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They are totally different substances from PMMA resins, thus should not exist in them.
PMMA resins should have excellent transparency and appearance but some foreign substances affect the transparency of them. Especially those foreign substances cause critical problems to the quality of light units and so on. LG MMA provides possible causes learnt by experience by the types of foreign substances. |
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 Colored Foreign Substance |
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Colored Foreign Substance refer to a foreign substance having its own peculiar color whileholding them against the light of polarizing microscope. The color white is excluded. |
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Type
Carbide, dust, resin+dust, fibroid material, iron pieces, wood, rubber, etc. |
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| White-colored Foreign Substance |
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White Foreign Substance is a foreign substance having white color while holding them against the light of polarizing microscope. |
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Types
Fiber(feather), macromolecular resin, pieces of glass, plastic film, resin particles, etc |
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| Florescent Foreign Substance |
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Fluorescent Foreign Substance is a foreign substance that is visible by naked eyes while holding them against the light of fluorescent lamp. |
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Types
Resin +dust, macromolecular resin, carbide, fiber(feather), resin particles, etc
Foreign substances with size 0.03mm² and over |
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| Pinhole |
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Inspect the sheet-typed PMMA resin sample produced by press mold visually with the strain tester (polarizing microscope) And then identify type and size of the detected foreign substance through a microscope. |
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| Inspection Measurements |
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Size of Foreign Substance : Inspect the foreign substances of 0.1mm² and smaller, and count them by the foreign substance value up to the size of 0.01mm² that is difficult to recognize by naked eye. |
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Classification of Foreign substances : Classify the foreign substances into three types of colored, white-colored and fluorescent substances, examine their forms and sizes under a microscope with a magnifications of 360 and below, and identify the factors. |
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Measurement Standard : Judge each of foreign substance by a lot according to the specs containing the values and sizes by grades. |
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| Inspection Method |
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Sampling : Put sample over 170g directly into a glass bottle and seal it up with plastic film. |
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Production of Specimen : Produce a specimen with size of 210mm × 210mm × 3mm by using Press Mold.( Follow the operating rules of Press Mold ) |
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Detection of Foreign Substance : Detect all the foreign substances which are visible under the polarizing microscope and examine them in the order of white foreign substances first and colored foreign substances later |
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Detection of fluorescent foreign substance : Place sample on a black paper and under a
fluorescent lamp, and detect all the foreign substances that are visible by naked eye. |
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Microscopic Examination : Classify the foreign substances by types and sizes under a microscope with a magnifications of 360 and below and analyze to find out the causes. |
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| Types of Foreign Substances Photo |
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