scholarly journals Flammability and Thermal Kinetic Analysis of UiO-66-Based PMMA Polymer Composites

Polymers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 4113
Author(s):  
Ruiqing Shen ◽  
Tian-Hao Yan ◽  
Rong Ma ◽  
Elizabeth Joseph ◽  
Yufeng Quan ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Mass Loss ◽  
Polymer Composites ◽  
Flame Retardants ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Protective Layer ◽  
Average Mass ◽  
Microscale Combustion Calorimeter ◽  
Combustion Calorimeter

Metal–organic frameworks (MOFs) are emerging as novel flame retardants for polymers, which, typically, can improve their thermal stability and flame retardancy. However, there is a lack of specific studies on the thermal decomposition kinetics of MOF-based polymer composites, although it is known that they are important for the modeling of flaming ignition, burning, and flame spread over them. The thermal decomposition mechanisms of poly (methyl methacrylate) (PMMA) have been well investigated, which makes PMMA an ideal polymer to evaluate how fillers affect its decomposition process and kinetics. Thus, in this study, UiO-66, a common type of MOF, was embedded into PMMA to form a composite. Based on the results from the microscale combustion calorimeter, the values of the apparent activation energy of PMMA/UiO-66 composites were calculated and compared against those of neat PMMA. Furthermore, under cone calorimeter tests, UiO-66, at only 1.5 wt%, can reduce the maximum burning intensity and average mass loss rate of PMMA by 14.3% and 12.4%, respectively. By combining UiO-66 and SiO2 to form a composite, it can contribute to forming a more compact protective layer, which shows a synergistic effect on reducing the maximum burning intensity and average mass loss rate of PMMA by 22.0% and 14.7%, respectively.

Retardant Properties of Nanosilica/PTFE Nanoparticals-Reinforced Polypropylene

2014 ◽  
Vol 1004-1005 ◽  
pp. 77-84 ◽  
Author(s):  
Zhen Lu Zhang ◽  
Dong Li Li ◽  
Wen Cai Xu ◽  
Ya Bo Fu ◽  
Rui Juan Liao
Keyword(s):  
Mass Loss ◽  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Thermoplastic Polymer ◽  
Maximum Heat ◽  
Average Mass ◽  
Melting Characteristics

This work reports the flammability properties of Nanocomposites reinforced with silica and PTFE nanoparticles and toughened with an elastomeric ethylene-vinyl acetate (EVA). Through trial and simulation study of the flame retardant thermoplastic polymer and melting characteristics of PP in the combustion process.The study found that modified PP composites have good flame retardancy compared to PP in case of fire relatively.In the study,the melting characteristics of the thermoplastic polymer affected the mass loss rate in the combustion stage.Nanocomposites experienced low plastic mass loss compared with PP, this has been related to pyrolysis mechanism of polymer.In general,The polymers undergoing depolymerization will lead to a rapid volatilization and therefore experienced much less melting.The results showed that:total heat release of nanocomposites was higher than polypropylene, while the average heat release rate, the maximum heat release rate, the average effective heat of combustion, the average mass loss rate, the average specific extinction area, and other indicators were lower than polypropylene.

scholarly journals Features of the kinetics of mass transfer processes in the process of firing ceramic materials

2018 ◽  
pp. 29-31
Author(s):  
O.M. Nedbailo ◽  
O.G. Chernyshyn
Keyword(s):  
Mass Transfer ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Ceramic Materials ◽  
The Body ◽  
Mass Content ◽  
Transfer Coefficients ◽  
Average Mass ◽  
Firing Ceramic

In article the technique of definition factors of carrying over weight of substance in the course of roasting ceramic materials which is based on exponent dependences of change mass bodies from time of its heating is offered. The process of firing ceramic materials is associated with the transfer of heat and mass of matter. Therefore, for a more complete calculation of the heat treatment mode, it is necessary to know the conditions for the mass transfer in the product being calcined. The aim of the work is to determine the mass transfer coefficients of the substance in the process of firing ceramic materials. The mass loss rate of the bound matter or the mass loss per unit time will be directly proportional to the average mass content of the body. On the other hand, the mass loss rate of the bound matter is numerically equal to the slope of the mass content kinetics curve. Proposed in the work formulas can be applied when studying the process of mass transfer during firing of samples from different clays, as when firing clay samples of different diameters under the same conditions, they will differ in the mass content (mass loss rate of the bound substance) during heating and their final relative amount (mass content) of the lost mass will be the same.

scholarly journals On the evolutionary status and instability mechanism of the Luminous Blue Variables (LBV)

1989 ◽  
Vol 113 ◽  
pp. 15-26
Author(s):  
André Maeder
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Light Curves ◽  
Evolutionary Status ◽  
Average Mass ◽  
Luminous Blue Variables ◽  
Ir Sources ◽  
Order Of Magnitude ◽  
Lower Luminosity

