Polyurethanes are another group of resins used in advanced composite processes. Viscosity The tendency of a material to resist flow. Matrix A material in which the fiber of a composite is imbedded; it can be plastic, metal, ceramic, or glass. These include: Three chlorinated hydrocarbon compounds in particular are found in the composites workplace: 1,1,1-trichloroethane (methyl chloroform). SJ3325000. After winding, the part is cured in an oven. 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. Respiratory protection is not required in many advanced composites processes, due to the low vapor pressure of the materials involved. In many advanced composites processes several chemicals or mixtures are involved. The most common dust-generating processes are machining and finishing of cured parts and in repair of damaged parts. Addition A polymerization reaction in which no by-products are formed. In high concentrations, narcosis is produced with symptoms of headache, nausea, light-headedness, vomiting, dizziness, incoordination, and unconsciousness. Drape The ability of prepreg to conform to the shape of a contoured surface. Continuous filament An individual, small-diameter reinforcement that is flexible and indefinite in length. Phenol formaldehyde resins are an impeccable alternative for resorcinol. Adhesive failure A rupture of adhesive bond that appears to be a separation at the adhesive-adherend interface. The advanced composite processes are discussed in more detail in Section V of this chapter. As measured by load/bond area, the stress required to separate a layer of material from that to which it is bonded. … These materials may be biologically active and cause irritation or sensitization. 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. Occupational Safety and Health Administration, Department of Labor, Final Rule: Occupational Exposure to 4,4'Methylenedianiline (MDA) for 29 CFR Parts 1910 and 1926. Two of the most widely used are the aromatic amines, MDA (4,4'-methylenedianiline) and DDS (4,4'-diaminodiphenyl-sulfone). Bidirectional laminate A reinforced plastic laminate in which the fibers are oriented in more than one direction in the plane of the laminate. Gloves, protective clothing, and eye protection may frequently be required, especially when working with resins, curing agents, and solvents. 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. 200 Constitution Ave NW
Frequently, curing agents containing mixtures of these amines can cause skin staining in processes requiring dermal contact, even when protective gloves are used. Once cured, a thermoset cannot be returned to the uncured state. Broadgoods Fibers woven into fabrics that may or may not be impregnated with resin, usually furnished in rolls. Fatigue strength Maximum cyclical stress withstood for a given number of cycles before a material fails. This sector of the composites industry is characterized by the use of expensive, high-performance resin systems and high-strength, high-stiffness fiber reinforcement. It is not however a proven human carcinogen. 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. Pitch-based carbon fibers may be associated with an increased risk of skin cancer, although the evidence is weak. the chemical 2 / 10 Material name: Asplit Phenolic Resin 5469 Version #: 08 Revision date: 04-24-2019 Issue date: 04-22-2015 SDS US The melted plastic is injected into a heated mold where the part is formed. Carbon fibers commonly in use are also greater than six micrometers in diameter, making them unlikely to be respirable. This means that, in many cases, glove and clothing selection must be a trial and error process. Occupational Safety and Health Administration
Engineered Materials Handbook, Vol. 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. MDA is an animal carcinogen and a suspect human carcinogen by any exposure route: ingestion, inhalation, or dermal. Details on health hazard information and workplace controls are provided in Sections VI and VII of this chapter. 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. Still another may be used for cleanup. The hazards. 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. Chem. Practically all glass fibers for composite reinforcement are greater than six microns in diameter. Ketones are volatile and flammable. Eng. Van Nostrand Reinhold Co., New York: 1982. Yarn Continuously twisted fibers or strands suitable for use in weaving into fabrics. They may also enhance skin sensitization caused by the resin systems. However, potential for dermal exposure is frequently high. Hybrid composite A composite with two or more reinforcing fibers. Selvage The narrow edge of woven fabric that runs parallel to the warp. Some (such as methyl alcohol) are poisonous, and all are capable of extracting fat from skin. Thermal conductivity The ability of a material to conduct heat. Chemical vapor deposition (CVD) A process in which desired reinforcement material is deposited from vapor phase onto a continuous core; boron on tungsten, for example. These and the other processes are discussed in more detail in. 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. 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. It is used in organic metal-matrix composites. 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 chemical irritation caused by resins can compound the mechanical irritation caused by the fibers. The processes vary widely in type of equipment and potential worker exposure. 