The following acute (short-term) health effects may occur immediately or shortly after exposure to Phenol : Contact can severely irritate and burn the skin and eyes POTENTIAL HEALTH EFFECTS Eye contact Dust/powder may irritate eye tissue. Occupational Safety and Health Administration, Department of Labor, Final Rule: Occupational Exposure to 4,4'Methylenedianiline (MDA) for 29 CFR Parts 1910 and 1926. Interlaminar   Existing or occurring between two or more adjacent laminae. These materials have also been adopted for use by the sporting goods suppliers who sell high-performance equipment to the golf, tennis, fishing, and archery markets. Repair of damaged PMC parts is frequently required. Preform   A fibrous reinforcement preshaped to approximate contour and thickness desired in the finished part. Lap joint   A joint made by bonding overlapped portions of two adherends. The melted plastic is injected into a heated mold where the part is formed. HAZARD STATEMENT: Ordinary use of this product is unlikely to produce significant exposure to hazardous chemicals. Van Nostrand Reinhold Co., New York: 1982. Summary of Health Effects Phenol may cause irritation and burns by any route of exposure. Liquid-crystal polymers   A newer type of thermoplastic, melt processible, with high orientation in molding, improved tensile strength, and high-temperature capability. Ceramic-matrix composites   Materials consisting of a ceramic or carbon fiber surrounded by a ceramic matrix, usually SiC (silicon carbide). Quasi-isotropic   Approximating isotropy by orientation of plies in several directions. H319 Causes serious eye irritation. H317 May cause … Resin rich   Localized area filled with resin but lacking reinforcement fiber. Phenolic resins are a safer alternative when used as crosslinkers in rubber products. Aliphatic and cycloaliphatic amines are strong bases and are considered to be severe eye and skin irritants. Thermosets are subdivided into several resin systems including epoxies, phenolics, polyurethanes, and polyimides. At the same time, much of the technology is new and not presented formally in secondary or undergraduate education. They may be biologically active and cause irritation or sensitization. 800-321-6742 (OSHA) Several advanced composite processes involve some worker contact with the resin mixture. The urea- and melamine-formaldehyde resins present similar hazards. Woven roving   A heavy, coarse fabric produced by the weaving of continuous roving bundles. Since these compounds act as catalysts for the reaction, they must contain active sites on their molecules. They are typically supplied as nonreactive solids (no chemical reaction occurs during processing) and require only heat and pressure to form the finished part. Storage life   The amount of time a material can be stored and remain suitable for use. Young's modulus   The ratio of normal stress to the corresponding strain for tensile or compressive stresses less than the proportional limit of the material. Since the advanced composite industry is relatively new and still developing, other processes may be developing or changing to meet new performance requirements. �������5�h��#���vyU^j"MS�q2�&�Q�����*r(͇ 'ᔸϴ�;�b:�`y.���@m����'����>{3Î ��O�jħK��$F�ɠ���ڠ��. Biaxial winding   A type of filament winding in which the helical band is laid in sequence, side by side, with no crossover of the fibers. Fatigue strength   Maximum cyclical stress withstood for a given number of cycles before a material fails. Co-cured   Cured and simultaneously bonded to another prepared surface. Like carbon fibers, glass fibers may also be coated with a sizing material to improve handling. Finish   Material applied to fibers, after sizing is removed, to improve matrix-to-fiber coupling. Prepregging involves the application of formulated resin products, in solution or molten form, to a reinforcement such as carbon, fiberglass or aramid fiber or cloth. The repair process may require the use of abrasive blasting as well as sanding to remove existing paint or coatings. Usually an inert atmosphere is provided inside the autoclave through the introduction of nitrogen or carbon dioxide. Creep   The dimensional change in a material under physical load over time beyond instantaneous elastic deformation. May cause allergic skin reaction in susceptible individuals. Nonwoven roving   A reinforcement composed of continuous rovings loosely gathered together. Engineered Materials Handbook, Vol. Ingredients of the paint or coating being removed, such as lead or chromates, may also be of concern. Acute exposure to high concentrations of benzene vapour can result in central nervous system depression (eg impaired thinking, blurred vision), arrhythmias as well as irritation of the skin, eyes and respiratory system. In addition to traces of free formaldehyde, they may also contain free phenol, and contact with these resins … Thermosets are by far the predominant type in use today. Condensation   A polymerization reaction in which simple by-products (for example, water) are formed. Hardener   A substance used to promote or control curing action by taking part in it; as opposed to