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.

Kinetic Parameters of Thermal Degradation of Polymers

The derivative expressions between activation energy (E) and the temperature at the maximum mass loss rate(Tmax) and between activation energy (E) and exponent (N) were deduced in the light of Arrhenius theory. It was found that the increase of activation energy results in the decrease of exponent and the increase of Tmax. The kinetic parameters were involved in the analysis of the thermal degradation of several polymers. The degradation kinetics of these polymers well complied with the prediction of the derivative expressions for the polymer degradation with single mechanism dominated.

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 and Decomposition Kinetics of Freeze Dried Cow and Camel Milk as well as Their Constituents

A study was conducted to evaluate thermal properties and degradation kinetic parameters of FD cow milk and camel milk powder. FT-IR was used to confirm the fat removal from the whole milk powder. Differential Scanning Calorimetry （DSC） was used to study the thermal transitions. DSC thermograms of WMP showed a two-step endotherm, the former at lower temperatures （cow milk 16-35 ℃, camel milk 25-60 ℃） and the later at higher temperatures （cow milk 75-125 ℃, camel milk 90-160 ℃）. The main difference observed between cow and camel milk was peak maximum temperature for fat melting, AH and other decomposition temperatures. The enthalpy of fat melting was 2.314 J/g and 3.397 J/g for cow and camel milk respectively. Thermogravimetric Analysis （TGA）/derivative thermogravimetric analysis （DTG） also showed two steps degradation. The first step involves lactose degradation and second step corresponds to combined degradation of protein and fat. Hence logβ vs 1000/T was plotted separately for individual components to determine cumulative value of activation energy using Flynn-Wall-Osawa method.

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.

Comparison of Photochemical and Thermal Degradation of Poly （Lactic Acid） Doped by Nanosilver

A comparison of thermal and photochemical degradation of poly （lactic acid） film materials （10/am） containing nanosilver are studied by FTlR （Fourier transform infrared） spectroscopy and DSC （differential scanning calorimetry）. Rates of thermal and photochemical degradation are determined by measuring the relative changes of absorbance （A/Ao） of selected bands in PLA （polylactic acid） spectra. Comparison of the effect of both degradation on PLA structure showed that nanosilver act as a stabilizer for photodegradation at 254 nm. As oppose, thermal degradation at 80 ~C indicate, that nanosilver accelerates PLA degradation at the temperature. Glass transition and crystallization/melting processes occurring in PLA and PLA/Ag nanocomposites during both degradation processes were also compared.

De-polymerization of Waste Polymers to Produce Hydrocarbon Fuel Utilizing Thermal Degradation

Waste plastics are one of the biggest environmental concerns the world faces today. Waste plastics exposure to the environment is very hazardous. Over time waste plastics photo-degrade and become very tiny dust particles. These dust particles contain very harmful compounds including benzene, sulfur, carbon and many others. According to studies, waste plastic pollutions are one of the biggest reasons for the depletion of the ozone layer and contributor of global warming. Many scientists have been trying to figure out how to utilize these waste plastics and convert them into useful energy sources. It is possible to convert waste plastics into energy because they are made from petroleum. Scientists have succeeded in developing many methods including pyrolysis, catalytic cracking, thermal degrading and others. The purpose of this experiment is to convert these environmentally harmful waste materials into useful energy source using simple and viable methods. A particular thermal degradation process was successful in extracting fuel from waste plastics at 370-420 ~C. In this paper we will discuss our performed experiment and provide detailed analysis of the produced fuel. Thorough instrumental analysis of the produced fuel showed very considerable results including high energy contents, low levels of harmful emissions and compatibility with various types of existing appliances.

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.

Thermal Oxidative Degradation and Ageing Performance of Silicone Rubber Filled with Attapulgite

The natural attapulgite(NAPT)was disaggregated by high-pressure homogenization technology combined with extrusion process to prepare the attapulgite with disaggregated rod crystal bundles(DAPT)and large specific surface area of 133.7 m^(2)/g.NAPT and DAPT were incorporated into the silicone rubber to obtain the composite NAPTSR and DAPT-SR by mechanical blending method,respectively.After thermal oxidative ageing at 300℃ for 0.5 h,temperature for the 5%weight loss increased greatly from 385℃ of the neat silicone rubber to 396-399℃ with addition of NAPT and DAPT.NAPT and DAPT enhanced the interaction between the filler nanoparticles and rubber matrix thus inhibited the nanoparticle agglomeration.The conservation rate of the side methyl group in NAPT-SR and DAPT-SR was greatly improved after ageing.Therefore,the thermal oxidative degradation and ageing performance of the silicone rubber composites was significantly reinforced.Moreover,DAPT could greatly restrain the growth of nanoparticles after ageing.Therefore,DAPT-SR showed the better retention of tensile strength(40.6%),elongation at break(34.9%)and tear strength(30.1%)compared with the corresponding mechanical properties of the neat silicone rubber(10.6%,7.4%,and 5.0%)after ageing.