Outdoor exposure tests of structural laminated veneer lumber I: evaluation of the physical properties after six years

2002 ◽  
Vol 48 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Tomoyuki Hayashi ◽  
Atsushi Miyatake ◽  
Masaki Harada
Keyword(s):  
Physical Properties ◽  
Outdoor Exposure ◽  
Laminated Veneer Lumber

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.

Outdoor exposure tests of structural laminated veneer lumber (II): evaluation of the strength properties after nine years

2005 ◽  
Vol 51 (5) ◽  
pp. 486-491 ◽  
Author(s):  
Tomoyuki Hayashi ◽  
Atsushi Miyatake ◽  
Feng Fu ◽  
Hideo Kato ◽  
Masahiko Karube ◽  
...  
Keyword(s):  
Outdoor Exposure ◽  
Strength Properties ◽  
Laminated Veneer Lumber

The Photometric Properties of the Ap Stars

1976 ◽  
Vol 32 ◽  
pp. 365-377 ◽  
Author(s):  
B. Hauck
Keyword(s):  
Physical Properties ◽  
Ap Stars

The Ap stars are numerous - the photometric systems tool It would be very tedious to review in detail all that which is in the literature concerning the photometry of the Ap stars. In my opinion it is necessary to examine the problem of the photometric properties of the Ap stars by considering first of all the possibility of deriving some physical properties for the Ap stars, or of detecting new ones. My talk today is prepared in this spirit. The classification by means of photoelectric photometric systems is at the present time very well established for many systems, such as UBV, uvbyβ, Vilnius, Geneva and DDO systems. Details and methods of classification can be found in Golay (1974) or in the proceedings of the Albany Colloquium edited by Philip and Hayes (1975).

The Infection of Cells by Bullet-Shaped Viruses

1969 ◽  
Vol 27 ◽  
pp. 372-373
Author(s):  
Frederick A. Murphy ◽  
Alyne K. Harrison ◽  
Sylvia G. Whitfield
Keyword(s):  
Electron Microscopy ◽  
Physical Properties ◽  
Host Cell ◽  
Thin Section ◽  
Cultured Cells ◽  
Cell Infection ◽  
Thin Section Electron Microscopy ◽  
Section Electron ◽  
Section Electron Microscopy

The bullet-shaped viruses are currently classified together on the basis of similarities in virion morphology and physical properties. Biologically and ecologically the member viruses are extremely diverse. In searching for further bases for making comparisons of these agents, the nature of host cell infection, both in vivo and in cultured cells, has been explored by thin-section electron microscopy.

Transmission electron microscopy of composite materials

1988 ◽  
Vol 46 ◽  
pp. 1012-1015
Author(s):  
K.P.D. Lagerlof
Keyword(s):  
Composite Materials ◽  
Physical Properties ◽  
Structural Defects ◽  
Structural Composites ◽  
Multiphase Materials ◽  
Structural Reinforcement ◽  
Transmission Electron ◽  
Reinforced Fiber ◽  
Particulate Reinforced Composites ◽  
Definition Of

Although most materials contain more than one phase, and thus are multiphase materials, the definition of composite materials is commonly used to describe those materials containing more than one phase deliberately added to obtain certain desired physical properties. Composite materials are often classified according to their application, i.e. structural composites and electronic composites, but may also be classified according to the type of compounds making up the composite, i.e. metal/ceramic, ceramic/ceramie and metal/semiconductor composites. For structural composites it is also common to refer to the type of structural reinforcement; whisker-reinforced, fiber-reinforced, or particulate reinforced composites [1-4].For all types of composite materials, it is of fundamental importance to understand the relationship between the microstructure and the observed physical properties, and it is therefore vital to properly characterize the microstructure. The interfaces separating the different phases comprising the composite are of particular interest to understand. In structural composites the interface is often the weakest part, where fracture will nucleate, and in electronic composites structural defects at or near the interface will affect the critical electronic properties.

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