scholarly journals The influence of high and low temperatures on the impact properties of glass-epoxy composites

2007 ◽  
Vol 72 (7) ◽  
pp. 713-722 ◽  
Author(s):  
Slavisa Putic ◽  
Marina Stamenovic ◽  
Branislav Bajceta ◽  
Predrag Stajcic ◽  
Srdjan Bosnjak
Keyword(s):  
Low Temperatures ◽  
Composite Structures ◽  
Room Temperature ◽  
Epoxy Composite ◽  
Epoxy Composites ◽  
Temperature Influence ◽  
Impact Properties ◽  
Different Temperatures ◽  
High And Low Temperatures ◽  
The Impact

The aim of this paper is to present the influence of high and low temperatures on the impact properties glass-epoxy composites. The impact strength an is presented for four different glass-epoxy composite structures at three different temperatures, i.e., at room temperature t=20?C, at an elevated temperature t=+50?C and at a low temperature t=-50?C. Standard mechanical testing was carried out on the composite materials with specific masses of reinforcement of 210 g m-2 and 550 g m-2 and orientations 0?/90? and ?45?. Micromechanical analysis of the failure was performed in order to determine real models and mechanisms of crack and temperature influence on the impact properties. .

scholarly journals Low-temperature tension properties of glass-epoxy composite materials

2005 ◽  
pp. 123-134
Author(s):  
Slavisa Putic ◽  
Marina Stamenovic ◽  
Branislav Bajceta ◽  
Predrag Stajcic ◽  
Srdjan Bosnjak
Keyword(s):  
Tensile Strength ◽  
Composite Material ◽  
Composite Materials ◽  
Room Temperature ◽  
Epoxy Composite ◽  
Epoxy Composites ◽  
Tension Properties ◽  
Different Temperatures ◽  
Stereo Microscope

The aim of this paper was to present the determination of tensile strength Rm and modulus of elasticity Et of glass-epoxy composites at two different temperatures (at room temperature t=20?C, and at t =?50?C). Standard mechanical testing was carried out on glass woven-epoxy composite material with different structures (two specific weights of reinforcement, 210 g/m2 and 550 g/m2) and orientations (0?/90? and ?45?). Micromechanical analysis of failure was performed on a stereo microscope and SEM in order to determine real models and mechanisms of crack.

scholarly journals CONSEQUENCES OF PRESOWING INFLUENCE OF LOW AND VARIABLE TEMPERATURES ON CARROT AND RADISH SEEDS

2019 ◽  
pp. 62-64
Author(s):  
S. R. Gasanov ◽  
S. A. Mammadova
Keyword(s):  
Low Temperatures ◽  
Raphanus Sativus ◽  
Seed Treatment ◽  
Growth And Yield ◽  
Average Weight ◽  
Vegetable Crops ◽  
Root Crops ◽  
Different Temperatures ◽  
Sowing Seed ◽  
The Impact

The study of the dynamics of plant growth and yield of vegetable crops (carrot variety Absheron winter (Daucus carota subsp. sativus (Hoffm.) Schьbl.) and radish variety Virovsky white (Raphanus sativus var.radicula Pers.)) was conducted in the field conditions after presowing exposure to different temperatures: I option – sowing of seeds exposed to low temperatures (for 15 days the swollen for 24 hours seeds were kept at a temperature of 0±1°С); Option II - sowing of seeds exposed to variable temperatures (for 5 days, the swollen for 24 hours seeds were exposed to variable temperatures of + 20°C (8 hours) and 0±1°C (16 hours) and then 10 days at a temperature of 0±1°C; K1 – sowing dry seeds; K2 – sowing soaked seeds. The impact on the seeds of low and variable temperatures caused an increase in growth processes, both in radish and carrot. Both studied crops showed a tendency to increase the yield to a greater extent when exposed to swollen seeds with variable temperatures. Thus, the average weight of radish crops exceeded the control variant by 47.1% and carrots by 27.6%. The yield of root crops per m2increased by 36.4% for radish and 30.0% for carrot. To increase the productivity of vegetable crops, we recommend using the studied methods of pre-sowing seed treatment in practice.

