Non-isothermal Reaction Kinetics Research Articles

Effect of ultrasound geometry on the production efficiency of damaged starch: Determining rheology parameters, and non-isothermal reaction kinetics

Present study investigates the effects of probe size geometry on thermodynamic kinetics, rheology, and microstructure of wheat and tapioca starch. Ultrasound treatment using different probe diameters (20 mm and 100 mm) significantly influenced the gelatinization process. Results showed reduced enthalpy (ΔH) and Gibbs energy (ΔG), indicating enhanced gelatinization efficiency. According to the results, using a 20 mm and 100 mm probe leads to a reduction of 52.7 % and 68.6 % in reaction enthalpy for wheat starch compared to native starch, respectively. Microstructure analysis revealed structural changes, with ultrasound treatment leading to granular fractures and a sheet-like structure with air bubbles. The rheological behavior of the starches is found to exhibit shear thinning behavior, with the Casson model providing the best fit for the experimental data. Moreover, rheology modeling using Herschel-Bulkley and power law models showed increased viscosity and shear stress in larger probes. Numerical simulation data demonstrated that probe size influenced ultrasonic pressure, sound pressure level, and thermal power dissipation density, affecting fluid motion and velocity field components. Moreover, the maximum dissipated power decreases from 8.43 to 0.655 mW/m3 with an increase in probe diameter from 20 to 100 mm. The average yield shear stress values are calculated as 3.36 and 3.14 for wheat and tapioca starches, respectively. The larger probe diameter leads to greater entropy increases, with tapioca starch showing a 4.72 % increase and wheat starch a 4.97 % increase, compared to 2.56 % and 3.11 %, respectively, with the smaller probe. Additionally, the Keller-Miksis model provided insights into bubble dynamics, revealing increased pressure and temperature with higher pressure amplitudes.

Investigation of ultrasound-assisted starch acetylation by single- and dual- frequency ultrasound based on rheology modelling, non-isothermal reaction kinetics, and flow/acoustic simulation

To achieve wheat starch acetylation (AC) with a high degree of substitution (DS), the acetylation process was carried out using various ultrasonication frequencies, including 25 kHz, 40 kHz, and 25 + 40 kHz. In the second step, wheat starch's ultrasound-assisted acetylation (UAA) is simulated using various approaches including the rheology models, non-isothermal reaction kinetics, and flow/acoustic modelling. The computational fluid dynamics (CFD) simulation solves the non-linear acoustic governing equation to determine the flow field and the amount of delivered ultrasound energy. The acetylated starch increased peak and final viscosity, with the highest values observed for the 25 + 40 kHz frequency than other single frequencies (25 kHz and 40 kHz). The viscosity of the starch is specified based on the experimental data using Herschel–Bulkley, power law, and Casson rheology models. According to differential scanning calorimetry (DSC) analysis, the gelatinization parameters and enthalpy of gelatinization (ΔHgel), were found to be lower in acetylated starches at the frequency of 25 + 40 kHz compared to those at frequencies of 25 kHz and 40 kHz, as well as native starches (NS). Moreover, the gelatinization process is examined by implementing the non-isothermal reaction kinetics to obtain the activation energy and reaction order. Based on the results obtained, implementing sonication at 25 kHz reduces the activation energy by 70.3 % compared to native starch. However, the same parameter is obtained to be 69.9 % and 67.1 % for the application of 40 and 25 + 40 kHz transducers, respectively. Additionally, during the sonication treatment, the yield shear stress increases between 24.1 and 31.8 %, based on the applied frequency. Morphology analysis determined by scanning electron microscopy (SEM) revealed that the surfaces and small granules underwent more damage in acetylated starches at frequencies of 25 kHz and 40 kHz. However, in acetylated starches at 25 + 40 kHz, the larger granules were more affected than the smaller ones.

On the p(x) approximation in the non-isothermal reaction kinetics by a generalized exponential integral the concept

A non-Arrhenius model based on the Mittag-Leffler function has been conceived as a basic concept. This approach allows modelling both sub-Arrhenius and super-Arrhenius behaviours and giving rise to modified temperature integrals.

