Thermal Oxidative Degradation Research Articles

Superior flame retardancy, antidripping, and thermomechanical properties of polyamide nanocomposites with graphene‐based hybrid flame retardant

AbstractGraphene is considered one of the most prominent halogen‐free multifunctional flame retardants for polymers, and the resultant nanocomposites also display a good balance of properties. However, the biggest concern nowadays is thermal oxidative degradation, which mainly affects the flame retardant (FR) efficiency of graphene. To improve the flame retardancy and thermal oxidative degradation efficiency, graphene was functionalized with a combination of polycyclotriphosphazes and siloxanes via a sol–gel surface modification method, yielding a graphene‐based hybrid FR (PSGO) containing multiple elements (P, N, S, and Si). The PSGO‐containing PA6 composite exhibited significant improvements in the water resistance, thermal, mechanical, and FR properties, as compared with those of 3‐isocyanatopropyltriethoxysilane functionalized graphene oxide (ITS‐GO) and siloxane‐modified polycyclotriphosphazenes (m‐PZS) individually. The peak heat release rate and total heat release values of the PA6 composites with 10 wt% PSGO decreased by 45.7% and 36.9%, respectively, compared to those of pristine PA6. Moreover, it was confirmed that 10 wt% PSGO in the PA6 composite resulting in a V–0 rating in the UL‐94 tests, even after the water immersion test. These attractive properties are attributed to the resistance to thermal‐oxidative degradation of PSGO and the improved interfacial interactions with the polymer matrix. Therefore, this PSGO can be used as a multifunctional modifier to improve the water resistance, thermal, mechanical, and FR properties of polymers.

Study of the toxicity of combustion products of polymer materials using chromatomass spectrometry

Introduction. Carrying out studies of the toxicity of combustion products (HCL50) of polymer materials: epoxy glue grade EK-5T and compound ELPLAST-180 ID according to GOST with the additional use of gas chromatography with mass selective detection. Objective. Experimental study of the toxicity of combustion products (HCL50) of polymer materials in various modes of thermal oxidative degradation: epoxy glue grade EK-5T and compound ELPLAST-180 ID, as well as a survey mass spectrometric analysis of products of thermal oxidative degradation. Material and methods. The studies were carried out in accordance with GOST 12.1.044-89. Equipment: “Toxicity” unit, “Infracar M2.01” gas analyzer, Focus GC chromato-mass-spectrometric instrumental complex with DSQ II mass spectrometer (Thermo Scientific, USA), Nova Medical Stat Profile automatic analyzer of blood gases, electrolytes and oximetry Model CCX (USA). Blood sampling was carried out in capillaries “Stat Profile Critical Care Express Capillary Tube 230 µL with Na Heparin” LOT 107669, CO2 chamber. Results. In the course of studying the products of outgassing of polymer materials using an exposure chamber and a gas chromatomass spectrometer, a significant increase in toxicity (4.8 times) of a mixture of chemicals released from epoxy glue EK-5T during the transition from thermal-oxidative decomposition (smoldering) to flame combustion was established. The toxicity index of the combustion products of the ELPLAST-180 ID compound under the same conditions increases by 1.8 times. A linear dependence of the percentage of lethality of laboratory animals on the integral indicator of the toxicity of combustion products has been established. Limitations. Studies of the toxicity of combustion products were carried out on non-metallic materials: epoxy glue EK-5T, compound ELPLAST-180 ID. These materials are planned to be used in hermetically sealed objects of the Navy. Conclusion. The expediency of using gas chromatography-mass spectrometry for assessing the combined effect of combustion products is shown.

Recent advances on the stability of dietary polyphenols

Recent advances on the stability of dietary polyphenols

Effect of torrefaction on thermal oxidative degradation kinetics of lignite using multi-distributed activation energy model

Torrefaction treatment is a promising method for lignite upgrading. However, its effect on the combustion characteristics has not been fully evaluated. In this study, the combustion characteristics of lignite and its upgrading samples by torrefaction were studied via non-isothermal thermogravimetric analysis. Results show that increasing the torrefication temperature decreases the volatile content while increasing the fixed-carbon in the fuels. The mole ratios of both H/C and O/C in the samples decreases as the torrefaction temperature increases. Torrefaction treatment significantly improves the combustion performance of lignite with a higher reactivity index S, and the optimum torrefaction temperature was determined to be 200 °C. The upgrading lignite by torrefaction at 200 °C has the lowest temperatures of Tf and Tp as well as the maximum corresponding DTG value. Furthermore, the results of three-parallel-DAEM model analysis results show that the activation energies corresponding to the three peaks are 176.1 kJ/mol, 186.5 kJ/mol and 221.7 kJ/mol, respectively, and that increasing torrefaction temperature had no significant effects on activation energies. With the torrefaction temperature increasing, the first standard deviation decreased while the third standard deviation increased.