AbstractVarious evolutionary sequences leading to LBV are examined. The sequence O-Of-LBV-WR-SN is well supported by the models; some LBV with relatively lower luminosity may turn into OH/IR sources. The overall duration of the LBV phase depends mainly on the average mass loss rate; for <Ṁ> = 10−3M⊙y−1, it lasts about 104y.Very massive stars undergo, when they reach logTeff= 3.9, strong departure from hydrostatic equilibrium due to supra-Eddington luminosities at some depth in the outer layers. This results in heavy mass loss, as the growth rate of the instability is very fast. We suggest that the amount of mass ejected in a shell episode is mainly determined by the mass of such a layer that its thermal adjustment timescale is within an order of magnitude of the stellar dynamical timescale. Simulations of B-light curves due to shell ejections by LBV are performed and some sensitive properties are identified.

scholarly journals The RCB Stars and their Circumstellar Material

1985 ◽  
Vol 87 ◽  
pp. 151-166
Author(s):  
M.W. Feast
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Circumstellar Dust ◽  
Average Mass ◽  
Circumstellar Material ◽  
Carbon Particles ◽  
Circumstellar Shell

RCB stars are surrounded by circumstellar dust and gas moving radially outwards at ~200 km/sec. The circumstellar shell is made up of discrete puffs of matter, a typical puff occupying an area ~0.03 of a complete shell. On the average puffs are ejected about once every 40 days (comparable with the known pulsation periods of RCB stars). The reddening law of the dust indicates that it is composed of small carbon particles (radii ~100A). The flux from the shell at L typically varies by 1 to 3 mags over periods of 1000-2000 days. The average mass loss rate is ~10−6MO/yr.

scholarly journals The mass function and average mass-loss rate of dark matter subhaloes

2005 ◽  
Vol 359 (3) ◽  
pp. 1029-1040 ◽  
Author(s):  
Frank C. van den Bosch ◽  
Giuseppe Tormen ◽  
Carlo Giocoli
Keyword(s):  
Dark Matter ◽  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Mass Function ◽  
Average Mass

scholarly journals Critical rates of stellar mass loss

1979 ◽  
Vol 83 ◽  
pp. 349-356 ◽  
Author(s):  
D. S. P. Dearborn ◽  
J. B. Blake
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Main Sequence ◽  
Mass Loss Rate ◽  
Critical Mass ◽  
Ob Stars ◽  
Average Mass ◽  
Original Mass ◽  
Moderate Mass ◽  
Rayet Star

Many of the effects of mass loss on OB stars have now been explored. Mass loss will cause a star to be overluminous for its mass (though less luminous than a star of its original mass) and, for moderate mass-loss rates, the luminosity decreases at the same rate as the mass contained in the convective core decreases causing the main sequence lifetime to remain unchanged (Chiosi and Nasi 1974, 1978, Deloore, DeGreve and Lamers 1977, Dearborn, Blake, Hainebach and Schramm 1978). Mass loss can also expose layers where 14N has been enhanced via the CNO tricyle (Dearborn and Eggleton 1977) and, in extreme cases, can produce a stripped helium core resembling a Wolf-Rayet Star (Hartwick 1967). While many of these phenomena (in particular the composition change) are more sensitive to the total mass removed than the formalism used to represent the mass loss, significant differences will result for the same average mass-loss rate depending on whether the mass was removed early (near the ZAMS), or late (near core hydrogen depletion). In addition, there appears to be a critical mass loss rate which depends on initial mass and separates those models which continue to evolve in a relatively normal (though subluminous) manner, and those models which evolve to a Wolf-Rayet configuration.

scholarly journals Decay of a long-term monitored glacier: the Careser glacier (Ortles-Cevedale, European Alps)

2013 ◽  
Vol 7 (4) ◽  
pp. 3293-3335 ◽  
Author(s):  
L. Carturan ◽  
C. Baroni ◽  
M. Becker ◽  
A. Bellin ◽  
O. Cainelli ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
European Alps ◽  
Systematic Observation ◽  
Average Mass ◽  
Observation Series ◽  
Area And Volume

Abstract. The continuation of valuable, long-term glacier observation series is threatened by the accelerated mass loss which currently affects a large portion of so-called "benchmark" glaciers. In this work we present the evolution of the Careser glacier, from the beginning of systematic observation at the end of the nineteenth century to its current condition in 2012. In addition to having one of the longest and richest observation record among the Italian glaciers, Careser is unique in the Italian Alps for its 45 yr mass balance series started in 1967. In the present study, variations in the length, area and volume of the glacier since 1897 are examined, updating the series of direct mass balance observations and extending it into the past using the geodetic method. The glacier is currently strongly out of balance and in rapid decay; its average mass loss rate over the last three decades was −1.5 m water equivalent per year, increasing to −2.0 m water equivalent per year in the last decade. If mass loss continues at this pace, the glacier will disappear within a few decades, putting an end to this unique observation series.

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