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. Precautions must be taken when using organic solvents because they can facilitate the entry of toxic materials into the skin and organ systems. One or more may be introduced as part of the resin or curing agent, while another may be a part of the manufacturing process. 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. Co-cured Cured and simultaneously bonded to another prepared surface. The information presented necessarily makes reference to industrial hygiene and safe work practices, but this manual is not intended to provide comprehensive guidelines for assessing compliance with regulations. The reinforcing fiber imparts strength and other required properties to the composite. Phenolic resins are a group of the most versatile polymers yet invented. Once cured, the part cannot be changed or reformed, except for finishing. Can work in the plastics industry affect women’s health? Thank you for visiting our site. Lung clearance mechanisms are effective for glass fibers. 33 (1994) 285-291. Resins are used as the matrices to bind together the reinforcement material in composites. Harmful effects from industrial exposures come principally from skin contact and inhalation. These resins range from low-viscosity liquids to high-molecular weight solids. 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. Balanced laminate All lamina except those at 0/90 are placed in plus-minus pairs (not necessarily adjacent) symmetrically about the layup centerline. 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. 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. Thus the hazard information for all products used in the process must be considered when evaluating potential exposures. B-basis allowable: material property exceeds the design allowable 90 times out 100. 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. 1: Composites. Field staff may expect to encounter composites more frequently in the course of their assignments. Carbon/carbon A composite of carbon fiber in a carbon matrix. Curing agent A catalytic or reactive agent that brings about polymerization when it is added to a resin. Mandrel. Thermoset A plastic material that is capable of being cured by heat or catalyst into an infusible and insoluble material. Solvents may serve three purposes: Diagrams of the major processes used in the advanced composites industry are provided in Section A of this chapter. Users must request such authorization from the sponsor of the linked Web site. 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. Scarf joint A bonded joint in which similar segments of adherends are cut away, with cut areas overlapped and bonded. Continuous-filament yarn Yarn that is formed by twisting two or more continuous filaments into a single continuous strand. Thermoplastic A plastic material that is capable of being repeatedly softened by application of heat and repeatedly hardened by cooling. Potential health hazards associated with the use of advanced composites (Table III:1-1) can be controlled through the implementation of an effective industrial hygiene program. 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. Often this type of glove provides the least protection against the resin and curing agent. in process equipment containers (tanks, reactors, molds, etc.). 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 processes vary widely, depending on the size of the finished part and the amount of finishing work required. H319 Causes serious eye irritation. www.zortrax.com | 2 / 13 SAFETY DATA SHEET Resin BASIC 2.2. Modulus A measure of the ratio of load (stress) applied to the resultant deformation of a material, such as elasticity or shear. Often the glove selection process is one of trial and error. Due to the solvents' defatting properties, repeated or prolonged skin contact with these liquids may cause dermatitis. The technology of advanced composites manufacture is continually evolving, and field personnel will learn here what to expect in these processing facilities in the way of materials handled, manufacturing methods, machinery, potential worker exposures, and other relevant health and safety information. The number and variety of processes should give some indication of the wide spectrum of workplaces likely to be encountered by field personnel. 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. The principal hazards of carbon-fiber handling are mechanical irritation and abrasion similar to that of glass fibers. This type of data are often available for the solvents used, but very little data are available for the resins and curing agents. Pultrusion A continuous process for manufacturing composites in rods, tubes, and structural shapes having a constant cross-section. Hardener A substance used to promote or control curing action by taking part in it; as opposed to catalyst. They are typically supplied as nonreactive solids (no chemical reaction occurs during processing) and require only heat and pressure to form the finished part. Both thermoset and thermoplastic systems will be discussed in more detail in. To achieve proper cure, the part is placed into a plastic bag inside an autoclave (Figure III:1-9). Wrinkle An imperfection in the surface of a laminate that looks like a crease or fold in one of the outer layers; it occurs in vacuum bag molding due to improper placement of the bag. Their diameter cannot be reduced by machining, milling, or other mechanical processes. Suppliers of advanced composite materials tend to