Thermogravimetric Analysis FTIR Research Articles

Co-combustion characteristics and kinetics of sludge/coal blends in 21%–50% oxygen-enriched O2/CO2 atmospheres

This research investigated the thermogravimetric analysis (TGA) and combustion kinetics of sewage sludge and Australian sub-bituminous coal and their blends with different mixing ratios (sludge/coal = 100/0, 80/20, 50/50, 20/80, 0/100 by weight) under air atmosphere (O2/N2 = 21/79 by volume), oxy-fuel combustion (O2/CO2 = 21/79, 25/75, 35/65, and 50/50 by volume), and pyrolysis (pure N2 atmospheres). The gaseous products that evolved from the TGA experiments were also analyzed using a Fourier transform infrared (FTIR) spectrometer under pyrolysis conditions. Results showed that the mixed fuel with higher coal blending ratio had higher ignition temperature, lower burnout temperature and larger combustion characteristic index. Furthermore, TGA–FTIR experiments of the 20 % sludge + 80 % coal blended fuel under nitrogen atmospheres showed more gasification components in pure coal than in sludge. The combustion kinetics analytical results via the Flynn–Wall–Ozawa method indicated that the larger the conversion degree, the smaller the obtained activation energy value. Under the oxy-fuel combustion conditions, when the oxygen concentration increased from 21 % to 50 % for the 20 % sludge + 80 % coal blended fuel, the ignition and burnout temperatures decreased, and the combustion characteristic index increased nearly three times. Oxygen enrichment can clearly improve combustion characteristics and flammability.

A novel effective halogen-free biomass-based chitosan derived flame retardant through microencapsulation technology for improved flame retardancy, thermal stability of polyurethane

In this study, chitosan (CS) from fish waste was used to prepare bio-based environmentally friendly flame retardants. The hydroxyl group (-OH) of CS and the ammonium group (NH4+) of ammonium polyphosphate (APP) formed CS-APP, which was to serve as the core material. Melamine–formaldehyde (MF) resin was synthesized as the shell material through microencapsulation technology with CS-APP to prepare the novel core-shell structured flame retardant, which was subsequently introduced into polyurethane (PU) to prepare the composites. This study employed thermogravimetric analysis (TGA), the limiting oxygen index (LOI), UL-94, cone calorimetry tests (CCT), thermogravimetric analysis-FTIR (TGA-FTIR), SEM, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, smoke concentration test and tensile test to characterize the structure, thermal properties, flame retardancy, char analysis and mechanical properties of the composites. The TGA results revealed that after the addition of flame retardant, the char yield increased from 0.5 wt% (pristine PU) to 12.0 wt% (the composite), and the thermal stability of the pristine PU was improved. Furthermore, the LOI increased from 18.2 % to 28.4 %, and the UL-94 level increased from fail to V-0 for the composites. These results revealed that adding MF(CS-APP) to pristine PU resulted in high flame-retarding performance of the composites.

A High-Phosphorus-Content Polyphosphonate with Combined Phosphorus Structures for Flame Retardant PET

A high-phosphorus-content polyphosphonate (PBDA), containing two phosphorus-based structures: phosphaphenanthrene (DOPO) and phenyl phosphonate groups, was synthesized and used in flame retardant polyethylene terephthalate (PET). Good self-extinguishing property (high UL 94 grade and LOI value), superior flame retardancy (lower heat/smoke release), and high quality retention (high carbon residue) were endowed to PET by PBDA. When 10 wt% PDBA was added, the peak heat release rate (pHRR), total heat release (THR), and total smoke rate (TSR) of PDBA/PET were found to be significantly reduced by 80%, 60.5%, and 21%, respectively, compared to the pure PET, and the LOI value jumped from 20.5% for pure PET to 28.7% with a UL-94 V-0 rating. The flame-retardant mode of action in PET was verified by thermogravimetric analysis-Fourier transform infrared (TGA-FTIR), pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), real-time FTIR, and scanning electron microscopy (SEM). Phosphaphenanthrene and phosphonate moieties in PDBA decomposed in sequence during heating, continuously releasing and keeping high-content PO· and PO2· radicals with a quenching effect and simultaneously promoting the formation of viscous crosslinked char layers causing a high barrier effect. PDBA mainly acted in the gas phase but the condensed-phase flame retardant function was also considerable.

