Correlation between the hot plate ignition test and other laboratory-scale flammability tests on rubber conveyor belts with fabric skeletons

The hot plate ignition test was conducted on ten different conveyor rubber belts with fabric skeletons. In this test, a 25 × 25 mm² belt sample was placed on a stainless steel plate in an electric furnace and heated. The ‘ignition temperature’ was determined on each sample in almost the same way as proposed in Canada. The test results were compared with those from other laboratory-scale flammability tests (i.e. the small-scale flame tests, the Oxygen Index test and the laboratory-scale gallery test). The calculated results of both sample and rank correlation coefficients imply that the ‘10 signition temperature’ in this hot plate ignition test has a correlation with the results from both the Oxygen Index test and the laboratory-scale gallery test, but that it has very little or no correlation with those from the small-scale flame tests. On the other hand, it is found that the ‘60 s ignition temperature’ in this test has a far better correlation both with the results from the small-scale flame tests and with the time to ignition in the laboratory-scale gallery test than the ‘10 s ignition temperature’.     

The influence of sample dimension on the critical oxygen index of thin polypropylene films

This investigation examines the influence of sample dimensions on the Critical Oxygen Index, as determined on a Stanton Redcoft Hot Flammability Test Apparatus instrument. The materials used were polypropylene films in a range of thicknesses from 40 μm up to 300 μm and polymethylmethacrylate of 1600 μm thickness. Both the Critical Oxygen Index and the rate of spared of burn in the samples were determined. It is concluded that, for polypropylene, the sample dimensions were important in determining the Critical Oxygen Index and the rate of spread of burn and, further, that the ratio of the volume of material burned in unit time to the volume flow of oxygen in the same time remains constant, the value of the constant being 2.5 × 10 ^?4. For polymethlmethacrylate, in confirmation of the work of Fenimore and Jones, the sample dimensions were unimportant when investigating the Critical Oxygen Index, although the rate of burn by volume showed a significant increase with sample width. The volume ratio showed a corresponding increase.     

Evaluation of the smoke and flammability characteristics of polymer systems

Using Oxygen Index and the XP-2 test to measure flammability and smoke characteristics, a broad spectrum of thermoplastic and thermoset polymers, both commercial and experimental, were investigated to elucidate the effect of structure on fire properties. In general, polymers with aliphatic backbones are very flammable, but their tendency to generate smoke is minimal. The addition of flame retardants, especially halogen compounds, while reducing their tendency to burn, increases the evolution of smoke. Halogen-containing polymers are usually non-flammable, with high Oxygen Indices, but display high smoke generation. Polymers containing an aromatic group in the side chain, such as polystyrene, are both highly flammable and high smoke producing. However, polymers with the aromatic group in the main chain, such as polysulfone, polycarbonate and polyphenylene oxide, are intermediate in both Oxygen Index and smoke generation. After investigation of the various test methods available, it is concluded that no one test will be satisfactory to measure the flammability characteristics of polymers and that a combination of methods must be used.     

Characterization of the burning behaviour of polymeric materials

Measurements of the limits of flaming and smoldering combustion and relative rates of burning under elevated temperatures and oxygen-depleted conditions have been used to characterize the fire behaviour of polymeric materials using a semi-empicical approach (based on scientific theory) in terms of Power Law Indices. The work was based on modified current tests; namely the Limiting Oxygen Index (ASTM D2863) at elevated temperatures and the Setchkin Flash and Self-Ignition Test (ASTM D1929) modified to operate in oxygen-depleted atmospheres and to record rate of weight loss. Results show that the relative flammability and rate of burning of materials can change markedly with fire environment, and confirms the need to test materials lunder conditions representative of those of the anticipated end-use hazard.     

The effect of sample size on the burning behaviour of thermoplastic materials in the critical oxygen index test

The dependence of the Critical Oxygen Index values of some thermoplastic materials on sample sixe is reported. The extent of melting of this class of material is shown to be important in determining the effect of sample size on the index.     

聚合物典型燃烧测试方法及其比较

文章阐述了聚合物阻燃理论的基本原理.对用于评价燃烧性能的主要阻燃特性和极限氧指数法、UL 94法、锥形量热仪法这三种典型测试方法做了介绍和比较.最后,展望了未来发展趋势.     

