Wet layup   The application of resin to dry reinforcement in the mold. Yarn   Continuously twisted fibers or strands suitable for use in weaving into fabrics. Bag molding   A technique in which the composite material is placed in a rigid mold and covered with a flexible bag, with pressure applied by vacuum, autoclave, press, or by inflating the bag. 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. 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. Inhalation of these amines can cause irritation of the nose and throat, and lung irritation with respiratory distress. End-users also tend to be large, and many are in the aircraft and aerospace businesses. Although they came into existence at the very start of the age of polymers, they continued to be developed into more and more applications. It is important to ascertain which type of carbon-fiber precursor is used in order to evaluate the hazards. Co-cured   Cured and simultaneously bonded to another prepared surface. Cross laminated   Material laminated so that some of the layers are oriented at various angles to the other layers with respect to the laminate grain. The dusts of high-melting solids like most anhydride curing agents are severe eye and skin irritants. The process may consist of several steps including cutting out of the damaged material, depainting of the surface to be repaired, patching and sanding of the damaged area, and repainting of the repaired area. Consolidation   A processing step that compresses fiber and matrix to reduce voids and achieve a desired density. Several of the solvent classes most commonly found in the PMC workplace are listed below, along with general hazard information. The melted plastic is injected into a heated mold where the part is formed. At the same time, much of the technology is new and not presented formally in secondary or undergraduate education. (The terms graphite and carbon are often used interchangeably.) Pultrusion   A continuous process for manufacturing composites in rods, tubes, and structural shapes having a constant cross-section. 200 Constitution Ave NW The resin is often partially cured to a tack-free state called "B-staging." Details on health hazard information and workplace controls are provided in Sections VI and VII of this chapter. Debond   An unplanned nonadhered or unbonded region in an assembly. Bearing stress   Applied load divided by bearing area (hole diameter times thickness). Scarf joint   A bonded joint in which similar segments of adherends are cut away, with cut areas overlapped and bonded. Glass transition   The reversible change in an amorphous polymer between a viscous or rubbery condition and a hard, relatively brittle one. While the polyols are relatively innocuous, the isocyanates can represent a significant respiratory hazard as well as a dermal hazard. 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). Carbon fiber   An important reinforcing fiber known for its light weight, high strength, and high stiffness that is produced by pyrolysis of an organic precursor fiber in an inert atmosphere at temperatures above 1,800° F. The material may also be graphitized by heat treating above 3,000° F. Catalyst   A substance used in small quantities to promote or control the curing of a compound without being consumed in the reaction. Resins are used as the matrices to bind together the reinforcement material in composites. Since the reinforced plastics, or polymer matrix composite industry is much larger than the subject of this chapter, the term "advanced composites" is used here to define this special segment of the industry. One or more may be introduced as part of the resin or curing agent, while another may be a part of the manufacturing process. Crystallinity   The quality of having a molecular structure with atoms arranged in an orderly, three-dimensional pattern. The aerospace industry, including military and commercial aircraft of all types, is the major customer for advanced composites. Again, the choice of curing agent depends on the cure and performance characteristics desired for the finished part. A number of solvents are used in the advanced composites industry. Exposure to the high-melting solids like trimellitic anhydride and tetraphthalic anhydride can cause respiratory sensitization. Because phenol is more soluble in the resin than in water, there is no liquefying significant health hazard MATERIAL SAFETY DATA SHEET ● Several solvents may be used in any one composite process. Since these compounds act as catalysts for the reaction, they must contain active sites on their molecules. These include: Three chlorinated hydrocarbon compounds in particular are found in the composites workplace: 1,1,1-trichloroethane (methyl chloroform). Broadgoods   Fibers woven into fabrics that may or may not be impregnated with resin, usually furnished in rolls. Summary of Health Effects Phenol may cause irritation and burns by any route of exposure. Boron fiber   A fiber usually of a tungsten-filament core with elemental boron vapor deposited on it to impart strength and stiffness. 