Durable flame retardant and dip-resistant coating of polyester fabrics by plasma surface treatment and UV-curing

Polyester fabric is ubiquitously applied for clothing, furniture and transportation, whereas its flammability with severe dripping often causes secondary hazards. Herein, it is highly imperative to impart excellent flame retardant to polyester fabric. In this work, a coating for polyester fabrics was prepared through a continuous dipping and ultraviolet (UV) curing process, which exhibited high-efficiency flame-retardant, anti-dripping and washing resistance. Firstly, the surface of polyester fabric was pretreated with plasma for providing more grafting sites of polyester fabric. Then, the flame retardant 6-((((2-(acryloyloxy) ethoxy) (oxo)(phenyl)phosphonio) oxy) methyl) dibenzo[c,e][1,2]oxaphosphinine 6-oxide (DPEA) and Tri(acryloyloxyethyl) phosphate (TAEP) were successfully synthesized and applied to the coating by UV-curing. In vertical burn test, the damage length of polyester with DPEA and TAEP (PET-D3/T4.5) was reduced from 300 mm of pristine PET to 100 mm with no dripping. In the Thermogravimetric Analysis (TGA) test, the char residue of PET-D3/T4.5 in nitrogen increased to 26.7 % compared with 9.7 % of pristine polyester. More specifically, the Peak Heat Release Rate (PHRR) and Total Heat Rate (THR) of PET-D3/T4.5 decreased 43.3 % and 22.2 % in the Micro-scale Combustion Calorimetry (MCC) test, which reflected excellent thermal stability and flame retardant properties. In addition, the Limiting Oxygen Index (LOI) of PET-D3/T4.5 only dripped from 24 % to 23.5 % after ten standard laundering cycles, indicating prominent water resistance. Remarkably, Thermogravimetric Analysis-Fourier transform infrared (TG-IR), Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS) have been performed for investigating the mechanism of flame retardant. Thus, a strategy with convenience and economics is proposed, which is of gargantuan significance to the improvement of coating durability through plasma surface treatment and UV-curing.

Dynamic Mechanical and Chemorheology Analysis for the Blended Epoxy System with Polyurethane Modified Resin

As the important matrix material, epoxy resin has been widely used in the composites for various fields. On account of the poor toughness of epoxy resin limiting their suitability for advanced applications, considerable interests have been conducted to modify the epoxy resin to meet the engineering requirements. In this study, the bio-based polyurethane (PU) modified resin was adopted to modify the pure bisphenol-A epoxy by blending method with various proportions. Aiming to illuminate the curing behavior, mechanical and thermal properties, the blended epoxy systems were characterized by viscosity-time analysis, dynamic mechanical analysis (DMA) at different frequencies and temperatures, mechanical tensile test, thermogravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. The results indicated that the introduction of PU modified epoxy was found to significantly inhibit the viscosity growth rates especially when the content of PU modified epoxy resin is higher than 60%. Notwithstanding the dynamic modulus and Tg reduced with the increment of PU modified epoxy, remarkable increment on the elongation at break was found and the flexibility was greatly promoted with the introduction of PU modified epoxy. The proportion of PU modified epoxy in the blends should be put balance considerations to obtain optimal mechanical properties. TGA results and FTIR spectrum demonstrated that the addition of PU modified epoxy did not change the thermal decomposition mechanism and chemical reaction mechanism, but the addition of PU modified epoxy inhibits the curing reaction of epoxy resin by measured and calculated the damping temperature domain ΔT from 35.7°C to 48.9°C.

Highly efficient flame‐retardant and transparent epoxy resin

AbstractIn this study, a high effective phosphorus‐containing flame retardant (DOP‐DDM) was synthesized using phenylphosphonic dichloride, p‐hydroxybenzaldehyde, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenan‐ threne‐10‐oxide (DOPO) and 4,4′‐diaminodiphenyl methane (DDM) as raw materials. The chemical structure of DOP‐DDM was confirmed by Fourier transform infrared spectroscopy (FT‐IR), 1H nuclear magnetic resonance (1H NMR) and 31P nuclear magnetic resonance (31P NMR). The epoxy resin (EP) material with 4.7 wt% DOP‐DDM (EP‐4.7) can reach V‐0 degree in UL 94 test and has LOI value as high as 33.5%. If neat EP (EP‐0) material is used as a control, even if the loading of DOP‐DDM in the flame‐retarded EP material reached 7.6 wt%, the transmittance can reach 96.8% of EP‐0. From cone combustion (CC) test, the peak of heat release rate (pHRR), total heat release (THR) and total smoke release (TSR) values of EP‐4.7 material were decreased in comparison to those of EP‐0. Compared with EP‐0 material, differential scanning calorimetry (DSC) and dynamic thermo mechanical (DMA) results showed that the glass transition temperature of EP‐4.7 material slightly increased, and the storage modulus (E′) and loss modulus (E′′) increased 65.7% and 47.3%, respectively. The morphology and graphitization degree of residual char after CC test were measured by SEM and Raman spectroscopy, respectively. Concurrently, the gas components of EP‐4.7 material were well analyzed by thermogravimetric analysis FTIR. All these results demonstrated that the DOP‐DDM played a role in gas‐phase and condensed‐phase.

