THERMAL DEGRADATION AND FLAME RETARDANCY OF CALCIUM ALGINATE FIBERS

Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride.The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry(TG),X-ray diffraction(XRD),limiting oxygen index(LOI) and cone calorimeter(CONE).The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34,and the heat release rate(HRR),total heat release(THR),CO and CO_2 concentrations during com...

Thermal Degradation Kinetics of N,N'-Di(diethoxythiophosphoryl)-1,4-phenylenediamine

The non-isothermal degradation kinetics of N,N＇-di（diethoxythiophosphoryl）-1,4-phenylenediamine in N2 was studied by TG-DTG techniques.The kinetic parameters,including the activation energy and pre-exponential factor of the degradation process for the title compound were calculated by means of the Kissinger and Flynn-Wall-Ozawa（FWO）method and the thermal degradation mechanism of the title compound was also studied with the Satava-Sestak methods.The results indicate that the activation energy and pre-exponential factor are 152.61 kJ/mol and 9.06×101 4s -1with the Kissinger method and 154.08 kJ/mol with the Flynn-Wall-Ozawa method,respectively.It has been shown that the degradation of the title compound follows a kinetic model of one-dimensional diffusion or parabolic law,the kinetic function is G（α）=α2and the reaction order is n=2.

THERMAL DEGRADATION OF POLY(ARYLENE SULFIDE SULFONE)/NMETHYLPYRROLIDONE CRYSTAL SOLVATE

The thermal degradation of poly（arylene sulfide sulfone）/N-methylpyrrolidone （PASS/NMP） crystal solvate was studied by thermogravimetric analysis （TGA） and was compared with pure PASS in order to determine the way in which the formation of the crystal solvate affected the thermal properties of the polymer. The activation energy of the solid state process was determined using Kissinger＇s method, which does not require knowledge of the reaction mechanism （RM）, to be 174.18 kJ/mol which was lower than that for pure PASS （E = 214 kJ/mol）. The study of master curves together with interpretation of integral methods, allows confirmation that the thermal degradation mechanism for PASS in the crystal solvate system is a decelerated Rn type, which is a solid-state process based on a phase boundary controlled reaction, in the conversion range considered. Whereas, the pure PASS follows a decelerated Dn thermodegradation mechanism in the same conversion range.

Thermal degradation and isothermal crystalline behavior of poly(trimethylene terephthalate)

Poly（trimethylene terephthalate） （PTT） is an excellent fiber material. Its thermal degradation and isothermal crystalline behaviors were in this study investigated using thermogravimetric analysis （TGA）, thermogravimetric analysis-Fourier transform infrared spectroscopy （TGA-FTIR） analysis, differential scanning calorimetry （DSC） and X-ray diffraction （XRD）. The thermal degradation mechanism of PTT follows Mclafferty rearrangement principle. The PTTwithintrinsicviscosity（IV） of 0.74 dL/g has a maximum crystallinity of about 55% at 190 ℃, as demonstrated by DSC and XRD measurements consistently.

SYNTHESIS,CHARACTERIZATION AND THERMAL DEGRADATION KINETICS OF POLY(IMINO ISOPHTHALOYL IMINO (2,4,8,10-TETRAOKSOASPIRO [5,5] UNDEKAN-3,9-DIPROPYLENE))

A new polymer,poly(imino isophthaloyl imino(2,4,8,10-tetraoksoaspiro[5,5]undekan-3,9-dipropylene)) [poly(IPIT)]was synthesized by an interfacial polycondensation reaction.The characterization of poly(IPIT)was conducted by using FT-IR,^(13)C-NMR,TG and DTA techniques.The kinetics of the thermal degradation of poly(IPIT)was investigated by thermogravimetric analysis at different heating rates.TG curves showed that the thermal decomposition of poly(IPIT) occurred in three stages.The apparent activation energie...