800-321-6742 (OSHA) DOT ID & Guide. Visual disturbances may also occur. The urea- and melamine-formaldehyde resins present similar hazards. Peel ply   Layer of material applied to a prepreg layup surface that is removed from the cured laminate prior to bonding operations and leaves a clean resin-rich surface ready for bonding. B-basis allowable: material property exceeds the design allowable 90 times out 100. Composite products range from skateboards to components of the space shuttle. These ingredients may be curing agents, accelerators, reactive diluents, pigments, etc. Warp   The yarns running lengthwise and parallel to the selvage in a woven fabric. Still another may be used for cleanup. Seven manufacturing processes are covered, along with two preliminary processes and two finishing processes. as a cleaning agent for removing residue from the process equipment. Polyaminoamide hardeners have a less irritating effect on the skin and mucous membranes than the aliphatic and cycloaliphatic amine hardeners, but may cause sensitization. The composites industry in the United States includes three manufacturing areas: Polymers, metals, and ceramics. Typically, a synthetic blasting agent, e.g., plastic media blast, is used. The principal hazards of carbon-fiber handling are mechanical irritation and abrasion similar to that of glass fibers. Selection of the proper protective materials should be based on permeation data, if available. Pitch-based carbon fibers may be associated with an increased risk of skin cancer, although the evidence is weak. Adhesive failure   A rupture of adhesive bond that appears to be a separation at the adhesive-adherend interface. Softwood plywood, bonded with phenolic resin Health Hazard Data Routes of entry Inhalation and skin Health hazards Indústria de Compensados Guararapes Ltda Rua Alcina Santos Araújo, 411 If panels are cut or sanded then wood dust may be inhaled or its contact to skin and may cuase irritation to sensitized individuals. Multifilament   A yarn consisting of many continuous filaments. Usually an inert atmosphere is provided inside the autoclave through the introduction of nitrogen or carbon dioxide. Frequently, curing agents containing mixtures of these amines can cause skin staining in processes requiring dermal contact, even when protective gloves are used. The number and variety of processes should give some indication of the wide spectrum of workplaces likely to be encountered by field personnel. In its pure state, phenol is a toxic and potentially deadly substance. Due to the solvents' defatting properties, repeated or prolonged skin contact with these liquids may cause dermatitis. Autoclave molding   A molding technique in which an entire assembly (layup) is placed into an autoclave at 50 to 100 psi, in order to consolidate layers of the part by removing entrapped air and volatiles. Advanced composites have been identified as an important growth sector in U.S. manufacturing. 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. Glass-transition temperature (Tg)   The approximate temperature at which increased molecular mobility results in significant changes in properties of a cured resin. After forming, the lay-up assembly is moved to an autoclave for cure under heat, vacuum and pressure. In the pultrusion process, continuous roving strands are pulled from a creel through a strand-tensioning device into a resin bath. It is not however a proven human carcinogen. Legionnaire's Disease, see OSHA's Safety and Health Topics Page for updated information. It is not normally used in PMC processes due to fiber damage in the plasticating barrel. Phenolic and amino resins are another group of PMC resins. See also B-stage, C-stage. Facebook; Twitter; LinkedIn; Syndicate; Phenol. A-basis allowable: material property exceeds the design allowable 99 times out of 100. Some of the more common thermosets include: Of these, epoxies are the most commonly used in today's PMC industry. Health Hazard Information Acute Effects: Inhalation and dermal exposure to phenol is highly irritating to the skin, eyes, and mucous membranes in humans. These include aliphatic and cycloaliphatic amines, polyaminoamides, amides, and anhydrides. Most of the fibers in use are considered to be in the nonrespirable range. Since the advanced composite industry is relatively new and still developing, other processes may be developing or changing to meet new performance requirements. Once cured, the part cannot be changed or reformed, except for finishing. Fabric, woven   A material constructed of interlaced yarns, fibers, or filaments. Reinforcement   A material added to the matrix to provide the required properties; ranges from short fibers through complex textile forms. Axial winding   A type of filament winding in which the filaments are parallel to the axis. Controlling Exposure to Hazardous Drugs, see OSHA's Safety and Health Topics Page for updated information. Several of the composites manufacturing processes are common to both segments. The selection of reinforcement material is based on the properties desired in the finished product. Usually includes application of heat to trigger curing of the resin. Specific gravity   The density (mass per unit volume) of a material divided by that of water at a standard temperature. Under normal conditions of storage and handling, no significant amounts of hazardous vapors should evolve from the "as sold" product. POTENTIAL HEALTH EFFECTS Eye contact Dust/powder may irritate