A phosphorous-based bi-functional flame retardant for rigid polyurethane foam

A bi-functional flame retardant for rigid polyurethane foam (RPUF), denoted as PDEP, was designed and synthesized. PDEP contained two phosphorus-based moieties: phosphophenanthrene (DOPO) and a phosphate (DEP), which may exert different functions at different temperatures. DEP and DOPO moieties in sequence decomposed with increasing temperature, continuously releasing and holding high-content phosphorus-oxygen free radicals with quenching effect and producing viscous residues to bond and integrate other char species leading to high barrier effect. The flame retardant modes of action of PDEP was confirmed by experiments using thermogravimetric analysis-Fourier transform infrared (TGA-FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), FTIR and SEM. PDEP was incorporated into RPUF system via co-cured with other polyol components. Using expandable graphite (EG) as additive-type flame retardant, an enhanced flame retardancy in RPUF was observed.

Fire-extinguishing characteristics and flame retardant mechanism of polylactide foams: Influence of tricresyl phosphate combined with natural flame retardant

Extrusion and compression molding techniques were used to process polylactide (PLA) foams using a mixture blowing agent. Tricresyl phosphate (TCP) and natural flame retardants (NFR) from pumpkin (PK) and soybean (SB) were added to rigid PLA foams and the flame retardant properties of the foams were investigated. The effects of TCP content, types and amounts of NFR, and the ratio of TCP to NFR were determined on the physical, thermal and morphological characteristics of the foams. The fire-extinguishing characteristics and flame retardant mechanism of PLA foams with TCP were studied by thermogravimetric analysis-Fourier transform infrared (TGA-FTIR), scanning electron microscope (SEM), limiting oxygen index (LOI), and UL-94 techniques. The results revealed the efficiency of TCP as a flame retardant for PLA foams. Increased TCP levels contributed to a significant enhancement in fire-extinguishing characteristics. Phosphoric acid from thermal decomposition of TCP was a key factor in the proposed mechanism of flame retardation. Flame inhibition and retarded ignition of the PLA foams were achieved at all compositions of TCP and NFR. Due to the presence of compounds such as cellulose, phosphate, and silica, both PK and SB could be used as effective NFRs for PLA foams. All these characteristics promise extended applications for PLA foam in bio, circular, and green economies.

Thermal degradation and pyrolysis study of brominated butyl rubber‐based damping material

This paper deals with the thermal stability and decomposition behavior of brominated butyl rubber‐based damping material (BRP). The raw materials, butyl rubber matrix (IIR) and brominated phenolic resin (PF), were also investigated as control. IIR shows one decomposition stage, while PF shows four weight loss stages. Flynn‐Wall‐Ozawa calculation indicates that BRP has thermal stability between IIR and PF. Thermogravimetric analysis–Fourier transform infrared (TGA‐FTIR) and pyrolysis–gas chromatography/mass spectrometry (GC/MS) were used to investigate the volatile products under nitrogen atmosphere. As expected, BRP shows combined thermal decomposition behavior of both IIR and PF. The degradation mechanism of BRP was proposed, which is not significantly influenced by the incorporation of PF. The application stability of BRP is worth to be noticed since the post‐cure effect, that is, the free radicals remained from vulcanization would cause additional cross‐linking when stored at 80°C to 120°C.

