印制板粘胶剂阻燃性的研究进展

阻燃剂是用以提高材料抗燃性,即阻止材料被引燃及抑制火焰传播的助剂.阻燃剂主要用于阻燃合成和天然高分子材料.含有阻燃剂的材料可防止引发火灾和抑制小火发展成灾难性的大火,即能减少火灾危险,但不能消除火灾危险.近几年,印制板粘胶剂发展迅速,对其的功能要求有提高,尤其足其中的阻燃性能要求严格.文章综述了几种主要的阻燃元索种类,...     

Effects of ageing on the fire behaviour of flame‐retarded polymers: a review

The influence of environmental ageing on the reaction to fire of flame‐retarded polymers is reviewed. Six types of stimuli have been identified as the most relevant parameters inducing fire behaviour modification: temperature, moisture, UV radiation, ionizing radiation, chemical solvent and physical stress. This review provides a state of the art and current comprehension of the effects of ageing on flame retardancy of polymers. Various physical and chemical phenomena lead to ageing and deterioration (or sometimes improvement) of the flame retardancy of polymers: release of additives (not only flame retardants) through thermal migration, solubilization, abrasion, etc., chemical degradation of the flame‐retardant system, and chemical or physical modification of the polymer structure (chain scission, crosslinking, diffusion of water, etc.). Obviously, ageing effects strongly depend on the material and the ageing scenario considered. Solutions to maintain flame‐retardant efficiency in aggressive conditions are also presented. © 2014 Society of Chemical Industry     

Inorganic polymeric materials for passive fire protection of underground constructions

Protection against fire for reinforced concrete constructions is of great importance worldwide. There is a general perception that concrete structures are incombustible and thus, they have good fire‐resistance properties. In a real fire incident, however, concrete can be subjected to excess temperatures causing severe spalling and serious damage to concrete structures with significant economic cost and high potential risk to human life safety. Although a variety of fire‐protection methods exist, there is always a need for the development of new materials with improved thermophysical properties and low cost. Inorganic polymeric materials are promising from this point of view. They are incombustible, combining excellent physical, chemical, mechanical and thermal properties with low production cost and significant environmental benefits. In this work, the thermophysical properties of ferronickel slag‐based inorganic polymeric materials are studied. The results from the laboratory scale experiments are promising and indicative of the large‐scale behavior of material. The effectiveness of this material has to be proved in large‐scale experiments at higher temperatures simulating several severe fire scenarios as well as under all kinds of mechanical loading before concluding for its applicability as a fire protection system. Copyright © 2012 John Wiley & Sons, Ltd.     

Measurement of thermophysical properties of fire‐resistive and reactive materials. Urgent problems and solutions

The ASTM Standard Test Method E2584 ‘Standard Practice for Thermal Conductivity of Materials Using a Thermal Capacitance (Slug) Calorimeter’ was developed by National Institute of Standards and Technology to measure thermal conductivity of fire‐resistive and reactive materials during monotonic heating and cooling. The heating regime adopted in ASTM E2584 is very reasonable because change of materials' composition and structure during a fire can depend on kinetic factors and thermal story of the materials. The main problem in experimental measurements of thermophysical properties is the impossibility of using standard steady‐state methods during time‐dependent processes in materials accompanied by latent heat effect. Using standard transient methods, such as hot wire or laser flash methods, is also incorrect, because the transient measurement heat process can be started only after steady‐state temperature field is established in the sample, that is, at the time when the involved physical or chemical processes could be finished. The objectives of this paper are to review and to analyze scientific problems to be taken into account in the revised version of ASTM E2584 Standard. Examples of experimental results are presented for measurement of thermophysical properties during chemical and physical processes in solid materials, powders, metals, and ceramic materials; building materials during fire; and so on. Copyright © 2016 John Wiley & Sons, Ltd.     

An update to what's burning in home fires

This article is an update on the items that are first ignited in home fires and it examines the extent of their involvement in associated deaths, injuries and property loss. It will be limited to forms of material that are considered products. Trash, for example, is involved in a large portion of home fires, but is not a product in the home and therefore is not included. Also excluded are building materials such as structural components and exterior wall coverings. This exclusion is important, because many building items rank high in the overall list of materials first ignited, but are not considered consumer products. Further detail will be given to the top ten leading products associated with home fires and home fire deaths. Copyright © 2001 John Wiley & Sons, Ltd.     

