Horn-like

All the double bonds in rubber have the Z (or cis) con figuration A different polymer of isoprene called gutta-percha has shorter polymer chains and E (or trans) double bonds Gutta percha is a tough horn like substance once used as a material for golf ball covers ... 

Plastics materials may be produced from casein by plasticising with water, extrusion and then cross-linking with formaldehyde (formolisation). The resultant products have a pleasant horn-like texture and are useful for decorative purposes. The amount of casein produced has decreased since World War n but was still one of the preferred materials for use in the decorative button industry until quite recently. 

Tetrafluoroethylene. Emulsion polymerisation of tetrafluoroethylene, catalysed by oxygen, yields polytetrafluoroethylene (Teflon) as a very tough horn-like material of high melting point. It possesses excellent electrical insulation properties and a remarkable inertness towards all chemical reagents, including aqua regia. 

Antler is the name of the bony material that makes up a deciduous pair of protrusions shed every year known as "antlers" on the heads of animals of the deer family, for example, reindeer, elk, and fallow deer. Antler has a composition similar to that of horn. Like bone, antler is made up of a hard and compact outer layer surrounding a core of spongy tissue. Since it is regularly shed from the body of the animal, it differs morphologically from horn, which is not shed (O Connor et al. 1987). 

For many purposes it is satisfactory to spread the moist inulin cake on a glass plate and allow it to dry in air. When dried this way, it takes on the form of hard horn-like masses which can be pulverized readily. The air-dried substance contains about 10% of water of hydration and a small quantity of inorganic impurities. The latter can be diminished to negligible proportions by repeating the process of solution and chilling, or by electrodialysis. 

To avoid the formation of horn-like masses, the moist inulin cake can be washed with 95% alcohol, followed by absolute alcohol. Inulin, however, has a tendency to retain alcohol.2... 

Also known as vulcanite and (mainly in the USA) hard rubber . The hard, horn-like product obtained when natural rubber and some synthetic rubbers such as nitrile (NBR) are vulcanised with a high proportion of sulphur or organic nonsulphur vulcanising agent. Butyl rubber and polysulphide rubber do not form ebonites. Ebullioscopy... 

White orthorhombic crystals density 6.66 g/cm melts at 373°C forms a horn-like mass on solidification vaporizes at 916°C decomposes slowly on exposure to light sparingly soluble in cold water (4.55 g/L at 0°C and 8.44 g/L at 20°C, respectively) moderately soluble in boiling water (44. Ig/L at 100°C) Ksp 6.60x10 at 25°C insoluble in alcohol slightly soluble in ammonia soluble in alkalies and also in sodium or potassium bromide solutions. 

The outside of the horn-like casque is often red, while the inside is a creamy yellow. This material was highly sought-after and, before the invention of firearms, very difficult to obtain. Asian artists produced snuff bottles, buttons, netsukes, and other small objects from this material. Sometimes the entire head of the bird would be retained, parts of it carved and some areas left in their natural state, sometimes even with feathers intact. Hornbill ivory is also known as golden jade, crane s crest, crane s bill, and ha-ting. 

Sectility. This is not a useftil test as horn, like tortoiseshell and plastic, can be paired with a sharp knife. 

FIGURE 7.9 (a) An aperture with two elliptical slots fed by horn-like waveguides and (b) magnitude of its -parameters... 

According to Winter et al. (1975a), it gives a burnt, horn-like note to a sugar syrup at a concentration of 1 ppm and a solvent, latex paint-like taste to a neutral soluble coffee base at 5 ppm. 

In Fig. 5.5(b) the control domain is depicted in the parameter plane of R and K. A typical horn-like control domain similar to the ones known from other coupling schemes [44] is found. Control is achieved in a range of values of the control amplitude K, which is widened and shifted to larger K with... 

The first man-made polymer was nitrocellulose (NC). The main use of the NC resins was a replacement of the natural and expensive materials, viz., ivory, tortoise shell products, amber, ebony, onyx or alabaster. The use of cellulose acetate (CA) as a thermoplastic began in 1926. Cellulose ethers and esters became commercially available in 1927. Casein crosslinked by formaldehyde gave horn-like materials — Galalith has been used to manufacture shirt buttons, or as imitation of ivory and porcelain [Pontio, 1919]. 

Figure 15.2 shows a diagrammatic detail of the vertebrae of the spine with the discs, the spinal cord and the back muscles attached to a horn-like projection from each vertebrate. The backbone pivots about the discs between the vertebrae with reactionary force applied by the muscles. The whole of the load that is lifted is taken by the spine. 

While vulcanization of NR and GP was the first purposeful modification of natural polymers, the first man-made polymer was nitrocellulose, NC, discovered by Braconnot in 1833 (see Appendix I). Several commercial products followed, e.g., Collodion (lacquers based on alcohol-ether solution), Parkesine (the first thermoplastic material hot rolled and formable into variety of shapes), Ivorite (used as a substitute for ivory). Celluloid (camphor plasticized NC). Cellulose acetate, CA, was introduced in 1869 by Schutzenberger. Casein crosslinking by formaldehyde resulted in a 1885-patent hy Kritsche and Spitteler for what later became known as Galalith, a horn-like material quite successfully used even today as an imitation of ivory and porcelain [Seymour, 1982 1989]. 

It is a colorless, aromatic, crystalline material originally derived from camphor oil but now mostly synthesized from pinene. It is used as a plasticizer for celluloid, cellulose nitrate, and lacquers. In 1870, the Hyatt brothers were awarded a U.S. patent for a horn-like compound of camphor and cellulose nitrate, which they called celluloid. The event marked the start of the U.S. plastics industry. 

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