Thermal degradation and pyrolysis behavior of wholly aromatic phosphorus-containing thermotropic liquid crystal copolyesters

In this study, the thermal degradation and pyrolysis behavior of three wholly aromatic phosphorus-containing thermotropic liquid crystal copolyesters (TLCP) were investigated. The non-isothermal degradation kinetic parameters were determined using the Kissinger and Friedman method. The copolyesters exhibited two degradation stages in air but only one in N2, and better thermal stability was observed for those containing more 10-(2,5-Dihydroxypheny)-10 h-9-oxa-10-phospha-phe-nanthrene-10-oxide (DOPO-HQ) units, which could be reflected by the thermogravimetric analyzer (TGA) data and E values. The TGA coupled with Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis-gas chromatograph-mass spectrometer (Py-GC-MS) results showed that DOPO-HQ decomposed first in the early stage of degradation, generating gaseous pyrolysis products and forming phosphorus-containing char residue in the later stages of degradation. However, the copolyesters produced more CO2 and less organic volatiles during thermal oxidative degradation. The morphology and FTIR spectra of the char residue obtained after TGA experiments showed a continuous and dense structure due to the presence of phosphorus moieties. The microscale combustion calorimeter (MCC) and limiting oxygen index (LOI) results showed that the copolyesters have excellent flame retardant properties, and the LOI value increases monotonically with increasing of DOPO-HQ content, having a maximum value up to 73.8%, due to its excellent gas-phase and condensed-phase fire inhibition mechanisms. Overall, the resulted phosphorus-containing thermotropic liquid crystal copolyesters exhibited excellent thermal stability and flame retardancy, the thermal degradation and pyrolysis research would be a good guidance for its processing and application.

Assembling MXene with bio-phytic acid: Improving the fire safety and comprehensive properties of epoxy resin

Phytic acid (PA)-modified MXene (P-MXene) was prepared combination selective etching with assemble method, and was mixed with epoxy resin (EP) to investigated its flame retardancy, thermal conductivity, conductivity and mechanical properties. P-MXene exhibited two-dimensional single layer structure and had good char-forming property with 86.7% char residue at 800 °C. The cone calorimetry test results showed that P-MXene endowed EP with excellent flame retardancy. Compared with pure EP, the peak heat release rate, peak smoke release rate, peak CO generation rate, and peak CO2 generation rate of EP composites with 2 phr P-MXene decreased by 38.6%, 31.6%, 38.7% and 40.6%, respectively. The flame retardant mechanism was attributed to physical barrier, catalyzing carbonization effect, oxidative thermal degradation and physical barrier effect. Additionally, the conductivity and mechanical properties of EP composites were slightly reduced. This work provides a promising method to design multifunctional polymers.

Polyoxymethylene/Reduced Graphene Oxide-g-Melamine Nano-composites With Low Formaldehyde Emission: Intercalation Structure and Synergistic Thermal Oxidative Stabilization Effect

Formaldehyde emission produced by polymer degradation would cause serious environment pollution. Melamine (MA) as highly efficient formaldehyde scavenger has been widely applied in polyoxymethylene (POM) industry. However, the volatilization, migration and physical loss of MA during processing and application have become a serious problem for POM production. In this work, MA was first grafted onto graphene oxide (GO) surface through amidation reaction, and reduced graphene oxide-g-melamine (rGO-MA) hybrid was prepared by subsequent reduction. The POM/rGO-MA nano-composite was then manufactured via conventional melt processing. By incorporation of MA, hydrogen bonding was enhanced for composite, and POM molecules were intercalated into reduced graphene oxide (rGO) layers effectively with high intercalation ratio, while rGO was exfoliated and uniformly distributed in POM matrix. Compared with neat POM, the formaldehyde emission amount (FEA) of POM/rGO-MA decreased notably by 50.8%, and the thermal degradation temperature and degradation activation energy (Ea) were improved significantly. Meanwhile, the retention of mechanical property of POM/rGO-MA remained stable, while melt index increased much slowly during thermo-oxygen aging process. By grafting MA onto rGO surface, both the thermal migration resistance of MA and radical scavenging ability of GO were enhanced, while rGO-MA exhibited excellent synergistic removal effect of formaldehyde generated by POM degradation. Besides, the composite showed extraordinary oxygen barrier property, and thermal oxidation degradation of POM was delayed effectively.

