Optical clarity

The abrasion resistance of ionomers is outstanding, and ionomer Aims exhibit optical clarity. In composite structures ionomers serve as a heat-seal layer. 

Polycarbonates are an unusual and extremely useful class of polymers. The vast majority of polycarbonates are based on bisphenol A [80-05-7] (BPA) and sold under the trade names Lexan (GE), Makrolon (Bayer), CaUbre (Dow), and Panlite (Idemitsu). BPA polycarbonates [25037-45-0] having glass-transition temperatures in the range of 145—155°C, are widely regarded for optical clarity and exceptional impact resistance and ductiUty at room temperature and below. Other properties, such as modulus, dielectric strength, or tensile strength are comparable to other amorphous thermoplastics at similar temperatures below their respective glass-transition temperatures, T. Whereas below their Ts most amorphous polymers are stiff and britde, polycarbonates retain their ductiUty. 

Fig. 5. Phase behavior of blends of a styrene—acrylonitrile copolymer containing 19 wt % of acrylonitrile with other SAN copolymers of varying AN content and as a function of the molecular weight of the two copolymers (° ) one-phase mixture ( ) two-phase mixtures as judged by optical clarity. Curve...

It would be incomplete for any discussion of soap crystal phase properties to ignore the colloidal aspects of soap and its impact. At room temperature, the soap—water phase diagram suggests that the soap crystals should be surrounded by an isotropic Hquid phase. The colloidal properties are defined by the size, geometry, and interconnectiviness of the soap crystals. Correlations between the coUoid stmcture of the soap bar and the performance of the product are somewhat quaUtative, as there is tittle hard data presented in the literature. However, it might be anticipated that smaller crystals would lead to a softer product. Furthermore, these smaller crystals might also be expected to dissolve more readily, leading to more lather. Translucent and transparent products rely on the formation of extremely small crystals to impart optical clarity. 

Color/Transparency. Almost all amorphous engineering thermoplastics, except PC and some polyester carbonates, are inherently colored. Even polycarbonates have yellowness indexes (YI) (36) of 0.1 to 5.0. Colorless material is produced from these resins by compounding with complementary blue dyes which reduce transmission. Ha2e in amorphous resins is an indication of particulates. Ha2e reduces optical clarity and transmission. 

High optical clarity (>95% in the visible range extending into the near infrared together with a good level of transparency to ultraviolet light). 

Polymethyl Methacrylate (PMMA), This material has exceptional optical clarity and resistance to outdoor exposure. It is resistant to alkalis, detergents, oils and dilute acids but is attacked by most solvents. Its peculiar property of total internal reflection is useful in advertising signs and some medical applications. 

SAN (Tg = 105°C ) is stiffer and has better chemical and heat resistance than the homopolymer. However, it is not as clear as polystyrene, and it is used in articles that do not require optical clarity, such as appliances and houseware materials. 

Because the quality and health aspects of foods cannot be measured by a single index, it necessarily follows that the subject of control methods in the canned food industry is very broad, and includes chemical, physical, organoleptic, and bacteriological tests, only the first of which is discussed here. The measurement of color, odor, optical clarity, texture, viscosity, and chemical composition has been used to evaluate canned foods, but in many cases the methods that are applicable to one product are either not applicable to another, or can be used only after considerable modification. 

Acrylic These polymethyl methacrylate (PMMA) plastics have high optical clarity,... 

Good gloss, weather resistance, optical clarity, and color excellent electrical properties... 

Optical clarity in comparison to conventionally filled polymers... 

The main feature of this plastic is its optical clarity. It is an excellent substitute for glass. It has good mechanical properties also. But as compared to glass, it has poor scratch resistance. PMMA is used to make attractive signboards and durable lenses for automobile lighting. It is also used in buildings for decorative purposes. 

Polycarbonates form a rather specialised class of linear polyesters, since they are formed from a diol, usually an aromatic diol, with a derivative of carbonic acid. The commercially useful products also differ from other types of polyester in that they are generally non-crystalline, melt-processable polymers of high 7J, possessing very high optical clarity and toughness. 

SAN (70% styrene, 30% acrylonitrile) has better heat and chemical resistance and is stiffer than PS. The optical clarity is not as good. SAN is used in a variety of houseware applications, particularly those things that will come in contact with food (chemical attack) and those that will end up in a dishwasher (heat attack). Coffee pots and throwaway tableware are good examples. 

Disadvantages — Flatness and optical clarity issues largely unsuitable for confocal scanners. 

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