catalyst. Wet layup   The application of resin to dry reinforcement in the mold. If a skin rash or dermatitis is observed there are several possible causes: improper work practices are being followed; the employee is deficient in personal hygiene practices; or. TTY These compounds are formed by reacting the polyol component with an isocyanate compound, typically toluene diisocyanate (TDI); methylene diisocyanate (MDI) and hexamethylene diisocyanate (HDI) are also widely used. Lung clearance mechanisms are effective for glass fibers. Layup   The placement of layers of reinforcement in a mold. E-glass   "Electrical glass"; the borosilicate glass most often used for the glass fibers in conventional reinforced plastics. Once cured, a thermoset cannot be returned to the uncured state. Grinding, routing and sanding are frequently used methods in both processes. Eng. Epoxy compounds are also referred to as glycidyl compounds. The curing agent, also known as hardener, acts as a catalyst and helps in curing the resin to a hard plastic. Circumferential winding   A type of filament winding in which the filaments are perpendicular to the axis. Structural bond   A bond joining load-bearing components of an assembly. Other solvents that may occasionally be used are: Heated curing areas including autoclaves; following the proper procedures for production, process and control equipment; proper use, maintenance, and cleaning of personal protective equipment; periodic inspection and maintenance of production, process and control equipment; and. Phenolic resin processing (uses of downstream users of phenolic resins) * Examples for processing: Use as an intermediate, use as a monomer etc., use as a solvent, use for the manufacturing of resins. Generally, the resins are of a larger molecular size and so are less likely to permeate protective materials than the curing agents and solvents. Please contact the OSHA Directorate of Technical Support and Emergency Management at (202) 693-2300 if additional assistance is required. The epoxy molecule can also be expanded or cross-linked with other molecules to form a wide variety of resin products, each with distinct performance characteristics. Thus the hazard information for all products used in the process must be considered when evaluating potential exposures. Bismaleimide   A type of polyimide that cures by an addition reaction, avoiding formation of volatiles, and has temperature capabilities between those of epoxy and polyimide. Glass fibers, used as reinforcement in PMC processes, are a continuous-filament form and not the glass-wool (random) type. Shelf life   The length of time a material can be stored and continue to meet specification requirements and remain suitable for its intended use. The hazards. Hazards Information: Nonflammable sheet, rod and tube material which causes dust when ground or machined. Filament winding   A process for fabricating composites in which continuous reinforcing fibers, either preimpregnated with resin or drawn through a resin bath, are wound around a rotating, removable mandrel. 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). 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. Fiber placement   A continuous process for fabricating composite shapes with complex contours and/or cutouts by means of a device that lays preimpregnated fibers (in tow form) onto a nonuniform mandrel or tool. Polyurethanes are polymers that are formed by reacting an isocyanate, like TolueneDiIsocyanate , Methylene Bisphenyl Isocyanate or Hexamethylene Di Isocyanate (also referred to as HDI) and alcohol. 800-321-6742 (OSHA) This may involve drilling, sanding, grinding, or other manual touch-up work. Potential worker exposure obviously will also vary widely, depending on the size and type of process being used. While the polyols are relatively innocuous, the isocyanates can represent a significant respiratory hazard as well as a dermal hazard. Aspect ratio   The ratio of length to diameter of a fiber. Bleeder cloth   A layer of woven or nonwoven material, not a part of the composite, that allows excess gas and resin to escape during cure. Crimp   A fiber's waviness, which determines the capacity of the fiber to cohere. Amide hardeners generally have only a slight irritant effect. However, due to the same properties epoxy products are a notorious cause of allergic skin disease among workers. Thermoplastics currently represent a relatively small part of the PMC industry. Damage tolerance   A measure of the ability of structures to retain load-carrying capability after exposure to sudden loads (for example, ballistic impact). The resin systems used to manufacture advanced composites are of two basic types: thermosetting and thermoplastic. Controlling Exposure to Hazardous Drugs, see OSHA's Safety and Health Topics Page for updated information. Some hydrophthalic anhydrides have high vapor pressures at the usual processing and curing temperatures and the vapors evolved during use of these curing agents can have an irritating effect on the skin, eyes, and respiratory tract. Doubler   Localized area of extra layers of reinforcement, usually to provide