• Journal of the Korean Applied Science and Technology
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• v.24 no.3
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• pp.278-286
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• 2007

As a part of enhancing the performance of wood-plastic composites (WPC), polypropylene (PP)/ nanoclay (NC)/ wood flour (WF) nanocomposites were prepared using melt blending and injection molding process to evaluate their thermal stability. Thermogravimetric analysis (TGA) was employed to investigate thermal degradation kinetics of the nanocomposites both dynamic and isothermal conditions. Dynamic scans of the TGA showed an increased thermal stability of the nanocomposites at moderate wood flour concentrations (up to 20 phr, percentage based on hundred percent resin) while it decreased with the addition of 30 phr wood flour. The activation energy $(E_a)$ of thermal degradation of nanocomposites increased when nanoclay was added and the concentration of wood flour increased. Different equations were used to evaluate isothermal degradation kinetics using the rate of thermal degradation of the composites, expressed as weight loss (%) from their isothermal TGA curves. Degradation occurred at faster rate in the initial stages of about 60 min., and then proceeded in a gradual manner. However, nanocomposites with wood flour of 30 phr heated at $300^{\circ}C$ showed a drastic difference in their degradation behavior, and reached almost a complete decomposition after 40 min. of the isothermal heating. The degree of decomposition was greater at higher temperatures, and the residual weight of isothermal degradation of nanocomposites greatly varied from about 10 to 90%, depending on isothermal temperatures. The isothermal degradation of nanocomposites also increased their thermal stability with the addition of 1 phr nanoclay and of wood flour up to 20 phr. But, the degradation of PP100/NC1/MAPP3/WF30 nanocomposites with 30 phr wood flour occurs at a faster rate compared to those of the others, indicating a decrease in their thermal stability.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2259-2264
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• 2009

A new high-energy organic potassium salt, 2-(dinitromethylene)-1,3-diazepentane potassium salt K(DNDZ), was synthesized by reacting of 2-(dinitromethylene)-1,3-diazepentane (DNDZ) and potassium hydroxide. The thermal behavior and non-isothermal decomposition kinetics of K(DNDZ) were studied with DSC, TG/DTG methods. The kinetic equation is $\frac{d{\alpha}}{dT}$ = $\frac{10^{13.92}}{\beta}$3(1 - $\alpha$[-ln(1 - $\alpha$)]$^{\frac{2}{3}}$ exp(-1.52 ${\times}\;10^5$ / RT). The critical temperature of thermal explosion of K(DNDZ) is $208.63\;{^{\circ}C}$. The specific heat capacity of K(DNDZ) was determined with a micro-DSC method, and the molar heat capacity is 224.63 J $mol^{-1}\;K^{-1}$ at 298.15 K. Adiabatic time-to-explosion of K(DNDZ) obtained is 157.96 s.

• Journal of the Korean Society of Tobacco Science
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• v.5 no.2
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• pp.55-62
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• 1983

Four of non- isothermal methods evaluating kinetics have been studied by using differential scanning calorimetry (DSC) and thermogravimetry (TG) and applied for kinetics of the thermal decomposition of cellulose. It is concluded that the heating evolution methods with DSC and approximative methods with TC can lead to satisfactory kinetic analysis. Results calculating the reacting order and the activation energy of cellulose decomposition were 1/2 order and 42kcaB/mol, respectively.

• Elastomers and Composites
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• v.51 no.2
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• pp.122-127
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• 2016

Thermal decomposition kinetics for two different types of polyurethane elastomers prepared with 2,2'-dichloro-4,4'-methylenedianiline (MOCA) and 3,5-dimethyl-thiotoluenediamine (Ethacure-300), based on PTMG/TDI isocyanate prepolymer, were studied using non-isothermal thermogravimetric analysis (TGA). Thermograms were obtained and analyzed using Friedman (FR) and Kissinger-Akahira-Sunose (KAS) methods for activation energy, $E_a$. The results obtained showed that decomposition reaction of both samples was observed similarly to occur through three different stages, i.e., initial stage with vaporization of low molecular weight materials, second stage of urethane linkage decompositions, and later stage of polyol segment decompositions. However, activation energy values at each stage for the sample cured with Ethacure-300 was much lower than those for the sample with MOCA, exhibiting relatively lower thermal stability for the sample with Ethacure-300 than that with MOCA.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.55-60
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• 2018

The thermal property is one of the most important characteristics in the field of energetic materials. Because energy materials release decomposition heat, differential scanning calorimetry (DSC) is frequently used for thermal analysis. However, thermodynamic events, such as melting can interfere with DSC kinetic analysis. In this study, we use isothermal mode for DSC measurement to avoid thermodynamic issues. We also merge accelerating rate calorimetry(ARC) data with DSC data to obtain a robust prediction results for small scale samples and for large scale samples as well. For the thermal property prediction, advanced kinetics and technology solutions(AKTS) programs are used.

