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  1. #1
    Mustafa Umut Sarac's Avatar
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    Glass powder + plastic : diy lens

    I am reading reports about increasing the r. index of optical plastics mixing them with some powders.
    I do not know the nature of these powders and I do not know the reason for puting the mix in oven ? Can you explain , why ?
    And what about high refractive index glass powders mixed with plastics ? Do they really transmit light better or is it a nontransparent medium ?

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    Mustafa Umut Sarac

    Veni Vidi Vici

  2. #2
    Ole
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    Unless the plastic has the same RI (Refractive Index) as the glass, it won't be transparent. And if it does, why add a different meterial?

    If the "powders" you refer to increase the RI of plastic, they must be completely dissolved in the plastic. That's the reason for baking the mix in an oven.

    One somple example of "mixed RI" substances is snow. Ice - high (relatively) RI, in Air - low RI. Non-transparent, somewhat translucent.

    Replace the air with water, and the RI's are much closer. But it still isn't transparent.

    Sugar in water - same: As long as the sugar is in grains, the mixture is non-transparent. When the sugar is dissolved and evenly distributed the mixture is transparent, and has a RI between that of water and sugar crystals.
    -- Ole Tjugen, Luddite Elitist
    Norway

  3. #3
    Mustafa Umut Sarac's Avatar
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    If powders completely dissolve in the plastic by heat , i think heat might be around 300 degrees celcius. Thiis is faraway better to melt glass at 1600 degrees.
    Ole , there are tens of papers at google on high refractive -2.4- plastics made by powder mixture. I think you can have a look and write what you found.
    I will find few links and add in 20 minutes.

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    Mustafa Umut Sarac

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    Mustafa Umut Sarac's Avatar
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    I read many papers mixing tio2 with plastics.
    I think even for a easier result , titanium dioxide can be mixed with salt and can be used to make insitu lenses as us soldiers produce their bullets from snow or sand at dan brown.

    Titanium Dioxide Crystal Types
    Titanium dioxide is manufactured in two crystal forms: anatase and rutile.

    Both anatase and rutile TiO2 produce high opacity due to their high refractive index in comparison with extenders, fillers and early pigments. See Figure 4.1.

    However, although anatase TiO2 was the first to be produced commercially, and represented a step-change in optical performance over the pigments that preceded it, the rutile form of TiO2 offers still higher opacity and durability.

    In fact, examination of the basic properties of the two crystal forms shows several differences – in specific gravity, hardness, refractive index, and relative tint strength. The oil absorption of commercial anatase and rutile pigments also varies – in part due to the different types of surface treatment applied to them. See Figure 4.2 (anatase) and Figure 4.3 (rutile) for crystal properties.

    Although both are 'white' pigments, they exhibit differences in tone with anatase pigments producing a bluer tone than rutile pigments. The reason for this can be found in their somewhat different reflectance curves across the visible and near visible spectrum. See Figure 4.4 for anatase and rutile reflectance curves.

    Thus, rutile TiO2 reflects radiation slightly better than anatase in all but the very blue end of the visible spectrum and in the ultra-violet region and is therefore slightly brighter. But because anatase TiO2 absorbs less light at the blue end of the spectrum, it has a visibly bluer tone than rutile pigment. It should be noted that the mass tone of either anatase or rutile pigments are also influenced by their purity with coloring ion impurities such as iron, niobium, vanadium and chromium having a significant effect on the color of a pigment.

    Because the rutile form absorbs more UV radiation, it further reduces the amount of energy available to degrade the binder system and provides relatively better durability to a system than anatase. However, the durability of rutile TiO2 pigment may be significantly improved by the addition of surface treatment.

    Although the difference in refractive index gives rutile pigments up to 15% opacity benefit over anatase pigments, the bluer tone and lower hardness of anatase pigments are beneficial in some applications, especially where low abrasivity may be an issue. Thus anatase pigments were originally the preferred choice for paper filling and coating and also for delustering of synthetic fibers, where the color of the application may degraded by abrasion of metal during frequent rubbing contact with machinery during processing.

    Where the highest possible optical efficiency and durability are required, rutile pigments are superior. In practice, virtually all paints and plastic applications are now pigmented with surface treated rutile pigments, with the coating specifically designed to maximize the performance properties required. Specially treated rutile pigments are also used in paper laminate applications where high opacity and good light stability are essential

  5. #5
    Mustafa Umut Sarac's Avatar
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    Nitto Denko Corp have developed a thermosetting resin with the highest refractive index in the world. It recorded a value of 1.76 while maintaining excellent thermal resistance and processing properties as a thermosetting material.

    The refractive index of the thermosetting resin can be increased through the addition titanium dioxide, zirconium dioxide and other metal oxide nanoparticles. This can lead to low power consumption and thinness through the enhancement of light emission-reception efficiency in equipment.

    Potential applications for this material include optical materials and optical communications-related optical materials for LCD, electroluminescent and other display types, as well as luminous and photosensitive devices such as LEDs and CCDs.

    Specific applications envisaged for this material include:

    · Element coatings for LED’s - Improving the light emission and reception efficiency of white LED’s.

    · Antireflective films for display devices - Such films will be able to improve the performance of LCD’s and other display devices

    · Microlenses for CCD’s - By increasing the amount of light received, the design of highly sensitive CCD’s and high definition CCD’s will be facilitated. This will lead to the design of smaller equipment.

    Advantages of this material include:

    · The high refractive index leads to excellent luminous and photosensitive efficiency

    · Excellent processing and thermal resistance properties

    · Even high refractive index materials can be achieved through the addition of other materials such as metal oxides

  6. #6
    Ole
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    Nanoparticles behave somewhat differently from powders.

    And you still need a perfectly even distribution of the nanoparticles to ensure consistent RI.

    BTW - in nature there's a third form of TiO2 called Brookite.
    -- Ole Tjugen, Luddite Elitist
    Norway

  7. #7
    Mustafa Umut Sarac's Avatar
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    Ole , do we still need to bake the nanoparticle salt or plastic mix ?

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    May be boiling nanoparticles with salty water is an answer to make homogene lens material ?
    Or may be they are using fast drying alcohol or acetone , i will learn and write.

  9. #9
    Ole
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    Mustafa,

    I believe the baking is to improve the distribution of the nanoparticles. I don't know how these nanoparticles behave, all I know is that some things get very strange when you get particles small enough - down there in the range of the wavelength of visible light. One example is Aluminium, which explodes spontaneously at that size...
    -- Ole Tjugen, Luddite Elitist
    Norway



 

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