THERMAL DEGRADATION OF THERMOTROPIC LIQUID CRYSTALLINE TERPOLYESTERS BASED ON VANILLIC ACID, p-HYDROXYBENZOIC ACID AND POLY(ETHYLENE TEREPHTHALATE )

Nine thermotropic liquid crystalline terpolyesters based on vaniUic acid(V), p-hydroxybenzoic acid(H) and poly(ethylene terephthalate)(E) were investigated by thermogravimetry to ascertain their thermostability and the kinetic parameters for thermal degradation. Overall activation energy data of the degradation had been calculated over the range 5 ～ 70% weight loss. The temperatures and the activation energy of the degradation lie in the ranges of 384 ～ 394 ℃ at a heating rate of 1℃/min and 176 ～ 205 KJ/mol at the weight loss of 5%, respectively, which suggests that the terpolyesters have good thermostability.

Thermal Degradation Kinetics of Deoxybenzoin Polymer

The thermal degradation behavior of 4, 4-bishydroxydeoxybenzoin-polyphosphonate( BHDB-PPN) was investigated by gas chromatograph-mass spectrometer( GC-MS)and thermogravimetric analysis( TGA). It was found that BHDBPPN exhibited a different char formation way from the previous proposed mechanism based on the residue analysis by Fourier transform infrared spectra( FTIR) and the gas phase analysis by GC-MS. The thermal degradation kinetics was studied through TGA at various heating rates to identify the activation energy of BHDBPPN at two decomposition stages which were mainly attributed to the evolved phenol and benzene respectively. It was demonstrated that the activation energy at the second stage was much higher than that at the first stage,indicating that more energy was required to break the P—C bond to form benzene in comparison to the formation of phenol.

Facet-dependent Thermal and Electrochemical Degradation of Lithium-rich Layered Oxides

Lithium-rich layered oxides(LLOs)are promising candidate cathode materials for safe and inexpensive high-energy-density Li-ion batteries.However,oxygen dimers are formed from the cathode material through oxygen redox activity,which can result in morphological changes and structural transitions that cause performance deterioration and safety concerns.Herein,a flake-like LLO is prepared and aberration-corrected scanning transmission electron microscopy(STEM),in situ high-temperature X-ray diffraction(HT-XRD),and soft X-ray absorption spectrum(sXAS)are used to explore its crystal facet degradation behavior in terms of both thermal and electrochemical processes.Void-induced degradation behavior of LLO in different facet reveals significant anisotropy at high voltage.Particle degradation originates from side facets,such as the(010)facet,while the close(003)facet is stable.These results are further understood through ab initio molecular dynamics calculations,which show that oxygen atoms are lost from the{010}facets.Therefore,the facet degradation process is that oxygen molecular formed in the interlayer and accumulated in the ab plane during heating,which result in crevice-voids in the ab plane facets.The study reveals important aspects of the mechanism responsible for oxygen-anionic activity-based degradation of LLO cathode materials used in lithium-ion batteries.In particular,this study provides insight that enables precise and efficient measures to be taken to improve the thermal and electrochemical stability of an LLO.

Thermal Degradation, Flame Retardance and Mechanical Properties of Thermoplastic Polyurethane Composites Based on Aluminum Hypophosphite

Aluminum hypophosphite （AP） was used to prepare flame-retarded thermoplastic polyurethane （FR-TPU） composites, and their flame retardancy, thermal degradation and mechanical properties were investigated by limiting oxygen index （LOI）, vertical burning test （UL-94）, thermogravimetric analysis （TGA）, cone calorimeter （CC） test, Fourier transform infrared （FTIR） spectroscopy, scanning electron microscopy （SEM） and tensile test. TPU containing 30 wt% of AP could reach a V-0 rating in the UL-94 test, and its LOI value was 30.2. TGA tests revealed that AP enhanced the formation of residual chars at high temperatures, and slightly affected the thermal stability of TPU at high temperatures. The combustion tests indicated that AP affected the burning behavior of TPU. The peak of heat release rate （PHRR）, total heat release （THR） and mass loss rate （MLR） greatly reduced due to the incorporation of AP. The tensile test results showed that both the tensile strength and the elongation at break slightly decreased with the addition of AP. The digital photos and SEM micrographs vitrified that AP facilitated the formation of more compact intumescent char layer. Based on these results mentioned above, the flame-retarding mechanism of AP was discussed. Both the self-charring during the decomposing process of AP and its facilitation to the charring of TPU led to the great improvement in the flame retardancy of TPU.