Evaluation of adhesion strength,flammability, and degradation of HBCD‐containing polyurethane adhesives

In this work, moisture curable flame retardant HTPB‐based polyurethane adhesives were synthesized. The influence of HBCD (Hexabromocyclododecane) as flame retardant on adhesion, degradation and change in flammability of synthesized HTPB‐based polyurethane has been studied. Relationship between phase separation in hard and soft domains and adhesion has also been investigated. FTIR analysis was used to determine phase separation in synthesized adhesives. Lap shear test was used to determine adhesion properties of adhesives applied on aluminum and glass substrates. Thermal Gravimetry analysis and Limited Oxygen Index (LOI) tests were carried out on flame retardant adhesives to evaluate effect of HBCD on degradation and flammability. Addition of HBCD to adhesives leads to reduction of thermal stability and lap shear strength for all substrates, in spite of flame retardant adhesives show higher LOI value. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of free radicals generating compounds towards the flammability of w-phosphonated polystyrenes — V

Summary Effect of some free-radicals generating compounds, such as organic peroxides, hydroperoxides and polysulfides, on the Oxygen Index of end phosphonated polystyrenes is investigated. It is shown that some combinations of end phosphonated polystyrene with free-radicals initiators, may be said to have a synergestic effect on flame-retardant properties of standard polystyrene.     

城市生活垃圾处理场渗滤液可生化性研究

根据安徽省某生活垃圾处理场渗滤液的检测资料,分析测定其化学耗氧量(CODCr)和生化需氧量(BOD5)。分别用三种不同的方法和标准判定渗滤液的可生化性,为兴建垃圾处理场渗滤液处理设施提供理论依据。     

The performance of various testing columns in small-scale horizontal burning studies

The use of Critical Oxygen Index testing columns in the horizontal configuration is investigated. Gas analysis results from within columns of simple design indicate that they are unsuitable for burning studies because of entrainment of the external atmosphere and recirculation of combustion products. A new design of column and holder is proposed that eliminates these effects and provides a possible means of studying small-scale horizontal combustion in different oxygen/nitrogen mixtures.     

Iron-containing compounds as flame retarding/smoke-suppressing additives for PVC

The incorporation of a range of iron-containing inorganic and organometallic compounds into a semi-rigid PVC formulation has been investigated. Limiting Oxygen Index and Smoke Density data were obtained across a wide range of formulations and the effects of the compounds on flammability and smoke generation are discussed. Iron-containing inorganic compounds appear to have little effect on the flammability of semi-rigid PVC but several of the organoiron compounds and iron oxides markedly reduce smoke formation.     

Identification of two pass regimes for nylon-66 based rods in the critical oxygen index test

Critical Oxygen Index (COI) values for rods of a nylon-66 based material of various diameters have been determined at 40°C. The existence of two discrete COI values has been identified for many sizes above a critical diameter: the two indexes correspond to clean burning and to burning with melting and dripping. The difference between the two indexes is dependent on rod diameter and can be greater than five units.     

Anomalous behaviour in certain versions of the critical oxygen index test

Measured Critical Oxygen Index values at 40°C for Opal polymethylmethacrylate (Perspex) sheet have been found to be remarkably dependent on the gas velocity within the column of the Hot Flammability Test Apparatus. Investigation of the atmosphere present in the column has indicated that the effect is almost solely attributable to varying quantities of ambient air entering the column as the flow rate is altered. A modification to the apparatus is proposed that successfully prevents this entrainment of air at normal testing flow rates.     

Factors that influence the critical oxygen index of various solids

The Critical Oxygen Index test has been used as a measure of the flammability of a wide range of substances, including plastics, textiles and liquids, since its introduction in 1966. The index, however, is only appropriate to the configuration and conditions used in the test, and extrapolation in order to predict the flammability of materials in a large-scale fire is not valid. The index is dependent on a number of sample and test parameters and these are reviewed; the ASTM test standard, the reproducibility of the results, and certain theoretical aspects are also discussed.     

含磷环氧树脂的合成及改性研究

9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)与环氧树脂E-51进行加成反应,生成含磷量1%、2%、3%的阻燃环氧树脂,其氧指数超过29,当磷含量超过2%时,其阻燃效果达到UL-94 V-0级,但随着DOPO含量的增加,环氧树脂固化物的拉伸强度从30MPa下降到26MPa,弯曲强度从98MPa下降到43MPa。通过对DOPO含磷环氧树脂添加三环氧丙基缩水甘油醚(TGIC)2.5%~10%后,其固化产物的氧指数略有下降,但初始分解温度(1%分解)均维持在300℃以上,以UL-94标准测定阻燃效果没有变化,但拉伸强度(10%TGIC添加量)分别提高36%、45%、67%。     

