scholarly journals Non-Isothermal Thermogravimetry of Selected Tropical Woods and Their Degradation under Fire Using Cone Calorimetry

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 708
Author(s):  
Linda Makovicka Osvaldova ◽  
Ivica Janigova ◽  
Jozef Rychly

For selected tropical woods (Cumaru, Garapa, Ipe, Kempas, Merbau), a relationship was established between non-isothermal thermogravimetry runs and the wood weight loss under flame during cone calorimetry flammability testing. A correlation was found for the rate constants for decomposition of wood in air at 250 and 300 °C found from thermogravimetry and the total time of sample burning related to the initial mass. Non-isothermal thermogravimetry runs were assumed to be composed from 3 theoretical runs such as decomposition of wood into volatiles itself, oxidation of carbon residue, and the formation of ash. A fitting equation of three processes was proposed and the resulting theoretical lines match experimental lines.

2014 ◽  
Vol 14 (4) ◽  
pp. 61-74 ◽  
Author(s):  
A. Kausar ◽  
W. Ullah ◽  
B. Muhammad ◽  
M. Siddiq

Abstract This study examined effect of inclusion of expanded graphite (Exp-G) on morphology, thermal, mechanical and flame retardant properties of PS, nitro-substituted polystyrene (N-PS) and amino-functional polystyrene (A-PS). FESEM showed exfoliated sheet morphology due to intercalation of N-PS and A-PS in expanded galleries. Tensile strength of A-PS materials (31.5-56.9 MPa) was higher than PS and N-PS. 10 % weight loss of A-PS nanocomposites (482-518 °C) was higher relative to pristine polymer and other nanocomposites. Cone calorimetry results revealed that there was lowering in PHHR of A-PS nanocomposites with 0.5 wt.% filler (428 kW/m2), while PS nanocomposites showed PHHR of 443 kW/m2.


2013 ◽  
Vol 864-867 ◽  
pp. 1954-1958 ◽  
Author(s):  
Bo Wang ◽  
Qiu Ping Zhou ◽  
Li Hong

The influence of Na2CO3on RF4-type waste printed circuit board (PCB) pyrolysis in carbon dioxide was studied with thermogravimetric analysis, and the reaction kinetics was calculated based on the Coats - Redfern method. It is shown that the weight loss process of waste PCB in carbon dioxide includes two stages. The first stage of weight loss is between 280 °C and 450 °C, at which the decomposition of epoxide resin leads to volatile materials release. The second stage of weight loss is the reaction between carbon residue and carbon dioxide between 600°C~960 °C, and carbon monoxide is formed. Addition of Na2CO3decreases the initial temperature of the second weight loss stage of waste PCB and increases the weight loss rate, which indicates the enhancement effect on gasification reaction between carbon residue and carbon dioxide. From the different mechanism function, the optimal mechanism function isf(a)=5(1-a)/4[-ln(1-a)]4and the range of activation energy is 75~135 kJ/mol.


Clay Minerals ◽  
1987 ◽  
Vol 22 (4) ◽  
pp. 447-456 ◽  
Author(s):  
S. A. T. Redfern

AbstractThe dehydroxylation of kaolinite has been investigated by isothermal thermogravimetry. Kinetic analysis using the Avrami equation shows that a combination of atomic mechanisms operates throughout the temperature range 734 K to 890 K. An empirical activation energy of 222 kJ mol-1 was calculated from the Arrhenius relationship using rate constants based on diffusion and homogeneous models. The activation energy (Ea) was calculated for a series of degrees of dehydroxylation by the time to a given fraction method, showing an increase in Ea during the early stages of the reaction. The isothermal plots indicate that OH is retained in the final stages of the reaction. The observations are explained in terms of a reaction mechanism in which kaolinite grains dehydroxylate from the edges inwards, parallel to (001).


2011 ◽  
Vol 201-203 ◽  
pp. 1714-1720 ◽  
Author(s):  
Jie Li ◽  
Lei Wang ◽  
Bao Wei Li ◽  
Bang Wen Zhang

In this paper, the method of microwave reduction roasting was applied to investigate the heating and weight loss process from hematite to magnetite in crude niobium concentrate under the protection of argon. The kinetics of microwave reduction roasting of hematite in crude niobium concentrate were analyzed and calculated at the temperature range of 500°C ~850°C by way of non-isothermal thermogravimetry and isothermal gravimetric analysis. Results from this investigation demonstrated that the activation energy of microwave reduction roasting calculated by non-isothermal thermogravimetry was 26.5769kJ•mol-1, and the activation energy calculated by isothermal gravimetric analysis was 64.1203kJ•mol-1. Compared with the method of reduction roasting under resistance heating, the activation energy of microwave reduction roasting was small, and the reaction rate was fast.


2011 ◽  
Vol 22 (1) ◽  
pp. 41-44 ◽  
Author(s):  
Norberto Batista de Faria-Júnior ◽  
Livia Etchebehere de Loiola ◽  
Juliane Maria Guerreiro-Tanomaru ◽  
Fábio Luis Camargo Villela Berbert ◽  
Mário Tanomaru-Filho

This study evaluated the effectiveness of 3 solvents (Citrol orange oil, Eucalyptol and Tetrachloroethylene) and 2 associations of solvents (Citrol orange oil+Tetrachloroethylene and Eucalyptol+Tetrachloroethylene) on 3 types of gutta-percha (conventional, thermoplastic and EndoREZ) and Resilon. Ten discs (10 mm diameter x 1 mm thick) from each material were prepared using standard metallic molds. Each specimen was weighed to determinate its initial mass. The specimens were immersed in the solvents for 10 min, followed by immersion in distilled water for 20 min, and were then reweighed to obtain the final mass. The mean weight loss determined the solvent capacity. Data were analyzed by ANOVA and Tukey's test at 5% significance level. Tetrachloroethylene was the most effective on conventional gutta-percha (p<0.05). Tetrachloroethylene was also the most effective on thermoplastic gutta-percha, but it was not significantly different (p>0.05) from Eucalyptol+Tetrachloroethylene, Citrol+Tetrachloroethylene, and Citrol. All solvents and associations presented little effectiveness on Resilon. The association Eucalyptol+Tetrachloroethylene was the most effective on EndoREZ, but it did not differ significantly (p>0.05) from Citrol+Tetrachloroethylene and Tetrachloroethylene. All evaluated substances presented solvent action. Tetrachloroethylene improved the effectiveness of both Citrol and Eucalyptol.


2015 ◽  
Vol 1096 ◽  
pp. 199-203 ◽  
Author(s):  
Miao Qin Wen ◽  
Tao Jiang ◽  
Ying Ding

Polyhedral oligemeric silsesquioxanes epoxy (POSS-EP) was prepared from 3-glycidyloxy-propyl-trimethoxysilane (KH-560) and tetramethylammonium hydroxide (TMAH) by hydrolytic condensation. POSS-EP was characterized using fourier-transformed infrared spectroscopy (FTIR), thermal gravity analysis (TGA) and gel permeation chromatography (GPC). When the mass ratio of KH-560 and 25wt% TMAH was 20:1 and the temperature of hydrolytic condensation was 80°C, T8 was the majority and certain a mount of T10. The temperature of POSS-EP in weight loss 5wt% and the maximum degradation rate was approximately 200°C. The residual weight for POSS-EP at 800°C was 33.5wt%. After the cotton fabric was treated with 5wt% POSS-EP by using toluene as solvent, its carbon residue was improved 60 times than untreated .


1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.


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