ASTM D Standard Test Method for Transparency of Plastic Sheeting. Clarity – ASTM D This test method covers the measurement of the transparency of plastic sheeting. While this test may be used for any transparent material. Find the most up-to-date version of ASTM D at Engineering
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ASTM D – 15 – Standard Test Method for Transparency of Plastic Sheeting
Share buttons are a little bit lower. The optical astk of a substance mainly depends on the Molecular structure, morphological characteristics type and amount of additives, processing conditions and post processing operations.
Knowledge of these optical properties is needed for several reasons: It is a fundamental property used for control the purity of the product and for optical parts design.
A specimen measuring 6. The total transmittance light is consists of the direct transmitted and diffused components which atm depending on the angular distribution of light.
There are two types of angle distribution.
Wide angle scattering Haze Narrow angle scattering Clarity or Transparency Haze is defined as the cloudy appearance on the surface of specimen. Its measured by quantity of light deviates by more than 2.
Transparency is defined as the light diffused in a small angle range within 2. The size of specimen is approximately 50mm in diameter. A detector in the sphere measures the total transmittance and haze.
The ring sensor mounted at the exit port of the sphere detects narow angle scattered light clarity. All specular gloss values are based on a primary reference standard. A polished black glass with an assign specular gloss value is The control knob is adjusted so that the meter indicates the value assigned to the primary standard.
Next, the sensor is placed on the specimen surface and the gloss value is read directly from the analog or digital display. If at any time an instrument fails to repeat readings of the standard to within 2 percent of the prior setting the intervening result should be rejected.
The gloss r1746 is directly read on the instrument. The specimen surface must be free from surface warpage, waviness, or curvature. The variables of appearance include glossiness or matness, opacity or transparency, smoothness or roughness, and metallic reflection or diffusion surfaces of parts of its rays. Colour is measured by a particular wavelength of light reflect and producing sensation in the observer eye.
There are following terminology to understand the colour theory. The two essential elements of visual colour evaluation are: A relatively flat, colored specimen is placed in a specimen holder.
A light source is illuminated. The L, a, b values are noted down. The L, a, b values are correlated with D11746, a, b Chart. Surface test areas shall be free from abrasion and warpage. Birefringence is referred to as stress birefringence and its contributions are: Orientation of the crystallites and the form birefringence arising from the interfaces between crystalline and amorphous regions.
From the orientation of the molecules further conclusions regarding the material properties can be derived. Another Polaroid plate, the analyzer, follows, being rotated with respect to the polarizer. The light is travelling in the direction perpendicular to aztm plane of the paper.
Since the refractive indexes nx and ny indirections x and y of the stressed polymer are different, the wavelengths of the two wave components tx and ty are also different, therefore the two waves will be out of phase when leaving. Specimen must be free from dust and dirt. With no sample in position the unit is standardized until a reading of relative to air is obtained.
If a calibrated standard is to be used, it is inserted in the specimen holder, and the instrument brought to balance upon the value assigned to the standard. The beam is blocked completely with a piece of block flet of paper. The specimen is placed in the specimen holder. The reading is recorded adtm percentage clarity directly from the measurement unit.
Plastic Optical Testing – ASTM d | Polyhedron Labs
aatm The difference in the two velocities shows up a birefringence. Stress optical sensitivity is define as the ability of some materials to exhibit double refraction of light when placed under stress. Awtm object is viewed from the opposite side of the light source The polarized light indicates the number of fringes or rings, which is related to the amount of stress, if light is used. Several additional techniques are used in conjunction with the basic photoelastic concept, which make it possible to analyze complex or unusual problems.
Briefly, these techniques are- Atm This technique is most often used on photoelastic coatings. Scattered — light photoelasticity: Proper intensity of light must be present.
Photoelasticity Photo-elasticity is a visual technique for measuring stresses. When a photo elastic material is strained and viewed under polarized light.
Plastic Optical Testing
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