Fire‐safe agent integrated with oyster shell and melamine polyphosphate for thermoplastic polyurethane

At present, thermoplastic polyurethane (TPU) is widely used, but there are still many defects in fire safety, such as burning with heavy smoke and dripping. In this article, OS@MP was synthesized by modifying oyster shell (OS) powder with melamine polyphosphate (MP) and then served as fire‐safe agent for TPU. The fire performance of TPU composites were investigated using microscale combustion colorimeter (MCC), cone calorimeter test (CCT), smoke density test (SDT), and thermogravimetric analysis/Fourier transform infrared (TG‐FTIR) spectrum analysis. The MCC and CCT results revealed that OS@MP could reduce the fire hazards of TPU composites. The peak heat release rate (pHRR) of the sample with 10.0 wt% OS@MP decreased to 170.86 kW/m2 from 1772.37 kW/m2 for pure TPU. And, the SDT results showed that OS@MP could significantly reduce the smoke production of TPU composites. The TG‐FTIR also confirmed that the noncombustible gases (including CO2, ammonia, and water vapor) produced by OS@MP have played a reinforcing role in TPU composites as well as a char formed on the surface of composites, which could act as a barrier to prevent the heat and air, reinforce the fire safety of TPU.

An efficient bio-based plasticizer for poly (vinyl chloride) from waste cooking oil and citric acid: Synthesis and evaluation in PVC films

Abstract In this study, a bio-based efficient plasticizer (acetylated-fatty acid methyl ester-citric acid ester, AC-FAME-CAE) for poly(vinyl chloride) (PVC) was synthesized by using waste cooking oil and citric acid as raw materials in very user-friendly approaches. Its structure was characterized by FTIR and 1H NMR. The epoxidation and ring opening reaction were investigated primarily using a GC-MS analysis. Tetrabutylammonium chloride (TBAC) was used as the catalyst of ring opening, and it dramatically accelerated the reaction process of carboxylic acid and epoxy bonds. The glass transition temperature (Tg) decreased to 26.32 °C, as determined by dynamic mechanical analysis (DMA), when 50 phr of AC-FAME-CAE was added. The mechanical and migration stabilities of PVC films with AC-FAME-CAE plasticizer were investigated using volatility and extraction tests as well as thermogravimetric analysis (TGA) and TGA–FTIR analysis. The mechanical properties of PVC films with AC-FAME-CAE plasticizer were obviously better than those of PVC films plasticized by ESO (epoxidized soybean oil) and as good as those of PVC films plasticized by DOP (dioctyl phthalate, 99%). The structure−property analysis of the AC-FAME-CAE as a PVC plasticizer confirmed that a higher molecular weight and more ester bonds could reduce the volatility and extraction loss and improve the compatibility and stability of PVC films.

Experimental Study of High Temperature Combustion for Enhanced Shale Gas Recovery

As an alternative to hydraulic fracture for shale gas recovery, high temperature treatments such as combustion and pyrolysis are being used to remove organic matters and decompose minerals from shale to increase shale rock permeability for gas recovery. In this study, shales obtained from Shang Gu Basin, Shangxi, China, were burned in an air environment at a temperature of 800 °C for 45 min to oxidize the organic matters to improve shale physical properties. Energy dispersive spectrometer (EDS), scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) tests were conducted to identify minerals and functional group inside the shale samples. The shale samples were also tested in a thermogravimetric analysis FTIR (TGA-FTIR) experiment to study the combustion characteristics and gas emission. The TGA curve shows that two weight loss peaks existed in the combustion process. The first peak occurring between 400 and 500 °C was found to be caused by oxidization of organic matter, and the second pe...

Preparation and characterization of novel thermal-stable vinylidene chloride–methyl acrylate–glycidyl methacrylate copolymer

ABSTRACTA novel copolymer was synthesized by vinylidene chloride (VDC)/methyl acrylate (MA)/glycidyl methacrylate (GMA). The Fourier transform infrared (FTIR) and 1H-nuclear magnetic resonance analyses indicated that the copolymer of VDC/MA/GMA (PVMG) was synthesized successfully. The influences of GMA on the molecular weight, melting point, and thermal stability of copolymer were investigated by gel permeation chromatograph, differential scanning calorimeter, thermogravimetric analysis–FTIR, respectively. The copolymerization eliminated the phenomenon of “double melting peaks” for poly(vinylidene chloride), and the melting point was reduced to 165°C. The GMA also enhanced the thermal stability of copolymer, which was proved by the increased decomposition temperature of copolymer. The existence of GMA caused the cross-linking of the copolymer, which contributed to the improvement of barrier performance of PVMG.