Non-isothermal crystallization kinetics and rheological behaviors of PBT/PET blends: effects of PET property and nano-silica content

ABSTRACT PBT and PET are subjected to thermal-oxidative degradation and thermomechanical degradation during the process of melt blending, which affect the polymer structure and properties. The effect of feed properties of PET and the addition of modified nanoparticles on blends are a question worthy of discussion. This work describes the melting and thermal stability, the crystallization behavior and non-isothermal crystallization kinetic, the rheological behaviors and mechanical properties of several PBT/PET blends prepared by twin-screw melt extrusion. Results show that the molecular chain of the polyester blends obtained by stable extrusion are not significantly degraded, there is only one obvious melting peak and crystallization peak on the thermal analysis curves, and the melting point is lower than either of the two polyesters. An appropriate amount of SD can effectively reduce the crystallization rate of the PBT material and extend the crystallization time. The rheological behavior of PBT/PET blends is complicated than PET raw materials and SD, as well as the melt processing temperature and shear rate will all affect the rheological behavior of the blends. For example, at low shear rate, polyester blends with SD exhibit strong shear thinning behavior. In general, the SD content affects the rheological property of blends in a way similar to the law of influence on crystallization behavior. When SD content is 0.3 wt%, a polyester product with higher elongation at break than pure PBT can be obtained. This can provide a useful reference for preparing commercialized polyester blend products with good melt processability and elongation by simple blending.

Mechanistic study on oxidative degradation and deposition of exo-tetrahydrodicyclopentadiene

The advancement of propulsion systems accelerates the exploitation and application of various high-energy–density (HED) fuels, and yet severe oxidative-fouling hinders the adoption of such fuels in thermal-stressed conditions. In this work, we investigated the overall thermal-oxidative degradation and deposition process of a typical HED fuel, exo-tetrahydrodicyclopentadiene (exo-TCD), known as JP-10 (NHOC = 39.6 MJ/L), with the presence of oxygen. The oxidation mechanism of exo-TCD at relatively low temperatures is illustrated on the basis of experimental and computational results. For the first time, the chirality of oxidation products has been discussed, revealing the potential impact of radical configuration on the oxidation process of exo-TCD. Besides, an in-depth investigation on the deposition formation process was carried out by analyzing the structure and composition of polymeric macromolecules with the assistance of TG-IR-GC/MS technique. The oxidative deposition of exo-TCD is illustrated with a three-step mechanism of “oxidation”, “polymerization”, and “deposition”. The solubility of macromolecular species formed upon oxidation is decisive for the deposition propensity of fuels. This work aims to provide a theoretical and methodological basis for the future study on the oxidative stability of HED fuels.

Optimization of Melt-mixing Transesterifi cation of Polylactide by Polyethylene Glycol Employing Response Surface Methodology

A process for preparing polylactide-block-polyethylene glycol (PLA-b-PEG) copolymers has been developed and optimized by employing a transesterifi cation reaction in a melt-mixing process. The reaction was carried out in a counter-rotating mixer unit, using polyethylene glycol (PEG) and tetrabutyl titanate (TBT) catalyst. The effects of PEG weight percentage, catalyst contents, temperatures, and rotor speeds on chemical structures of the resulting PLA-b-PEG were examined, in terms of number average molecular weight (Mn), weight average molecular weight (Mw), in-chain PEG contents (wt.% PEG), and specifi c mechanical energy (SME) imparted by the mixer. The process parameters were optimized using a central composite rotatable design (CCRD) response surface methodology (RSM). The CCRD was designed with four variables at three levels of variations (-1, 0, -1), four replicates center point, and a redundancy factor (α) of 2.000. The responses (Mn, Mw, wt.% PEG, and SME) from 28 experimental trials were analyzed by a multiple linear regression fi tting, a second-order equation, and the RSM model. Mn and Mw of the products were determined by gel permeation chromatography (GPC). The in-chain PEG content was examined by nuclear magnetic resonance (1H-NMR) spectroscopy. The results show that the PEG weight percentage and the reaction temperature signifi cantly affect (P< 0.05) Mw and Mn of the products, which are drastically decreased with an increase in the PEG weight percentage and temperature. A quadratic interaction is observed between the PEG weight percentage and temperature, indicating that high reaction temperature leads to lower PEG conversions, due to undesirable competing thermal-oxidative degradations of PEG in the presence of the catalyst. Optimum operating conditions on the PEG weight percentage, catalyst contents, temperatures, and rotor speed for obtaining high Mw with high wt.% PEG was identifi ed. Although the optimal conditions are observed at the boundary level, the model serves as a platform for effective preparation of PLA-b- PEG copolymers with designed molecular weight and chemical structures. Further optimization of the model may be conducted by extending the range of independent factor levels. The resulting fl exible PLA-b-PEG copolymers, with tunable structures and properties, have high potential for use as singlecomponent degradable bioplastics with excellent mechanical properties, plasticizers, or toughening agent for enhancing PLA’s toughness.