Determining the quasi-real-time change in the glass transition temperature of a thermoset resin under cure using fast scanning calorimetry

A fast scanning calorimetric method to obtain the time and temperature dependence of the glass transition temperature (Tg) under a chemical reaction was reported. The cross-linking reaction of an epoxy-amine system is perfectly suppressed by an ultrafast temperature scan. By inserting the quenching and fast heating measurements in an isothermal or non-isothermal process, the quasi-real-time change in Tg during cure can also be obtained from a single piece of neat resin. In addition, the relation between Tg and conversion is obtained in a full range of conversion by combining with the conventional analysis of isothermal or non-isothermal reaction kinetics using differential scanning calorimetry or temperature modulated differential scanning calorimetry.

Non-Isothermal Reaction Kinetics Study of MgO-C Refractories with Added Low-Ash Consent Graphite

Magnesia-carbon (MgO-C) is widely used in metallurgical furnaces due to its excellent slag thermal shock and corrosion resistance properties. Carbon is non-wettable by slag, which protects MgO, but oxidises in the presence of oxygen. An experiment was undertaken to investigate the oxidation resistance of MgO-C in non-isothermal conditions through evaluation of kinetic laws. MgO-C samples with 2,8% ash content graphite and resin binder were prepared and their oxidation behaviour with respect to weight loss was determined in a specially designed furnace. Samples were fired from 700 to 1400°C at heating rates of 3, 5, 7 and 9 K per minute. Their continuous weight loss was measured at 50 K intervals. In order to find the mechanism(s) associated with oxidation of MgO-C samples, a reduced time ‘∅’ plot analysis was carried out for the samples. For all temperatures and samples, the initial oxidation mechanism was observed to obeya chemical reaction-controlled second order chemical mechanism followed by diffusion processes at higher temperatures.

Across-Phase Biomass Pyrolysis Stoichiometry, Energy Balance, and Product Formation Kinetics

Predictive correlations between reactions occurring in the gas, liquid, and solid phases are necessary to economically utilize the thermochemical conversion of agricultural wastes impacting the food, water, and energy nexus. On the basis of an empirical mass balance (99.7%), this study established the overall reaction stoichiometry (C33.42H45.95O20.26N0.22S0.14 = 0.50C20.08H57.21O22.46N0.20S0.22 + 1.72H2O + 0.10H2 + 1.07CH4 + 0.02C2H4 + 0.06C2H6 + 2.21CO2 + 2.05CO + 0.28C63.75H32.47O3.23N0.43S0.12) and energy balance for the slow pyrolysis of lignocellulosic pecan shell waste biomass at 10 °C min–1 up to 500 °C. In situ thermogravimetry–gas chromatography and diffuse reflectance infrared fourier transform spectroscopy (DRIFTs) were used to link the gas-, liquid-, and solid-phase nonisothermal reaction kinetics. Gaussian fit-based deconvolution of individual gaseous product formation rates (hydrogen, methane, carbon monoxide, carbon dioxide, ethylene, and ethane in mg min–1) suggested the relationships bet...

Ca(II) and Ba(II) methyl carbazate energetic complexes: syntheses, crystal structures, and properties

New energetic materials, [Ca(MCZ)3(H2O)2](ClO4)2 and {[Ba2(MCZ)4(H2O)2(μ1-ClO4)2(μ2-ClO4)2]0.5}n, are synthesized and tried as alternatives to common primary explosives. Both the crystal structures were determined by single-crystal X-ray diffraction. The crystal of [Ca(MCZ)3(H2O)2](ClO4)2 belongs to the monoclinic, P21/c space group, a = 14.168(3) Å, b = 8.5938(18) Å, c = 18.889(4) Å, β = 111.234(2)°, V = 2143.8(8) Å3, ρ = 1.6893 g cm−3, and {[Ba2(MCZ)4(H2O)2(μ1-ClO4)2(μ2-ClO4)2]0.5}n belongs to the triclinic, P-1 space group, a = 7.166(2) Å, b = 10.461(2) Å, c = 11.738(4) Å, α = 110.563(5)°, β = 93.799(2)°, γ = 96.864(3)°, V = 812.4(4) Å3, ρ = 2.185 g cm−3. Their thermal stabilities were investigated by differential scanning calorimetry (DSC), and exothermic peak temperatures with a heating rate of 10 °C min−1 are 249.7 and 181.7 °C, respectively. Non-isothermal reaction kinetics parameters were calculated via both Kissinger’s method and Ozawa-Doyle’s method to work out EK = 124.6 kJ mol−1, lgAK = 10.38, EO = 126.7 kJ mol−1 for the calcium complex and EK = 100.3 kJ mol−1, lgAK = 9.50, EO = 102.6 kJ mol−1 for the barium complex. Additionally, the critical temperatures of thermal explosion, ΔS≠, ΔH≠, and ΔG≠ were calculated as −231.2 J K−1 mol−1, 120.417 kJ mol−1, 236.728 kJ mol−1 for the calcium complex and −230.6 J K−1 mol−1, 96.723 kJ mol−1, 195.938 kJ mol−1 for the barium complex. As for their explosive nature, sensitivities toward impact and friction were tested. Both [Ca(MCZ)3(H2O)2](ClO4)2 and {[Ba2(MCZ)4(H2O)2(μ1-ClO4)2(μ2-ClO4)2]0.5}n are insensitive to friction (>360 N); their impact sensitivities are acceptable (20 and 13 J). Both compounds are energetic complexes.

