Optically opaque fibers

In general, textile fibers should be optically opaque so that their refractive indexes need to be significantly different from those of their most common environments, namely, air and water. Luster and color are two optical properties that relate to a fiber s aesthetic quatity and consumer acceptance. 

In spite of the fact that both studies have reported important spectral features associated with the structure-property relationship, an Achilles heel of both approaches results from the necessity of using optically transparent films to allow infrared light to pass through the sample. New materials, such as fibers and composites, cannot be studied by transmission FT-IR techniques because they are often optically opaque. Thus, in order to monitor structural changes induced by external forces, it is necessary to utilize a method permitting the detection of infrared spectra on any material, regardless of its optical properties, shape or thickness. 

In this application, the process analyzer is used in the vis-NIR spectral region to measure the clear top layer on a co-extruded polymer film. The bottom layer is pigmented to an opaque white color and its thickness cannot be determined by this method. Prior to the installation of the fiber-optic spectroscopy system, film samples were measured manually in the laboratory by a subtractive scheme. First, the total thickness of a sample was measured on a manual profilometer. The top layer of the polymer was removed with methylene chloride. The sample was then repositioned on the profilometer as closely as possible to the originally measured spot and the thickness of the second white layer was determined. The thickness of the top layer was then determined by difference. 

It is clear that the acoustic emission technique is capable of providing valuable information on the in situ strength of surface treated fibers, especially at very small gauge lengths approaching the critical aspect ratio of the fiber in the composite. The AE method should also be useful in extending the SFC test to opaque matrix resins, through which fiber fracture cannot be observed by the optical microscope. 

The optical properties of ceramics result in some of their most important applications. In their pure form, most dielectric single crystals and glasses are transparent to visible light. This behavior is very different from that of metals and semiconductors, which, unless they are very thin (<1 pm), are opaque. Many ceramics and glasses also show good transparency to infrared (IR) radiation. This property has led to the use of glasses for optical fibers for high-speed communications. 

Optical Properties. When light falls on a nylon fiber, it can be partially transmitted, absorbed, or reflected, depending on the cross-section shape and the nature of any second substance added during polymerization or melt spinning. Additive-free nylon with a standard round cross section has a translucent high sheen luster. The inherent luster of the fiber and the color introduced in dyeing are important optical properties that relate to a fabric s visual quality and its acceptance by the customer. Fibers that need to be opaque or to cover well in... 

Inorganic lead compounds were used in paints and organic compoimds in fuel to increase octane number, until concerns about lead s toxic properties arose. Lead is relatively opaque to ionizing radiation and is a valuable shielding material in X-ray applications and nuclear facilities. Another market for lead is in alloys that are used as solders in applications ranging from circuit boards to heat exchangers. Lead is also used in acoustic barrier panel, glassware and ceramic, and fiber optic cables. 

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