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Limiting Oxygen Index (limiting + oxygen_index)
Selected AbstractsInvestigation of flame retardancy and physical,mechanical properties of zinc borate/boric acid polyester compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Miyaser Demirel Abstract The glass fiber reinforced polyester composite materials were prepared with varying contents of boric acid, zinc borate, and magnesium hydroxide as flame retardants to improve the flame retardancy of the composites. Experimental results showed that boric acid exhibited a good flame retardant effect on the polyester composite. When boric acid content is used as 15 wt %, the Limiting Oxygen Index (LOI) value of the composite reached upto 25.3. The increase in boric acid content from 15 to 30 wt %, the LOI values of composite were enhanced from 25.3 to 34.5 by 9.2 units. The LOI values of the composite samples increased with increasing boric acid content. The smoke density results showed that the addition of glass fiber and flame retardants decreased the smoke density of the unreinforced polyester resin. The mechanical properties of the composites have decreased by the addition of flame retardants. The scanning electron micrographs taken from fracture surfaces were examined. The flame retardants, such as boric acid, were well dispersed in the glass fiber reinforced polyester composites and obviously improved the interfacial interaction between glass fibers and polyester composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] EVA Nanocomposites Elaborated with Bentonite Organo-Modified by Wet and Semi-Wet MethodsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 9 2007Miguel Angel Cárdenas Abstract EVA copolymer/organoclay nanocomposites were prepared using melt-compounding. Organoclays were obtained using wet and semi-wet modification methods. These methods enable us to obtain organoclays with adequate modifier incorporation, but organoclays with a homogeneous and narrow agglomeration size distribution were obtained only with the wet method. TS and EB were higher for nanocomposites obtained with organoclays prepared using the wet method. Analysis of Limiting Oxygen Index, UL94 test and Cone Calorimeter test showed that the retardant properties of nanocomposites were also influenced by the kind of modifiers and the modification method. [source] Graft copolymerization modification of silk fabric with an organophosphorus flame retardantFIRE AND MATERIALS, Issue 5 2010Guan Jinping Abstract This paper mainly deals with flame retardance of a silk fabric treated with a vinyl phosphate dimethyl 2-(methacryloyloxyethyl) phosphate (DMMEP) onto silk fabric by a graft copolymerization technique. This paper also explores the relationship between limiting oxygen index (LOI) and weight gain of DMMEP treated silk fabric. The paper also investigates the whiteness, handle, tensile strength and laundering durability of treated silk fabric. Microscale combustion calorimetry (MCC) is applied to test the heat release rate of silk fabric. Thermal gravimetric analysis (TG) and differential thermal analysis (DTA) are carried out to investigate the thermal decomposition behavior of DMMEP treated silk fabric. The kinetic parameters, activation energy and pre-exponential factor are determined using the Kissenger method. Copyright © 2009 John Wiley & Sons, Ltd. [source] Zinc hydroxystannate-coated metal hydroxides as flame retardant and smoke suppression for flexible poly vinyl chlorideFIRE AND MATERIALS, Issue 4 2009Hongqiang Qu Abstract Zinc hydroxystannate (ZHS)-coated metal hydroxides were prepared. The effects of ZHS-coated metal hydroxides on flame retardancy and smoke suppression of flexible poly vinyl chloride were studied by means of the limiting oxygen index, smoke density rating and the char yield test. The mechanism was investigated by thermogravimerty (TG), differential thermal analysis, and differential TG analysis and scanning electron microscopy. The results showed that ZHS-coated metal hydroxides are more effective flame retardant and smoke suppressant than metal hydroxides, and it appears that tin compound may exert its action in both the condensed and vapor phases, but mainly in condensed phases as a Lewis acid. Copyright © 2009 John Wiley & Sons, Ltd. [source] Tetrakis(trimethysilyl)hypophosphate P2O2(OTMS)4: Synthesis, reactivity and application as flame retardantHETEROATOM CHEMISTRY, Issue 7 2007Catherine Ruflin The preparation of tetrakis(trimethy- silyl)hypophosphate, P2O2(OTMS)4 (TMS = SiMe3), which is easily obtained from cheap starting materials, is reported. Reaction with protic substrates (H2O, alcohols) proceeds under stepwise cleavage of silylethers, ROTMS, and formation of hypophosphoric acid, P2O2(OH)4. Amines in the presence of molecular sieves lead to desilylation and formation of ammonium salts of the [P2O2(OTMS)2(O,)2] dianion. On cotton fabrics, P2O2(OTMS)4 hydrolyzes to give P2O2(OH)4 within about 1 h when exposed to air, and this compound acts as an efficient flame retardant (limiting oxygen index >26%) even at low loadings (P content <3%). © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:721,731, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20373 [source] Effect of boron-containing materials on the flammability and thermal degradation of polyamide 6 composites containing melamineJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Mehmet Do Abstract Three different boron-containing substances,zinc borate (ZnB), borophosphate (BPO4), and a boron- and silicon-containing oligomer (BSi),were used to improve the flame retardancy of melamine in a polyamide 6 (PA-6) matrix. The