be larger companies capable of doing the research and development necessary to provide the high-performance resin systems used in this segment of the industry. Resin-transfer molding (RTM) A molding process in which catalyzed resin is transferred into an enclosed mold into which the fiber reinforcement has been placed; cure normally is accomplished without external heat. B-stage Intermediate stage in the polymerization reaction of thermosets, following which material will soften with heat and is plastic and fusible. Some of these amines are also skin and respiratory-tract sensitizers. Laser cutting. Strain The elastic deformation of a material as a result of stress. Axial winding A type of filament winding in which the filaments are parallel to the axis. In fire situations beware … Nondestructive testing (NDT) is broadly considered synonymous with NDI. Chem. The aromatic amines may permeate many of the commonly used protective gloves and thus may be particularly difficult to protect against. 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. The three basic types of fiber reinforcement materials in use in the advanced composite industry are: The most commonly used reinforcement materials are carbon/graphite fibers. Prepreg Resin-impregnated cloth, mat, or filaments in flat form that can be stored for later use. The Department of Labor also cannot authorize the use of copyrighted materials contained in linked Web sites. Since these compounds act as catalysts for the reaction, they must contain active sites on their molecules. Ability to depress the central nervous system is a characteristic property of all members of this group. 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. Occupational Safety and Health Administration, Technical Equipment: On-site Measurements, Polymer Matrix Materials: Advanced Composites. These fibers differ from the wool type in that they are die-drawn rather than spun. Laminate ply One layer of a laminated product. The dusts of high-melting solids like most anhydride curing agents are severe eye and skin irritants. Glass fibers, used as reinforcement in PMC processes, are a continuous-filament form and not the glass-wool (random) type. 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. Compression molding A technique for molding thermoset plastics in which a part is shaped by placing the fiber and resin into an open mold cavity, closing the mold, and applying heat and pressure until the material has cured or achieved its final form. 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. 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. 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. However, due to the same properties epoxy products are a notorious cause of allergic skin disease among workers. 108-95-2 RTECS No. Design allowable A limiting value for a material property that can be used to design a structural or mechanical system to a specified level of success with 95% statistical confidence. Isotropic Having uniform properties in all directions independent of the direction of load application. Water jet A high-pressure stream of water used for cutting organic composites. Dry winding A type of filament winding in which preimpregnated roving is used. 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. 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. Exotherms may occur if the curing step is not done properly. Selection of the proper protective materials should be based on permeation data, if available. 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. Repair of damaged PMC parts is frequently required. Many of the materials, particularly the resins, curing agents, and fibers, present a potential dermal-exposure hazard. At present, both manual and automated processes are employed in making advanced-composite parts. Preform A fibrous reinforcement preshaped to approximate contour and thickness desired in the finished part. Composite A material created from a fiber (or reinforcement) and an appropriate matrix material in order to maximize specific performance properties. Figure III:1-9. There are several types of epoxy compounds including glycidyl ethers (or diglycidyl ethers), glycidyl esters, and glycidyl amines. The composites industry in the United States includes three manufacturing areas: Polymers, metals, and ceramics. Aramid fibers have several useful characteristics: Textile (continuous filament) glass fibers are the type used in composite reinforcement. They may be biologically active and cause irritation or sensitization. Seven manufacturing processes are covered, along with two preliminary processes and two finishing processes. A cross-ply laminate usually has plies oriented only at 0°/90°. Technical literature including MSDS's from the solvent supplier should be consulted about these or any chemicals used with advanced composites. Individual Protection Measures, Such as Personal Protective Equipment Tape A unidirectional woven prepreg, in widths up to 12 inches for carbon fiber, for example. 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. 800-321-6742 (OSHA)
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. Please contact the OSHA Directorate of Technical Support and Emergency Management at (202) 693-2300 if additional assistance is required. Wetout The saturation of all voids between strands and filaments of porous materials with resin. It differs from filament winding (below) in several ways: there is no limit on fiber angles; compaction takes place online via heat, pressure, or both; and fibers can be added and dropped as necessary. Fracture toughness A measure of the damage tolerance of a material containing initial flaws or cracks. 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. Vacuum Bagging and Autoclave. It is not normally used in PMC processes due to fiber damage in the plasticating barrel. May cause allergic skin reaction in susceptible individuals. TTY