Methyl carbazate energetic complexes: Transition metal perchlorates – Syntheses, crystal structures and properties

A series of transition metal (1 Mn(II), 2 Ni(II), 3 Cu(II), 4 Zn(II) and 5 Cd(II)) methyl carbazate perchlorate energetic complexes were synthesized in aqueous solution. The crystal structures were determined by single-crystal X-ray diffraction. The complex [Cu(MCZ)2](ClO4)2 belongs to the triclinic P1¯ space group. The Mn(II), Ni(II), Zn(II) and Cd(II) complexes all are monoclinic, P21/c space group. Their thermal stabilities were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). All the compounds show good thermal stabilities (1, 2, 4 and 5 under 200°C; 3 under 160°C). Non-isothermal reaction kinetics parameters, the critical temperatures of thermal explosion, ΔS≠, ΔH≠ and ΔG≠ were calculated. Their impact and friction sensitivities were tested, and their sensitivity levels are acceptable. The coordinated perchlorates reduce the thermal stability, but improve the decomposition rate immensely as well as the sensitivities.

Study on the catalytic effect of diaminoglyoxime on thermal behaviors, non-isothermal reaction kinetics and burning rate of homogeneous double-base propellant

This paper reports thermolysis of diaminoglyoxime (DAG) as a ballistic modifier, and its effects on the thermal behaviors, non-isothermal decomposition reaction kinetics, and burning rates of the homogeneous double-base propellant formulations. Thermal analysis studies were performed by thermogravimetric analysis and differential thermogravimetry (TG-DTG) and differential scanning calorimetry techniques. According to the resulted data, it was found that DAG could change the thermal decomposition mechanism function, thermokinetic parameters and kinetic equation of the propellants. Evaluation of DAG as a ballistic modifier in double-base propellant formulations indicated that it brings down the pressure index to 0.068 compared to 0.24 for the control composition in the pressure range 5–7 Mpa. The results showed that the main exothermal decomposition reaction of the propellant sample in the absence of DAG has the mechanism function of \( f(\alpha ) = \frac{3}{2}\left( {1 - \alpha } \right)^{4/3} [\left( {1 - \alpha } \right)^{ - 1/3} - 1]^{ - 1} \) and the kinetic equation of \( {\raise0.7ex\hbox{${{\text{d}}\alpha }$} \!\mathord{\left/ {\vphantom {{{\text{d}}\alpha } {{\text{d}}t}}}\right.\kern-0pt} \!\lower0.7ex\hbox{${{\text{d}}t}$}} = 1.60 \times 10^{17} \left( {1 - \alpha } \right)^{4/3} [\left( {1 - \alpha } \right)^{ - 1/3} - 1]^{ - 1} e^{{ - 2.21 \times 10^{4} /{\text{T}}}} \), while modified propellant with DAG has a different function mechanism and kinetic equation as following: \( f(\alpha ) = \frac{5}{2}\left( {1 - \alpha } \right)\left[ { - { \ln }\left( {1 - \alpha } \right)} \right]^{3/5} \) and \( {\raise0.7ex\hbox{${{\text{d}}\alpha }$} \!\mathord{\left/ {\vphantom {{{\text{d}}\alpha } {{\text{d}}t }}}\right.\kern-0pt} \!\lower0.7ex\hbox{${{\text{d}}t }$}} = 9.28 \times 10^{40} \left( {1 - \alpha } \right)\left[ { - { \ln }\left( {1 - \alpha } \right)} \right]^{3/5} e^{{ - 4.66 \times 10^{4} /{\text{T}}}} \), respectively.

