A review on flammability of epoxy polymer,cellulosic and non‐cellulosic fiber reinforced epoxy composites

Natural fiber is well‐known reinforcement filler in polymer‐matrix composites. Composite components like organic polymers and natural fibers are natural fire conductors as the natural fiber consists of cellulose, hemicellulose, and lignin, and hence are as highly flammable as wood. Natural fiber reinforced composite materials are progressively being used in a variety of applications where their fire response is a hazardous consideration, for example, in the automotive (transportation) and building‐construction industries. As a result, an awareness of their performance or response during a fire and the use of conventional fire retardants are of great importance, as they are subject to thermal decomposition when exposed to intensive high heat or fire sources. In this review paper, fire flammability is the main concern for cellulosic and non‐cellulosic fiber‐reinforced polymer composites, especially epoxy composites. This paper reviews the literature on the recent developments in flammability studies concerning polymers, epoxy polymers, cellulosic‐fibers, and non‐cellulosic fiber‐reinforced epoxy bio‐composites. The prime objective of this review is to expand the reach of “fire retardants for polymer materials and composites” to the science community, including physicists, chemists, and engineers in order to broaden the range of their applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermal degradation and flame retardancy of rigid polyurethane foams containing a novel intumescent flame retardant

A novel cheap macromolecular intumescent flame retardants (MIFR) was synthesized, and its structure was a macromolecule containing phosphorus characterized by IR. Rigid polyurethane foam (PUF) filled with MIFR as fire retardant additive was prepared. The effects of MIFR on properties such as density, compressive strength, flame-retardant behavior, thermal stability, and morphology of char were studied. The compressive strength of the MIFR-filled PUF increased initially and then decreased with further increase of MIFR content while its density straightly increased. Its flammability and burning behavior were characterized by UL 94 and limiting oxygen index (LOI). Twenty five percent of MIFR was doped into PUF to get 24.5 of LOI and UL 94 V-0. Activation energy for the decomposition of samples was obtained using Kissinger equation. The resultant data show that for PUF containing MIFR, compared with PUF, the mass loss, thermal stability, and the decomposition activation energy decreased, the char yield increased, which shows that MIFR can catalyze decomposition and carbonization of PUF to form an effective charring layer to protect the underlying substrate.     

Effects of Halloysite Nanotube Reinforcement in Expandable Graphite Based Intumescent Fire Retardant Coatings Developed Using Hybrid Epoxy Binder System

In this study, the effects of halloysite nanotubes (HNTs) reinforcement in expandable graphite based intumescent fire retardant coatings (IFRCs) developed using a polydimethylsiloxane(PDMS)/phenol BA epoxy system were investigated. Intumescent coating formulations were developed by incorporating different weight percentages of HNTs and PDMS in basic intumescent ingredients (ammonium polyphosphate/melamine/boric acid/expandable graphite, APP/MEL/BA/EG). The performance of intumescent formulations was investigated by furnace fire test, Bunsen burner fire test, field emission electron microscopy (FESEM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier transform infrared analysis (FTIR). The Bunsen burner fire test results indicated that the fire performance of HNTs and PDMS reinforced intumescent formulation has improved due to the development of silicate network over the char residue. Improved expansion in char residue was also noticed in the formulation, SH(3), due to the minimum decomposition of char carbon. FESEM and TEM results validated the development of silicate network over char layer of coating formulations. A considerable mass loss difference was noticed during thermal gravimetric analysis (TGA) of intumescent coating formulations. Reference formulation, SH(0) with no filler, degraded at 300 °C and lost 50% of its total mass but SH(3), due to synergistic effects between PDMS and HNTs, degraded above 400 °C and showed the maximum thermal stability. XRD analysis showed the development of thermally stable compound mulltie, due to the synergism of HNTs and siloxane during intumescent reactions, which enhanced fire performance. FTIR analysis showed the presence of incorporated siloxane and silicates bonds in char residue, which endorsed the toughness of intumescent char layer produced. Moreover, the synergistic effect of HNTs, PDMS, and other basic intumescent ingredients enhanced the polymer cross-linking in binder system and improved fire resistive performance of coatings.     

