scholarly journals Lifetime Prediction of Polymers: To Bet, or Not to Bet—Is This the Question?

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1383 ◽  
Author(s):  
Ignazio Blanco
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Polymeric Materials ◽  
Real Data ◽  
Degradation Process ◽  
Decomposition Temperature ◽  
Successful Completion ◽  
Initial Decomposition Temperature ◽  
Activation Energy Of Degradation ◽  
High And Low Temperatures

Polymers are a great and very important category of organic compounds that have changed our lifestyle. In the last eighty years, we have used them for the most varied applications, and from the first structural ones we began to investigate their durability, which can be fatal in the successful completion of the application for which the material was designed. Over the last thirty years, the environmental problems related to the disposal of polymers that have completed their lifecycle have begun to arise, and the need to foresee their end of life has become increasingly urgent. In this manuscript, the reliability of the lifetime predictions of polymeric materials is faced with comparing measurements obtained at low temperature with those carried out at high temperatures, in the molten state. The obtained data were treated by a well-established kinetics model and discrepancies were observed in the two different conditions (high and low temperatures), which led to a mismatching between expected and real data. A correction of the data extrapolated from measurements obtained at high temperatures, by using a novel equation which takes into account the induction period (IP) of the degradation process, is proposed. Considerations about the useful parameters, namely initial decomposition temperature (Ti), activation energy of degradation (Ea), and glass-transition temperature (Tg), to be used for making predictions, are also carried out.

Synthesis of Tung Oil-Based Bi-Dihydrogen-Maleimide

2012 ◽  
Vol 554-556 ◽  
pp. 787-791
Author(s):  
Jin Hua Zhou ◽  
Xun Jun Du ◽  
Han Zhou Sun ◽  
Yu Xiong Wu ◽  
Xiao Feng Tan ◽  
...  
Keyword(s):  
Heat Resistance ◽  
Polymeric Materials ◽  
Decomposition Temperature ◽  
Target Product ◽  
Optimal Conditions ◽  
Initial Decomposition Temperature ◽  
Tung Oil ◽  
Renewable Biomass ◽  
Good Heat Resistance ◽  
Good Heat

Started from Tung oil, a renewable biomass material of china, a new kind of bismaleimide, Tung oil-based bi-dihydrogen-maleimide (TOBBDHMI) was synthesized by the reaction of methyl-α-eleostearate-maleic anhydride adduct (MEMAA) and 4,4'-diphenylmethane disocyanate (MDI). The optimal conditions for synthesis were catalyst triethylamine dosage 1.0%, mole ratio of MEMAA to MDI 2.4:1, reaction temperature 75°C and reaction time 2 h, which gave yield 82.4% for TOBBDHMI (calculated from MDI). The melting point of the product was 186.6 °C~189.3 °C, initial decomposition temperature was 270 °C and final decomposition temperature was 510 °C, which showed the product has good heat resistance. The target product is potential to be used alone or with other bismaleimide monomers to improve polymeric materials’ heat resistance and/or mechanical properties.

Temperature Tolerance in Young Pacific Salmon, Genus Oncorhynchus

1952 ◽  
Vol 9 (6) ◽  
pp. 265-323 ◽  
Author(s):  
J. R. Brett
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Oncorhynchus Tshawytscha ◽  
Prolonged Exposure ◽  
Pacific Salmon ◽  
Vertical Gradient ◽  
Temperature Tolerance ◽  
Preferred Temperature ◽  
High And Low Temperatures ◽  
Temperature Responses

Lethal limits of high and low temperatures were determined for the young of five species of Pacific salmon, the spring (Oncorhynchus tshawytscha), the pink (O. gorbuscha), the sockeye (O. nerka), the chum (O. keta) and the coho (O. kisutch).For acclimation temperatures ranging from 5° to 24 °C. significant differences between species in their resistance to high temperatures was obtained. The spring and coho were most resistant. The pink and chum salmon were least resistant, and the sockeye was distinguishable from the latter two by greater resistance for prolonged exposure to high temperatures. No species could tolerate temperatures exceeding 25.1 °C. when exposed for one week.A fanning-out of the opercula was shown to be directly correlated with the onset of death from a low temperature. By use of this criterion mixed lethal effects at low temperatures were demonstrated and found to be influenced by the size of the fish and by the salinity of the water. None of the species could withstand temperatures lower than 4 °C. when acclimated to 20 °C. and above. When taken from holding troughs as low as 5 °C., coho and sockeye could not tolerate long exposure (four days) to 0 °C.In a vertical gradient little difference in preferred temperature was observed, either between species or for different acclimation temperatures. The 12° to 14 °C. stratum was the region of greatest concentration.Specific differences in temperature responses are in keeping with taxonomic and ecological distinctions.