• Journal of Welding and Joining
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• v.18 no.5
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• pp.55-62
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• 2000

A metallurgical model for the phase transformation kinetics at Coarsened Grain Heat Affected Zone(CGHAZ) on the basis of Johnson-Mehl-Avrami equation(JMA equation) was proposed. In this model, the effect of prior austenite grain size on the transformation and the morphological changes of ferrite were considered. Isothermal dilatometer tests were performed to determine the effect of prior austenite grain size (AGS) on the austenite decomposition to ferrite and pearlite in a plain carbon steel. By comparing the calculated volume fraction with measured data, the reliability of the developed model was discussed.

• Journal of the Korean Ceramic Society
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• v.33 no.8
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• pp.909-914
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• 1996

In this research [RCOOH]-$\varepsilon$-Caprolactam-Montmorillonite was synthesized by reaction between Na-Mont-morillonite (10-Carboxy-n-decyl)dimethylethylammonium (=RCCOH) ion and $\varepsilon$-Caprolactame-Motmorillonite ob-tained was 3.62$\AA$ After heat treatment of this intercalations complex at 37$^{\circ}C$ in high vacuum for 12 h 24 h, 40 h and 90 h the basal spacing was reduced to 35.8$\AA$, 34.2, 17.5 $\AA$ and 16.6$\AA$ respectively. The calculated amount of free $\varepsilon$-caprolactame included int he intercaltions complex and that of $\varepsilon$-caprolactame which is interca-lated into the interlayer space of montomorillonite and still remained after heat treatment are 4.6~4.9 and 0.5 molecules per unite cell of montmorillonite respectively.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.296-302
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• 2006

The kinetics of the thermal-oxidative decomposition of waste polyurethane (PU) according to oxygen concentration has been studied using a non-isothermal thermogravimetric technique at several heating rates from 10 to $50^{\circ}C/min$. A kinetic model accounting for the effects of the oxygen concentration by the differential and integral method based on Arrhenius equation was proposed to describe the thermal-oxidative decomposition of waste PU. To obtain the information on the kinetic parameters such as activation energy, reaction order, and pre-exponential factor, the thermogravimetric analysis curves and its derivatives have been analyzed using the kinetic analysis method proposed in this work. From this work, it was found that reaction orders for oxygen concentration had a negative sign, and activation energy decreased as the oxygen concentration increased. It was also found that the kinetic parameters obtained from the integral method using the single heating rate experiments varied with heating rates. Therefore, it is thought that the differential method using the multiple heating rate experiments more effectively represents the thermal-oxidative decomposition of waste polyurethane.

• Journal of Adhesion and Interface
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• v.14 no.1
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• pp.1-12
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• 2013

Multi core-shell composite particles were prepared by the water-born emulsion polymerization of various core monomers such as methyl methacrylate (MMA), ethyl methacrylate (EMA) and shell monomers such as MMA, EMA, 2-hydroxyl ethyl methacrylate (2-HEMA), glycidyl methacrylate (GMA) and methacrylic acid (MAA) in the presence of different concentrations of sodium dodecyl benzene sulfonate (SDBS). The following conclusions are drawn from the conversion, particle size and distribution, average molecular weight, molecular structure, glass transition temperature with DSC, contact angle after plasma treatment, tensile strength and isothermal decomposition kinetics. In the case of the concentration of 0.02 wt% SDBS, the conversion of MMA core-(EMA/GMA) shell composite particles was excellent as 98.5%. In the case of the concentration of 0.03 wt% SDBS, the particle size of EMA core-(MMA/GMA) shell composite particles was high as $0.48{\mu}m$. We confirmed that 3 points of glass transition temperatures appear for multi core-shell composite particles compared to 1~2 points of glass transition temperatures appear for general copolymer particles. Overall, the adhesion strength of shell composite particles was in the order of EMA/MAA > EMA/2-HEMA > EMA/GMA.

• Fibers and Polymers
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• v.4 no.4
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• pp.188-194
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• 2003

Phase behavior and spinodal phase separation kinetics in binary blends of a random copolymer of vinylidene fluoride and trifluoroethylene (75/25) [P(VDF/TrFE)] and poly(l,4-butylene adipate) (PBA) have been investigated by means of optical microscopic observation and time-resolved light scattering. The blends exhibited a typical lower critical solution temperature (LCST)∼${34}^{\circ}C$ above the melting temperature of the P(VDF/TrFE) crystals over the entire blend composition range. P(VDF/TrFE) and PBA were totally miscible in the temperature gap between the melting point of P(VDF/TrFE) and the LCST. Temperature jump experiments of the 3/7 P(VDF/TrFE)/PBA blend were carried out on a light-scattering apparatus from a single-phase melt state (${180}^{\circ}C$) to a two-phase region (205∼${215}^{\circ}C$). Since the late stage of spinodal decomposition (SD) is prevalent in the 3/7 blend, SD was analyzed using a power law scheme. Self-similarity was preserved well in the late stage of SD in the 3/7 blend.