Mechanism and kinetics of thermal degradation of insulating materials developed from cellulose fiber and fire retardants

The mechanism and kinetics of thermal degradation of materials developed from cellulose fiber and synergetic fire retardant or expandable graphite have been investigated using thermogravimetric analysis. The model-free methods such as Kissinger–Akahira–Sunose (KAS), Friedman, and Flynn–Wall–Ozawa (FWO) were applied to measure apparent activation energy (E_α). The increased E_α indicated a greater thermal stability because of the formation of a thermally stable char, and the decreased E_α after the increasing region related to the catalytic reaction of the fire retardants, which revealed that the pyrolysis of fire retardant-containing cellulosic materials through more complex and multi-step kinetics. The Friedman method can be considered as the best method to evaluate the E_α of fire-retarded cellulose thermal insulation compared with the KAS and FWO methods. A master-plots method such as the Criado method was used to determine the possible degradation mechanisms. The degradation of cellulose thermal insulation without a fire retardant is governed by a D3 diffusion process when the conversion value is below 0.6, but the materials containing synergetic fire retardant and expandable graphite fire retardant may have a complicated reaction mechanism that fits several proposed theoretical models in different conversion ranges. Gases released during the thermal degradation were identified by pyrolysis–gas chromatography/mass spectrometry. Fire retardants could catalyze the dehydration of cellulosic thermal insulating materials at a lower temperature and facilitate the generation of furfural and levoglucosenone, thus promoting the formation of char. These results provide useful information to understand the pyrolysis and fire retardancy mechanism of fire-retarded cellulose thermal insulation.

     

Differential thermal and thermogravimetric analyses of bound water content in cellulosic substrates and its significance during cellulose hydrolysis by alkaline active fungal cellulases

Various cellulosic substrates were examined for bound water content by differential thermal analysis (DTA) and thermogravimetry (TG). Samples were heated in the range of 30-100 degrees C at a rate of 3 degrees C/min. DTA vaporization curves for different cellulose samples indicated that the bound water (Wf) was vaporized at higher temperature than free water (Wf) at the surface. Weight loss was observed in two stages, corresponding to Wf and Wb in TG curves. The bound water content was dependent on the degree of crystallinity of cellulose. Among different cellulosic substrates, Walseth cellulose showed the highest bound water content, and it also was found to be the least crystalline. The alkaline-active, alkali-stable cellulase was obtained from the alkalotolerant Fusarium sp. The substrate specificity and viscometric characteristics confirmed the enzyme to be an endoglucanase. The Wb content of Walseth cellulose was lowered during the enzymatic hydrolysis. The possible application of bound water analysis in understanding the hydrolysis of cellulosic substrates of different crystallinity is discussed.     

Response of a glass/phenolic composite to high temperatures

Determining the response of composite phenolic materials to fire remains a major unsolved problem that is important for high consequence safety analysis. Difficulties arise when thermophysical property measurements are obscured by decomposition reactions. This article presents several decomposition experiments and models for a phenolic resin impregnated into chopped 1.27-by-1.27 cm glass fabric. The thermal response of the material was measured using thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and laser flash diffusivity (LFD). The TG data was used to develop a 5-step decomposition mechanism describing mass loss due to reaction; the DSC data was used to describe the energy changes associated with these reactions; and the LFD data was used to describe energy flow into the decomposing material. An effective thermal conductivity model was used to partition energy transport by gas conduction, solid conduction, and diffusive radiation. The dynamic gas volume fraction is treated as a field variable to extrapolate thermal transport properties at high temperatures where decomposition is prevalent. These various models have been implemented into a finite element response model with an example calculation that includes uncertainty.     

The fire-retarding effect of inorganic phosphorus compounds on the combustion of cellulosic materials

The pyrolysis and combustion of cellulosic substances treated with MAP and DAP have been studied using thermal analysis, flame spread tests and a specifically designed apparatus for smoldering combustion test. The samples used were: cotton string, cotton fabric and pure cellulose powder. Diammonium Phosphate (DAP) and Monoammonium Phosphate (MAP) can reduce the combustion and pyrolysis maximum mass loss temperature, decrease the initial pyrolysis temperature and considerably increase mass residue. Moreover, MAP and DAP reduce the flaming combustion rate of cellulosic materials and completely inhibit smoldering combustion. This study can facilitate a better understanding of the mechanism of pyrolysis and combustion of fire-retarded cellulosic materials.     