Effect of Alkali Treatment and Molding Temperature on Flexural and Impact Properties of Coir-Fibre-Epoxy Composite

2015 ◽  
Vol 24 (4) ◽  
pp. 096369351502400
Author(s):  
C. K. Tai ◽  
R. Ahmad ◽  
H. M. Akil ◽  
M. M. Ratnam
Keyword(s):  
Room Temperature ◽  
Alkali Treatment ◽  
Flexural Modulus ◽  
Impact Resistance ◽  
Compression Molding ◽  
Impact Properties ◽  
Molding Temperature ◽  
Coir Fibre ◽  
Fibre Composites ◽  
The Impact

The combined effects of alkali treatment and compression molding temperature on the flexural strength and impact resistance of woven coir fibre composites are investigated. Ten pieces of composites plates made from single-layer woven coir fibre fabricated under different process parameters were used in the study. Five pieces of the coir woven fibre were treated with 6% sodium hydroxide (NaOH) solution while another five were left untreated. The compression molding temperature were varied between room temperature (25°C), 50°C, 75°C, 100°C and 125°C. The flexural properties of the composite were evaluated using the three-point flexural test, while the impact resistance was investigated by drop weight impact tests using a specially designed indenter. The indentation radius on each test specimen was measured using a 3-D metrology system and the depth of indentation was determined from the geometry of the indenter. The results show that the maximum flexural load to failure is improved by 38.9% when the fibres were treated and the compression molding temperature is increased to 125°C. The flexural modulus generally decreased with increase in the molding temperature. The depth of indentation in the treated coir woven composites is lower than that of untreated fibre composite at all molding temperatures. The impact resistance of both untreated and treated fibre composites decreased with the increase in the compression molding temperature. Composites fabricated by molding at room temperature, 50°C and 75°C using treated fibre produced the best impact properties.

scholarly journals Unbeeinflußbarkeit ihrer Wirkung auf Ribonuclease durch Cystamin und tiefe Temperaturen

1966 ◽  
Vol 21 (12) ◽  
pp. 1165-1170 ◽  
Author(s):  
H. Jung
Keyword(s):  
Cross Section ◽  
Low Temperatures ◽  
Room Temperature ◽  
High Efficiency ◽  
Reduction Factor ◽  
Biological Damage ◽  
Nuclear Collisions ◽  
Different Temperatures ◽  
Fast Protons ◽  
Mev Protons

Slow protons having energies below 1.5 keV dissipate their kinetic energy in matter through elastic nuclear collisions. By this process atoms are displaced out from their original positions in macromolecules. This was recently shown to cause biological damage with high efficiency. Experiments are described to test the possibility of modifying the sensitivity of ribonuclease towards elastic collisions by protective agents and by low temperatures. When cystamine is present during irradiation dry ribonuclease is protected against the action of “ionizing” fast protons (2 MeV), the dose reduction factor being 1.8. But no protection is observed when inactivation is achieved by elastic nuclear collisions (proton energy 1 keV and 1.4 keV). Similar results were obtained when the irradiations were carried out at different temperatures. Using 2 MeV protons the radiosensitivity of ribonuclease was found to be 3 times higher at room temperature than at 125 °K, but when using slow protons of 1.4 keV energy the inactivation cross section turned out to be independent of temperature. This shows that the action of elastic nuclear collisions can be modified neither by cystamine nor by low temperatures.

The effect of temperature on the oxygen consumption of isolated human umbilical arteries

1970 ◽  
Vol 48 (6) ◽  
pp. 377-381 ◽  
Author(s):  
Carol Colthart ◽  
Margot R. Roach
Keyword(s):  
Oxygen Consumption ◽  
Low Temperatures ◽  
Arrhenius Plot ◽  
Post Partum ◽  
Effect Of Temperature ◽  
Metabolic Processes ◽  
Different Temperatures ◽  
High And Low Temperatures ◽  
Umbilical Arteries

The oxygen consumption [Formula: see text] of isolated segments of 40 human umbilical arteries was measured at different temperatures from 5 °C to 37 °C with a modified Fenn microrespirometer. The values varied from 8 μl/g per h at 8 °C to 70 μl/g per h at 37 °C. The Arrhenius plot was nonlinear, and the Q10 varied from 0.11 (30–40 °C) to 1.8 (20–30 °C) and 7.1 (10–20 °C). This suggests that the metabolic processes may be different at high and low temperatures. The results were consistent for at least 5 h post partum, and did not seem to vary from one segment of the cord to another.

