Polymers translucent/opaque resins

We will begin our discussion with the base polymer itself. While it is not an additive, it is obviously a main component of our total system and must be discussed in coloristic terms. From a color standpoint, there are three classifications of resins transparent, translucent, and opaque resins. 

There is bound to be one problem with resin glass polyalkenoate cement. Because the matrix is a mixture of hydrogel salt and polymer, lightscattering is bound to be greater than in the conventional material. Moreover, the zinc oxide-containing glass of class II materials is bound to be opaque. This makes it difficult to formulate a translucent material and is the reason why their use is restricted to that of a liner or base. However, the class II material cited will be radio-opaque because it uses strontium and zinc, rather than calcium, in the glass. 

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. 

Most polymers fall in the class of translucent resins. These include acetal, polyamide, polybutylene terephthalate (PBT), polyethylene, and polypropylene as examples. There are very few neat polymers that are truly opaque (this depends on thickness as well). Liquid crystal polymer (LCP) is an example of a typically opaque polymer. It is theorized that these semicrystalline and crystalline resins will scatter some portion of incident light due to spherulitic crystal structure and the amorphous-crystalline region interfaces themselves. 

One can assume that blends of polymers will be more difficult to color than any single component by itself. Diffuse reflection can increase due to internal light reflection or scattering at phase interfaces if the polymers are at least partially immiscible or their refractive indices are significantly different. Blends of translucent polymers are typically more opaque than either resin alone. Furthermore, colorant stability (thermal or chemical) can be adversely affected by the presence of the other polymer(s). As in the case of neat polymers, both circumstances will result in a restricted achievable color gamut for the polymer blend. An example of a prominent polymer blend is GE s Noryl (PS/PPO), which certainly colors much differently than the polystyrene component by itself. 

Tetrafluoroethene homopolymer Tetrafluoroethylene polymer Tetrafluoroethylene polymers Tetrafluoroethylene resin Ciassification Thermoplastic homopolymer Definition Polymer of tetrafluoroethylene Empiricai (C2p4)x Formuia [CF2CF2]x, x 20,000 Properties Wh. translucent to opaque solid m.w. 400,000-9,000,000 dens. 2.2 useful temp, range cryogenic to 260 C melts to vise, gel 327 C Shore hardness 55-56 tens. str. 3500-4500 psi elong. 200-300% ( break) chem. inert exc. thermal/chem. resist. lowcoeff. of friction high elec, insulation nonflamm. 

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