stiffness or strength for fastening or other abrupt load transfers. A vacuum is applied to the bag to remove air and volatile products. Analysis and review of epidemiologic data and human and animal toxicity data indicates that occupational exposure to MDA may result in reversible liver toxicity (hepatotoxicity). For problems with accessibility in using figures and illustrations in this document, please contact the Office of Science and Technology Assessment at (202) 693-2095. Volatiles   Materials in a sizing or a resin formulation that can be vaporized at room or slightly elevated temperature. Butt joint   A joint in which parts are joined with no overlap. Roving   A collection of bundles of continuous filaments either as untwisted strands or as twisted yarns. Impact strength   A material's ability to withstand shock loading as measured by the work done in fracturing a specimen. These alcohols are volatile and flammable. Details on health hazard information and workplace controls are provided in Sections VI and VII of this chapter. However, in the case of resins and curing agents, not much data are available. The aerospace industry, including military and commercial aircraft of all types, is the major customer for advanced composites. Thermosetting resins predominate today, while thermoplastics have only a minor role in advanced composites manufacture. Composite products range from skateboards to components of the space shuttle. Buckling (composite)   A failure usually characterized by fiber deflection rather than breaking because of compressive action. Advanced composites are replacing metal components in many uses, particularly in the aerospace industry. Tape laying   A fabrication process in which prepreg tape is laid side by side or overlapped to form a structure. Scarf joint   A bonded joint in which similar segments of adherends are cut away, with cut areas overlapped and bonded. Physico-chemical hazards: none Health hazards: causes skin and eye irritation, may cause an allergic skin reaction Environmental hazards: none. Hand layup   A fabrication method in which reinforcement layers, preimpregnated or coated afterwards, are placed in a mold by hand, then cured to the formed shape. These processes vary widely, depending on the size of the finished part and the amount of finishing work required. Some of the most commonly used curing agents in the advanced composite industry are the aromatic amines. Specific gravity   The density (mass per unit volume) of a material divided by that of water at a standard temperature. Selvage   The narrow edge of woven fabric that runs parallel to the warp. Fiber reinforcement fabric or mat is laid by hand into a mold and resin mixture is poured or injected into the mold cavity. At present, both manual and automated processes are employed in making advanced-composite parts. Areal weight   The weight of fiber per unit area (width times length) of tape or fabric. One of the older plastics processes, injection molding is also the most closed process. The supplier's Material Safety Data Sheet (MSDS) should be consulted for more specific hazard information. ASM International, Metals Park, Ohio: 1987. The Department of Labor does not endorse, takes no responsibility for, and exercises no control over the linked organization or its views, or contents, nor does it vouch for the accuracy or accessibility of the information contained on the destination server. The basic process types are described below. Bias fabric   A fabric in which warp and fill fibers are at an angle to the length. In an epoxy system, the resin components have very low vapor pressures and they are not present as a volatilized airborne hazard. Resin formulation consists of mixing epoxy or other resins with other ingredients to achieve desired performance parameters. May cause skin or eye irritation. Also called resistal. The most common dust-generating processes are machining and finishing of cured parts and in repair of damaged parts. Precautions must be taken when using organic solvents because they can facilitate the entry of toxic materials into the skin and organ systems. Inhalation of very large amounts of benzene can also result in death. Phenol formaldehyde resins are an impeccable alternative for resorcinol. Vapors of the volatile amines may cause conjunctivitis and visual disturbances. In June 1987, the International Agency for Research on Cancer (IARC) categorized continuous-filament glass fibers as not classifiable with respect to human carcinogenicity. Unidirectional   Refers to fibers that are oriented in the same direction, such as unidirectional fabric, tape, or laminate, often called UD. Other aromatic amines used in the advanced composites industry include m-phenylene diamine and the various isomers of toluenediamine. Health Hazard Information Acute Effects: Inhalation and dermal exposure to phenol is highly irritating to the skin, eyes, and mucous membranes in humans. This page requires that javascript be enabled for some elements to function correctly. These and the other processes are discussed in more detail in. 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