Use and Misuse of Accelerated Aging Tests

1946 ◽  
Vol 19 (2) ◽  
pp. 444-460
Author(s):  
J. M. Buist ◽  
G. N. Welding
Keyword(s):  
Physical Properties ◽  
Accelerated Aging ◽  
Outdoor Exposure ◽  
General Term ◽  
Accurate Information ◽  
General Criterion ◽  
Elongation At Break ◽  
Small Depth ◽  
Skin Formation ◽  
The Difference

Abstract 1. The general term, aging, covers many different changes. When carrying out both natural and accelerated aging tests, it is essential to distinguish clearly between these changes and to test them separately if confusion is to be avoided. The chief agents responsible for aging are light, ozone, and oxygen, with or without heat. Each one of these can cause several types of degradation, the predominant type depending on the rubber and the conditions. 2. It is important to appreciate the difference between crazing and atmospheric cracking. Crazing is caused by the action of oxygen stimulated by light, whereas atmospheric cracking is due to attack by ozone on stretched samples. 3. It is suggested that crazing is produced in Williams' inelastic skin, and that the light-catalyzed oxidation which causes these effects is the same as that studied by Morgan and Naunton. 4. The only types of aging which require light are skin formation, crazing, and discoloration, and it is misleading to use light to test other types of aging. In the present state of knowledge the routine use of ultraviolet lamps should be abandoned until further work is done on the effect of different wave lengths. Instead, an enclosed arc should be used with a spectrum as close as possible to that of sunlight. The results of many light tests have been made useless by the omission of certain obvious precautions. For example, radiation of too great an intensity should be avoided, and the samples should not be stretched. 5. It is futile trying to use ovens, bombs or ultraviolet lamps as accelerated tests for atmospheric cracking, and it is impossible to correlate these tests with outdoor aging of stretched samples. The only accelerated test, at present, is the exposure of stretched samples to ozone. 6. When evaluating atmospheric cracking, exposure to ozone should be in darkness so as to reduce skin formation and crazing ; similarly, in outdoor exposure tests the stretched samples should be shielded from direct light. 7. In oven and bomb tests at high temperatures, the absorption of oxygen is so rapid in relation to the rate of diffusion that it can penetrate only to a small depth before being absorbed. Samples are, therefore, heterogeneous and there are several resulting deficiencies in the measurements of physical properties. Ovens and especially bombs, operated at lower temperatures, should give more accurate information. 8. Oxygen bomb tests, apart from requiring less time than those in an oven at the same temperature, are preferable as the samples are less heterogeneous at a given stage of degradation. 9. In oven or bomb tests, comparisons should be made only between samples of similar shape, and standard dimensions should be specified for general use. 10. When assessing the value of antioxidants, care should be taken to avoid mutual contamination by using special individual containers. 11. To follow oven or bomb aging at least two physical properties should be measured. 12. As a general criterion of aging, elongation at break, in the absence of reversion, is most suitable to follow oven or bomb aging. Modulus should be checked in case reversion occurs, and if so, tensile strength is to be preferred to elongation at break. 13. When heat aging tests are used as service tests, the physical properties should be measured at the temperature of aging. 14. To be able to coördinate results from different laboratories in this country, a detailed study of the accelerated aging of a single compound should be undertaken. Such a program requires the coöperation of all the main laboratories in this country.

On the sources of cosmopolitanism as an idea: The Russian and the European views

2020 ◽  
pp. 44-69
Author(s):  
E. E. Dmitrieva
Keyword(s):  
Comparative Literature ◽  
Literary History ◽  
World Literature ◽  
Literary Work ◽  
General Term ◽  
Literary Process ◽  
The Difference ◽  
Literary Environment

The article is concerned with the difference in understanding of the term ‘cosmopolitan’ inRussiaandFrance. Often considered a predominantly negative phenomenon inRussia, cosmopolitanism fi st provoked a discussion at the time when the emphasis shifted from ideology to understanding of the historical-literary process. Since the late 18th c., the idea of the possible existence of a literary work within the global literary environment (the concept of world literature)   was adjusted by the ‘golden chain’ metaphor, which enabled implementation of the ‘universality’ concept as a unity principally separate from the French idée universelle. During this evolutionary period emerged a distinctive subject of literary history: fi st, ‘humanity’ as a general term (initially identifi    with universalism or cosmopolitanism), and then ‘a nation’. But it is the discovery of the national that the author believes is connected with particularism and provincialism,   the latter summoning the memory of the noble intention of universalism and cosmopolitanism. An interim summary of the process was produced by Joseph Texte, a professor of comparative literature inLyon, at the end of the 19th c.

scholarly journals Malpigmentation of Common Sole (Solea solea) during Metamorphosis Is Associated with Differential Synaptic-Related Gene Expression

