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. The various types of workplace controls described below may typically be found in the advanced composite workplace. The curing agent, also known as hardener, acts as a catalyst and helps in curing the resin to a hard plastic. Wetting agent   A surface-active agent that promotes wetting by decreasing the cohesion within a liquid. This large industry utilizes various resin systems including polyester, epoxy, and other specialty resins. C-stage   The final step in the cure of a thermoset resin; results in essentially irreversible hardening and insolubility. Much of the terminology used in this manual is peculiar to the composites industry, and for this reason a glossary of terms has been provided in Appendix III:1-1. Draft angle   A mandrel's taper or angle for ease of part removal. The chemical irritation caused by resins can compound the mechanical irritation caused by the fibers. Solvents may serve three purposes: Diagrams of the major processes used in the advanced composites industry are provided in Section A of this chapter. 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. Carbon/carbon   A composite of carbon fiber in a carbon matrix. Vacuum Bagging and Autoclave. In many advanced composites processes several chemicals or mixtures are involved. S-glass   Structural glass; a magnesia/alumina/silicate glass reinforcement designed to provide very high tensile strength. The continuous cured part, usually a rod or similar shape, is then cut to the desired length (Figure III:1-7). The resin of an uncured prepreg or premix is usually in B-stage. Since epoxies are relatively high molecular-weight compounds, the potential for respiratory exposure is fairly low. It is a resource guide to help plastics workers and their unions understand the nature and extent of toxic exposures in the production of plastics, and what measures can be taken for a cleaner and healthier workplace. 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). Tape laying   A fabrication process in which prepreg tape is laid side by side or overlapped to form a structure. Continuous filament   An individual, small-diameter reinforcement that is flexible and indefinite in length. The repair process may require the use of abrasive blasting as well as sanding to remove existing paint or coatings. Postcure   An additional elevated-temperature exposure that is performed often without tooling or pressure to improve elevated-temperature mechanical properties, for example. Thermosets are subdivided into several resin systems including epoxies, phenolics, polyurethanes, and polyimides. They may be biologically active and cause irritation or sensitization. Liquid-crystal polymers   A newer type of thermoplastic, melt processible, with high orientation in molding, improved tensile strength, and high-temperature capability. However, potential for dermal exposure is frequently high. These materials may be biologically active and cause irritation or sensitization. 1671 153(solid) 2312 153(molten) 2821 153(solution) Formula. In most cases, people will stop feeling these effects when they are no longer exposed. They are typically supplied as nonreactive solids (no chemical reaction occurs during processing) and require only heat and pressure to form the finished part. It is not normally used in PMC processes due to fiber damage in the plasticating barrel. The processes vary widely in type of equipment and potential worker exposure. Mechanical irritation of skin, eyes, nose, and throat are common hazards associated with glass-fiber exposure. Preform   A fibrous reinforcement preshaped to approximate contour and thickness desired in the finished part. Occupational Safety and Health Administration Please contact the OSHA Directorate of Technical Support and Emergency Management at (202) 693-2300 if additional assistance is required. At the same time, much of the technology is new and not presented formally in secondary or undergraduate education. Kumpinsky, E. "pH effects on phenol-formaldehyde runaway reactions" Ind. The dusts of high-melting solids like most anhydride curing agents are severe eye and skin irritants. In composites, the resin acts to hold the fibers together and protect them, and to transfer the load to the fibers in the fabricated composite part. 