Applied Industrial Hygiene Special Issue: December 1989. 200 Constitution Ave NW
An ongoing survey of workers in a carbon-fiber production plant shows no pulmonary function abnormalities and no evidence of dust-related disease. The selection of reinforcement material is based on the properties desired in the finished product. Thermoplastic granules are fed via a hopper into a screw-like plasticating barrel where melting occurs (Figure III:1-8). Kumpinsky, E. "A study on resol-type phenol-formaldehyde runaway reactions," Ind. Hoop stress Circumferential stress in a cylindrically shaped part as a result of internal or external pressure. Toughness Tendency of a material to absorb work. The reinforcement is saturated by dipping through the liquid resin (solution form, see Figure III:1-1) or by being impregnated through heat and pressure (hot melt form, see Figure III:1-2). B-stage Intermediate stage in the polymerization reaction of thermosets, following which material will soften with heat and is plastic and fusible. Metal-matrix composites Materials in which continuous carbon, silicon carbide, or ceramic fibers are embedded in a metallic matrix material. Denier A numbering system for yarn and filament in which yarn number is equal to weight in grams of 9000 meters of yarn. The National Institute for Occupational Safety and Health (NIOSH) Section Navigation. In plain weave, the warp and fill fibers alternate to make both fabric faces identical; in satin weave, the pattern produces a satin appearance, with the warp tow over several fill tows and under the next one (for example, eight-harness satin would have warp tow over seven fill tows and under the eighth). In an epoxy system, the resin components have very low vapor pressures and they are not present as a volatilized airborne hazard. The ‘Hazard classification and labelling’ section shows the hazards of a substance based on the standardised system of statements and pictograms established under the CLP (Classification Labelling and Packaging) Regulation. Buckling (composite) A failure usually characterized by fiber deflection rather than breaking because of compressive action. Storage life The amount of time a material can be stored and remain suitable for use. Polyurethanes are another group of resins used in advanced composite processes. These include: Three chlorinated hydrocarbon compounds in particular are found in the composites workplace: 1,1,1-trichloroethane (methyl chloroform). Handbook of Composites. It is not normally used in PMC processes due to fiber damage in the plasticating barrel. The evidence from human and animal studies was evaluated by IARC as insufficient to classify continuous-filament glass fibers a possible, probable, or confirmed cancer-causing material. Nondestructive testing (NDT) is broadly considered synonymous with NDI. Continuous-filament yarn Yarn that is formed by twisting two or more continuous filaments into a single continuous strand. Braiding Weaving fibers into a tubular shape. Tensile strength The maximum tensile stress sustained by a plastic specimen before it fails in a tension test. Two of the most common are 4,4'-methylene-dianiline (MDA) and 4,4'-sulfonyldianiline (DDS). Should the handling of these hardeners generate dust, measures should be taken to prevent inhalation. Selection of the proper protective materials should be based on permeation data, if available. Thermosets are by far the predominant type in use today. Nonwoven roving A reinforcement composed of continuous rovings loosely gathered together. In addition to traces of free formaldehyde, they may also contain free phenol, and contact with these resins in the uncured state is to be avoided. Amorphous Polymers that have no order to their molecules, thus no crystalline component. At normal temperatures these resins do not give off vapour but when they are heated, formaldehyde is evolved which is a potential respiratory sensitiser and has been shown in experiments to cause cancer in animals. Bearing stress Applied load divided by bearing area (hole diameter times thickness). Anisotropic The tendency of a material to exhibit different properties in response to stresses applied along axes in different directions. In addition to its natural complexity, phenolics machining also brings with it its fair share of hazards to watch out for, too. Contact molding A technique in which reinforcement and resin are placed in a mold, with cure taking place at room temperature with a catalyst/promoter system, or in a heated oven. Many of the solvents and some of the curing agents present a potential inhalation hazard. Vacuum bag molding A molding technique in which the part is cured inside a layer of film, from which entrapped air is removed by vacuum. Pp 64-67. The OSHA permissible exposure limits (PEL'S) for MDA are 10 ppb (parts per billion) expressed as an 8-hour time-weighted average, and a short-term exposure limit (STEL) of 100 ppb averaged over any 15-minute period for either general industry or construction uses of MDA. Airborne fiber of this diameter does not reach the alveoli and is nonrespirable. Most of the fibers in use are considered to be in the nonrespirable range. Curing agents, or hardeners, used with the epoxy resins are mostly amines, amides, or anhydrides. Epoxy resins have been in use in U.S. industry for over 40 years. Toxicology studies indicate the dusts should probably be controlled at levels below the PEL for inert dust, but not approaching the PEL for crystalline quartz. Materials within these categories are often called "advanced" if they combine the properties of high strength and high stiffness, low weight, corrosion resistance, and in some cases special electrical properties. Circuit One complete traverse of the fiber feed mechanism of a filament-winding machine. Tape A unidirectional woven prepreg, in widths up to 12 inches for carbon fiber, for example. While aerospace is the predominant market for advanced composites today, the industrial and automotive markets will increasingly see the use of advanced composites toward the year 2000. Advanced composite workplace manufacture advanced composites may permeate many of the most common are 4,4'-methylene-dianiline ( ). Pictograms: Signal Word: DANGER phenolic resin health hazards statements: H315 causes skin irritation proper! And solvents separation of a material formed from fibers or strands suitable for use in weaving fabrics! 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