Effect of Storage and Temperature on Flexibility of Natural and Synthetic Rubbers

1948 ◽  
Vol 21 (4) ◽  
pp. 864-876
Author(s):  
John B. Gregory ◽  
Irving Pockel ◽  
John F. Stiff
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Strain Curve ◽  
Polymer Chains ◽  
Stress Strain Curve ◽  
Low Temperature Storage ◽  
Synthetic Rubber ◽  
Loading And Unloading ◽  
Temperature Storage ◽  
Natural And Synthetic

Abstract A new method for measuring the flexibility of rubber has been described. The method consists essentially in determining the stress-strain curve obtained by loading and unloading a loop formed from a one-inch by six-inch strip cut from a test slab. A coefficient of flexibility independent of the thickness of the sample and, in addition, information on per cent resilience were obtained. By the use of the method described, the behavior of various natural and synthetic rubber gas mask facepiece compounds was studied during one month to three months' exposure at various temperatures down to −20° F. Progressive stiffening probably due to crystallization was found for natural rubber, GR-I, and GR-M compounds at low temperatures. No tendency to crystallize was noted for the GR-S compound. Of the crystallizable polymers GR-I was the most resistant, and GR-M the least resistant to stiffening during low temperature storage. It is of course evident that different polymers have inherently different degrees of resistance to low temperatures. Disregarding these inherent differences the work reported indicates that the resistance of elastomer compounds to stiffening during prolonged low temperature storage is favored by the following: 1. Use of interpolymers made from monomer mixtures having a relatively large proportion of each component, thus obtaining mutual intereference with crystallization. 2. Use of a “tight” cure which probably so impedes the movement of the polymer chains as to make crystallization difficult.

scholarly journals THE PROPERTIES OF THE CONIDIA OF STRAINS OF THE ACTINOMYCETE STREPTOMYCES LUCENSIS AND STREPTOMYCES VIOLACEUS DURING STORAGE AT LOW TEMPERATURES

Food systems ◽  
2018 ◽  
Vol 1 (3) ◽  
pp. 27-32 ◽  
Author(s):  
Natalya Yu. Sharova ◽  
Tatyana V. Vybornova ◽  
Anastasia A. Printseva ◽  
Bairta S. Manzhieva
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Saline Solution ◽  
Native Solution ◽  
Aqueous Sodium Chloride Solution ◽  
Glycerin Solution ◽  
Low Temperature Storage ◽  
Temperature Storage

Collection cultures of actinomycetes are mainly stored in a dried state on adsorbents. Practiced low-temperature storage of actinomycetes at minus 70°C. The article presents the results of investigations of the properties of the conidia of strains of the actinomycete Streptomyces lucensis VKPM Ac–1743 and Streptomyces violaceus VKPM Ac–1734 is in the process of storage at minus 12°C and minus 18°C in glycerin solution and in 0,9 % aqueous sodium chloride solution. It was found that the inhibitory activity in the native solution for the studied strains stored in the glycerin solution at minus 12°C and plus 4°C, as a result of their subsequent cultivation on the starch hydrolyzate for 120 h is at the level of (450 ± 10) IE/cm3. The indicator for crops stored at minus 18°C was higher (560 ± 10) IE/cm3. Low-temperature storage of conidia in saline solution is less effective. Pigmentation is more active in the cultivation of strains stored at minus 18°C.

Compressive Plasticity of Zr-Based Bulk Metallic Glass at Low Temperature

2012 ◽  
Vol 443-444 ◽  
pp. 583-586
Author(s):  
Ya Juan Sun ◽  
Ri Ga Wu ◽  
Hong Jing Wang
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Low Temperatures ◽  
Room Temperature ◽  
Shear Bands ◽  
Strain Curve ◽  
Testing Temperature ◽  
Stress Strain Curve

The mechanical properties of a new Zr-based bulk metallic glass at low temperatures were investigated. The results indicate that the fracture strength increases significantly (4.9%) and the global plasticity increases somewhat when testing temperature is lowered to 123K. The stress-strain curve of the sample deformed exhibits more serrations and smaller stress drop due to formation of more shear bands at low temperature than at room temperature.