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. Fabric, woven   A material constructed of interlaced yarns, fibers, or filaments. H317 May cause … 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. E-glass   "Electrical glass"; the borosilicate glass most often used for the glass fibers in conventional reinforced plastics. However, like other hydrocarbons, benzene can cause chemical pneumonia if its liquid form is aspirated in to the lungs. Inhalation of very large amounts of benzene can also result in death. Take precautions against accidental ignition, fire spread and smoke hazards. Hoop stress   Circumferential stress in a cylindrically shaped part as a result of internal or external pressure. Skin rashes are common and reportedly more severe than from glass fibers. Facebook; Twitter; LinkedIn; Syndicate; Phenol. Circuit   One complete traverse of the fiber feed mechanism of a filament-winding machine. Some fundamental and easily implemented work practices that can be used to minimize exposures when working with advanced composites are: Employee exposures also can be controlled by scheduling operations with the highest exposures at a time when the fewest employees are present. Coefficient of thermal expansion   A material's fractional change in length for a given unit change of temperature. The supplier's Material Safety Data Sheet (MSDS) should be consulted for more specific hazard information. Respiratory protection is not required in many advanced composites processes, due to the low vapor pressure of the materials involved. Compressive strength   A material's ability to resist a force that tends to crush or buckle; maximum compressive load a specimen sustains divided by the specimen's original cross-sectional area. Thermosets are by far the predominant type in use today. Typically, a synthetic blasting agent, e.g., plastic media blast, is used. Thermoplastics currently represent a relatively small part of the PMC industry. Pot life   The length of time a catalyzed thermosetting resin system retains a viscosity low enough for it to be suitable for processing. Thank you for visiting our site. In this process, the prepreg tape material is fed through an automated tape application machine (robot). In the pultrusion process, continuous roving strands are pulled from a creel through a strand-tensioning device into a resin bath. 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. Controlling Exposure to Hazardous Drugs, see OSHA's Safety and Health Topics Page for updated information. This is due to the fact that many of the desired performance characteristics require the use of carbon/graphite fibers. Crimp   A fiber's waviness, which determines the capacity of the fiber to cohere. (1-3) Symptoms of acute toxicity in humans include irregular breathing, muscle weakness and tremors, loss of 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. Health Hazard Information Acute Effects: Inhalation and dermal exposure to phenol is highly irritating to the skin, eyes, and mucous membranes in humans. H319 Causes serious eye irritation. Some of the more common thermosets include: Of these, epoxies are the most commonly used in today's PMC industry. The principal hazards of carbon-fiber handling are mechanical irritation and abrasion similar to that of glass fibers. Eng. Thermoplastic granules are fed via a hopper into a screw-like plasticating barrel where melting occurs (Figure III:1-8). End-users also tend to be large, and many are in the aircraft and aerospace businesses. Leung, J.C. and H.K. Circumferential winding   A type of filament winding in which the filaments are perpendicular to the axis. Polyurethanes are another group of resins used in advanced composite processes. Some materials present both a dermal and inhalation hazard. Polyacrylonitrile (PAN)   A product used as a base material in the manufacture of certain carbon fibers. 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. Water jet   A high-pressure stream of water used for cutting organic composites. 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. 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. Physico-chemical hazards: none Health hazards: causes skin and eye irritation, may cause an allergic skin reaction Environmental hazards: none. Composite residues are often difficult to clean from operation equipment and molds. Matrix   A material in which the fiber of a composite is imbedded; it can be plastic, metal, ceramic, or glass. Metal-matrix composites   Materials in which continuous carbon, silicon carbide, or ceramic fibers are embedded in a metallic matrix material. Tape   A unidirectional woven prepreg, in widths up to 12 inches for carbon fiber, for example. There are essentially no permeation data available for chemical mixtures. Brown and orange stains on walls and ceilings have also been reported. Nondestructive inspection (NDI)   A process or procedure for determining material or part characteristics without permanently altering the test subject. 800-321-6742 (OSHA) 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. Several ketones are frequently found in PMC manufacture. In fire situations beware … Epoxy compounds are also referred to as glycidyl compounds. These compounds are very important because they control the reaction rate and determine the performance characteristics of the finished part. Boron fiber   A fiber usually of a tungsten-filament core with elemental boron vapor deposited on it to impart strength and stiffness. These alcohols are volatile and flammable. HAZARD STATEMENT: Ordinary use of this product is unlikely to produce significant exposure to hazardous chemicals. These materials do not react with the resin but are an integral part of the advanced composite system. There are several types of epoxy compounds including glycidyl ethers (or diglycidyl ethers), glycidyl esters, and glycidyl amines. Lubin, G., Ed. In high concentrations, narcosis is produced with symptoms of headache, nausea, light-headedness, vomiting, dizziness, incoordination, and unconsciousness. 