Transparency and Opacity

Opacity or transparency is important when the amount of light to be transmitted is a consideration. These properties are usually measured as haze and luminous transmittance. As reviewed haze is defined as the percentage of transmitted light through a test specimen that is scattered more than 2.5° from the incident beam. Luminous transmittance is the ratio of transmitted light to incident light. Table 5-7 provides the optical and various other properties of different transparent plastics. 

Some definitions of key terms used in identifying optical conditions are reviewed 

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Paper and Board. For standards, see Table 1 ( Opacity and Transparency ). Methods of measurement are specified for the reflectance of paper and board (non-fluorescent), and the opacity or transparency of paper (to measure the transmitted light). 

Recrystallization too is attributable to the pigment having a specific solubility in the plastic. As in other media, it is demonstrated primarily in a change of transparency or opacity in transparent colorations and in the depth of shade in white reductions. Lack of recrystallization stability becomes evident for example in the manufacture and processing of pigment-plasticizer pastes and in various polymers at elevated processing temperatures. 

And although om natural and personal detector, the retina, shows us a tranquil sky, with a light scatter of stars across it, striking only by its steadfast inaction, the new sky revealed by telescopes and satellites sensitive to invisible emissions is one of tempest. It is animated by the birth of clouds, the creative explosion of stars and the transition of the Universe from opacity to transparence. Human perception now contemplates regions once forbidden to it. 

A glaze is defined as a thin layer on the surface of a ceramic product,either glassy or partially crystalline. Its main function is to render impermeable the surface of a porous body, to permit application of decoration techniques, and in some cases to improve the technological properties. In contrast to enamels, to which glazes are related by their naturp as well as function, a lower degree of opacity is usually required and transparent glazes are frequently employed. 

Full range of colors from colorless and transparent, with increasing opacity through white to black... 

Although certain of the above factors have been listed separately, in practice quite a few have to be considered in combination. For example, the practicability of any design has to be related to the process of manufacture and this may equally apply to the grade of plastic employed and the constituents found in the plastic. It is therefore intended to discuss some of the above factors on a broad basis and then consider the safety and functional clearance of a particular plastic pack in greater depth. Design can be considered as a relationship between size, shape, texture, colour, including opacity or transparency, the type of closure and the functional and aesthetic requirements of the pack. 

Mandelbrot s relationship (eq 18) assumes that the objects are perfectly rigid and stick immediately and irreversibly at each point of intersection (chemically equivalent to an infinite condensation rate). In fact, fractal objects are more or less compliant, and the sticking probability is always 1. These factors mitigate the criterion for mutual transparency for example, if the condensation rate is reduced, screening is less effective, and objects with D > 1.5 can interpenetrate. Because the condensation rate of silica depends strongly on pH (see Figure 3), the transparency or opacity and ultimately the film porosity can be manipulated by the addition of acid or base catalyst (24). 

Transparency (low opacity) and color are important in situations where the product should be seen, but these properties has been little studied.19,26,27... 

How do transparency, opacity, and gloss correlate with polymer morphology Explain. 

The great economic and cultural success achieved by plastics can be attributed largely to their optical properties. The ability of semi-synthetics to mimic the rich colours and opacity or transparency of natural materials endeared them... 

Translucency -s n(t)-se (ca. 1610) n. Appearance state between complete opacity and complete transparency partially opaque. 

The type of chain extender used was found to play a dominant role in the preparation of flexible, transparent polyurethanes, as mentioned previously. Use of low block ratios (i.e. low hard-segment content) was found necessary to obtain soft materials. However, soft-segment crystallization can result in opacity, so care is necessary. Samples T20, T21 and T22 of Table 12.4 are examples where soft-segment crystallization has occurred, and the resulting materials show opacity and high hardness. 

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