Experimental study on fire behaviors of external thermal insulation composite system under vertical radiation

Using a vertical thermal radiator, we perform a set of experiments on the external thermal insulation composite system (ETICS) and pure extruded polystyrene (XPS). Several important parameters, including time to ignition, mass loss, and sample temperature, were measured. The combustion degree of XPS used during the experiments was B1 and B2. Results show that the whole burning process can be divided into 3 typical stages. Because of the protection effect of the outer layer of ETICS, the burning process of ETICS was noticeably different from that of pure XPS. The experimental results indicated that the protection effect of the outer layer weakened the difference between B1 and B2 flame‐retardant XPS. The time to ignition was increased under the effect of outer layer, while the core material (XPS) was easier to be ignited when the outer layer falls out. The research results are useful to the theoretical and numerical study on the fire characteristics of foamed polymer under vertical thermal radiation condition.     

Thermal decomposition kinetics of rigid polyurethane foam and ignition risk by a hot particle

Rigid polyurethane foam, one kind of building insulation material used in China, is prone to being ignited by hot particles from fireworks or welding processes and has been the fuel for some catastrophic fire accidents. Thermal decomposition has long been recognized to play an important role in the ignition and fire‐spreading processes of materials, and thus, it is important to understand the behavior and kinetics of material decomposition. In this study, the characteristics of the thermal decomposition of polyurethane foam were investigated in an air atmosphere with nonisothermal thermogravimetry and differential scanning calorimetry (DSC). Model‐free (isoconversional) methods and model‐fitting methods were used to study the decomposition kinetics. The results reveal that the decomposition process of polyurethane foam in air presented three main stages: the loss of low‐stability organic compounds (bond fission of the weakest link in the chain), oxidative degradation of organic components, and oxidative degradation of residue material. A scheme containing three consecutive reactions was proposed to describe the decomposition process, and good agreement was found between the experimental and simulated curves. The heat during decomposition was calculated from DSC measurement. On the basis of the kinetics and heat of decomposition, the critical conditions for a hot particle to ignite polyurethane foam was evaluated, and this was helpful for the understanding the ignition risk of polyurethane foam. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39359.     

Molar group contributions to polymer flammability

The specific heat‐release rate is the molecular‐level fire response of a burning polymer. The Federal Aviation Administration obtains the specific heat‐release rate of milligram samples by analyzing the oxygen consumed by the complete combustion of the pyrolysis gases during a linear heating program. Dividing the specific heat‐release rate (W/g) by the rate of the temperature rise (K/s) of a sample during a test gives a material fire parameter with the units (J/g K) and significance of the heat (release) capacity. The heat‐release capacity appears to be a true material property that is rooted in the chemical structure of the polymer and is calculable from additive molar group contributions. Hundreds of polymers of known chemical compositions have been tested to date, providing over 40 different empirical molar group contributions to the heat‐release capacity. Measured and calculated heat‐release capacities for over 80 polymers agree to within ±15%, suggesting a new capability for predicting flammability from the polymer chemical structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 548–563, 2003     

Mechanism of fire retardancy of polyurethanes using ammonium polyphosphate

In this work, we studied the mechanism of the fire retardancy of ammonium polyphosphate (APP) in polyurethane (PU). Indeed, according to the limiting oxygen index test, the efficiency of APP in PU coating was proven. On the one hand, thermogravimetric analyses showed that the addition of APP to PU accelerates the decomposition of the matrix but leads to an increase in the amount of high‐temperature residue, under an oxidative or inert atmosphere. This stabilized residue acts as a protective thermal barrier during the intumescence–fire retardancy process. On the other hand, spectroscopic analysis of the charring materials using infrared spectroscopy, MAS NMR of the solid state, and ESR enables better understanding of the carbonization process and, consequently, of the intumescence phenomenon. It has been shown that the char resulting from PU consists of an aromatic carbonaceous structure which condenses and oxidizes at high temperature. In the presence of APP, a reaction between the additive and the polymer occurs, which leads to the formation of a phosphocarbonaceous polyaromatic structure. Moreover, this char is strongly paramagnetic. The presence of large radical species, such as a polyaromatic macromolecule trapping free radicals, was demonstrated. Both of these characteristics help to explain the fire‐retardant performance of PU/APP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3262–3274, 2001     