eye tissue. The potential for respiratory exposure is increased when the resin mixture is applied by spraying or when curing temperatures are high enough to volatilize the resin mixture. Also called resole. Additives   Ingredients mixed into resin to improve properties. Skin   A layer of relatively dense material used in a sandwich construction on the surface of the core. 1: Composites. Carbon/graphite fibers dominate the advanced composites industry and may be made from any of three precursors, as discussed in Section C. However, the PAN-based carbon fibers are the predominant form in use today. They are typically supplied as nonreactive solids (no chemical reaction occurs during processing) and require only heat and pressure to form the finished part. In an epoxy system, the resin components have very low vapor pressures and they are not present as a volatilized airborne hazard. Often this type of glove provides the least protection against the resin and curing agent. It is used in organic metal-matrix composites. Chem. Products based on epoxy resins as a binder have become popular in various settings, among which the construction industry and in windmill blade production, as a result of their excellent technical properties. The industry can be generally divided into two basic segments, industrial composites and advanced composites. Handbook of Composites. Honeycomb may also be metallic or polymer materials in a rigid, open-cell structure. Brown and orange stains on walls and ceilings have also been reported. The processes vary widely in type of equipment and potential worker exposure. Hybrid composite   A composite with two or more reinforcing fibers. Two of the most common are 4,4'-methylene-dianiline (MDA) and 4,4'-sulfonyldianiline (DDS). Eng. The chemical irritation caused by resins can compound the mechanical irritation caused by the fibers. As measured by load/bond area, the stress required to separate a layer of material from that to which it is bonded. Balanced laminate   All lamina except those at 0/90 are placed in plus-minus pairs (not necessarily adjacent) symmetrically about the layup centerline. Delamination   The separation of a laminated plastic material along the plane of its layers. Planar winding   A type of filament winding in which the filament path lies on a plane that intersects the winding surface. health hazards found in the plastics industry and what can be done to control them. Some of the most commonly used curing agents in the advanced composite industry are the aromatic amines. Physico-chemical hazards: none Health hazards: causes skin and eye irritation, may cause an allergic skin reaction Environmental hazards: none. Selection of the proper glove for protection is important. 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. Phenolic resins boards are a new substitute of wood in highly aggressive environments. This sector of the composites industry is characterized by the use of expensive, high-performance resin systems and high-strength, high-stiffness fiber reinforcement. 200 Constitution Ave NW … Stress   The internal force that resists change in size or shape, expressed in force per unit area. X axis   The axis in the plane of the laminate used as 0 degree reference; the Y axis is the axis in the plane of the laminate perpendicular to the X axis; the Z axis is the reference axis normal to the laminate plane in composite laminates. 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. Gloves, protective clothing, and eye protection may frequently be required, especially when working with resins, curing agents, and solvents. 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 Like carbon fibers, glass fibers may also be coated with a sizing material to improve handling. www.OSHA.gov. Thermosets are subdivided into several resin systems including epoxies, phenolics, polyurethanes, and polyimides. However, respirators may be required where: Dust levels are high (resin mixing, finishing, repair); Large surface areas and significant hand work are involved; and. Sizing materials may be epoxy resins, polyvinyl acetate-chrome chloride, polyvinyl acetate-silane, polyester-silane, or epoxy-silane compounds. Out-life   The period of time a prepreg material remains in a handleable form and with properties intact outside of the specified storage environment; for example, out of the freezer in the case of thermoset prepregs. Exotherms may occur if the curing step is not done properly. These solvents may cause eye, nose, and throat irritation, and prolonged contact with the liquid may result in defatting of the skin and resultant dermatitis. The Department of Labor also cannot authorize the use of copyrighted materials contained in linked Web sites. However, they do have the potential to cause eye, skin, and upper respiratory tract irritation as a result of the mechanical properties of the fibers. Aramid   Aromatic polyamide fibers characterized by excellent high-temperature, flame-resistance, and electrical properties. Polymer   A very large molecule formed by combining a large number of smaller molecules, called monomers, in a regular pattern. Other aromatic amines used in the advanced composites industry include m-phenylene diamine and the various isomers of toluenediamine. This combination of properties makes advanced composites very attractive for aircraft and aerospace structural parts. Laser cutting. Isolation (e.g., isolated storage, separate process areas, enclosures, closed systems) and local exhaust ventilation are the primary engineering controls found in advanced composites processes. Van Nostrand Reinhold Co., New York: 1982. Circuit   One complete traverse of the fiber feed mechanism of a filament-winding machine. 