scholarly journals Modification of placenta blood serum proteins under low temperature effect

2013 ◽  
Vol 59 (2) ◽  
pp. 219-234
Author(s):  
O.V. Falko ◽  
N.G. Zemlianskykh ◽  
O.V. Lipina ◽  
O.S. Procopyuk
Keyword(s):  
Low Temperature ◽  
Blood Serum ◽  
Low Temperatures ◽  
Structural Changes ◽  
Serum Proteins ◽  
Protein Structures ◽  
Aggregate Formation ◽  
Low Temperature Storage ◽  
Blood Serum Proteins ◽  
Temperature Storage

Changes in environmental physical and chemical factors upon freeze-thawing and low temperature storage of biological samples can result in impairments of protein structures. This work specifies spontaneous and diamide-induced protein aggregations of placenta blood serum stored at -20° and -196°C during 2 years with SDS-PAGE. It was shown that storage of placenta blood serum at low temperatures did not cause any quantitative and qualitative changes in fraction distribution of proteins denatured with SDS in comparison to the native samples which were not frozen. Application of b-mercaptoethanol revealed that placenta blood serum proteins upon freeze-thawing did not form spontaneous aggregates linked by disulphide bridges. Oxidation of amino acid sulfhydryl groups induced by diamide and accompanied by high molecular aggregate formation proved to be a quite effective way for indirect estimation of structural changes in protein upon low temperature effects. In samples thawed after low temperature storage the protein aggregation with 4 mM diamide was significantly higher than in native serum. These discrepancies between native and frozen-thawed samples are stipulated by impairments of protein structure under low temperature and increased in accessibility of reactive SH-groups of proteins for oxidation with diamide. Structural changes in placenta blood serum proteins, which caused by low temperatures and revealed by elevated sensibility to diamide-induced aggregate formation, did not depend on temperature (-20° и -196°C) and storage terms (2 years and 3 weeks). They reflect protein reaction to freeze-thawing processes and could be sequence of ice crystal formation which takes place in unprotected media.

A multifactorial study of conditions influencing longevity of neem (Azadirachta indica) seeds

1998 ◽  
Vol 8 (4) ◽  
pp. 473-482 ◽  
Author(s):  
Moctar Sacandé ◽  
Folkert A. Hoekstra ◽  
Jaap G. van Pijlen ◽  
Steven P. C. Groot
Keyword(s):  
Low Temperature ◽  
Azadirachta Indica ◽  
Low Temperatures ◽  
Oil Content ◽  
Metabolic Stress ◽  
Neem Seed ◽  
Low Temperature Storage ◽  
Open Storage ◽  
Extreme Sensitivity ◽  
Temperature Storage

AbstractThe longevity of neem, Azadirachta indica, seeds from African Sahelian (Burkina Faso) and Asian (Sri Lanka) provenances was studied over two years of storage under different conditions of moisture and temperature. After drying to equilibrium moisture content (MC) at different relative humidities at 20°C, seeds were placed in open storage at 20°C or hermetically sealed in packets at temperatures ranging from −20 to +20°C. There was hardly any difference in storage behaviour between seed batches / lots, whatever their provenance. Seeds originating from mature yellow fruits lived longer than seeds from green or brown fruits. In all storage experiments with seeds having MCs ≥ 10%, viability was preserved best at 10−15°C, indicating that neem seed is chilling (and freezing) sensitive. There was no survival longer than 2 years under these conditions. At MCs of 4–8%, seeds were considerably more tolerant of low temperature storage and had 40–60% viability after 2 years at all temperatures tested (−20 to +20°C). However, the seeds were sensitive to imbibitional stress, which could be alleviated by imbibition at temperatures of 25–30°C or above. The difficult storage behaviour of neem seed seems to stem from: (1) the sensitivity to low temperatures at MCs ≥ 10%; (2) the extreme sensitivity to imbibitional stress after storage at ≤ 8% MC; (3) underestimation of the water activity due to the high oil content of the neem seeds, causing unexpected metabolic stress in the higher MC and temperature range.

