Preform technology

An improvement in the production of foamed composite-door panels was reported by Schumacher et al (7). The process consists of the use of the SRIM process and a low-viscosity urethane foam system. In addition, vinyl- and glass-mat preform technology and IMR (internal mold release) were employed. The demold time at 75 C was 45 seconds, and molded densities were 400 to 800 g/cm. ... 

Buckley, M., March 2011. A Report on 3D Preform Technologies for Advanced Aerospace Structures, Airbus, UK. 

Jander, M. (1991) Industrial RTM New Developments in Moulding and Preforming Technologies, Technical report, Owens Corning Fiberglas, Battice. 

P. Mitschang, A. Ogale, J. Schlimbach, F. Weyrauch, C. Weimer (2003) Preform technology a necessary requirement for quality controlled LCM-processes, Polym. Polym. Compos. 11, 605. 

Figures 4 and 10 reprinted from Polym. Polym. Compos., Vol. 11,2003, Authors P. Mitschang, A. Ogale, J. Schlimbach, F, Weyrauch, C. Weimer, Title Preform technology a necessary requirement for quality controlled LCM-processes, p. 605, Copyright (2004), with permission from Kate Evans, Rapra Technology Ltd., Shawbury, Shrewsbury, Shropshire, SY 4 4NR, UK. 

Puro, A., Kell, K.-J. Complete determination of stresses in fiber preforms of arbitrary cross section. J. Lightwave Technology. 1992, 10(8) 1010-101f. 

Textile technology is used to mechanically or aerodynamicaHy arrange textile fibers into preferentially oriented webs. Fabrics produced by these systems are referred to as dry-laid nonwovens. Dry-laid nonwovens are manufactured with machinery associated with staple fiber processing, such as cards and gametts, which are designed to manipulate preformed fibers in the dry state. Also included in this category are nonwovens made from filaments in the form of tow, and fabrics composed of staple fibers and stitching filaments or yams, ie, stitchbonded nonwovens. 

This technology also allows the control of refractive index profiles by doping. AH vapor-phase techniques use a vapor stream of volatile haUdes such as SiCl, GeCl, BCl, or POCl, and gases such as CI2 or O2. The reactants are oxidized and deposited onto a substrate to produce a soHd glass preform which is then drawn into a fiber. The variations of the technique differ in the way the reactants are oxidized (16). 

An OFRR of approximately 75 pm in outer diameter (OD) is produced by rapidly pulling a capillary preform (Polymicro Technologies, Phoenix, AZ) under heat, followed by HF etching to further reduce the wall thickness to around 4 pm. The OFRR pulling system is home-built and has been detailed in Chap. 14. The wall thickness is determined from measuring the bulk RI sensitivity using different concentrations of ethanol water mixture with known RI44. 

We use polystyrene-Z>-polybutadiene block copolymers as the starting material with preformed polymer architecture. These polymers are comparatively cheap and easily accessible.1 For the present problems a series of narrowly distributed polystyrene-6-polybutadiene block copolymers with rather different molecular weights were synthesized via anionic polymerization (Figure 10.4, Table 10.1). As a test for the modification of technological products, a commercial triblock copolymer was also used. 

Therefore the preparation of an activated, preformed polymer which was capable of reacting directly with the protein molecules in solution provided a less traumatic one-step incorporation of the protein into the polymer. This new method retained the biological activity of the attached protein and was more reproducible. As one possible application of our technology, the development of a novel immunoassay is also described here. 

SOL-GEL TECHNOLOGY FOR THIN FILMS, FIBERS, PREFORMS, ELECTRONICS AND SPECIALTY SHAPES edited by Lisa C. Klein... 

Modern Manufacturing Techniques. Manufacturing techniques for making bulk vitreous silica are for the most part improved variations of the historical processes. The main exception is the sol—gel process (see Sol-gel technology). All processes involve the fusion or viscous sintering of silica particles. The particles can be in the form of a loose powder or a porous preform. The powders can be made from natural quartz or from the decomposition of chemical precursors, such as silicon tetrachloride, and tetraethylorthosilicate (1 EOS). In some approaches, such as flame hydrolysis, the powder is produced and fused in a single step. The improvements made to these techniques deal mainly with the procedures used to prepare the powders, that is, to control purity and particle size, and the specific conditions under which the powders are consolidated. 

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