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. Several of these compounds are reactive diluents and are sometimes added to the basic resin to modify performance characteristics. Release agents   Materials that are used to prevent cured matrix material from bonding to tooling. Occupational Safety and Health Administration Skin rashes are common and reportedly more severe than from glass fibers. Structural bond   A bond joining load-bearing components of an assembly. Most parts made by hand lay-up or automated tape lay-up must be cured by a combination of heat, pressure, vacuum, and inert atmosphere. The various types of workplace controls described below may typically be found in the advanced composite workplace. Resin   A material, generally a polymer, that has an indefinite and often high molecular weight and a softening or melting range and exhibits a tendency to flow when it is subjected to stress. While the polyols are relatively innocuous, the isocyanates can represent a significant respiratory hazard as well as a dermal hazard. Interlaminar   Existing or occurring between two or more adjacent laminae. Catalysts, inhibitors, flame retardants, and other additives may be included to obtain specific end-use properties and improve processing, storage, and handling characteristics. Suggested Strategies in Screening for Health Effects in Personnel who Work with Composites. Of these, epoxy systems currently dominate the advanced composite industry. The continuous cured part, usually a rod or similar shape, is then cut to the desired length (Figure III:1-7). It is made with stronger yarns in a tighter construction than the body of the fabric to prevent raveling. In June 1987, the International Agency for Research on Cancer (IARC) categorized continuous-filament glass fibers as not classifiable with respect to human carcinogenicity. Peel strength   Strength of an adhesive bond obtained by stress applied "in a peeling mode.". Thank you for visiting our site. 800-321-6742 (OSHA) The part is then cured under heat and pressure (Figure III:1-6). Bias fabric   A fabric in which warp and fill fibers are at an angle to the length. PELS for these chemicals are set at levels designed to avoid any significant health risk and are achievable with proper material handling procedures, ventilation and housekeeping. Interlaminar shear   The shearing force tending to produce displacement between two laminae along the plane of their interface; usually the weakest element of a composite. Eng. As automated processes become more predominant, the costs of advanced composites are expected to decline to the point at which these materials will be used widely in electronic, machinery, and surface transportation equipment. in process equipment containers (tanks, reactors, molds, etc.). The basic epoxy compounds most commonly used in industry are the reaction product of epichlorohydrin and bisphenol-A. Permeation data are available for many industrial chemicals, especially solvents. Once cured, a thermoset cannot be returned to the uncured state. The retina of the eye might be damaged not only by direct contact but also from MDA absorbed through ingestion. Composites are classified according to their matrix phase. 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. After the reinforcement is passed through the resin-impregnation bath, it is drawn through a shaping die to form the desired cross-section; curing takes place before the laminate can depart from that cross-section. Symptoms of systemic poisoning often involve an initial, transient CNS stimulation, followed rapidly by CNS depression. Crimp   A fiber's waviness, which determines the capacity of the fiber to cohere. Phenolic resins are a group of the most versatile polymers yet invented. Toughness   Tendency of a material to absorb work. Fauske. Likewise, machining these phenolics often creates a huge amount of abrasive … Polar winding   A type of filament winding in which the filament path passes tangent to the polar opening at one end of the chamber and tangent to the opposite side of the polar opening at the other end of the chamber. This may involve drilling, sanding, grinding, or other manual touch-up work. However, like other hydrocarbons, benzene can cause chemical pneumonia if its liquid form is aspirated in to the lungs. However, due to the same properties epoxy products are a notorious cause of allergic skin disease among workers. The second of the essential ingredients of an advanced composite system is the curing agent or hardener. These alcohols are volatile and flammable. The bismaleimides and polyamides are relative newcomers to the advanced composite industry and have not been studied to the extent of the other resins. 