Effects of calcium carbonate on thermal characteristics, reaction kinetics and combustion behaviors of 5AT/Sr(NO3)2 propellant

The effects of CaCO3 on thermal and combustion characteristics of solid propellants composed of the novel green energetic material 5AT/Sr(NO3)2 are examined. Thermogravimetry–derivative thermogravimetry (TG–DTG), thermocouple measurements and closed bomb calorimetry are all employed to study the reaction mechanisms obtained when using CaCO3 as a cooling additive. In this manner, the combustion temperatures, burning rates, pressure exponents, thermal behaviors and non-isothermal reaction kinetics of solid propellant specimens are assessed. The combustion of the 5AT/Sr(NO3)2 propellant with added CaCO3 can be divided into two regions. The initial region is dominated by condensed phase reactions and exhibits a lower decomposition temperature, lower activation energy and higher burning rate. These results demonstrate that the addition of CaCO3 increases the reactivity of the propellant. The latter region is primarily associated with gas phase reactions, and the decomposition temperature and activation energy all appear to be elevated in this region, although the exhaust gas temperature and burning rate are greatly reduced. The pressure exponent is also reduced significantly in this stage, providing evidence for increased combustion stability. The thermal characteristics of the decomposition reaction as observed microscopically indicate significant synergistic effects of the CaCO3 on the burning behavior. CaCO3 addition has been shown to generate a significant cooling effect and the combination of this compound with 5AT/Sr(NO3)2 results in a propellant with excellent thermal behavior and steady combustion. This propellant formulation is safe, scalable and inexpensive and therefore CaCO3 appears to be an ideal agent for the modification of the gas generation performance of solid propellants.

Synthesis, crystal structure and thermal behavior of a new 1D polymeric strontium complex with tetrazole-1-acetic acid

A new 1D polymeric strontium compound (Sr(tza)2(H2O)2)n was synthesized by reaction of tetrazole-1-acetic acid (Htza) with strontium carbonate, and characterized by X-ray single crystal diffraction, elemental analysis and IR spectroscopy. The central Sr(II) atom is coordinated by eight O atoms from 4 tza − ions and two water molecules. A zigzag chain along the c-axis is constructed by the tridentate tza − anion bridging two Sr(II) atoms. Differential scanning calorimetry (DSC) and thermogravimetric-differential thermogravimetric (TG-DTG) analyses were applied to assess the thermal decomposition behav- ior. The kinetic parameters were obtained by non-isothermal reaction kinetics, and the Arrhenius equation can be expressed as lnk = 22.17-258.2 × 10 3 /RT. The critical temperature of thermal explosion values, �S / = , �H / = andG / = were obtained at 562 K as, −65.71 J mol −1 K −1 , 255.51 kJ mol −1 and 291.78 kJ mol −1 , respectively.

Reaction Kinetics for Lead‐Free 0.94(K0.5Na0.5)NbO3–0.06LiNbO3 Ceramic Synthesis with Ultrasonic Irradiation

The effects of ultrasonic irradiation treatment at room temperature on the nonisothermal reaction kinetics for the formation of 0.94(K0.5Na0.5)NbO3‐0.06LiNbO3 (0.94KNN–0.06LN) lead‐free piezoelectric ceramics were studied. It was observed that sonication dramatically decreased the sizes of the starting material aggregates and enhanced the interaction between the individual reactants even at room temperature. Through quantitative analyses on the activation energies of the decomposition of the starting alkali carbonates and formation of the resulting perovskite phase, it was found that the activation energies decreased with increasing ultrasonic power. More interestingly, the activation barrier for the decomposition of the carbonates was reduced to below the critical value for the crystallization of the perovskite phase with the high irradiation power, so that the reaction of forming the perovskite phase was not rate‐limited by the decomposition of the carbonates. This finding highlights the significance of ultrasound utility in processing KNN‐based ceramics with reduced synthesis temperature and thus improved control of chemical stoichiometry.

3,6-Bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine–based energetic strontium(II) complexes: synthesis, crystal structure, and thermal properties

Two energetic strontium(II) complexes with nitrogen-rich 3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine (BTATz) were synthesized. The metal complexes were characterized by IR, elemental analysis, and single-crystal X-ray diffraction. DSC and TG-DTG were used to study the thermal behavior, non-isothermal decomposition reaction kinetics, self-accelerating decomposition temperature (T SADT), thermal ignition temperature (T TIT), critical temperature of thermal explosion (T b), and the adiabatic time-to-explosion (t TIad). The data indicate competitive energetic materials.

