Beaded fibers

Chapter 1 (Photochromic Polymers). Like most chemical reactions, photochromic reactions are influenced significantly by the media in which they occur. This chapter surveys the interactions between photochromic entities and polymer matrices in which they are incorporated either by binding them covalently to polymer backbones or by dissolving or suspending them in polymer solids. Polymeric materials play a very crucial role in studies on photochromism, particularly from a practical viewpoint since the various applications of photochromic materials invariably require that they possess definite forms like films, sheets, plates, fibers, beads, and so on, depending on the application. 

At the sol-gel transition, the molecular structure of the gel determines the probability that a gel will dry in one piece or will break into fragments. It is convenient to think of this transition as the formation of the last bond needed to create an infinite molecule. However, this transition has not been defined in terms of thermodynamics, so it may be misleading to call it the sol-gel transition at all. Yet, in practice the transition is determined by qualitative inspection when an abrupt Increase in viscosity occurs. The goal of this work with TEOS is to find the optimum combination of variables which gives a structure at the sol-gel transition which can be processed to form variously fibers, beads, frits, microballoons, shapes, seals, coatings or inorganic sponges. 

Polyphenylene sulfide Glass fiber bead reinforced High heat appUcations... 

Lam, R. C., and Kardos, J. L. The Permeability and Compressibility of Aligned and Cross-Plied Carbon Fiber Beads During Processing of Composites. SPE ANTEC, pp. 1408-12, May 1989. 

Materials used such as stifFer plastics can reduce hysteresis heating. Crystalline TPs for example (the popularly used acetal and nylon) can be stiffened by 25 to 50% with the addition of fillers and reinforcements. Others used include ABS, polycarbonates, polysulfones, phenylene oxides, polyurethanes, and thermoplastic polyesters. Additives, fillers, and reinforcements are used in plastics gears to meet different performance requirements (Chapter 1), Examples include glass fiber for added strength, and fibers, beads, and powders for reduced thermal expansion and improved dimensional stability. Other materials, such as molybdenum disulfide, polytetrafluoroethylene (PTFE), and silicones, may be added as lubricants to improve wear resistance. 

System (g/mol) Initiation of Fiber/Beads Continuous Fiber ... 

Edelman, G. M., Rutishauser, U., Millette, C. F. Cell fractionation and arrangement on fibers, beads and surfaces. Proc. nat. Acad. Sci. (Wash.) 68, 2153—2157... 

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