Effect of lanthanum cerium methionine on the properties of natural rubber

Lanthanum cerium methionine was synthesized using the metathesis method and its molecular formula was confirmed as La0.35Ce0.65Cl3(C5H10NO2S)3·2H2O via Inductively Coupled Plasma Optical Emission Spectrometer, FTIR, and thermogravimetry-differential scanning calorimetry characterization methods. Lanthanum cerium methionine can significantly reduce the activation energy of the vulcanization reaction. The vulcanization kinetics model is used to fit the vulcanization curve of the rubber, and the obtained vulcanization activation energy of lanthanum cerium methionine for rubber is E1 = 76.89 KJ/mol, E2 = 102.36 KJ/mol and E3 = 126.00 KJ/mol. The above value is lower than pristine rubber. The Kissinger method and Flynn–Wall–Ozawa method were used to analyze the activation energy of thermal-oxidative degradation of vulcanized rubber. It was found that the rubber added with lanthanum cerium methionine exhibited higher thermal-oxidative degradation activation energy compared to that of pristine rubber; in addition, it was more difficult to age under the same environment. These results indicated that lanthanum cerium methionine can be not only used as a vulcanization accelerator, but also plays a role in resisting thermal and oxygen aging.

Evidence from Thermal Aging Indicating That the Synergistic Effect of Glyoxal and Sodium Sulfite Improved the Thermal Stability of Conformational Modified Xanthan Gum.

Xanthan gum is prone to thermal oxidative degradation, which limits its applications. However, conformational changes in xanthan gum and appropriate stabilizers may improve its thermal stability. Therefore, in this study, we aimed to establish a strategy to maintain the viscosity of xanthan gum during long-term storage at high temperatures. We modified the original strain used for xanthan gum production by genetic engineering and added stabilizers during the production process. The structure and thermal stability of the resulting xanthan gum samples were then determined. Pyruvyl deficiency, combined with the addition of sodium sulfite and glyoxal during the production process, was found to significantly improve the maintenance of viscosity. The apparent viscosity of the new xanthan gum solution remained above 100 mPa·s after being stored at 90 °C for 48 days. Fourier-transform infrared spectra and scanning electron microscopy images showed that pyruvate-free xanthan gum with added stabilizers had more extensive cross-linking than natural xanthan gum. In conclusion, these findings may contribute to the use of xanthan gum in applications that require high temperatures for a long period of time.

Investigation on the failure behavior and compressive performance of rigid polyurethane foam treated under aerobic/anaerobic high temperature random vibration

In this paper, the thermal vibration damage of rigid polyurethane foam (RPUF) under the action of oxygen, temperature and vibration was systematically studied by the combination of experiment and finite element analysis. The damage degree of RPUF was evaluated by their compressive mechanical properties and energy absorption properties. The results of Fourier infrared spectrum (FTIR) and nuclear magnetic resonance (13C NMR) showed that the thermal degradation of the carbamate group was the main chemical failure process of RPUF in the aerobic/anaerobic high temperature environment. Particularly, the thermal oxidative degradation of ether bonds occurred in an aerobic high temperature environment. It was also proved by the simulation results of Discrete Fourier Transform (DFT). Compression experiments showed that with the increase of temperature, the compressive mechanical properties and energy absorption properties of the RPUF gradually decrease until they reach the minimum value at 150 °C.These compressive performances of the thermal vibration group (treated in thermal vibration environment) were lower than the corresponding heat treatment group (treated in heat treatment environment). In the 50–300Hz, 550–800Hz and 1050–1300Hz, the failure degree of the low-frequency stage (50–300Hz) is also the highest among the thermal vibration group. At this time, the elastic modulus and compression yield strength of the aerobic 150 °C thermal vibration group were 14.47 MPa and 1.17 MPa, respectively, which were 19.6% and 9.3% lower than the anaerobic 150 °C thermal vibration group.