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. MDA is an animal carcinogen and a suspect human carcinogen by any exposure route: ingestion, inhalation, or dermal. Thermoset resins require addition of a curing agent or hardener and impregnation onto a reinforcing material, followed by a curing step to produce a cured or finished part. Doubler   Localized area of extra layers of reinforcement, usually to provide stiffness or strength for fastening or other abrupt load transfers. Synonyms & Trade Names Carbolic acid, Hydroxybenzene, Monohydroxybenzene, Phenyl alcohol, Phenyl hydroxide CAS No. Several other types of curing agents are also used in the advanced composite industry. Free formaldehyde, which is present in trace amounts and may be liberated when their resins are processed, can irritate the mucous membranes. Unbond   Area of a bonded surface in which bonding of adherends has failed to occur, or where two prepreg layers of a composite fail to adhere to each other; also denotes areas where bonding is deliberately prevented to simulate a defective bond. Aramid fibers are used to achieve high-strength, high-modulus reinforcement in plastic composites. Ability to depress the central nervous system is a characteristic property of all members of this group. Adverse Human Health Effects Eye: Essentially non-irritating to eyes Skin Contact: Prolonged exposure not likely to cause significant irritating. Co-woven fabric   A reinforcement fabric woven with two different types of fibers in individual yarns; for example, thermoplastic fibers woven side by side with carbon fibers. Dry winding   A type of filament winding in which preimpregnated roving is used. Like the epoxies, these compounds have a very low vapor pressure and usually do not present an airborne hazard unless in a mixture that is sprayed or cured at high temperatures. Pressure-bag molding   A molding technique in which a flexible bag is placed over the contact layup in the mold, sealed, and clamped in place, and pressure applied by compressed air, which forces the bag against the part while the part cures. Advanced composite systems are divided into two basic types, thermosets and thermoplastics. It may be used to provide continuous reinforcement in woven roving, filament winding, pultrusion, prepregs, or high-strength molding compounds, or it may be used chopped. TTY Aramid fibers have several useful characteristics: Textile (continuous filament) glass fibers are the type used in composite reinforcement. Areal weight   The weight of fiber per unit area (width times length) of tape or fabric. These alcohols do not usually present serious hazards in the industrial setting. See A-stage, C-stage. Occupational Safety and Health Administration, Technical Equipment: On-site Measurements, Polymer Matrix Materials: Advanced Composites. Pp 64-67. Honeycomb   Resin-impregnated material manufactured in, usually, hexagonal cells that serves as a core material in sandwich constructions. Studies of some graphite-epoxy finishing operations found respirable fractions ranging from 25% to 100%. The supplier's Material Safety Data Sheet (MSDS) should be consulted for more specific hazard information. Drape   The ability of prepreg to conform to the shape of a contoured surface. Nondestructive inspection (NDI)   A process or procedure for determining material or part characteristics without permanently altering the test subject. Field staff may expect to encounter composites more frequently in the course of their assignments. Solvents may serve three purposes: Diagrams of the major processes used in the advanced composites industry are provided in Section A of this chapter. Film adhesive   An adhesive in the form of a thin, dry, resin film with or without a carrier, commonly used for adhesion between layers of laminates. Currently, these fibers are produced from three types of materials known as precursor fibers: Aramid fibers are another human-made product. Some of these amines are also skin and respiratory-tract sensitizers. 34 (1995) 3096-3101. These fibers are produced by manufacturing the basic polymer, then spinning it into either a paper-like configuration or into fiber. Ingestion: Essentially non-irritating to cause injury. They may be biologically active and cause irritation or sensitization. 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. Thus the hazard information for all products used in the process must be considered when evaluating potential exposures. The great majority of filling materials are embedded within compound granules that are large enough not to constitute an inhalation hazard. Silicon carbide fiber   A reinforcing fiber with high strength and modulus; density is equal to that of aluminum. Resin starved   Localized area lacking sufficient resin for wetout of the fibers. Pitch   A residual petroleum product used in the manufacture of certain carbon fibers. Composite residues are often difficult to clean from operation equipment and potential worker exposure is frequently high is performed without... Die-Drawn rather than breaking because of insufficient spread or excessive pressure impact strength a material be. System retains a viscosity low enough for it to impart strength and ;. Aerospace businesses stimulation phenolic resin health hazards followed rapidly by CNS depression B-staging. including,! 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