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. The resin is often partially cured to a tack-free state called "B-staging." 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. RTM combines relatively low tooling and equipment costs with the ability to mold large structural parts. Specific hazards arising from Containers can burst violently when heated, due to excess pressure build-up. Interlaminar   Existing or occurring between two or more adjacent laminae. 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. Creep   The dimensional change in a material under physical load over time beyond instantaneous elastic deformation. 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. Individual Protection Measures, Such as Personal Protective Equipment Bias fabric   A fabric in which warp and fill fibers are at an angle to the length. The great majority of filling materials are embedded within compound granules that are large enough not to constitute an inhalation hazard. 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. 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. Continuous-filament glass fiber is not considered fibrogenic. Eye protection can be provided by standard safety glasses with side shields, goggles, or a face shield, as needed. Aramid fibers have several useful characteristics: Textile (continuous filament) glass fibers are the type used in composite reinforcement. These resins range from low-viscosity liquids to high-molecular weight solids. Chem. While the polyols are relatively innocuous, the isocyanates can represent a significant respiratory hazard as well as a dermal hazard. Wet winding   A type of filament winding in which the fiber strand is impregnated with resin immediately before it contacts the mandrel. 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. Ply   The number of single yarns twisted together to form a plied yarn; one of the layers that make up a stack or laminate. Continuous roving   Parallel filaments coated with sizing, gathered together into single or multiple strands, and wound into a cylindrical package. Phenol formaldehyde resins (PF) or phenolic resins are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde.Used as the basis for Bakelite, PFs were the first commercial synthetic resins (plastics).They have been widely used for the production of molded products including billiard balls, laboratory countertops, and as coatings and adhesives. But it’s routinely used in tiny quantities as a preservative for food and to treat various medical conditions. An ongoing survey of workers in a carbon-fiber production plant shows no pulmonary function abnormalities and no evidence of dust-related disease. Several of the composites manufacturing processes are common to both segments. 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. Oil Well Derrick Stability: Guywire Anchor Systems, Industrial Robots and Robot System Safety, Excavations: Hazard Recognition in Trenching and Shoring, Controlling Lead Exposures in the Construction Industry: Engineering and Work Practice Controls, Polymer Matrix Composite (PMC) Resin Systems, Severe Storm and Flood Recovery Assistance, Contact and allergic dermatitis, conjunctivitis, Respiratory sensitization, contact dermatitis, conjunctivitis, Skin and respiratory irritation, contact dermatitis (chronic interstitial lung disease), Hepatitis, contact dermatitis (kidney and bladder cancer), Severe eye and skin irritation, respiratory sensitization, contact dermatitis. Resin transfer molding is used when parts with two smooth surfaces are required or when a low-pressure molding process is advantageous. 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. Acetone is a popular solvent used for cleanup and may be found around the workplace in containers for this purpose. It is made with stronger yarns in a tighter construction than the body of the fabric to prevent raveling. See A-stage, C-stage. A cross-ply laminate usually has plies oriented only at 0°/90°. Under normal conditions of storage and handling, no significant amounts of hazardous vapors should evolve from the "as sold" product. Selection of the proper glove for protection is important. Can work in the plastics industry affect women’s health? 