Synthesis, structure, and thermal behavior of a 2-D polymeric Ca(II) compound with tetrazole-1-acetic acid

A 2-D polymeric Ca(II) compound, [Ca(tza)2(H2O)2] n , was synthesized by the reaction of tetrazole-1-acetic acid with calcium carbonate. The product was characterized by X-ray single-crystal diffraction, elemental analysis, and IR spectroscopy. The calcium center is six-coordinate in a slightly distorted octahedral configuration by four carboxylic oxygens from four different tza− ligands and two waters. The 2-D supramolecular laminar structure in b-axis × c-axis plane was constructed via four bridging tza− ions connecting one Ca(II) with four adjacent Ca(II) ions. Differential scanning calorimetry and thermogravimetric–differential thermogravimetric analysis were applied to assess the thermal decomposition behavior. The kinetic parameters were obtained by non-isothermal reaction kinetics, and the Arrhenius equation can be expressed as lnk = 21.96–262.2 × 103/RT. The values of critical temperature of thermal explosion, ΔS≠ , ΔH≠ , and ΔG≠ were obtained as 574 K, −67.62 J mol−1 K−1, 257.52 kJ mol−1, and 295.59 kJ mol−1, respectively.

Effects of Lead Complex-Based BTATz on Thermal Behaviors, Non-Isothermal Reaction Kinetics and Combustion Properties of DB/RDX-CMDB Propellants

The composite double base(DB)/hexogen(RDX)-modified double base(CMDB) propellants(Nos.DB001 and CMDB100) were prepared with the lead complex of 3,6- bis(1H-1,2,3,4- tetrazol- 5- ylamino)-1,2,4,5-tetrazine(LCBTATz),with and without the ballistic modifier.Their thermal behaviors and nonisothermal decomposition reaction kinetics were investigated by thermogravimetry,derivative thermogravimetry(TG- DTG),and differential scanning calorimetry(DSC).For the LCBTATz-DB propellant,there was one mass loss stage in the TG curve and one exothermic peak in the DSC curve over the temperature range350-540 K.For LCBTATz-CMDB,there were two continuous exothermic stages in the TG curve,and only one corresponding exothermic peak in the DSC curve over the range 390-540 K.The exothermal decomposition reaction mechanisms of LCBTATz-DB and LCBTATz-CMDB follow the functions f(α)=α-1/2and f(α)=2(1-α)3/2,respectively(α:conversion degree).The self-accelerating decomposition temperatures(TSADT),thermal ignition temperatures(TTITT),critical temperatures of thermal explosion(Tb),adiabatic timesto-explosion(tTlad),and thermodynamic parameters of activation reaction were calculated,and the thermal safety was evaluated.For DB001,TSADT=444.50 K,TTITT=453.96 K,Tb=471.84 K,and tTlad=39.36 s.For CMDB100,TSADT=442.38 K,TTITT=452.89 K,Tb=464.13 K,and tTlad=21.3 s.As a high-efficiency combustion catalyst,LCBTATz in double-base propellants increases the propulsion rate and reduces the pressure index for larger scale pressures.This makes the DB propellant appear to have a significant super burning effect at 2- 8 MPa and a"mesa effect"at 8-12 MPa.Meanwhile,the pressure exponent of the CMDB propellant decreased to 0.18.

Synthesis, structure, thermal behavior and energetic properties of a new 2D polymeric Ba(II) compound with tetrazole-1-acetic acid

A new energetic Ba(II) coordination polymer [Ba(tza)2]n (where tza = tetrazole-1-acetic acid anion) was synthesized and characterized by X-ray single crystal diffraction, elemental analysis and IR spectroscopy. In the molecule, the central Ba(II) cation was coordinated by eight carboxylic O atoms from six different tza ions. Quadridentate tza anion bridged three various Ba(II) atoms and formed a 2D supramolecular network. Differential scanning calorimetry (DSC) and thermogravimetric differential thermogravimetric (TG DTG) analyses were applied to assess the thermal decomposition behavior. The kinetic parameters were obtained by non-isothermal reaction kinetics, and the Arrhenius equation can be expressed as lnk = 22.47 – 291× 103/RT. Critical temperature of thermal explosion, thermodynamic parameters, energy of combustion, enthalpy of formation and sensitivities of [Ba(tza)2]n were measured or calculated to argue that as a potential energetic material.