Effect of copper sulfate pentahydrate on the structure and properties of poly(vinyl alcohol)/graphene oxide composite films

ABSTRACTPoly(vinyl alcohol) (PVA)/graphene oxide (GO)/copper sulfate pentahydrate (CuSO4·5H2O) composite films were prepared by the solution casting method, and the effect of CuSO4·5H2O on the structure and properties of the PVA/GO composites was investigated. Fourier transform infrared (FTIR) analysis proved the crosslinking interaction between CuSO4·5H2O and the OH group of PVA. The crystallinity of the composite films increased first and then decreased. For the composite films, the tensile strength, Young's modulus, and yield stress values improved with increasing CuSO4·5H2O, whereas the elongation at break decreased compared with that of the neat PVA/GO composite film. The thermogravimetric analysis (TGA) and derivative thermogravimetry (DTG) patterns of the PVA/GO/CuSO4·5H2O composite films showed that the thermal stability decreased; this was consistent with the TGA–FTIR analysis. A remarkable improvement in the oxygen‐barrier properties was achieved. The oxygen permeability coefficient was reduced by 60% compared to that of the neat PVA/GO composite film. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44135.

Effect of N,N′-diallyl-phenylphosphoricdiamide on ease of ignition, thermal decomposition behavior and mechanical properties of poly (lactic acid)

In this study, a novel poly (lactic acid) (PLA) composite with low flammability based on N,N′-diallyl-phenylphosphoricdiamide (PO-AA) and PLA was developed via traditional melt compounding. PO-AA exhibited high efficiency on reducing the ease of ignition of PLA without scarifying the mechanical and thermal properties of PLA. Only 1 wt% of PO-AA containing PLA composite passed V-0 rating with 3.2 mm (thickness of the specimen), while 2 wt% of PO-AA addition made PLA passed V-0 rating with thickness of 1.6 mm. The improvement also performed on increased limiting oxygen index (LOI) of PLA composites. The melting and crystallization behavior of PLA and PLA/PO-AA composites were studied by differential scanning calorimetry (DSC). Meanwhile, thermal stability and thermal decomposition kinetics were studied by means of thermogravimetric analysis (TGA). Furthermore, the evolved gaseous products of PLA and PLA/PO-AA (1 wt%) were characterized by TGA coupled with Fourier transform infrared spectroscopy (TGA–FTIR) test. Finally, the impact of PO-AA on viscoelastic and tensile properties was investigated by dynamic oscillatory shear measurement and tensile test.

Unraveling the mechanism of thermal and thermo-oxidative degradation of tannic acid

The thermal and thermo-oxidative degradation of hydrolysable tannin, i.e. tannic acid is reported. The study on thermal and thermo-oxidative degradation mechanism of tannic acid was carried out by using several advanced thermal characterization techniques such as Thermogravimetric analysis (TGA) coupled with Fourier-Transform Infrared (FTIR) Spectroscopy (TGA–FTIR), pyrolysis–gas chromatography–mass spectroscopy (Py–GC–MS) and Attenuated Total Reflectance (ATR)–FTIR. The condensed phase and gaseous phase degradation studies were combined to deduce a probable degradation pathway for tannic acid molecule at high temperature under nitrogen and air atmosphere.

New Flexible and Transparent Solution-Based Germanium-Sulfide Polymeric Materials

New flexible and transparent materials based on germanium sulfide were obtained using GeCl4 and 1,3-propanedithiol as precursors. These materials have transparency in the ultraviolet-visible (UV-Vis) spectral region (about 70%), thermal stability up to 200 °C and glass transition located at temperatures below 0 °C (-37 °C, -56 °C and -59 °C) as shown by differential scanning calorimetry (DSC) curves. Scanning electron microscopy (SEM) images showed that the polymer is homogeneous and presents formation of crystals in some regions of the surface. These polymers also exhibit Ge-S bonds in its structure, as can be observed through Fourier transform infrared (FTIR) (bands at 399, 401, 432 and 470 cm-1) and Raman (peaks at 361 and 430 cm-1) spectroscopies, and the diffraction patterns X-rays, which suggest the formation of a mixture of GeS2 and GeO2phases (also confirmed through energy-dispersive X-ray analysis). The coupled thermogravimetric analysis / Fourier transform infrared (TG/FTIR) technique was used to investigate the degradation of the sample. Taken together, the results of these characterizations suggest optical applications, and usability at low temperatures.