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2273
Author(s):  
Menelaos Kavouras ◽  
Emmanouil E. Malandrakis ◽  
Ewout Blom ◽  
Kyriaki Tsilika ◽  
Theodoros Danis ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nervous System ◽  
De Novo ◽  
Close Association ◽  
Ionic Channels ◽  
Long Term Potentiation ◽  
General Term ◽  
The Difference ◽  
Common Sole

In farmed flatfish, such as common sole, color disturbances are common. Dyschromia is a general term that includes the color defects on the blind and ocular sides of the fish. The purpose was to examine the difference in gene expression between normal pigmented and juveniles who present ambicoloration. The analysis was carried out with next-generation sequencing techniques and de novo assembly of the transcriptome. Transcripts that showed significant differences (FDR < 0.05) in the expression between the two groups, were related to those of zebrafish (Danio rerio), functionally identified, and classified into categories of the gene ontology. The results revealed that ambicolorated juveniles exhibit a divergent function, mainly of the central nervous system at the synaptic level, as well as the ionic channels. The close association of chromophore cells with the growth of nerve cells and the nervous system was recorded. The pathway, glutamate binding–activation of AMPA and NMDA receptors–long-term stimulation of postsynaptic potential–LTP (long term potentiation)–plasticity of synapses, appears to be affected. In addition, the development of synapses also seems to be affected by the interaction of the LGI (leucine-rich glioma inactivated) protein family with the ADAM (a disintegrin and metalloprotease) ones.

The Quality Analysis of Hallux Valgus Videos on YouTube

2021 ◽  
Author(s):  
Enes Sari ◽  
Levent FAZLI Umur
Keyword(s):  
Hallux Valgus ◽  
Information Quality ◽  
Statistical Significance ◽  
Poor Quality ◽  
Quality Analysis ◽  
Accurate Information ◽  
Youtube Videos ◽  
The Mean ◽  
The Difference

BACKGROUND:The aim of this study was to evaluate the information quality of YouTube videos on hallux valgus. METHODS:A YouTube search was performed using the keyword 'hallux valgus' to determine the first 300 videos related to hallux valgus. A total of 54 videos met our inclusion criteria and evaluated for information quality by using DISCERN, Journal of the American Medical Association (JAMA) and hallux valgus information assessment (HAVIA) scores. Number of views, time since the upload date, view rate, number of comments, number of likes, number of dislikes, video power index (VPI) values were calculated to determine video popularity. Video length (sec), video source and video content were also noted. The relation between information quality and these factors were statistically evaluated. RESULTS:The mean DISCERN score was 30.35{plus minus}11.56 (poor quality) (14-64), the mean JAMA score was 2.28{plus minus}0.96 (1-4), and the mean HAVIA score was 3.63{plus minus}2.42 (moderate quality) (0.5-8.5). Although videos uploaded by physicians had higher mean DISCERN, JAMA, and HAVIA scores than videos uploaded by non-physicians, the difference was not statistically significant. Additionally, view rates and VPI values were higher for videos uploaded by health channels, but the difference did not reach statistical significance. A statistically significant positive correlation was found between video length and DISCERN (r= 0.294, p= 0.028), and HAVIA scores (r= 0.326, p= 0.015). CONCLUSIONS:This present study demonstrated that the quality of information available on YouTube videos about hallux valgus was low and insufficient. Videos containing accurate information from reliable sources are needed to educate patients on hallux valgus, especially in less frequently mentioned topics such as postoperative complications and healing period.

Physical properties of biaxially oriented PA6 film for simultaneous stretching and sequential processing

2011 ◽  
Vol 31 (1) ◽  
Author(s):  
Masao Takashige ◽  
Toshitaka Kanai
Keyword(s):  
Impact Strength ◽  
Physical Properties ◽  
Physical Property ◽  
High Impact ◽  
Thermal Shrinkage ◽  
Double Bubble ◽  
Biaxial Stretching ◽  
High Impact Strength ◽  
The Difference ◽  
Stretching Process

Abstract There are two different stretching processes that produce the biaxially oriented film, namely the tenter process and double bubble tubular film process. Furthermore, there are two tenter processes, i.e., the sequential biaxial stretching process and simultaneous biaxial stretching process. There is no report describing the difference among film physical properties of the three different processes. The biaxially oriented polyamide film using the double bubble tubular process has good balanced physical property and high impact strength, thus it is used for proper applications utilizing their advantage properties. In this report, the influence of each biaxial stretching process on film physical properties of polyamide, which has hydrogen bond, was studied in detail. As a result, the tentering process film has anisotropic tensile properties between machine direction (MD) and transverse direction (TD). This result was influenced by a later stretching process, namely TD stretching. On the contrary, the double bubble tubular film has good balanced properties, especially thermal shrinkage and impact strength. Tentering simultaneous stretching film has much larger shrinkage in MD than in TD. The sequential stretching film has larger shrinkage in TD than in MD. The double bubble tubular film has high impact strength, because it corresponds to the balanced molecular orientation.