combustion and thermal degradation characteristics of PA-6 composites were investigated with the limiting oxygen index (LOI), the UL-94 standard, thermogravimetric analysis (TGA)/Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). A slight increase was seen in the LOI values of a sample containing BSi (1 wt %). BPO4 at high loadings showed a V0 rating (indicating the best flame retardancy) and slightly lower LOI values in comparison with samples with only melamine. For ZnB and BSi, glassy film and char formation decreased the dripping rate and sublimation of melamine, and this led to low LOIs. According to the TGA,FTIR results, the addition of boron compounds did not change the decomposition product distribution of melamine and PA-6. The addition of boron compounds affected the flame retardancy by physical means. The TGA data showed that boron compounds and melamine reduced the decomposition temperature of PA-6. According to the DSC data, the inclusion of boron compounds increased the onset temperature of sublimation of melamine and also affected the flame retardancy negatively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Flammability and mechanical properties of wood flour-filled polypropylene compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010M. B. Abu Bakar Abstract Polypropylene (PP) composites filled with wood flour (WF) were prepared with a twin-screw extruder and an injection-molding machine. Three types of ecologically friendly flame retardants (FRs) based on ammonium polyphosphate were used to improve the FR properties of the composites. The flame retardancy of the PP/WF composites was characterized with thermogravimetric analysis (TGA), vertical burn testing (UL94-V), and limiting oxygen index (LOI) measurements. The TGA data showed that all three types of FRs could enhance the thermal stability of the PP/WF/FR systems at high temperatures and effectively increase the char residue formation. The FRs could effectively reduce the flammability of the PP/WF/FR composites by achieving V-0 UL94-V classification. The increased LOI also showed that the flammability of the PP/WF/FR composites was reduced with the addition of FRs. The mechanical property study revealed that, with the incorporation of FRs, the tensile strength and flexural strength were decreased, but the tensile and flexural moduli were increased in all cases. The presence of maleic anhydride grafted polypropylene (MAPP) resulted in an improvement of the filler,matrix bonding between the WF/intumescent FR and PP, and this consequently enhanced the overall mechanical properties of the composites. Morphological studies carried out with scanning electron microscopy revealed clear evidence that the adhesion at the interfacial region was enhanced with the addition of MAPP to the PP/WF/FR composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Synthesis and characterization of dicyanate monomers containing methylene spacersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008G. Anuradha Abstract The bisphenols containing methylene spacer were prepared by treating eugenol/2-allyl phenol with 2,6-dimethyl phenol/guiacol/o -cresol in the presence of AlCl3. All the bisphenols were converted to their respective cyanate esters by treating with CNBr. The structural confirmation was done by FTIR, 1H NMR, 13C NMR spectral methods, and elemental analysis. Thermal characterization was done by DSC and TGA. DSC transition shows that the Tg is in the range of 208,239°C. The Tg is highest for the cyanate ester Cy(b) with symmetric structure. The Tg of the cured network depends on the length and symmetry of the monomer, Tg being higher for shorter and the para-substituted monomers. The T10 values are in the range of 364,381°C. The char yield is in the range of 47,53%. From the char yield, the limiting oxygen index (LOI) value was determined, which is used to confirm the flame retardancy of the cyanate ester resins. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Fire-resistant effect of nanoclay on intumescent nanocomposite coatingsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Zhen-yu Wang Abstract The aim of the study is the development of an intumescent nanocomposite coating to provide fire protection for the metallic substrate. Acrylic nanocomposites containing nanoclay and relative intumescent nanocoatings are prepared. The effect of nanoclay on the thermal degradation of an intumescent nanocomposite coating is analyzed by using differential thermal analysis, thermogravimetry, and X-ray diffraction. The influence of the added content of nanoclay on fire performance is studied by a fire protection test and measurements of the limiting oxygen index and effective thermal conductivity. The distribution of nanoparticles in the acrylic nanocomposite is characterized by transmission electron microscopy. The flame-retardant efficiency of the intumescent nanocomposite coating is improved by 1.5% well-distributed nanoclay particles. However, 3% nanoclay produces a negative effect on the fire performance of the coating. Fire protection tests and scanning electron microscopy observations reveal that the fire-retardant property of a conventional intumescent coating is destroyed by aging, whereas the nanocomposite coating modified with 1.5% nanoclay demonstrates good aging and fire resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1681,1689, 2007 [source] Microencapsulation of ammonium polyphosphate: Preparation, characterization, and its flame retardance in polypropylenePOLYMER COMPOSITES, Issue 8 2008Kun Wu Microencapsulated ammonium polyphosphate (MCAPP) with a melamine,formaldehyde (MF) resin coating