Induction of chill-induced ripening in Fuji apples is a function of both temperature and time

2003 ◽  
Vol 43 (10) ◽  
pp. 1255 ◽  
Author(s):  
J. Jobling ◽  
R. Pradhan ◽  
S. C. Morris ◽  
N. L. Wade
Keyword(s):  
Carboxylic Acid ◽  
Low Temperature ◽  
Low Temperatures ◽  
Acid Oxidase ◽  
Continuous Exposure ◽  
Controlled Atmosphere ◽  
Practical Solution ◽  
Low Temperature Storage ◽  
Increased Activity ◽  
Temperature Storage

Ethylene production is stimulated by chilling in some cultivars of apples, citrus, cucumbers and pears. The apple varieties Granny Smith, Lady Williams and Fuji can be induced to ripen by a period of chilling at 0°C in air, which hastens the onset of the rise in ethylene production.Fuji apples were susceptible to rapid ripening if stored in air at low temperatures (<10°C). The induction of rapid ripening occurred in both early and late harvested fruit and was correlated with increased activity of 1-aminocyclopropane-1-carboxylic acid oxidase during low temperature storage. The induction of rapid ripening caused the fruit to soften more quickly after cold storage than after continuous exposure to 20°C. Rapid ripening could be prevented by storing fruit in controlled atmosphere (CA) storage (2%�O2 and <1% CO2). Fruit had lower internal ethylene levels following CA storage than following low temperature air storage. The practical solution for growers would therefore be to store Fuji apples in CA, even for short periods, to optimise fruit quality for the consumer.

The effect of low temperature on preparasitic juveniles of Romanomermis (Nematoda: Mermithidae)

Nematology ◽  
1999 ◽  
Vol 1 (5) ◽  
pp. 507-511
Author(s):  
Yufang Peng ◽  
Yi Song ◽  
Jinzhang Song ◽  
Edward G. Platzer
Keyword(s):  
Low Temperature ◽  
Survival Time ◽  
Low Temperatures ◽  
Field Tests ◽  
Low Temperature Storage ◽  
Temperature Storage

Abstract This study showed that at low temperatures (-2 to 2C), more than 90% of the preparasitic juveniles of Romanomermis yunanensis and Romanomermis sp. survived for 8 and 5 days, respectively, but at 26 to 28 C and 16 to 18 C, the 90% survival time for preparasites of these species was 24 and 48 h, respectively. The percentage of mosquitoes infected by preparasites of R. yunanensis maintained at low temperature for 8-11 days was 87.5-94.3%. Preparasites of Romanomermis sp. maintained for 5 days at low temperature infected 81.5 and 55.1% of the mosquitoes in the laboratory and field tests, respectively. This infectivities were not significantly different (P > 0.05) from the pre-storage values. This data indicates that low temperature storage prolonged the survival time and had no effect on the infectivity of the preparasitic juveniles of these Romanomermis species. Effet de basses temperatures sur les juveniles infestants de Romanomermis (Nematoda: Mermithidae)- La presente etude montre qu'a basse temperature (de- 2 a + 2 C) plus de 90% des juveniles preparasites de Romanomermis yunanensis et Romanomermis sp. survivent, respectivement, 8 et 5 jours tandis qu'entre 26 et 28 C ou 16 et 18 C leur survie n'est que de 24 et 48 h, respectivement. Le pourcentage des moustiques infestes par les juveniles preparasites de R. vunanensis maintenus a basse temperature pendant 8 a 11 jours variait de 87,5 a 94,3%. Les juveniles preparasites de Romanomermis sp. maintenus 5 jours a basse temperature infestent 81,5% de moustiques lors de tests au laboratoire et 55,1% lors de tests au champ. Ces taux d'infestivite ne sont pas significativement differents (P > 0 . 05) de ceux releves avant stockage. Ces donnees indiquent que le stockage a basse temperature prolonge le temps de survie des juveniles preparasites de ces especes de Romanomermis et n'a aucun effet sur leur infestivite.