The estimation of pig bone age for forensic application using thermogravimetric analysis

An accurate means of determining bone age is a goal for forensic scientists. In this study, thermogravimetric analysis (TGA) has been used to examine pig bone specimens of different post-mortem age. Analysis of bone in both air and nitrogen atmospheres reveals a decrease in total mass loss as the bones age. Two mass loss steps due to the decomposition of the organic bone components were observed and show decreasing trends with age for decomposition in an air atmosphere. In a nitrogen atmosphere the decomposition was observed to be more complex and age dependence of the mass loss for each step was not identified. The TGA data, however, demonstrates the potential of the technique as a means of estimating post-mortem age of forensic bone specimens.     

Reaction pathway to CZTSe formation in CdI2

The thermal decomposition of cotton and hemp fibers was studied after mild alkaline treatments with tetramethyl-, tetraethyl- and tetrabutylammonium hydroxides with the goal of modeling the chemical activation during carbonization of cellulosic fibers. The thermal decomposition was studied by thermogravimetry/mass spectrometry and pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). The treated samples decomposed in two temperature ranges during heating in the thermobalance. At lower temperature, tetraalkylammonium hydroxides (TAAH) ionically bonded to the cellulose molecules were decomposed; moreover, the alkaline agents initiated the partial decomposition of cellulose. Those fiber segments, which were not accessible for TAAH, decomposed at similar temperatures as the original cotton and hemp samples. It is known that quaternary ammonium hydroxides swell the cellulosic fibers; however, the results of this study proved that there was a chemical interaction between the alkaline swelling agents and cotton or hemp fibers at rather low temperatures (200–300 °C). The evolved products indicated that the alkaline chemicals reacted with the cellulose molecules and alkylated compounds were formed. This observation was confirmed by thermochemolysis experiments carried out by Py–GC/MS using tetramethylammonium hydroxide reagent. The thermochemolysis experiments under mild conditions resulted in the methylation of the glucoside units and levoglucosan, and no peeling reactions of the sugar units were observed as during strong alkaline conditions described in the literature.

     

Catalytic pyrolysis of Phragmites (reed): Investigation of its potential as a biomass feedstock

In this paper, thermogravimetry, TG, and pyrolysis are used for the thermochemical evaluation of the common reed (Pragmites australis) as a candidate biomass feedstock. The TG analysis indicated that the material loses 4% of its weight below 150 °C through dehydration. The main decomposition reaction occurs between 200 and 390 °C. The rate of weight loss, represented by the derivative thermogravimetric, DTG, signal indicated a multi-step reaction. Kinetic analysis helped in the resolution of the temperature ranges of the overlapping steps. The first step corresponds to the degradation of the hemi-cellulosic fraction and the second to the cellulosic fraction degradation. The TG and DTG signals of reed samples treated with increasing concentration of potassium carbonate (0.6–10 wt%) indicated a catalytic effect of the salt on reed decomposition. The temperature of maximum weight loss rate, DTGmax, exponentially decreased with increasing catalyst content, whilst the initial temperature of the decomposition decreased linearly. The pyrolysis studies were carried out in a Pyrex vertical reactor with sintered glass disc to hold the sample and to aid the fluidization with the nitrogen stream flowing upwards. The reactor was connected to a cyclone and condenser and a gas sampling device. Tar and char are collected and weighed. The gas chromatographic analysis of the evolved gases demonstrated the effect of pyrolysis temperature (400, 450, and 500 °C) on their composition. The temperature increase favors the yields of hydrocarbons, carbon monoxide and hydrogen at the expense of methanol and carbon dioxide. Similarly, reed samples treated with K2CO3 at 10 wt% were pyrolyzed and analyzed. Comparisons for the various parameters (yields, gas composition and carbon–hydrogen recovery) between the untreated and catalyzed reed conversion were also made.     

Development of a reconversion method for uranyl nitrate to oxide in the reconversion step of reprocessing of irradiated fuel

Ammonium uranyl carbonate (AUC) precipitation is developed for the conversion of uranyl nitrate to oxide in the uranium reconversion step of reprocessing of irradiated fuel by the addition of ammonium carbonate salt. Different precipitation conditions of AUC are studied. The solubility of AUC as a function of uranium concentration in the feed at different temperatures using ammonium carbonate salt as precipitant is studied. This study indicates that 95-99.8% of uranium is recovered as AUC by precipitating 5-125 g/l of uranium with loss of uranium (250-10 ppm) in the filtrate by adding ammonium carbonate salt. It is also observed that the solubility of AUC increased as the concentration of uranium decreased. Thermal decomposition is carried out by thermogravimetry/differential thermal analysis (TG/DTA) and evolved gas analysis-mass spectrometry (EGA-MS) to find out AUC decomposition and gases evolved during decomposition. Studies are also carried out to characterize AUC by using X-ray diffraction (XRD). The data show that AUC obtained by the above conditions is very much consistent with published information.     