Vibrational properties of BaFe11.1Sc0.9O19 hexaferrite at high and low temperatures

2020 ◽  
Vol 34 (33) ◽  
pp. 2050381
Author(s):  
A. I. Mammadov ◽  
N.T. Dang ◽  
R. Z. Mehdiyeva ◽  
À. V. Trukhanov ◽  
R. E. Huseynov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Temperatures ◽  
Low Temperatures ◽  
Structural Phase ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
Hexagonal Symmetry ◽  
Powder Samples ◽  
Raman Modes ◽  
High And Low Temperatures

[Formula: see text] hexaferrite compound was synthesized, the crystal structure was studied by the X-ray diffraction method. Powder samples were prepared from the mark “analytical grade” oxides [Formula: see text], [Formula: see text] and carbonate BaCO3. It was found that under normal conditions and at room temperatures, the crystal structure of this compound has hexagonal symmetry with the P63mmc space group. The lattice parameters correspond to the values: [Formula: see text] and [Formula: see text]. Atomic dynamics of [Formula: see text] hexaferrite in the range of low temperatures of [Formula: see text] and high temperatures of [Formula: see text] were studied. As a result of the analysis of the spectra obtained by the Raman spectroscopy method, it was determined that the structural phase transition does not occur in this compound over a wide temperature range [Formula: see text]. At the room temperature, the obtained Raman modes are observed at both low and high temperatures.

scholarly journals Effect of Soil Temperature in the Emergence of Maize Seeds

2018 ◽  
Vol 11 (1) ◽  
pp. 479 ◽  
Author(s):  
Heloisa O. dos Santos ◽  
Renato C. C. Vasconcellos ◽  
Beatriz de Pauli ◽  
Raquel M. O. Pires ◽  
Elise M. Pereira ◽  
...  
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Seedling Emergence ◽  
Genetic Material ◽  
Germination Percentage ◽  
Seed Vigor ◽  
Department Of Agriculture ◽  
Maize Seeds ◽  
Germination Process ◽  
High And Low Temperatures

Temperature is one of the most important factors in the germination process, which influences the absorption of nutrients required for growth and development of the plant, germination uniformity, and seed vigor maintenance. Low temperatures can result in deformation of the leaves and the apex of the plant, and high temperatures hamper the development of them. The objective of this work was to evaluate the ideal temperature values for germination in each genetic material used, highlighting the most suitable for each condition. The experiment was conducted at the Central Seed Laboratory at the Department of Agriculture of the Lavras Federal University, where germination percentage, first germination count, seedling emergence and emergence speed were evaluated. The experimental design was completely randomized, with a factorial scheme of 4 × 5, in which it was analyzed four lines (L30, L64, L63, and L91) at five different germination temperatures (15, 20, 25, 30 and 35 ºC). An analysis of variance was done and for the comparison between means, the Scott Knott test was used, at a 5% probability. It can be observed that the lines L63 and L91 were more susceptible to low germination temperatures and lines L30 and L64 do not tolerate high temperatures. Also, the evaluation of temperature-controlled substrate germination proved to be a promising technique to identify tolerant and susceptible lines for germination in both high and low temperatures.

THE CAUSE OF BOLTING IN SWEDE TURNIPS (BRASSICA NAPUS VAR. NAPOBRASSICA (L.) PETERM.)

