Optical properties translucency

Mechanical property (strength) + optical property (translucency) + favorable processing properties... 

Optical Properties and Radiation Effects. Within the range of wavelengths measured (uv, visible, and near-ir radiation), Teflon PFA fluorocarbon film transmits slightly less energy than FEP film (29) (Table 6). In thin sections, the resin is colorless and transparent in thicker sections, it becomes translucent. It is highly transparent to it radiation uv absorption is low in thin sections. Weather-O-Meter tests indicate unlimited outdoor life. 

Optical Properties. Owing to the high crystallinity of HDPE, most thick-waHed articles made from HDPE resins are opaque. Significant surface roughness can also add to the opacity. Thin HDPE film, in contrast, is translucent, but its transparency is significantly lower than that of LDPE or LLDPE film. The ultraviolet transmission limit of HDPE is around 230 nm. 

Optical Properties. Haze is the most common optical property problem that depends on colorants. Because dyes ate dissolved into the resin system, they contribute Htde or no practical haze to the system. Pigments can have significant haze, which is a combination of the pigment itself and the quahty of dispersion of the pigment. In an opaque appHcation haze is not a concern, but in transparent or translucent appHcations haze development becomes an important criterion in colorant evaluation. 

There are plastics that are transparent and translucent in the unpiginented state. They have a range of optical properties that make them interesting for a wide spectrum of optical applications that extends from windows to lens systems to sophisticated applications involving action via polarized light. Used for over a half century are aircraft canopies (thermoformed) and windows in many different structures. 

For certain AB cements, used in dentistry, optical properties are important for their overall acceptability as materials. The two particular properties of interest have been colour and translucency, both of which need to match natural tooth material as closely as possible if good aesthetics are to be developed (Wilson McLean, 1988). Of the AB cements currently used in dentistry, the glass-ionomer cement has the best aesthetics, since it has a... 

Optical properties are related to both the degree of crystallinity and the actual polymer structure. Most polymers do not possess color site units, so are colorless and transparent. But, some phenolic resins and polyacetylenes are colored, translucent, or opaque. Polymers that are transparent to visible light may be colored by the addition of colorants, and some become opaque as a result of the presence of additives such as fillers, stabilizers, moisture, and gases. 

Repeat this scenario with just about any common object you can think of, and you begin to understand why polymers are so common. Plastics come in an extremely wide range of compositions, with different physical and mechanical properties, chemical resistance, and cost. They can be molded, blow-molded, extruded, and shaped into an infinite variety of one-, two-, and three-dimensional shapes and objects. They can be made optically clear translucent, opaque, textured, and multicolored. They have made available to all of us household items that were once enjoyed only by the extremely wealthy (Wascher 1988). Thus the evolution of what many call the Plastic Age was inevitable. 

The optical properties of ceramics are useful in the ultraviolet, visible, and infrared ranges of the electromagnetic spectrum, and one key quantity used to describe the optical property of a material is the refractive index, which is a function of the frequency of the electromagnetic radiation. Other quantities used to characterize optical performance are absorption, transmission, and reflection these three properties sum to unity and are also frequency dependent. The last three properties govern many aspects of how light interacts with materials in windows, lenses, mirrors, and filters. In many consumer, decorative, and ornamental applications, the esthetic qualities of the ceramic, such as color, surface texture, gloss, opacity, and translucency, depend critically on how light interacts with the material. 

For some applications, a refractive index is important. A match between the particle size of some barium grades and the refractive index of matrix material allows the formulation of products with desirable optical properties. A series of synthetic barium sulfates is produced by Sachtleben Chemie which have particle sizes between 4 and 10 pm. If the particle size of these barium sulfates is well coordinated with the refractive index of the matrix polymer, semi-opacity combined with translucency results. This permits the foimulation of a light disperser in lampshades or in illuminated advertising displays. The coirect particle size can be calculated from the equation d = (lOOn - 141)/2, where n is the refractive index of the resin and d the particle size of barium sulfate. 

Crystallinity is important in determining optical properties because the refiaetive index of the crystalline region is always higher than that of the amorphous component irrespeetive of whether the amorphous component is in the glassy or rubbery state. This difference in refractive indices of the component phases leads to high scattering and consequently, the translucency or haziness of semicrystalline polymers. For a purely amorphous polymer, this does not occur, and hence amorphous polymers are usually transparent. Therefore the state of polyethylene terephthalate can be explained as follows ... 

Optical properties White and translucent due to high crystallinity. Limited range of colours available. 

Many polymers in everyday use contain fillers and colouring agents that render them opaque. The optical properties of the base polymer are thus obscured. On the other hand the clarity of optical transmission of many polymers and the fact that they are almost colourless, coupled with their low density and excellent mechanical properties, are the reasons for their use to replace glass in many applications. In other applications glass would be totally inappropriate because of its greater brittleness. Other polymers, such as the ubiquitous polyethylene, are often colourless but translucent rather than transparent. 

Predesigned particles of impact modifiers are based on core-shell technology. Core is involved in impact modification and shell improves adhesion between PVC and impact modifier particles.Three major combinations are used methacrylate-butadiene-styrene, MBS, which has a core made out of butadiene-styrene copolymers and shell made out of methylmethacrylate-styrene copolymer, acrylic impact modifiers, AIM, which have a core made out of acrylic and shell from polymethylmethacrylate, and silicone-acrylic have multilayer structures with silicone-acrylic in the core. MBS has excellent compatibility with PVC, similar to ABS, which is used as an impact modifier of PVC, as well. In both cases of ABS and MBS, weather resistance is lacking, therefore they are used for indoor applications only. At the same time, MBS gives translucent to crystal clear products, whereas with AIM, only translucent products are possible. In order to improve optical properties of AIM, it has to be reformulated. For transparent products, the core is made out of acrylic-styrene copolymers. Comparing silicone and all acrylic impact modifiers, PVC containing silicone-based products has superior low temperature impact properties. The incorporation of silicone into an acrylic impact modifier provides excellent weatherability, and thermal stability. It has shown improved retention of impact after outdoor weathering in PVC. ... 

Zhang H, Kim B-N, Morita K, Hiraga HYK, Sakka Y (2011) Effect of sintering tempraature on optical properties and microstiucture of translucent zirconia prepared by high-pressure spark plasma sintering. Sci Technol Adv Mater 12 055003... 

Another optical property is defined as haze, which is of importance mainly in packaging. It is measured by light diffraction, namely as the fraction of impinging light that is diffracted above 2.5 . When haze exceeds 30%, the material becomes translucent. 

The presence of crystalline regions tends to rednce the level of light transmission, and pnre semicrystalline polymers in moderate thickness are generally translucent. They include the polyolehns, polyamides, and thermoplastic polyesters. However, several crystallizing polymers can be made into highly transparent, relatively thick prodncts. They are polymethylpentene and polyethyleneterepthalate. Films of many crystallizing polymers, particnlarly oriented hhns, can also be transparent See also optical properties. 

Water-clear transparency is probably the single unique and most important attribute of polycarbonate. It is of such importance because there are very few transparent polymers—especially with high optical properties. The vast majority of polymers are opaque, with a few families providing degrees of translucency. And while it is certainly true that polycarbonate is of interest in applications other than those requiring clarity, it is also true that approximately one-half of all the polycarbonate sold is formulated... 

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