The instability of plastic flow of metals at very low temperatures

1957 ◽  
Vol 240 (1221) ◽  
pp. 229-242 ◽  
Keyword(s):  
Plastic Deformation ◽  
Transition Temperature ◽  
Low Temperature ◽  
Plastic Flow ◽  
Temperature Rise ◽  
Aluminium Alloys ◽  
Low Temperatures ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Discontinuous Flow

The low-temperature unstable plastic deformation of aluminium alloys is described. It is shown that discontinuities in the stress-strain curve are caused by a localized temperature rise produced during the deformation. The calculated magnitudes of the drops in load and the transition temperature between smooth and discontinuous flow agree reasonably well with the experimental observations. It is believed that all metals should exhibit unstable deformation at sufficiently low temperatures.

scholarly journals Perlakuan Panas untuk Mengurangi Gejala Kerusakan Dingin pada Mangga (Mangifera indica L.) var. Gadung selama Penyimpanan pada Suhu Rendah

2017 ◽  
Vol 1 (1) ◽  
pp. 8
Author(s):  
Gysberth Pattiruhu ◽  
Yohannes Aris Purwanto ◽  
Emmy Darmawanty
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Mangifera Indica ◽  
Chilling Injury ◽  
Hot Water ◽  
Low Temperature Storage ◽  
Stage Of Development ◽  
Chemical Content ◽  
Temperature Storage

Mango (Mangifera indica L.) is perishable horticulture product. Commercially, mango fruits are harvested at the mature-green stage of development and are handled at low temperatures to facilitate shipping. However, long term low temperature storage of mature-green mango fruits is currently risky because of chilling injury (CI). The ojective of this study was to examine quality changes of mango during storage at 8 oC after heatshock treatment. Heatshock treatment consist of hot water treatment (HWT) at temperature of 55 oC in 3 and 10 minutes and intermittent warming (IW) at temperature 20 oC for 1 day after 2 and 3 days of low temperature storage. The result showed that HWT of 55 oC in 3 minutes could decrease of weight loss and maintain the quality and chemical content of mango during storage at low temperatures. While IW treatment after 2 and 3 days at low temperature storage in this study was not effective in reducing chilling injury and maintaining quality of mango.Keywords: chilling injury, hetshock treatment,low temperature storage, mango

Retraction Test for Serviceability of Elastomers at Low Temperatures

1951 ◽  
Vol 24 (3) ◽  
pp. 684-696 ◽  
Author(s):  
O. H. Smith ◽  
W. A. Hermonat ◽  
H. E. Haxo ◽  
A. W. Meyer
Keyword(s):  
Low Temperature ◽  
Low Temperatures ◽  
Room Temperature ◽  
Large Deformations ◽  
Prolonged Storage ◽  
Temperature Index ◽  
Low Temperature Storage ◽  
Compression Set ◽  
Low Temperature Flexibility ◽  
Temperature Storage

Abstract Elastomer vulcanizates progressively stiffen as the temperature is lowered. Additional stiffening, due to crystallization, may occur as exposure to low temperatures is prolonged. The available methods of testing the low temperature flexibility of rubber and rubberlike materials do not reveal the losses in flexibility caused by crystallization except by using prolonged storage at low temperatures. A retraction test employing large deformations, which greatly increases the rate of crystallization, has been developed. This test rapidly gives a temperature index correlating with the stiffness of elastomer vulcanizates after storage at low temperatures, and can be used to measure the merit for low temperature applications of both crystallizable and noncrystallizable elastomers. This test in conjunction with conventional (room temperature) tests has been used successfully to study the low temperature performance of Hevea, GR-S, Paracril, and polybutadiene vulcanizates along with vulcanizates of many experimental elastomers. Correlation of results with cold compression set and hardness after low temperature storage has been excellent and substantiates the usefulness of the test.

USS 9% NICKEL STEEL

Alloy Digest ◽  
1964 ◽  
Vol 13 (8) ◽  
Keyword(s):  
United States ◽  
Fracture Toughness ◽  
Low Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Nickel Steel ◽  
Low Temperature Storage ◽  
United States Steel Corporation ◽  
Steel Corporation ◽  
Temperature Storage

Abstract USS 9% Nickel Steel was specifically developed for low-temperature storage vessels operating down to minus 320 F. It is recommended for cryogenic service. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness. Filing Code: SA-166. Producer or source: United States Steel Corporation.

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