The effects of inorganic borates on the burning of PVC

The flammability of flexible poly(vinyl chloride) sheet containing barium, calcium and zinc borates, alone and in combination with antimony oxide, was measured by BS2782-508C and ASTM D2863. A statistical comparison of these tests was made. Barium and calcium borates, with or without antimony oxide, had little or no effect on flame retardancy, but zinc had a synergistic effect with antimony oxide. The value of these inorganic borates in reducing smoke is compared using the Stanton Redcroft F.T.B. Unit, an attachment of the manufacturer's Critical Oxygen Index (C.O.I.) test. This test consists of passing the smoke from the C.O.I, test directly into a chamber where the maximum smoke density is measured using a light source and photocell assembly. Formulations containing zinc borate and antimony oxide gave the least smoke. The advantages of zinc borate in flame retardant poly(vinyl chloride) were found to be offset by inferior mechanical and electrical properties and heat stability, unless small amounts of epoxidised oil were added. The degree of hydration of the zinc borate was not critical.     

低熔点硫酸盐对软质PVC的阻燃与消烟性能研究

制得的硫酸盐混合物熔点低，在适当温度下熔融时，能有效地保护PVC降解过程中形成的剩磷，从而能提高剩碳率，提高阻燃与消烟性能。氧指数、烟密度、DTA、TG、SEM等证明了低熔点的硫酸盐是一种优良的填料性的、具有阻燃与消烟性的阻燃消烟剂，具有很好的消烟性，当添加量达40份时，烟密度能下降45％。研究表明其对力学性能的影响比其它填料小。     

阻燃聚酰胺的研究

本文对含阻燃剂的聚酰胺6进行了熔体流变性能、极限氧指数、热失重和力学性能的研究。加入阻燃剂后,熔体粘度稍有增加,非牛顿指数均为0.81,熔体粘流活化能变大(58.5kJ/mol)。极限氧指数值随阻燃剂加入而线性增加可达到26％以上,阻燃剂具有协同效应。阻燃聚酰胺6纤维的力学性能有所降低。     

Thermal stability of polypropylene/carbon nanofiber composite

Thermal stability of polypropylene and carbon nanofibre composite system has been studied using Thermogravimetric Analysis, Limited Oxygen Index (LOI), Flammability, Calorimetry, and Oxidation Induction Time techniques. Definite improvement in thermo‐oxidative stability of the composite system has been observed. Improvement in LOI and a distinct change in the burning characteristics suggest a reduction in potential fire hazards. The nanocomposite system will have enhanced anti‐ageing characteristics and require more stringent conditions for the initiation of burning and the ultimate impact of burning will be less. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3574–3578, 2006     

Effect of calcium carbonate filler on the fire and smoke properties of moulded polypropylene

‘Oxygen Index’, ‘Rate of Burning and Extent of Burning of Self-supporting Plastics in a Horizontal Position’ and ‘Vertical Flammability’ tests were used for examination of polypropylene copolymer HW 607M and the same copolymer filled with 40% w/w calcium carbonate. Room-scale studies were also carried out using a range of standard ignition sources. In the latter tests, measurements of the levels of smoke generated in the test chamber were monitored continuously, and intermittent measurements were made of the carbon monoxide concentrations. Small-scale testing showed that addition of the filler to the polypropylene raised the limiting oxygen index of the polymer from 17.8 to 20.3, which is only marginally lower than the oxygen concentration in ambient air (20.9); this introduces the possibility of a filled polypropylene which is not ignitable in air. However, the results of the UL94 and ASTM D635 tests did not show significant differences in flammability and rates of vertical and horizontal flame spread as between the two materials, through the unfilled polymer produced extensive burning droplets early in both tests whilst the filled polymer did not. Such droplets can spread fires to floor coverings, so that the filled plastic might be preferable in application. In our laboratory tests, the filled samples gave considerably lower smoke generation than the unfilled ones. At high heat fluxes they generated considerably less smoke than (smaller) unfilled samples containing the same mass of polymer. This suggests that the calcium carbonate has specific smoke-suppressant activity and is not merely acting as a polymer diluent. In larger-scale tests, unfilled samples were readily ignited by a domestic match, whilst the filled samples required an ignition source of 43 kJ (some six times greater than the match source) in order to light them and sustain ignition. The filled polymer did not melt on ignition and there was no lateral spread of flame from the sample. Smoke generation was considerably lower, the average optical density at maximum obscuration being 0.27, compared with 0.84 for the unfilled control. In particular, smoke suppression achieved by use of calcium carbonate at higher heat-flux levels is considerably greater than that expected for an inert diluent.