Cable and Wire Application: Adoption of Nanomagnesium Hydroxide Blended with LDPE/EVA for Mechanical and Physical Properties

2013 ◽  
Vol 701 ◽  
pp. 202-206
Author(s):  
Ahmad Aroziki Abdul Aziz ◽  
Sakinah Mohd Alauddin ◽  
Ruzitah Mohd Salleh ◽  
Mohammed Iqbal Shueb
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Melt Flow Index ◽  
Low Density Polyethylene ◽  
Flow Index ◽  
Low Density ◽  
Elongation At Break ◽  
Mechanical And Physical Properties ◽  
Poly Ethylene ◽  
Loading Amount

Effect of nanoMagnesium Hydroxide (MH) nloading amount to the mechanical and physical properties of Low Density Polyethylene (LDPE)/ Poly (ethylene-co vinyl acetate)(EVA) nanocomposite has been described and investigated in this paper. The tensile strength results show that increased amount of nanofiller will decrease and deteriorate the mechanical properties. The elongation at break decreased continuously with increasing loading of nanofiller. Generally, mechanical properties become poorer as loading amount increase. Melt Flow Index values for physical properties also provide same trend as mechanical properties results. Increase filler amount reduced MFI values whereby increased resistance to the flow.

scholarly journals Non-fullerene acceptor organic photovoltaics with intrinsic operational lifetimes over 30 years

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yongxi Li ◽  
Xiaheng Huang ◽  
Kan Ding ◽  
Hafiz K. M. Sheriff ◽  
Long Ye ◽  
...  
Keyword(s):  
High Efficiency ◽  
Bulk Heterojunction ◽  
Low Cost ◽  
Accelerated Aging ◽  
Outdoor Exposure ◽  
Buffer Layers ◽  
Organic Photovoltaic ◽  
Light Illumination ◽  
Energy Technology ◽  
Operational Lifetime

AbstractOrganic photovoltaic cells (OPVs) have the potential of becoming a productive renewable energy technology if the requirements of low cost, high efficiency and prolonged lifetime are simultaneously fulfilled. So far, the remaining unfulfilled promise of this technology is its inadequate operational lifetime. Here, we demonstrate that the instability of NFA solar cells arises primarily from chemical changes at organic/inorganic interfaces bounding the bulk heterojunction active region. Encapsulated devices stabilized by additional protective buffer layers as well as the integration of a simple solution processed ultraviolet filtering layer, maintain 94% of their initial efficiency under simulated, 1 sun intensity, AM1.5 G irradiation for 1900 hours at 55 °C. Accelerated aging is also induced by exposure of light illumination intensities up to 27 suns, and operation temperatures as high as 65 °C. An extrapolated intrinsic lifetime of > 5.6 × 104 h is obtained, which is equivalent to 30 years outdoor exposure.

Ceramics

1998 ◽  
Author(s):  
Norman Herz ◽  
Ervan G. Garrison
Keyword(s):  
Physical Properties ◽  
Raw Materials ◽  
General Term ◽  
Raw Material ◽  
Petrographic Analysis ◽  
Ceramic Product ◽  
Primary Interest ◽  
Archaeological Ceramics ◽  
Ethnographic Studies ◽  
Insight Into

Archaeological ceramics refers to products made primarily of clay and containing variable amounts of lithic and other materials as well. The term ceramic is derived from the Greek keramos, which has been translated as "earthenware" or "burned stuff." Ceramics include products that have been fired, primarily pottery but also brick, tile, glass, plaster, and cement as well. Since pottery is by far the most important archaeologically, and the methods of sampling and study are largely applicable to the others, this chapter is devoted primarily to pottery. Pottery then is the general term used here for artifacts made entirely or largely of clay and hardened by heat. Today, a distinction is sometimes made between pottery, applied to lower-quality ceramic wares, and the higher-grade product porcelain. No such distinction will be made here, so the term pottery alone will be used. Raw material that goes into the making of a pot includes primarily clay, but also varying amounts of temper, which is added to make the material more manageable and to help preserve the worked shape of the pot during firing. Of primary interest in ceramic studies are 1. the nature and the source of the raw materials—clays, temper, and slip (applied surface pigment)—and a reconstruction of the working methods of ancient potters; 2. the physical properties of the raw materials, from their preparation as a clay-temper body through their transformations during manufacture into a final ceramic product; 3. the nature of the chemical and mineral reactions that take place during firing as a clue to the technology available to the potter; and 4. the uses, provenance, and trade of the wares produced. Much of the information needed to answer these questions is available through standard geochemical and petrographic analysis of ceramic artifacts. Insight into the working methods of ancient potters also has been obtained through ethnographic studies of cultures where, because of isolation or conservative traditions or both, ancient methods have been preserved.