Thermal degradation behavior and gas phase flame‐retardant mechanism of polylactide/PCPP blends

ABSTRACTThe thermal degradation behavior of the blend based on polylactide (PLA) and poly(1,2‐propanediol 2‐carboxyethyl phenyl phosphinate) (PCPP) was investigated by the thermogravimetric analysis (TGA). Thermal degradation activation energies (Ea) of neat PLA and PLA/15% PCPP blend were calculated via the Flynn–Wall–Ozawa method. The Ea of the blends increased with the addition of PCPP increasing when the conversion was higher than 10%. In addition, the appropriate conversion models for the thermal degradation process of PLA and PLA/15% PCPP were studied via the Criado method. At the same time, the main gaseous decomposition products of PLA and its blend were identified by TGA/infrared spectrometry (TGA–FTIR) analysis. And it revealed that the PCPP improved the flame‐retardant property of PLA via altering the release of the flammable gas and nonflammable gas. Moreover, the PCPP improved the flame‐retardant property of PLA by inhibiting exothermic oxidation reactions in the combustion, which was further proved by pyrolysis–gas chromatography–mass spectrometry analysis. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40480.

Fire Self-Extinguishing Cotton Fabric: Development of Piperazine Derivatives Containing Phosphorous-Sulfur-Nitrogen and Their Flame Retardant and Thermal Behaviors

Recent studies have shown interest in flame retardants containing phosphorus, nitrogen and sulfur a combination small molecule with a promising new approach in preparing an important class of flame retardant materials. Tetraethyl piperazine-1,4-diyldiphosphonate (TEPP) and O,O,O’,O’- tetramethyl piperazine-1,4-diyldiphosphonothioate (TMPT), based on Piperazine derivatives, were prepared successfully and their structures were proved by means of 1H, 13C and 31P NMR. Cotton twill fabric was treated with both compounds to provide different add-on levels. Thermogravimetric Analysis (TGA), microscale combustion calorimeter (MCC), vertical and 45° flame test and limiting oxygen index (LOI) were performed on the treated cotton fabrics and showed promising results. When the treated twill fabrics (5 wt% - 7 wt% add-ons) were tested using the vertical flammability test (ASTMD6413-11), we observed that the ignited fabrics self extinguished and left behind a streak of char. Limiting oxygen index (LOI, ASTM 2863-09) was utilized to determine the effectiveness of the flame retardant on the treated fabrics. LOI values increased from 18 vol% oxygen in nitrogen for untreated twill fabric to a maximum of 30 vol% for the highest add-on of twill. Furthermore, Scanning Electron Microscope (SEM), Attenuated Total Reflection-Infrared (ATR-IR), and Thermogravimetric Analysis-Fourier Transform Infrared (TGA-FTIR) spectroscopy were employed to characterize the chemical structure on the treated fabrics, as well as, the surface morphology of char areas of treated and untreated fabrics. Additionally, analysis of the release gas products by TGA-FTIR shows some distinctive detail in the degradation of the treated fabrics during the burning process.

The pyrolysis behaviors of ternary copolyimide derived from aromatic dianhydride and aromatic diisocyanates

ABSTRACTA polyimide (PI) based on benzophenone‐3,3′,4,4′‐tetracarboxylic acid dianhydride, toluene diisocyanate (TDI), and 4,4′‐methylenebis (phenyl isocyanate) (MDI) has been synthesized via a one‐step polycondensation procedure. The resulting PI possessed excellent thermal stability with the glass transition temperature (Tg) 316°C, the 5% weight loss temperature (T5%) in air and nitrogen 440.4°C and 448.0°C, respectively. The pyrolysis behaviors were investigated with dynamic thermogravimetric analysis (TGA), TGA coupled with Fourier transform infrared spectrometry (TGA–FTIR) and TGA coupled with mass spectrometry (TGA–MS) under air atmosphere. The results of TGA–FTIR and TGA–MS indicated that the main decomposition products were carbon dioxide (CO2), carbonic oxide (CO), water (H2O), ammonia (NH3), nitric oxide (NO), hydrogen cyanide (HCN), benzene (C6H6), and compounds containing NH2, CN, NCO or phenyl groups. The activation energy (Ea) of the solid‐state process was estimated using Ozawa–Flynn–Wall (OFW) method which resulted to be 143.8 and 87.8 kJ/mol for the first and second stage. The pre‐exponential factor (A) and empirical order of decomposition (n) were determined by Friedman method. The activation energies of different mechanism models were calculated from Coats–Redfern method. Compared with the activation energy values obtained from the OFW method, the actual reaction followed a random nucleation mechanism with the integral form g(α) = −ln(1 − α). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40163.