Thermal Decomposition of Silver Flake Lubricants

There is a thin layer of organic lubricant on commercial silver flake surfaces. This lubricant layer is a fatty acid salt formed between a fatty acid and silver flake surfaces. Thermal decomposition behavior of the silver flake lubricant is investigated in this study. The heat flow and mass loss of a silver flake are studied using differential scanning calorimetry (DSC) and thermogravimetry (TG), respectively. The silver flake is also oven heated to different isothermal temperatures (150,190, 250 and 300°C) for one h. Then chemical nature of the lubricant of the heated silver flake sample are studied using diffuse reflectance infrared Fourier transfer spectroscopy (DRIFTS). Based on the results, a mechanism of thermal decomposition of the silver flake lubricant is proposed. It is found that decomposition of the lubricant - the fatty acid salt -includes the release of the fatty acid, formation of short chain acids by decomposition of hydrocarbon moiety of the fatty acid, and formation of alcohols through decarbonation of the short chain acids. This revised version was published online in July 2006 with corrections to the Cover Date.     

不同氛围下绿原酸的热解行为及其裂解产物中苯酚含量分布规律研究

采用热重分析法(TGA)及在线裂解气相色谱-质谱联用仪(Py/GC - MS)研究了烟草中绿原酸在不同氛围下的热解行为及其含量分布规律.先用TGA确定了绿原酸在氮气氛围中的主要热失重区间,选取4个典型的温度点,再结合卷烟在高温燃烧区的3个温度点,分别在惰性(氦气)和有氧(含9％氧气的氮氧混合气)氛围中进行热裂解实验,对...     

The use of thermal desorption GC/MS to study weight loss in thermogravimetric analysis of di-acid salts

Thermal desorption gas chromatograph mass spectrometry (TD GC/MS) was used to study weight loss in thermogravimetric analysis (TGA). The technique of thermal desorption utilizes the same temperature heating rate as the TGA to thermally desorb volatiles from solid sample matrices. Volatiles were cryo-trapped at −60 °C. After thermal desorption is complete, the trapped volatiles are separated by a GC capillary column and identified by mass spectrometry. In this study, the TD GC/MS was applied in pharmaceutical development to understand the chemical reactions attributed to the weight loss in the thermal decomposition of two dicarboxylic acid salts of a drug substance. These two salts exhibited different thermal stabilities. The thermally induced chemical reactions obtained from these two salts included dehydration and decarboxylation. Thermal degradation compounds were identified and reaction pathways for decomposition were proposed. The stability of the salts is dependent on the identity of the dicarboxylic acids from which they were generated. The information obtained from TD GC/MS helps better understand the weight loss process in thermogravimetric analysis.     

Thermal behavior of typical weak basic ion exchange resin

Thermal behaviors of typical weak basic ion exchange resins (301 and 315) were studied with thermogravimetry, elemental analysis, and Fourier transform infrared spectrometer in this study. Results indicated that there were three stages for 301 resin mass loss, the first stage and the second stage were mainly related to the decomposition of functional group, and the third stage was the decomposition of main chain. Whereas there were two stages for 315 resin mass loss, the first stage was elimination of moisture, and the second stage was the decompositions of functional group and main chain. Moreover, the decomposition of tertiary amine had three stages, the polyamine was a continuous mass loss process, and the thermostability of tertiary amine was weaker than that of polyamine.     

