The majority of them do not affect the clarity of the polymer. ... 

In a study of the flame retardance of styrene-methyl methacrylate copolymer with covalently bound pyrocatechol-vinyl phosphate, diethyl p-vinyl benzyl phosphonate, or di(2-phenyl ethyl phosphonate) groups. Ebdon and co-workers [23] obtained data on their decomposition behaviour. This was achieved by reducing the rate of liberation of flammable methyl methacrylate monomer during combustion. Possible mechanisms for these processes are suggested. Other methacrylate copolymers which have been the subject of thermal degradation studies include PMMA-N-methylmaleimide-styrene [24] and PMMA-ethylene vinyl acetate [25-27]. 

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