Kinetic Analysis of Pyrolysis and Thermo-Oxidative Decomposition of Tennis String Nylon Wastes.

Thermal degradation of nylon-6 tennis string nylon wastes in inert nitrogen and air atmospheres was investigated by means of multiple heating-rate thermogravimetric analyses. The results obtained under the heating rates of 5–20 K/min are compared in terms of degradation feature and specific temperature for two atmospheres. Using nonisothermal data, kinetic analysis was thoroughly conducted using various isoconversional model-free methods, including Starink, Madhusudanan–Krishnan–Ninan, Tang, Coats–Redfern, and Flynn–Wall–Ozawa methods. With these kinetic analysis methods, the activation energy over the entire degradation process was successfully calculated. By means of the model-fitting master-plots method, the first-order chemical reaction model was determined to be the most appropriate mechanism function for describing pyrolysis and oxidative thermal degradation of nylon-6 waste. Using kinetic parameters, satisfactory matching against experimental data resulted using the Coats–Redfern method for both cases. Furthermore, thermodynamic parameters such as changes in entropy, enthalpy, and Gibbs free energy during thermal degradation processes were evaluated.

Morphology and Tensile Properties as a Function of Welding Current in Thermoplastic Induction Welds

Abstract Compared to other conventional joining methods, induction welding offers the superiority of avoiding mechanical degradation and satisfying the need for weight reduction in the aircraft industry. In this paper, a metal mesh was adapted as an induction component in the induction welding of polyetheretherketone (PEEK) with various currents. The effect of welding current on the microstructure and mechanical properties of the induction welding joint was further investigated. The results indicate that induction welding joints with the narrow thickness of the fusion zone and high tensile strength can be attained in the welding current range of 7.05 A to 11.05 A. However, when the current exceeds 13.91 A, the excessive heat input leads to the unsteady flow of PEEK or even thermal oxidative degradation and thermal decomposition, which increases the thickness of the fusion zone and reduces the tensile strength of the joint. In addition, the principal fracture mode presents cohesive failure, thereby promoting the tensile strength of the joint.

Effect of processing conditions and catalyst type on the thermal oxidative degradation mechanisms and melt stability of metallocene and Ziegler‐catalyzed ethylene‐1‐hexene copolymers

AbstractPolyolefins have traditionally been polymerized via the heterogeneous Ziegler Natta (Z‐N) catalysts since their discovery in the 1950s, but the later developments of the homogeneous single site metallocene/methylaluminoxane (MAO) catalysts have opened the possibility for the synthesis of polyolefin polymers and copolymers (commercialized in the 1990s) with highly defined microstructure and great degree of control of their molecular architecture resulting in some unique beneficial properties compared to their Z‐N counterparts. The main aim of the work reported here was to examine critically the effects of the processing conditions during multipass extrusions on the molecular and rheological characteristics of metallocene‐catalyzed linear low density polyethylene and a Ziegler‐Natta‐based counterpart polymer and on the thermoxidative (in the melt) stability of their melts and their stabilization. Both polymers examined here were based on ethylene‐1‐hexene copolymers and produced by the same manufacturer with similar density and melt index (MI) values. The melt stability and rheological properties of the polymers were determined from melt flow and capillary rheometric measurements. The molecular characteristics were investigated using GPC for molecular weight determination, 13C‐NMR for short chain branching, 1H‐NMR and FTIR for the type and concentration of unsaturation groups, FTIR for carbonyl‐containing compounds and chemical analysis for hydroperoxide determination. The processibility of the two polymers was compared through examination of different processing conditions (die temperatures 210–285°C, screw speeds 50–200 rpm) used for a multipass extrusion process. Further, the effects of the processing conditions on the melt thermoxidation of the differently catalyzed LLDPE polymers were investigated. The results demonstrated that both the catalyst type and the processing conditions have a great effect on both the rheological and the themoxidative behavior of the polymers as well as on the balance between the competing oxidative reactions taking place in the polymer melt, for example, chain scission and crosslinking reactions. The results obtained for the different multipass extrusion conditions of the two polymers have illustrated clearly that the degradation mechanisms during their melt processing are substantially different. The melt degradation route of the Ziegler‐catalyzed polymer was shown to be dominated by chain scission reactions under all the processing conditions examined, and more so at the higher shear rates and temperatures. By contrast, the evidence clearly showed that the metallocene‐catalyzed polymer gave rise to crosslinking reactions that predominated even under the more severe processing conditions, that is, higher temperatures and shear rates.