Characterization of the complexing agents’ influence on bioscouring cotton fabrics by FT-IR and TG/DTG/DTA analysis

The nature of the complexing agents used in the bioscouring process of cotton fabrics aiming to eliminate the non-cellulosic compounds (pectin, waxes, etc.) and to improve the hydrophilic and wetting properties influences the thermal behaviour and the FT-IR spectra of the textile materials. In this paper, we study the influence of the experimental conditions and complexing agent nature (sodium citrate or disodium EDTA salt) on the pectin elimination in bioscouring treatment of cotton fabric by FT-IR and TG/DTG/DTA analysis. The changes from FT-IR spectra of the specific bands (absorbance intensity at 2916, 2852, 1732 and 1640/1642 cm^?1) were evaluated. The thermal behaviour of the investigated samples’ fabric by using TG/DTG/DTA analysis was studied at 30–600 °C temperature range, in air atmosphere. All samples showed three mass-loss steps due to the elimination of humidity, decomposition of the non-cellulosic and cellulosic components (main degradation stage of the samples) and thermo-oxidative decomposition of the formed degradation products. The T_onset values corresponding to the main decomposition step, the mass-loss values (%Δm) and the % residual mass (at 600 °C) were influenced by the complexing agent nature as well as the concentration and the action time of the commercial enzyme product. In addition, the calcium content of some samples treated with and without ultrasound was determined using atomic absorption spectroscopy method (AAS) in order to correlate the results with TG/DTG/DTA analysis. The obtained results have shown that the synergistic action of experimental conditions (enzyme concentration, pH, enzyme product action time, ultrasound) and the presence of sodium citrate as a biodegradable complexing agent led to the elimination of a higher amount of pectin from the cotton samples than that eliminated when using EDTA.     

An evaluation of discarded tires as a potential source of fuel

The destructive distiliation of rubber tire samples was studied by thermogravimetry, differential scanning calorimetry, combustion calorimetry, and mass spectroscopy. The decomposition reaction was found to be exothermic and produced a mass loss of sixty-five percent. The products from the distillation process were a solid residue with a heating value of about ?3 × 10⁷ J kg^?1. a liquid with a heating value of about ?4 × 10⁷ J kg^?1, and a combustible gas of undetermined heating value. The gas evolution curves which were obtained indicate that a variety of organic materials are evolved simultaneously during decomposition of the rubber polymer.     

酚醛树酯的热解动力学模型

建立了一种利用热重峰值分析进行酚醛树酯热解动力学研究的方法, 这种方法利用热重谱峰上几个特征点的数据来确定动力学参数. 根据酚醛树酯热解DTG曲线的特点, 把酚醛树酯的热解过程分解成三个阶段, 用峰值分析法对每个反应阶段分别建模, 通过三个反应阶段的叠加得到了一个酚醛树酯分阶段热解动力学模型, 该模型能够很好地描述酚醛树酯的热解过程.     

Thermal degradation and fire behaviour of unsaturated polyesters filled with metallic oxides

Nano-alumina and submicron alumina trihydrate particles were incorporated into an unsaturated polyester resin at various loadings. The morphologies of composites showed that only nano-alumina was correctly dispersed. The thermal degradation behaviour of the composites was studied using thermogravimetric analysis and Py-GC/MS, while their fire behaviour was investigated using cone calorimeter and pyrolysis combustion flow microcalorimeter. Synergistic effects on thermal stability and heat release rate were observed for combinations between both submicron filler and nanofiller. The best result for fire behaviour was obtained for a global loading of 10wt% with an equal mass ratio for both kind of particles. Mass loss curves also showed increased char yield. The interest of combining particles with different sizes has been discussed as well as the role of water release, regarding activations energies of degradation processes.     

Assessment of evolution of loss on ignition matter during heating of iron ores

Ironmaking involves reduction of iron ores to metallic iron using coke, coal or gas as reductants. Although different iron ore reduction processes exist, prior to each reduction type, commonly, the hydroxyl and clay materials present in the iron ores undergo decomposition as a first stage. The mass loss during decomposition of these materials is termed as Loss on Ignition (LOI). The aim of this work is to apply a computer aided thermoanalytical technique to evaluate five different iron ore types during decomposition of the LOI matter and determine associated decomposition temperature ranges and heats of reactions. Fourier Transform Infrared (FTIR) spectroscopy and thermogravimetric analysis (TG) were also incorporated to support the analysis interpretation. Three distinctive temperature ranges of decomposition of iron ore LOI matter were detected. The first region was associated with dehydration of the hygroscopic moisture at a temperature range between 100 and 150 °C. The second region occurred at a temperature range between 260 and 425 °C during which strongly bonded water was released and the OH groups associated with primarily iron oxyhydroxides were fractured. The third range, which occurred at a temperature range of 530 and 605 °C, was related to decomposition of the aluminosilicate clay materials.