Thermal degradation of epoxidized natural rubber in presence of neodymium stearate

The effect of neodymium stearate （NdSt） synthesized by saponification method on thermal degradation and thermo-oxidative degradation of expoxidized natural rubber with 25 mol.% epoxidation （ENR25） was investigated by thermogravimetric analysis （TGA）, and the structure of ENR25 vulcanized with NdSt after thermo-oxidative decomposition was characterized using Fourier transform infared spectroscopy-attenuated total-reflectance （FTIR-ATR）. The thermal degradation kinetic parameters of ENR25 with different loadings of NdSt were determined by Coats-Redfern method. The results showed that the thermal degradation of ENR25 in nitrogen was a one-step reaction regardless of NdSt content, whereas the thermo-oxidative degradation was a multiple-step reaction. The thermal and thermo-oxidative stability of the ENR25 vulcanizates with the addition of NdSt was higher than that of pure ENR25 vulcanizates. The ENR25 vulcanizates with the incorporation of 1 phr （per hundred parts of rubber） NdSt imparted the highest activa- tion energy （E） of thermal and thermo-oxidative degradation. This could be attributed to the many unoccupied orbits in rare earth Nd, which could capture the free radicals and make the epoxide groups stable in the process of thermal and thermo-oxidative degradation for ENR25.

AMMONIUM SULFAMATE FLAME RETARDED POLYAMIDE 6:MORPHOLOGY AND THERMAL DEGRADATION

The effect of ammonium sulfamate （AS） content on the flame retardancy of polyamide 6 （PA6） was studied. It is found that the limiting oxygen index （LOI） of PA6 increases with the increase of AS content and the flame retardancy of PA6 is significantly improved. The morphology of the residues after combustion was examined by means of scanning electron microscopy （SEM）. SEM results show that AS facilitates the formation of the intumescent char layer with honeycomb-like structure, which inhibits the transfer of heat and mass, and thus improves the flame retardancy of PA6. The thermal degradation of AS flame retarded PA6 was studied by thermogravimetric analysis （TGA）. The Kissinger method was applied to estimate the activation energy （Ea） of the degradation. The activation energy of the thermal degradation of PA6 decreases by adding AS, indicating that AS can promote the degradation of PA6.

Thermal and Thermo-oxidative Degradation of Flame Retardant High Impact Polystyrene with Triphenyl Phosphate and Novolac Epoxy Resin

Thermal and thermo-oxidative decomposition and decomposition kinetics of flame retardant high impact polystyrene （HIPS） with triphenyl phosphate （TPP） and novolac type epoxy resin （NE） were characterized using thermo-gravimetric experiment. And the flammability was determined by limited oxygen indices （LOI）. The LOI results show that TPP and NE had a good synthetic effect on the flame retardancy of HIPS. Compared with pure HIPS, the LOI values of HIPS/NE and HIPS/TPP only increased by about 5%, and the LOI value of HIPS/TPP/NE reached 42.3%, nearly 23% above that of HIPS. All materials showed one main decomposition step, as radical HIPS scission predominated during anaerobic decomposition. TPP increased the activity energy effectively while NE affected the thermal-oxidative degradation more with the help of the char formation. With both TPP and NE, the materials could have a comparable good result of both thermal and thermal-oxidative degradation, which could contribute to their effect on the flame retardancy.

Synthesis,Characterizations,Magnetism and Thermal Degradation of a 2-Fold Interpenetrated 3D Cobalt-Organic Framework

A new coordination polymer,[Co_(2)(L)_(2)(4,4'-bipy)]_(n)·3nH_(2)O(1)based on 5-(3-methyl-5-phenyl-4H-1,2,4-tri-azol-4-yl)isophthalic acid(H_(2)L)and 4,4'-bipyridine(4,4'-bipy)has been hydrothermally synthesized and character-ized by single-crystal X-ray diffraction,XRPD,IR,and elemental analysis.Temperature-dependent magnetic sus-ceptibility and thermal degradation for 1 were also studied.The asymmetric unit of compound 1 consists of two crystallographically independent Co(II)ion,two L^(2−)ligand,one 4,4'-bipy ligand,and three lattice water molecules.The 2D triangle networks were linked by the bridging 4,4'-bipy ligand to give rise to a 2-fold interpenetrated 3D architecture.The simplest cyclic motif of the 2D networks is a triangle ring consisting of three Co(II)cations and three L^(2−)ligands.So we can define Co(II)ions as 4-connected nodes and the L^(2−)ligands as 3-connected nodes.Thus,the 3D structure can be described as a 2-fold parallel interpenetrated ins InS 3,4-conn topology.