Considerations in Low-Temperature Mechanical Behavior of Polymer Composite Materials

2015 ◽  
Vol 760 ◽  
pp. 323-328
Author(s):  
Stefan Cotae ◽  
Constantin Popescu ◽  
Horatiu Iancau
Keyword(s):  
Tensile Strength ◽  
Mechanical Behavior ◽  
Fiber Orientation ◽  
Low Temperatures ◽  
Composite Structures ◽  
Room Temperature ◽  
Experimental Program ◽  
Independent Variables ◽  
Factorial Method ◽  
Degree Of Reinforcement

In this paper it has been sought to highlight the mechanical behavior of composite structures at low temperatures compared to mechanical behavior at room temperature. For researches an experimental program has been conceived and built using factorial method. In this method, as dependent variable was taken the tensile strength (σr), while as independent variables were taken: the fiber orientation angles (θ), the degree of reinforcement (Mf) of the composite structure and the temperature (t) at which the tests were carried out (+25°C,-25°C and-50°C respectively). It has been used a complex experimental installation, specific to tests at low temperatures.

scholarly journals The Viability ofBact. coliandBact. aerogenesin Water. A Method for the Rapid Enumeration of these Organisms

1935 ◽  
Vol 35 (3) ◽  
pp. 437-448 ◽  
Author(s):  
A. E. Platt
Keyword(s):  
River Water ◽  
Rapid Method ◽  
Environmental Conditions ◽  
Low Temperatures ◽  
Room Temperature ◽  
Sterile Water ◽  
Raw Water ◽  
Direct Plating ◽  
Rapid Enumeration ◽  
Different Temperatures

1. The survival of coliform organisms was studied in river water, either raw or sterilised, kept at different temperatures.2. For determining the coliform count and the differentialcoli-aerogenescount in sterilised river water, direct plating of the water on agar, with subsequent study of a number of colonies picked at random, was used. For raw river water the rapid method described by Wilson and his colleagues (1935) was used, which obviates the necessity of plating and of colonial examination.3. WhenBact. coliandBact. aerogeneswere held in stored river water, which was protected from agitation, they underwent a gradual decrease in numbers and finally disappeared. At 37°C. they died out rapidly, but survived for a much longer time at temperatures in the neighbourhood of 0°C. They were able to survive longer in sterile water than in raw water.4. Observations, however, made on water kept at room temperature and subjected to gentle aeration showed that not only did the organisms not die out, but that they actually multiplied, so that their numbers were considerably higher at the end of two months than at the beginning of the experiment.5. In raw river water coliform bacilli survived longer at room temperature when kept in the dark than in daylight.6. On the whole,aerogenes1proved more resistant thanBact. colito the environmental conditions provided. This was particularly noticeable in samples kept at room temperature (18°C.). In samples of raw water kept at 37°C.aerogenesproved slightly more resistant thancoli, while at 0–2°C. the reverse was true.7. The general conclusion seems to be that, except at very low temperatures,aerogenesis likely to survive longer in raw river water thanBact. coli.8. This conclusion is clearly of importance in the interpretation of thecoli-aerogenesresults in water analysis.

Effect of hybridization on the impact properties of flax/basalt epoxy composites: Influence of the stacking sequence

2019 ◽  
Vol 214 ◽  
pp. 476-485 ◽  
Author(s):  
M.R. Ricciardi ◽  
I. Papa ◽  
V. Lopresto ◽  
A. Langella ◽  
V. Antonucci
Keyword(s):  
Epoxy Composites ◽  
Stacking Sequence ◽  
Impact Properties ◽  
The Impact
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