The kinetics of non-isothermal iron and aluminum powder mixtures sintering in protective atmosphere

In this paper, the analysis of non-isothermal reaction kinetics of pure elemental Fe and Al powders sintered in argon atmosphere is presented. The attention was drawn to the numerical methods which increase the accuracy of kinetic and thermodynamical parameters evaluation such as activation energy, enthalpy of formation and Avrami power factor. The verification of proposed phase transformation model associated with sintering process of elemental Fe and Al powders is also presented. DSC, XRD and SEM techniques showing the relationship between the phenomena of phase transformations in FeAl intermetallic alloy are applied. The results of determination of activation energy, enthalpy of formation and Avrami power factor for phase transformations occurring during the process, based on JMA kinetic model, Kissinger equation and stoichiometric calculations assumed a sequence of changes are presented. Moreover, the hypothetical model of intermetallic phase synthesis and transformation in elemental component is presented.

Synthesis, crystal structure, thermal decomposition, and non-isothermal reaction kinetic analysis of an energetic complex: [Mg(CHZ)3](ClO4)2 (CHZ = carbohydrazide)

An energetic complex [Mg(CHZ)3](ClO4)2 was synthesized by the reaction of carbohydrazide (CHZ) with magnesium perchlorate. The product was characterized by X-ray single-crystal diffraction, elemental analysis, and IR spectroscopy. The crystal belongs to the monoclinic system with space group P2(1)/n. Cell parameters: a = 10.034(2) Å, b = 8.5069(16) Å, c = 21.285(4) Å, β = 100.901(3)°, V = 1784.1(6) Å3, Z = 4. The central magnesium is six-coordinate with three oxygen atoms of carbonyl groups and three terminal nitrogen atoms of the hydrazine groups from three CHZs to form a distorted octahedron. Differential scanning calorimetry and thermogravimetric-differential thermogravimetric analysis were applied to assess the thermal decomposition behavior. The kinetic parameters were obtained by non-isothermal reaction kinetics. The equation can be expressed as . Moreover, the values of critical temperature of thermal explosion, ΔS≠ , ΔH≠ , ΔG≠ , and the energy of combustion were obtained as 284°C, −169.76 J mol−1 K−1, 65.46 kJ mol−1, 154.27 kJ mol−1, and 6759 kJkg−1, respectively.

Model-fitting and model-free nonisothermal curing kinetics of epoxy resin with a low-volatile five-armed starlike aliphatic polyamine

This paper reports the original work on the nonisothermal curing reaction of bisphenol A epoxy resin (DGEBA) and N,N,N′,N′,N′′-penta(3-aminopropyl)-diethylenetriamine (PADT). The nonisothermal reaction kinetics of DGEBA/PADT is systematically investigated using dynamic DSC with the model-fitting and advanced model-free isoconversional methods. The high reaction heats (115–118kJ/mol) indicate that PADT can efficiently cure DGEBA, and the reaction activation energy is 55.4kJ/mol. The further reaction kinetic analysis with the Málek method discloses the autocatalytic characteristic, and the Šesták–Berggren model is able to well simulate the reaction rate. Furthermore, the dependence of the effective activation energy on conversion is established from the model-free kinetic analysis with the Vyazovkin method, from which the reaction mechanisms are discussed in detail. Additionally, the isothermal conversion predication from the nonisothermal data is accomplished using the two methods, respectively, with an acceptable match obtained.

Synthesis and nonisothermal reaction of a novel acrylonitrile-capped poly(propyleneimine) dendrimer with epoxy resin

A novel acrylonitrile-capped poly(propylene imine) dendrimer (PAN4) was synthesized and characterized with FTIR and 1H-NMR. PAN4 and its precursor (poly(propylene imine) dendrimer (1.0GPPI) were employed to cure bisphenol A epoxy resin (DGEBA), and the nonisothermal reaction kinetics of DGEBA/PAN4 and DGEBA/1.0GPPI was systematically investigated using a differential scanning calorimeter (DSC) in a comparative way. The apparent activation energies determined with the Kissinger method were 59.7 kJ/mol for DGEBA/1.0GPPI and 53.9 kJ/mol for DGEBA/PAN4. Applied the Malek method, it was found that a two-parameter autocatalytic model (SB(m, n)) could well simulate the reaction rates, and further analysis of the reaction rate constants showed PAN4 could cure DGEBA at a greatly decreased rate by a factor a more than ten compared with 1.0GPPI control.