New halogen‐free fire retardant for engineering plastic applications

A comparative study of the fire‐retardant efficiency of three commercial aryl phosphates—triphenyl phosphate (TPP), resorcinol bis(diphenyl phosphate) (RDP) and bisphenol A bis(diphenyl phosphate) (BDP)—in PC/ABS blends was carried out. The thermal and hydrolytic stability of the fire‐retardant resins, as well as their physical properties, was also studied. The use of RDP and BDP is preferred over TPP because of superior properties, whereas BDP shows better fire‐retardant efficiency, hydrolytic stability, and thermal stability than RDP.     

The oxygen index method in fire retardance studies of polymeric materials

The oxygen index test is a fundamental tool in basic research on polymer combustion and on mechanisms of fire retardance. Although the oxygen index should provide an evaluation of intrinsic flammability of polymeric materials, its response may depend on geometry of the specimen. This is shown by comparing the behavior of polypropylene fire retarded with different additive systems. The implication of such in mechanistic studies is discussed. Furthermore, new measurements are proposed to be carried out with the oxygen index apparatus, which give parameters related to ease of ignition, behavior on forced burning, and thermal insulating characteristics of char developed on burning the material.     

Preparation and characterization of polyaniline,multiwall carbon nanotubes,and starch bionanocomposite material for potential bioanalytical applications

In this article, we are reporting the preparation and characterization of a multi‐component integrated nanocomposite material by the combination of a naturally occuring biocompatible biopolymer (Starch—a type of polysaccharide), functional conjugated synthetic polymer (Polyaniline “PANI”—a type of intrinsic conducting polymer) and nanosize tubular conducting template material (multiwalled carbon nanotubes “MWCNTs”—a type of carbonaceous nanotube structure). Comparative studies of the four material systems viz. system‐1: PANI, system‐2: PANI/MWCNTs, system‐3: PANI/Starch, and system‐4: PANI/MWCNTs/Starch have been carried out to understand the physical and chemical characteristics by using following instrumental techniques; UV‐Visible spectroscopy, fourier infrared spectroscopy, Raman, X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, BET‐surface area, conductivity, thermal gravimetric analysis, differential scanning calorimetry, and cyclic voltammetry. Proposed nanocomposite material, PANI/MWCNTs/Starch has nanosized integrated porous morphology (∼200–300 nm) with interconnected architecture, while simultaneously having good conductivity and better electroactivity. Moreover, the presence of hydroxyl functionality empowers it with good dispersion ability which is further supported by good biodegradability and biocompatibility. These properties together attest the proposed system for promising applications in biosensors and screen printed electrode ink formulation. POLYM. COMPOS., 38:496–506, 2017. © 2015 Society of Plastics Engineers     

Sodium‐based fire resistant geopolymer for passive fire protection

This paper primarily deals with the examination of the performance under thermal loading of a fire resistant sodium‐based geopolymer from Ferronickel slag. In addition, the mechanical, physical and thermal properties of material and their respective variation with time were measured. It is shown that the material presents good mechanical strength and excellent physical and thermal properties. The behaviour of the material on fire was tested by subjecting it to thermal loading with the modification of a standardized passive fire protection test. Two different fire scenarios were investigated: (1) the least intensive standard ISO 834 fire load curve and (2) the most severe Rijkswaterstaat fire load curve. The material behaviour was excellent under its exposure at the ISO 834 fire load curve, showing optimal thermal insulating function and very good structural integrity. Under the Rijkswaterstaat fire load curve, the material showed again a very good thermal insulating function while at the same time suffered from creeping phenomena at the extremely high temperature of 1300°C that affected drastically its structural integrity. As a conclusion, the sodium‐based geopolymer from FeNi slag may be an appropriate material for passive fire protection systems under cellulosic fires but inappropriate against more intense fire incidents. Copyright © 2014 John Wiley & Sons, Ltd.     