layer was prepared by in situ polymerization. MCAPP was characterized by Fourier transform infrared, X-ray photoelectron spectroscopy, and so on. The results show that the microencapsulation with MF resin leads to a decrease in the particles' size and water absorption. The flame retardant action and mechanism of MCAPP and ammonium polyphosphate (APP) in polypropylene are studied using limiting oxygen index (LOI) and UL 94 test, and their thermal stability is evaluated by thermogravimetric analysis. The LOI value of the PP/MCAPP composite at 30 wt% loading is 30.5%, whereas the corresponding value of the PP/APP composite is only 20%. Moreover, the LOI values of the PP/MCAPP/PER composites are higher than the ones of the PP/APP/PER composites. In the UL 94 test, the PP/MCAPP/PER composites with suitable ratios of MCAPP to PER can reach the V-0 rating, and the best rating of the PP/APP/PER composites is V-1. V-1. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Study on flame retardance of co-microencapsulated ammonium polyphosphate and dipentaerythritol in polypropylenePOLYMER ENGINEERING & SCIENCE, Issue 12 2008Zhengzhou Wang Co-microencapsulated ammonium polyphosphate and dipentaerythritol [M(A&D)] was prepared using a melamine-formaldehyde (MF) resin by in situ polymerization method, and characterized by XPS. The co-microencapsulation of ammonium polyphosphate and dipentaerythritol (DPER) leads to a great improvement in water solubility of the additives. The flame retardant effect of M(A&D) in polypropylene (PP) is evaluated using limiting oxygen index (LOI) and UL 94 test, and the water resistance of the PP/M(A&D) composites is also studied. The flame retardant properties and water resistance of the PP/M(A&D) composites are much better than the ones of the PP/APP/DPER composites. Moreover, the thermal stability of the PP/M(A&D) composites is improved compared with the PP/APP/DPER composites. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Fireproofing of polyurethane elastomers by reactive organophosphonatesPOLYMER INTERNATIONAL, Issue 1 2003Wassef El Khatib Abstract Polyurethane elastomers were prepared with hydroxytelechelic polybutadiene (HTPB) as polyol, modified 4,4,-diphenylmethane diisocyanate (modified MDI) as liquid polyisocyanate, and phosphonate diols as chain extenders and flame retardant compounds. These phosphonate diols were synthesized by radical thiol,ene addition of allyl or vinyl dialkyl phosphonate to 3-mercapto-1,2-propanediol. For various percentages of phosphorus (0 to 3%, w/w), polyurethane elastomers remain stable up to 250,°C. The percentage of residual char at 600,°C increases with increasing phosphorus content. For the soft segments, no variation in the glass transition temperature (Tg) is observed as the percentage of P increases, whereas the Tg of hard segments increases. Above 0.5% phosphorus content, the limiting oxygen index (LOI) becomes higher than the percentage of oxygen in the air. © 2003 Society of Chemical Industry [source] Effects of poly(ethylene- co -propylene) elastomer on mechanical properties and combustion behaviour of flame retarded polyethylene/magnesium hydroxide compositesPOLYMER INTERNATIONAL, Issue 7 2002Zhengzhou Wang Abstract Magnesium hydroxide-based halogen-free flame retarded linear low density polyethylene composites containing poly(ethylene- co -propylene) elastomer were prepared in the melt process and subsequently vulcanized thermally. Influences of the elastomer on the mechanical properties, combustion characteristics and crystallization behaviour of polyethylene/magnesium hydroxide composites have been investigated. The results from the mechanical tests show that the incorporation of a suitable amount of elastomer into polyethylene/magnesium hydroxide composites after vulcanization can increase both the tensile strength and elongation greatly, compared with those of the composites without the elastomer. It has been found that the properties such as limiting oxygen index, UL-94 rating, the time to ignition and the rate of heat release of polyethylene/magnesium hydroxide/elastomer composites are all improved in comparison with polyethylene/magnesium hydroxide composites at the same retardant level. Scanning electron microscopy studies show that the incorporation of the elastomer into polyethylene/magnesium hydroxide composites improves the compatibility between the filler and the polymer substrate. The degrees of crystallinity of polyethylene/magnesium hydroxide/elastomer composites decrease with increasing the elastomer content. © 2002 Society of Chemical Industry [source] Phosphorylated copolymers containing pendant, crosslinkable spiro orthoester moietiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2006J. Canadell Abstract The synthesis of a novel spiro orthoester containing monomer, 1,4,6-trioxaspiro[4.4]-2-nonylmethyl acrylate, is presented. This monomer was polymerized via a free-radical system to yield the homopolymer and a series of copolymers with phosphorus-containing comonomers. Diethyl vinyl phosphonate, allyldiphenylphosphine oxide, and diethyl(methacryoyoxymethyl)phosphonate were used in various feed ratios to produce copolymers with different phosphorous concentrations containing crosslinkable spiro orthoester side-chain units. The crosslinking of the polymers was performed cationically with ytterbium triflate, and in all cases, the expansion of the polymer was observed. Moreover, the incorporation of phosphorus into the copolymers increased the limiting oxygen indices, regardless of the percentage of phosphorus used. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6728,6737, 2006 [source] | ||||||||||