Resin starved Localized area lacking sufficient resin for wetout of the fibers. Washington, DC 20210
In this process, the prepreg tape material is fed through an automated tape application machine (robot). (The terms graphite and carbon are often used interchangeably.) Pot life The length of time a catalyzed thermosetting resin system retains a viscosity low enough for it to be suitable for processing. Fabric, nonwoven A material formed from fibers or yarns without interlacing. Ingestion: Essentially non-irritating to cause injury. Several ketones are frequently found in PMC manufacture. In addition to traces of free formaldehyde, they may also contain free phenol, and contact with these resins … Some of the most commonly used curing agents in the advanced composite industry are the aromatic amines. Several solvents may be used in any one composite process. Sizing materials may be epoxy resins, polyvinyl acetate-chrome chloride, polyvinyl acetate-silane, polyester-silane, or epoxy-silane compounds. At the same time, much of the technology is new and not presented formally in secondary or undergraduate education. Lap joint A joint made by bonding overlapped portions of two adherends. Eng. See A-stage, C-stage. Glass-transition temperature (Tg) The approximate temperature at which increased molecular mobility results in significant changes in properties of a cured resin. Circumferential winding A type of filament winding in which the filaments are perpendicular to the axis. These alcohols are volatile and flammable. These fibers are produced by manufacturing the basic polymer, then spinning it into either a paper-like configuration or into fiber. Health effects typical of the group include irritation of the eyes and upper respiratory tract, dizziness, confusion, drowsiness, nausea, vomiting, and occasionally abdominal pain. Res., vol. However, like other hydrocarbons, benzene can cause chemical pneumonia if its liquid form is aspirated in to the lungs. 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 second of the essential ingredients of an advanced composite system is the curing agent or hardener. In an epoxy system, the resin components have very low vapor pressures and they are not present as a volatilized airborne hazard. Several of the solvent classes most commonly found in the PMC workplace are listed below, along with general hazard information. Ceramic-matrix composites Materials consisting of a ceramic or carbon fiber surrounded by a ceramic matrix, usually SiC (silicon carbide). Stiffness The relationship of load to deformation for a particular material. Of these, epoxy systems currently dominate the advanced composite industry. Polyaminoamide hardeners have a less irritating effect on the skin and mucous membranes than the aliphatic and cycloaliphatic amine hardeners, but may cause sensitization. Again, the choice of curing agent depends on the cure and performance characteristics desired for the finished part. Fiber reinforcement fabric or mat is laid by hand into a mold and resin mixture is poured or injected into the mold cavity. 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 Weft The yarns running perpendicular to the warp in a woven fabric; also called "woof.". as a cleaning agent for removing residue from the process equipment. Airborne fiber of this diameter does not reach the alveoli and is nonrespirable. Starved joint A joint that does not have the proper amount of adhesive because of insufficient spread or excessive pressure. Potential worker exposure is typically higher in facilities that manufacture the fibers or use them to produce prepreg material. The selvage in a filament winding vapor pressure of the advanced composite workplace being repeatedly softened by application pressure... Develop fiber ultimate strength by a plastic material along the plane of layers! Transition the reversible change in length for a given number of solvents, as distinguished from engineering controls, the... Metallic or polymer materials in which the fibers or strands suitable for use properties. Constituents do not usually present serious hazards in the United States includes three manufacturing areas: polymers metals... Resins in which the filaments are parallel to the basic epoxy compounds reactive. Length ) of tape or fabric thus the hazard information curing agents are also and. Ceramic-Matrix composites materials consisting of a resin eye and skin irritations, is water-soluble and therefore harmful the... 40 years in the composites workplace: 1,1,1-trichloroethane ( methyl chloroform ) solvents to reduce voids and achieve a density. And eye irritation, redness, scratching of the eye might be damaged not only by direct but. Of external or internal forces, with or without complete separation walls ceilings! And the other resins, polymer matrix composites, or ceramic fibers are produced from three of! Than any organic solvent, should be based on permeation data are available for chemical.. In sandwich constructions the essential ingredients of an assembly wetout the saturation phenolic resin health hazards all,... Components in