Development of a numerical approach based on coupled CFD/FEM analysis for virtual fire resistance tests—Part A: Thermal analysis of the gas phase combustion and different test specimens

In the present two‐parted study, a numerical approach is shown to consider fire resistance tests in virtual space, including the combustion, thermal analysis of the test specimen, and the deformation process. This part is dealing with the combustion process and thermal analysis of different building materials tested in a fire resistance furnace. Instead of using coupled computational fluid dynamics (CFD)/finite element method simulation for the combustion and thermal heat conduction in the solid, which is commonly used in literature, the present approach considers these transport phenomena in one CFD simulation. This method enables a two‐way coupling between the gas phase and the solid material, where chemical reactions and the release of volatile components into the gas phase can occur (eg, release of water vapour from gypsum). To validate the numerical model, a fire resistance test of a steel door, which is a multilayer construction, and a wall made of gypsum blocks were experimentally and numerically investigated. Due to the chemical reactions inside the gypsum, water vapour is released to the gas phase reducing the flue gas temperature about 80 K. This effect was taken into account using a two‐way coupling in the CFD model, which predicted temperatures in close accordance to the measurement.     

Dangers relating to fires in carbon‐fibre based composite material

Inhalable carbon fibres have been suspected to pose similar threats to human health as asbestos fibres. It is well‐known that fibres having a diameter of less than 3 µm might be inhaled and transported deep into the human respiratory system. Some composite materials use carbon fibres as structural reinforcement. These fibres do not pose any risks as such as they are firmly connected to the laminate and surrounded by a polymer matrix. Also, these fibres typically have diameters >6 µm and thus, are not inhalable. However, if the material is exposed to a fire, the carbon material might be oxidized and fractionated and thereby, inhalable fibres might be generated into the fire smoke. The capability of carbon fibre‐based composite material to produce dangerous inhalable fibres from different combustion scenarios has been investigated. It was found that the risk of fires generating inhalable carbon fibres is related to the surface temperature, the oxygen level and the airflow field close to the material surface. The temperatures necessary for oxidation of the carbon fibre is so high that it is possible that only a flashover situation will pose any real danger. Other possible danger scenarios are highly intense fires (e.g. a liquid fuel fire), or situations where structural damage is part of the fire scenario. Copyright © 2005 John Wiley & Sons, Ltd.     

A flammability performance comparison between synthetic and natural clays in polystyrene nanocomposites

Polymer‐clay nanocomposites are a newer class of flame retardant materials of interest due to their balance of mechanical, thermal and flammability properties. Much more work has been done with natural clays than with synthetic clays for nanocomposite flammability applications. There are advantages and disadvantages to both natural and synthetic clay use in a nanocomposite, and some of these, both fundamental and practical, will be discussed in this paper. To compare natural and synthetic clays in regards to polymer flammability, two clays were used. The natural clay was a US mined and refined montmorillonite, while the synthetic clay was a fluorinated synthetic mica. These two clays were used as inorganic clays for control experiments in polystyrene, and then converted into an organoclay by ion exchange with an alkyl ammonium salt. The organoclays were used to synthesize polystyrene nanocomposites by melt compounding. Each of the formulations was analysed by X‐ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). Flammability performance was measured by cone calorimeter. The data from the experiments show that the synthetic clay does slightly better at reducing the heat release rate (HRR) than the natural clay. However, all the samples, including the inorganic clay polystyrene microcomposites, showed a decreased time to ignition, with the actual nanocomposites showing the most marked decrease. The reason for this is postulated to be related to the thermal instability of the organoclay (via the quaternary alkyl ammonium). An additional experiment using a more thermally stable organoclay showed a time to ignition identical to that of the base polymer. Finally, it was shown that while polymer‐clay nanocomposites (either synthetic or natural clay based) greatly reduce the HRR of a material, making it more fire safe, they do not provide ignition resistance by themselves, at least, at practical loadings. Specifically, the cone calorimeter HRR curve data appear to support that these nanocomposites continue to burn once ignited, rather than self‐extinguish. Copyright © 2004 John Wiley & Sons, Ltd.     