Thermal-oxidative degradation behavior and process of vulcanized styrene-butadiene rubber

Thermal-oxidative degradation behavior and process of vulcanized styrene-butadiene rubber

Preparation of a novel oligomer type compatibilizer for polypropylene/polystyrene blend

A polystyrene–g–2,2,6,6-tetramethylpiperidine 1-oxyl radical (PS–g–TEMPO) copolymer was formed during thermal-oxidative degradation of PS/hindered amine light stabilizer (HALS) under heat treatment by thermal equilibrium. The optimum preparation condition was identified at 150 °C for 21 h by assessment of the temperature and aging time dependences of the molecular weight and thermal properties. The optimized copolymer was reacted with polypropylene (PP). A PS–g–PP grafted copolymer-type compatibilizer was reactively prepared with the copolymer/PP at 200 °C melt mixing temperature. The tetrahydrofuran-soluble part of the PP/PS/PS–g–TEMPO blend was analyzed as the PS–g–PP copolymer. The PS–g–PP showed a broad melting peak in the range from 125 °C to 160 °C. The PP grafting ratio was approximately 4%, as calculated by pyrolysis gas chromatography mass spectrometry (Py-GC/MS) analysis. The reactive polymer blend of the PP/PS/PS–g–TEMPO showed significant improvement in mechanical properties and ductile fracture surface as compared with PP/PS. The HALS loading easily produced an excellent compatibilizer for PP/PS mechanical improvement.

ПІДВИЩЕННЯ ВОГНЕЗАХИСНОЇ ЕФЕКТИВНОСТІ ІНТУМЕСЦЕНТНИХ ЕПОКСИДНИХ ПОКРИТТІВ СПОЛУКАМИ ІНТЕРКАЛЬОВАНОГО ГРАФІТУ

Investigation of the effect of nitrate oxide graphite on the parameters of char layer, obtained from the system of ammonium polyphosphate / melamine / pentaerythritol / epoxy resin under the influence of temperatures of 200–800 °С. Methodology. A fire retardant mixture was chosen as a model intumescent system ammonium polyphosphate / melamine / pentaerythritol. As a polymer component was used bisphenols A / F epoxy resin together with a polyamidoamine hardener. Nitrate oxide graphite was obtained by oxidation of natural scaly graphite with fuming nitrogen acid. The effect of impurities of nitrate oxide graphite was determined by thermogravimetry on the intumescence coefficient of intumescent compositions and the mass of the char residue intumescent compositions in temperature range of 200–800 °С. Findings. The influence of nitrate oxide graphite on the characteristics was studied of char layer of epoxy intumescent system ammonium polyphosphate / melamine / pentaerythritol / epoxy resin. The study of thermal oxidative degradation was carried out intumescent compositions in the temperature range 200–800 °С. It was shown that intercalated graphite compounds increase the thermal stability of the formed char layer at temperatures > 600 °С. Determined intumescence coefficients and thermogravimetric analysis of modified intumescent systems was performed nitrate oxide graphite with different degrees of intercalation, in the conditions of 200–800 °С. It was established that the optimal parameters of the char layer are in terms of volume intumescence coefficient and mass of the char residue are provided by graphites, which contain 15–25% of intercalant in its composition. But the results obtained allow us to determine nitrate oxide graphite as a promising modifier of epoxy intumescent systems to increase its fire protection efficiency. Originality. The influence of degree of intercalation of nitrate oxide graphite was studied on the characteristics of char layer of epoxy intumescent system for the first time. Practical value. The optimal content of intercalant in nitrate oxide graphite was established for the development of formulations of intumescent epoxy coatings with increased fire retardant properties.

Synthesis of modified amino-aldehyde oligo (poly) mers and study of their thermal stability

In the article are discussed the relevance of obtaining amino aldehyde oligomers and the study of their basic physicochemical properties and determines that the synthesis conditions and the ratio of the starting components play an important role on the properties and structure of the synthesized amino aldehyde oligomers. Using the Differential thermal analysis (DTA) method, it was proved that the modification of the urea-formaldehyde oligomer with acrylic acid helps to increase the thermal oxidative degradation of the resulting products. In this case, the modifier - acrylic acid strongly chemically binds with amino aldehyde oligomers, which leads to an increase in the heat resistance of the samples.