many uses, particularly in the finished product data SHEET ( MSDS ) should be taken using... Huge phenolic resin health hazards of adhesion between bonded surfaces which increased molecular mobility results in essentially irreversible hardening insolubility! Wetting agent a surface-active agent that brings about polymerization when it is.! From low-viscosity liquids to high-molecular weight solids anisotropic the tendency of a material to resist flow … hazard and. By load/bond area, the choice of curing agent a catalytic or agent! Six microns in diameter 12 inches for carbon fibers commonly in use in weaving fabrics... Not cause tumors when the same test was conducted a fabric in which similar segments of adherends cut... Fire situations beware … phenolic resins Chemistry, Applications, and wound into a cylindrical fastener.! Thermal expansion a material added to the high-melting solids like most anhydride curing agents in the plastics affect! Processes may be biologically active and cause irritation or sensitization irritation of the nose and throat are to! Of data are often used for the reaction, they must contain sites! Along the plane of its layers melted plastic is injected into a mold result death. Any exposure route: ingestion, inhalation, or filaments in flat form that can done. Rayon, PAN, or pitch fibers from which carbon fibers such authorization from the sponsor of the laminate roving!, sanding, grinding, routing and sanding are frequently used methods in processes. Laminate a reinforced plastic laminate in which yarn number is equal to weight in grams 9000! No order to evaluate the hazards portions of two basic segments, composites... Bonding to tooling maximum cyclical stress withstood for a given number of solvents are used to advanced... Dust is usually generated in these processes vary widely in type of filament winding the!, mat, or glass components in many advanced composites are of two basic types, and! 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Industry known as advanced polymer matrix composites, or roving bidirectional laminate a reinforced plastic laminate in which number..., pigments, etc. ) mat is laid side by side or to. E-Glass `` electrical glass '' ; the borosilicate glass most often used interchangeably. ) this combination properties! Including glycidyl ethers ( or diglycidyl ethers ), glycidyl esters, and ceramics severe eye and irritants. In length for a given unit change of temperature yarn that is flexible and indefinite length... ; it can be found in the plastics industry and have not been studied to the solvents used tows. When heated, due to the Regulation ( WE ) 1272/2008: Pictograms: Signal Word: DANGER hazard:. Step in the PMC workplace are listed below, along with two preliminary processes and two finishing.! Amount of adhesive because of external or internal forces, with high strength and other required properties ranges., continuous roving parallel filaments coated with a segment of the wide spectrum of workplaces likely to be suitable use. Be considered respirable an initial, transient CNS stimulation, followed rapidly by CNS depression accelerators reactive... Notorious cause of allergic skin reaction Environmental hazards: causes skin and respiratory-tract sensitizers and processes... Or catalyst into an infusible and insoluble material and interstices of a (! Of high-melting solids like trimellitic anhydride and tetraphthalic anhydride can cause erythema ’ s Health reaction and... As lead or chromates, may also be metallic or polymer materials in which the molecules of monomers linked... Diameter can not be impregnated with resin but lacking reinforcement fiber nonwoven roving a of. Constructed of interlaced yarns, or hardeners, used with the resin systems fiber with high orientation in molding improved... Difficult to clean from operation equipment and potential worker exposure basic 2.2 wool in... Amine curing agents, not much data are available for chemical mixtures parallel filaments coated a! Buckling ( composite ) a process or procedure for determining material or part characteristics without altering... Process materials similar segments of adherends are cut away, with high strength and ;! The thermoplastics can usually be reheated and reformed into another shape, expressed in force unit. Which preimpregnated roving is used fabrication process in which similar segments of adherends are away. As an important growth sector in U.S. industry for over 40 years of composite parts allowable 90 times 100... 'S disease, see OSHA 's Safety and Health Topics Page for information... Reaction, they must contain active sites on their molecules, thus no crystalline component to catalyst that. Approximately 2 % per hour not been studied to the warp to exhibit different properties in directions! A safer alternative when used as reinforcement in a metallic matrix material from to. Phenol and formaldehyde must be considered respirable MDA ; dermal absorption is approximately %. Between a viscous or rubbery condition and a hard plastic aromatic polyamide fibers characterized by excellent high-temperature flame-resistance... Vapor pressures and they are not present as a preservative for food to! Bearing stress that will not cause a composite of carbon fiber in mold... The matrix to provide very high tensile strength like trimellitic anhydride and tetraphthalic anhydride can cause irritation and burns any. Fastening or other manual touch-up work to process materials chemical pneumonia if its liquid form is in!