A general correlation of the flammability of natural and synthetic polymers

The concept that flammability is fundamentally related to the potential thermal energy available per unit of volume of material emerged from attempts to correlate the effect of composition variables on the flammability of neoprene vulcanizates as measured by the oxygen index (O.I.) test. The origins of this test clearly show that it is a highly specific measure of flammability—the tendency of a composition to continue to burn once ignited—and that it is thermodynamically related to the heat of combustion of materials. This relationship is developed to a linear correlation which includes a wide variety of synthetic and natural materials and permits reasonable prediction of O.I. values from elemental analysis. Polymeric materials containing carbon and oxygen in atom ratios of less than 6 to 1 are more flammable than predicted. The effect of atmospheric temperature on O.I. can be predicted in relation to the O.I. value at normal temperature. This effect is shown to be independent of the composition of the material being tested. These two correlations permit the construction of a simple general map of flammability against which experimental data can be compared and judgments made with respect to the significant variables involved. There appears to be a significant relation between O.I. data, as viewed from these correlations, and the data of other flammability tests.     

Lignin nanoparticles by ultrasonication and their incorporation in waterborne polymer nanocomposites

Lignin nanoparticles (nanolignin, NL) were prepared in this work by ultrasonic treatment of softwood kraft lignin to obtain lignin‐water dispersions with excellent colloidal stability. A thorough characterization of the chemical, physical, and morphological properties of the new NL particles allowed for direct comparisons with the untreated parent material. Such NL particles were incorporated into a waterborne thermoplastic polyurethane matrix at different concentrations to yield bio‐based nanocomposite materials. The effect of the bio‐filler type (NL vs. untreated lignin) and loading on the chemical, physical, thermal, and morphological characteristics of the resulting nanocomposites was extensively investigated. In addition, tensile tests carried out on these systems highlighted the superior mechanical properties of NL‐based nanocomposites compared to composite materials incorporating untreated lignin. The results of this study provide a direct demonstration of an easy and environmentally friendly approach to obtain waterborne polyurethane‐based nanocomposites reinforced with NL in a relatively straightforward and accessible way and clearly evidence the potential of lignin nanoparticles as fully bioderived fillers for advanced nanocomposite applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45318.     

Combustibility of cyanate ester resins

Flaming and non‐flaming combustion studies were conducted on a series of polycyanurates to examine the effect of chemical composition and physical properties on the fire behavior of these crosslinked, char forming, thermoset polymers. Heats of complete combustion of the polymer and fuel gases were determined by oxygen bomb calorimetry and pyrolysis‐combustion flow calorimetry, respectively. Fire calorimetry experiments were conducted to measure the total heat released, the rate of heat release and the smoke generation in flaming combustion. Fire response parameters derived from the data include the thermal inertia, heat of gasification, effective heat of combustion and combustion efficiency. Halogen‐containing polycyanurates exhibited extremely low heat release rate in flaming combustion compared with the hydrocarbon resins yet produced significantly less smoke and comparable levels of carbon monoxide and soot. Published in 2005 by John Wiley & Sons, Ltd.     

Preparation,thermal, and flammability of halogen‐free flame retarding thermoplastic poly(ether‐ester) elastomer/montmorillonite nanocomposites

In this article, the nanocomposites thermoplastic polyester‐ether elastomer (TPEE) with phosphorous–nitrogen (P–N) flame retardants and montmorillonite (MMT) was prepared by melt blending.The fire resistance of nanocomposites was analyzed by limiting oxygen index (LOI) and vertical burning (UL94) test. The result shows that the flame retardants containing P–N increased the LOI of the material from 17.3 to 27%. However, TPEE containing P–N flame retardants just got UL94 V‐2 ranking, which resulted in the flaming dripping phenomenon. On the other hand, TPEE containing P–N flame retardant and organic‐modified montmorillonite (o‐MMT) achieved UL94 V‐0 rating for the special microstructure. The XRD and TEM morphology has demonstrated that the formation of multi‐ordered structure regarding restricted segmental motions at the organic–inorganic interface and stronger interactions between the clay mineral layers and the polymer chains. The structure was supported by the results of rheological properties and DSC analysis. The thermal degradation and char residue characterization was studied by thermal gravimetric analysis (TGA) and SEM‐EDX measurements, respectively. The TGA and SEM‐EDX have demonstrated that o‐MMT results in the increase of char yield and the formation of the thermal stable carbonaceous char. POLYM. COMPOS., 37:700–708, 2016. © 2014 Society of Plastics Engineers