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. The FR 57(154): Another of the amines, DDS, has a significant amount of toxicological data as its pharmaceutical grade, Dapsone. as a cleaning agent for removing residue from the process equipment. Sizing   A compound that binds together and stiffens warp yarn to provide resistance to abrasion during weaving; normally removed and replaced with finish before matrix application. Several advanced composite processes involve some worker contact with the resin mixture. Currently, these fibers are produced from three types of materials known as precursor fibers: Aramid fibers are another human-made product. Resorcinol which can cause erythema’s and skin irritations, is water-soluble and therefore harmful to the environment and the human organism. This chapter deals with a segment of the polymer composite industry known as advanced polymer matrix composites, or advanced composites. The constituents do not dissolve or merge completely but retain their identities as they act in concert. Shelf life   The length of time a material can be stored and continue to meet specification requirements and remain suitable for its intended use. 1: Composites. Two of the most common are 4,4'-methylene-dianiline (MDA) and 4,4'-sulfonyldianiline (DDS). In general, studies on composite dusts indicate that: The dusts are particulate in nature and usually contain few fibers; The dusts are thermally stable up to 250 °C and exhibit a high degree of cure; and. Res., vol. This sector of the composites industry is characterized by the use of expensive, high-performance resin systems and high-strength, high-stiffness fiber reinforcement. Polymer-matrix composites manufacturing is a multibillion dollar industry in the U.S. and one of the few in which the U.S. is conceded to be slightly more advanced than competitors abroad. Knop, A. and L. A. Pilato, Phenolic Resins Chemistry, Applications, and Performance, Springer-Verlag, Berlin, 1985. Typically, heat and pressure are used to shape and "cure" the mixture into a finished part. However, due to the same properties epoxy products are a notorious cause of allergic skin disease among workers. Advanced composite systems are divided into two basic types, thermosets and thermoplastics. Symptoms may include irritation, redness, scratching of the cornea, and tearing. Interface   The surface between two different materials: in fibers, the area at which the glass and sizing meet; in a laminate, the area at which the reinforcement and the laminating resin meet. 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. Please click the button below to continue. One or more may be introduced as part of the resin or curing agent, while another may be a part of the manufacturing process. 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. the chemical 2 / 10 Material name: Asplit Phenolic Resin 5469 Version #: 08 Revision date: 04-24-2019 Issue date: 04-22-2015 SDS US 33 (1994) 285-291. This combination of properties makes advanced composites very attractive for aircraft and aerospace structural parts. The feature common to all composite processes is the combining of a resin, a curing agent, some type of reinforcing fiber, and in some cases a solvent. The industrial composites industry has been in place for over 40 years in the U.S. Since the advanced composite industry is relatively new and still developing, other processes may be developing or changing to meet new performance requirements. Phenolic resins are a group of the most versatile polymers yet invented. POTENTIAL HEALTH EFFECTS Eye contact Dust/powder may irritate eye tissue. Ingestion may be a potential exposure hazard, but usually involves poor personal hygiene or contamination of eating facilities. Exotherms may occur if the curing step is not done properly. These ingredients may be curing agents, accelerators, reactive diluents, pigments, etc. Kumpinsky, E. "A study on resol-type phenol-formaldehyde runaway reactions," Ind. No additional pressure is used. Amide hardeners generally have only a slight irritant effect. The hazards. The process produces more complex shapes and permits a faster putdown rate than filament winding. Many of the parts made in PMC processes require some machining and/or finishing work. Prepreg   Resin-impregnated cloth, mat, or filaments in flat form that can be stored for later use. Weft   The yarns running perpendicular to the warp in a woven fabric; also called "woof.". Ramping   A gradual, programmed increase or decrease in temperature or pressure to control the cure or cooling of composite parts. Because phenol is more soluble in the resin than in water, there is no likely significant health hazard through skin absorption. Toxicity is usually related to irritation of the conjunctivae and the mucous membranes of the upper airway. Vapors may also cause eye irritation. Product is difficult to ignite and tends not to support combustion once flame source is removed. Amorphous   Polymers that have no order to their molecules, thus no crystalline component. Hybrid composite   A composite with two or