The Mechanical and Optical Properties of Injection-moulded PMMA, Filled with Glass Particles of a Matching Refractive Index

2017 ◽  
Vol 25 (6) ◽  
pp. 453-462 ◽  
Author(s):  
Wolfgang Wildner ◽  
Dietmar Drummer
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Injection Moulding ◽  
Surface Defects ◽  
Elongation At Break ◽  
Filling Degree ◽  
Moulding Process ◽  
Injection Moulding Process ◽  
The Difference ◽  
Optical And Mechanical Properties

In this paper, the optical and mechanical properties of injection-moulded plates (thickness: 1 mm) made of poly(methyl methacrylate) (PMMA) and glass particles as filler with a matching refractive index are investigated. Tests show that the orientation resulting from the injection moulding process greatly affects the tensile strength and elongation at break, whereas the elastic modulus merely depends on the filling degree, which is investigated up to 13 vol.%. In terms of the optical properties, the specimens’ haze depends on the difference in the refractive index between a glass and polymer. However, the absolute value of haze increases with increasing filling degree and decreasing particle size. Surface defects resulting from the injection moulding process were found to be the primary reason for this haze, even with identical RI between PMMA and glass.

scholarly journals Investigation on compatibility of PLA/PBAT blends modified by epoxy-terminated branched polymers through chemical micro-crosslinking

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 39-54 ◽  
Author(s):  
Bo Wang ◽  
Yujuan Jin ◽  
Kai’er Kang ◽  
Nan Yang ◽  
Yunxuan Weng ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Glass Transition ◽  
Sem Analysis ◽  
Branched Polymers ◽  
Poly Lactic Acid ◽  
Elongation At Break ◽  
Butylene Terephthalate ◽  
The Difference ◽  
Physical And Chemical ◽  
The Impact

AbstractIn this study, a type of epoxy-terminated branched polymer (ETBP) was used as an interface compati- bilizer to modify the poly lactic acid (PLA)/poly(butylene adipate-co-butylene terephthalate) (PBAT) (70/30) blends. Upon addition of ETBP, the difference in glass transition temperature between PLA and PBAT became smaller. By adding 3.0 phr of ETBP, the elongation at break of the PLA/PBAT blends was found increased from 45.8% to 272.0%; the impact strength increased from 26.2 kJ·m−2 to 45.3 kJ·m−2. In SEM analysis, it was observed that the size of the dispersed PBAT particle decreased with the increasing of ETBP content. These results indicated that the compatibility between PLA and PBAT can be effectively enhanced by using ETBP as the modifier. The modification mechanism was discussed in detail. It proposes that both physical and chemical micro-crosslinking were formed, the latter of which was confirmed by gel content analysis.

scholarly journals The Secrets of Beautiful Hair: Why is it Flexible and Elastic?

Cosmetics ◽  
2019 ◽  
Vol 6 (3) ◽  
pp. 40 ◽  
Author(s):  
Mikako Ezure ◽  
Noriyuki Tanji ◽  
Yukari Nishita ◽  
Takashi Mizooku ◽  
Shinobu Nagase ◽  
...  
Keyword(s):  
Physical Properties ◽  
Layered Structure ◽  
Outer Layer ◽  
New Technology ◽  
Selective Reduction ◽  
Cell Distribution ◽  
Cortical Cells ◽  
The Difference ◽  
The Relationship ◽  
Hair Surface

Beautiful hair, so called “SHINAYAKA” hair in Japanese, has a good appearance not only when stationary but also when in motion, and it is a highly desirable hair condition for Japanese consumers. We investigated such SHINAYAKA hair, which was selected by sensory evaluation, for the relationship between physical properties, such as flexibility and elasticity, and hair structure. It has already been reported that human hair cortical cells have two types, similar to wool: the ortho-like cortex and the para-like cortex. Microscopic observation revealed that the ortho-like cortex is distributed in the outer layer of the hair (near the hair surface) and the para-like cortex exists in the inner layer (near the center of the fiber). This cell distribution, a concentric double-layered structure, was deemed to be a characteristic of SHINAYAKA hair. Furthermore, analysis of physical properties showed the difference between the elasticity of the outer layer and inner layer, and that this difference was bigger in SHINAYAKA hair compared to other hair. This phenomenon was observed not only in Japanese hair, but also in Caucasian hair. In addition, we have developed a new technology for creating “SHINAYAKA” hair by treatment with succinic acid. Inflexible and inelastic hair can be changed by this treatment, and its flexibility and elasticity improve by selective reduction of stiffness of the outer layer.

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