Kinetics and mechanism of thermal degradation of vegetable-tanned leather fiber

Thermal degradation of vegetable-tanned leather fiber(VLF)was investigated by thermogravimetric analysis aiming to know the exact kinetics and degradation mechanism.The thermogravimetric(TG)and differential thermogravimetric(DTG)curves showed that decomposition of the VLF occurs mainly in the range of 150-600℃,and the latter exhibits asymmetrical peak with a pronounced shoulder.The decomposition process was first analyzed by deconvolution of the experimental DTG curves,followed by reconstruction of the weight loss profiles of two individual processes.Several common isoconversional approaches were applied to calculate the activation energy over a wide range of conversion for the sample,including modified Kissinger-Akahira-Sunose(MKAS),Friedman,and Flynn-Wall-Ozawa.The average activation energy of vegetable-tanned leather fiber was found to be 241.9 kJ mol^(−1) by MKAS method.The activation energy values obtained for the pseudocomponents representing highly-crosslinked and low-crosslinked collagen in VLF were given as 190.6 and 124.8 kJ mol^(−1),respectively.Generalized master plots results suggested that the reaction mechanism for highly-crosslinked collagen follows the random nucleation and growth process at conversion values lower than 0.5.When the conversion is higher than 0.5,the mechanism tends to random scission model.For low-crosslinked collagen,the degradation is mainly governed by random nucleation and nuclei growth.The gaseous products of VLF thermal degradation were analyzed with an online-coupled TG-Fourier transform infrared spectroscopy system.

Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane composite

The thermal degradation behaviors of poly-carbonate/polymethylphenylsilsesquioxane(FRPC)com-posites were investigated by thermogravimetric analysis(TGA)under isothermal conditions in nitrogen atmo-sphere.The isothermal kinetics equation was used to describe the thermal degradation process.The results showed that activation energy(E),in the case of isothermal degradation,was a quick increasing function of conversion(α)for polycarbonate(PC)but was a strong and decreasing function of conversion for FRPC.Under the isothermal condition,the addition of polymethylphenylsilsesquioxane(PMPSQ)retardanted the thermal degradation and enhanced the thermal stability of PC during the early and middle stages of thermal degradation.It also indicated a possible existence of a difference in nucleation,nuclei growth,and gas diffusion mechanism in the thermal degradation process between PC and FRPC.Meanwhile,the addition of PMPSQ influenced the lifetime of PC,but the composite still met the demand in manufacturing and application.

Evalution of Thermal Oxidative Degradation of Trimethylol-propane Trioleate by TG/DTA/DSC

In order to evaluate the thermal oxidation degradation behavior of lubricant with different antioxidants,the thermal kinetics equation based on the anlyses of thermogravimetry(TG),differential thermal analysis(DTA),and differential scanning calorimetry(DSC)was established,respectively,to calculate the activation energy of lubricant thermal-oxidative reaction.The thermal analyses of TG and DTA were employed to determine the thermal decomposition properties of ester oils trimethylolpropane trioleate(TMPTO)with butyl-octyl-diphenylamine/octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate/amine-phenol combination antioxidant.The activation energy of the lubricating oil adding antioxidant is increased relative to the TMPTO base oil,and the order of activation energy are Ec(93.732 kJ·mol^(-1))>Ed(88.71 kJ·mol^(-1))>Eb(58.41 kJ·mol^(-1))>Ea(46.32 kJ·mol^(-1)).The experimental results show that octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate in TMPTO has favorable resistance to thermal oxidation and decomposition.The thermal analysis method of DSC accurately reflects the heat exchange of lubricant thermal-oxidative reaction.The order of activation energy is calculated to ED(144.385 kJ·mol^(-1))>EC(110.05 kJ·mol^(-1))>EB(97.187 kJ·mol^(-1))>EA(66.02 kJ·mol^(-1)).It is illustrated that the amine-phenol combination antioxidant has the best thermal oxidation resistance,which is the same as what the oxidation onset temperature effected.