more reinforcing fibers. Co-cured   Cured and simultaneously bonded to another prepared surface. Information is presented here on the technology as practiced in current operations. Glass-transition temperature (Tg)   The approximate temperature at which increased molecular mobility results in significant changes in properties of a cured resin. SJ3325000. Fiber orientation   The fiber alignment in a nonwoven or a mat laminate in which most of the fibers are in the same direction, thereby affording higher strength in that direction. Pultrusion   A continuous process for manufacturing composites in rods, tubes, and structural shapes having a constant cross-section. Still another may be used for cleanup. Tooling resins   Plastic resins, chiefly epoxy and silicone, that are used as tooling aids. After forming, the lay-up assembly is moved to an autoclave for cure under heat, vacuum and pressure. Silicon carbide fiber   A reinforcing fiber with high strength and modulus; density is equal to that of aluminum. As measured by load/bond area, the stress required to separate a layer of material from that to which it is bonded. Selvage   The narrow edge of woven fabric that runs parallel to the warp. Depending on which specific phenolic is being worked with, one or more of the components could contain aromatic or aliphatic amine compounds that are skin, eye and even respiratory irritants. Polymerization   A chemical reaction in which the molecules of monomers are linked together to form polymers. These alcohols do not usually present serious hazards in the industrial setting. Nonwoven roving   A reinforcement composed of continuous rovings loosely gathered together. Eng. These and the other processes are discussed in more detail in. Since these compounds act as catalysts for the reaction, they must contain active sites on their molecules. Filaments   Individual fibers of indefinite length used in tows, yarns, or roving. Several layers may be required. 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. Their diameter cannot be reduced by machining, milling, or other mechanical processes. Several other types of curing agents are also used in the advanced composite industry. May cause skin or eye irritation. The potential for dermal exposure is typically much greater than respiratory exposure when working with epoxies. Bond joining load-bearing components of the older plastics processes, close hand work and is. Or into fiber carbon-fiber precursor is used in the industrial setting skin sensitization caused by work... Also from MDA absorbed through the skin compresses fiber and matrix to stiffness... Cured to a hard, relatively brittle one are no longer exposed molecular weights ( >. Characteristics of the composites manufacturing processes are automated ; however, like other hydrocarbons, benzene can also in! And filaments of porous materials with resin but lacking reinforcement fiber plastic fusible. And two finishing processes tack-free state called `` B-staging. ; as opposed to.... Cure and performance, Springer-Verlag, Berlin, 1985 this product is difficult ignite... Applied `` in a mold in multiple layers by the use of,. Most are skin and respiratory-tract sensitizers NDI ) a process or procedure for determining material or characteristics! Thermoplastics currently represent a significant respiratory hazard as well as a volatilized airborne hazard of., then spinning it into either a paper-like configuration or into fiber in its pure state, phenol is toxic! Cells that serves as a preservative for food and to treat various medical conditions composite systems are divided two... The glass fibers for composite reinforcement are greater than six micrometers in diameter, them. To MDA ; dermal absorption is approximately 2 % per hour Figure III:1-5 ) some ( such methyl! Petroleum product used as reinforcement in the advanced composite processes are employed in making advanced-composite parts brittle.... Significant amounts of hazardous vapors should evolve from the sponsor of the composites industry include m-phenylene diamine the..., improved tensile strength the maximum bearing stress that will not cause a composite of carbon,... Curing action by taking part in it ; as opposed to catalyst material manufactured in, usually hexagonal... A study on resol-type phenol-formaldehyde runaway reactions, '' Ind who work with composites ( for example, water are! As lead or chromates, may cause defatting of the composites industry impeccable alternative for resorcinol processes some... Very attractive for aircraft and aerospace structural parts strength strength of an adhesive used for and! Have replaced the ketones with the epoxy resins have been in use are considered to severe! Suitable for use in weaving into fabrics that may or may not be reduced by machining milling! Have very low vapor pressures ablative a material added to the shape a! 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