1934 ◽  
Vol 11 (6) ◽  
pp. 733-750 ◽  
Author(s):  
F. H. Peto
Keyword(s):  
Brassica Napus ◽  
Low Temperature ◽  
High Temperatures ◽  
Root Development ◽  
Growth Temperature ◽  
Vegetative Growth ◽  
Low Temperatures ◽  
Initial Growth ◽  
High And Low Temperatures ◽  
Low Temperature Treatments

The relation of growth temperature to "bolting" (premature seed-stalk development) in swede turnips was investigated by growing plants in a greenhouse at high and low temperatures for different periods of time at various stages of their development. It was found that an initial growth temperature of approximately 53° F. for 30 to 50 days induced incipient bolting 71 days after seeding, as indicated by a rapid increase in internode length accompanied by a retarded root development. Flowering was inhibited to a large extent by growth temperatures above 65° F. in plants that had shown incipient bolting as a result of previous low-temperature treatments. None of the plants grown continuously at high temperatures gave any indication of bolting. It may be concluded, therefore, that high temperatures favor vegetative growth while low temperatures favor sexual reproduction.

Simple Systems

2017 ◽  
Author(s):  
Jochen Rau
Keyword(s):  
Magnetic Field ◽  
Low Temperatures ◽  
General Framework ◽  
Gibbs State ◽  
Macroscopic System ◽  
Basic Model ◽  
System A ◽  
Paramagnetic Salt ◽  
High And Low Temperatures ◽  
Simple Systems

Even though the general framework of statistical mechanics is ultimately targeted at the description of macroscopic systems, it is illustrative to apply it first to some simple systems: a harmonic oscillator, a rotor, and a spin in a magnetic field. These applications serve to illustrate how a key function associated with the Gibbs state, the so-called partition function, is calculated in practice, how the entropy function is obtained via a Legendre transformation, and how such systems behave in the limits of high and low temperatures. After discussing these simple systems, this chapter considers a first example where multiple constituents are assembled into a macroscopic system: a basic model of a paramagnetic salt. It also investigates the size of energy fluctuations and how—in the case of the paramagnet—these fluctuations scale with the number of constituents.

Low solubility of alumina in enstatite and uncertainties in estimated palaeogeotherms

1978 ◽  
Vol 288 (1355) ◽  
pp. 471-486 ◽  
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Alumina Content ◽  
Equilibrium Solubility ◽  
Low Solubility

Spurious kinks in estimated palaeogeotherms may result from small errors in the calibration of the geothermometers and geobarometers. New data indicate that the equilibrium solubility of alumina in enstatite is even less than shown by recent studies, and that the slopes (d T /d P ) of the isopleths of equal alumina content are steeper than hitherto believed. Consequently, pressures of equilibration estimated from current formulations of the orthopyroxene-garnet geobarometer will be too high at high temperatures (> 1200 °C) and too low at low temperatures.

scholarly journals Environmental temperature during early life affects the personality of mosquitofish in adulthood

2021 ◽  
Author(s):  
Haifeng Li ◽  
Xinyu ZHang ◽  
Yi Wu ◽  
Feng ZHang ◽  
CHunlin Li
Keyword(s):  
Body Length ◽  
High Temperatures ◽  
Low Temperatures ◽  
Early Life ◽  
Environmental Temperature ◽  
Phenotypic Trait ◽  
Behavioral Syndrome ◽  
Growing Up ◽  
Female Fish ◽  
Behavioral Traits

Abstract Personality has been observed in a variety of animal taxa with important implications in ecology and evolution. Exploring the influence of environmental temperature during early life on personality could help to understand the ontogeny of this phenotypic trait in animals. In this study, we reared newborn mosquitofish Gambusia affinis at high (30°C) and low (25°C) water temperatures and measured their shyness and exploration upon sexual maturity. We tested the repeatability of each behavioral trait; the correlation between them; and the effects of rearing temperature, sex, and body length on the behaviors. When growing up at low temperatures, female fish exhibited repeatability in shyness and exploration, and males exhibited marginal repeatability in shyness. However, neither of the 2 behaviors were repeatable when the fish were reared at high temperatures. There was a negative correlation between shyness and exploration, indicating that the 2 behaviors comprise a behavioral syndrome in this species. Mosquitofish reared at high temperatures were more explorative than those reared at low temperatures, while there was no difference in shyness between the 2 treatments. Body length and sex had no significant effects on the average values of the 2 behaviors. The results indicate that environmental temperature during early life could shape the personality of mosquitofish and modify the average of the behavioral traits. These findings might provide insights to understand the ontogeny of animal personality and how changes in environmental temperature influence animal dispersal by shaping their personality.

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