Degradation of PAI/PEI Enamel under High Temperature (Up to 400°C)

This work deals with the understanding of the degradation of the primary insulation (PEI/PAI) of rotating machines working temporarily under high-temperature. The main domain of application of these motors is the smoke extraction either from tunnels or underground parking when a fire occurs. In such a critical situation, the internal temperature of the motor winding may reach temperatures up to 400°C. Under such very high thermal stresses, the behaviour of the electrical insulation is not well understood. This work proposes an analysis of the decomposition gases under very high temperatures and the corresponding degradation pathway. A simple method is proposed to identify whether the insulation of such motors has been strongly damaged during the working time at very high temperatures, thus allowing estimating if it can still continue to operate.

Study of the kinetic behaviour of biomass and coal during oxyfuel co-combustion

In this study,the thermogravimetric analysis(TGA)method has been used to evaluate the kinetic behavior of biomass,coal and its blends during oxyfuel co-combustion.The thermogravimetric results have been evaluated by the Coats-Redfern method and validated by Criado’s method.TG and DTG curves indicate that as the oxygen concentration increases the ignition and burn out temperatures approach a lower temperature region.The combustion characteristic index shows that biomass to coal blends of 28%and 40%respectively can achieve enhanced combustion up to 60%oxygen enrichment.In the devolatilization region,the activation energies for coal and blends reduce while in the char oxidation region,they increase with rise in oxygen concentration.Biomass,however,indicates slightly different combustion characteristic of being degraded in a single step and its activation energies increase with rise in oxygen concentration.It is demonstrated in this work that oxygen enrichment has more positive combustion effect on coal than biomass.At 20%oxygen enrichment,28%and 40%blends indicate activation energy of 132.8 and 125.5 kJ·mol^-1 respectively which are lower than coal at 148.1 kJ·mol^-1 but higher than biomass at 81.5 kJ·mol^-1 demonstrating synergistic effect of fuel blending.Also,at char combustion step,an increase in activation energy for 28%blend is found to be 0.36 kJ·mol^-1 per rise in oxygen concentration which is higher than in 40%blend at 0.28 kJ·mol^-1.

CHEMICAL SYNTHESIS,SPECTRAL CHARACTERIZATION AND STABILITY OF SOME ELECTRICALLY CONDUCTING POLYMERS

The synthesis, characterization, thermal degradation and stability of polyaniline （PANI）, poly（m-nitroaniline）, poly（m-chloroaniline） and poly（o-methylaniline） were reported. Different properties were measured and compared with PANI to find out the effect of electron donating groups （-CH3） and electron withdrawing groups （-Cl, -NO2）. It was found that the presence of any type of substitution in the benzene ring of aniline increased the solubility but reduced the yield, thermal stability and electrical conductivity. Two probe methods were used to measure the electrical conductivity of these polymers. The structural properties of these polymers were characterized by using FTIR and UV-Vis spectroscopic methods. Thermal degradation and stability of these polymers were explained by using thermogravimetric analysis （TGA） and conductivity measurements.

A mechanistic study of flame retardance of novel copolyester phosphorus containing linked pendant groups by TG/XPS/direct Py-MS

The flame retardant mechanism of the copolyester phosphorus containing linked pendant groups was investigated by thermogravimetric （TG）, X-ray photoelectron spectroscopy （XPS） and direct insertion probe pyrolysis mass spectrometry （DP-MS） technique. TG results show that the incorporation of phosphorus containing unit linked pendant groups can destabilize the copolyester due to the cleavage of P-CH2 bond, and phosphorus containing units cannot promote the char-formation of the copolyester during the thermal degradation of the copolyester. XPS spectra indicate that with the increase of the temperature, the P-CH2 bonds of the copolyester break down gradually, the concentration of phosphorus in the condensed phase products decrease gradually and the chemical state of phosphorus does not change in the temperature of 250-380 ℃. Direct pyrolysis MS suggests that the P-CH2 bonds cleavage occurs at pendant groups and species containing phosphorus can volatilize into the gas phase. A flame retardant mechanism is proposed for the gas phase mode of action of the halogen-free copolyester phosphorus containing linked pendant groups.