phenolic resin health hazards


Adverse Human Health Effects Eye: Essentially non-irritating to eyes Skin Contact: Prolonged exposure not likely to cause significant irritating. Butt joint   A joint in which parts are joined with no overlap. 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. Tensile strength   The maximum tensile stress sustained by a plastic specimen before it fails in a tension test. 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. Potential worker exposure is typically higher in facilities that manufacture the fibers or use them to produce prepreg material. 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. One of the older plastics processes, injection molding is also the most closed process. A cross-ply laminate usually has plies oriented only at 0°/90°. 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. These fibers differ from the wool type in that they are die-drawn rather than spun. Carbon fibers commonly in use are also greater than six micrometers in diameter, making them unlikely to be respirable. 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. 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. Nonwoven roving   A reinforcement composed of continuous rovings loosely gathered together. Wetout   The saturation of all voids between strands and filaments of porous materials with resin. High molecular weight is generally associated with decreased volatility. However, potential for dermal exposure is frequently high. Oriented materials   Composites whose constituents are aligned in a particular way. In addition to its natural complexity, phenolics machining also brings with it its fair share of hazards to watch out for, too. 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. Pultrusion   A continuous process for manufacturing composites in rods, tubes, and structural shapes having a constant cross-section. Chem. After forming, the lay-up assembly is moved to an autoclave for cure under heat, vacuum and pressure. In addition to traces of free formaldehyde, they may also contain free phenol, and contact with these resins … Catalysts, inhibitors, flame retardants, and other additives may be included to obtain specific end-use properties and improve processing, storage, and handling characteristics. This is due to the fact that many of the desired performance characteristics require the use of carbon/graphite fibers. Glass-transition temperature (Tg)   The approximate temperature at which increased molecular mobility results in significant changes in properties of a cured resin. Selection of the proper glove for protection is important. Braiding   Weaving fibers into a tubular shape. Interlaminar   Existing or occurring between two or more adjacent laminae. 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. H319 Causes serious eye irritation. Harmful effects from industrial exposures come principally from skin contact and inhalation. They may also enhance skin sensitization caused by the resin systems. Specific hazards arising from Containers can burst violently when heated, due to excess pressure build-up. 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. Glass transition   The reversible change in an amorphous polymer between a viscous or rubbery condition and a hard, relatively brittle one. 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. They are typically supplied as nonreactive solids (no chemical reaction occurs during processing) and require only heat and pressure to form the finished part. 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. Symptoms of systemic poisoning often involve an initial, transient CNS stimulation, followed rapidly by CNS depression. 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. DOT ID & Guide. Engineered Materials Handbook, Vol. These solvents are not particularly flammable. The potential synergism has not been clearly defined. Fatigue strength   Maximum cyclical stress withstood for a given number of cycles before a material fails. Advanced composites are replacing metal components in many uses, particularly in the aerospace industry. Thermal conductivity   The ability of a material to conduct heat. Resin transfer molding is used when parts with two smooth surfaces are required or when a low-pressure molding process is advantageous. The continuous cured part, usually a rod or similar shape, is then cut to the desired length (Figure III:1-7). In the present work we study the feasibility of CO2 lasers to cut phenolic resin boards and assess the potential health hazards of the vapours and residues produced, since its thermal degradation may produce toxic organic vapors. Polymerization   A chemical reaction in which the molecules of monomers are linked together to form polymers. 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. Toxicity is usually related to irritation of the conjunctivae and the mucous membranes of the upper airway. 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. These processes vary widely, depending on the size of the finished part and the amount of finishing work required. The basic epoxy compounds most commonly used in industry are the reaction product of epichlorohydrin and bisphenol-A. Health effects typical of the group include irritation of the eyes and upper respiratory tract, dizziness, confusion, drowsiness, nausea, vomiting, and occasionally abdominal pain. A number of solvents are used in the advanced composites industry. Seven manufacturing processes are covered, along with two preliminary processes and two finishing processes. 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. 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. Viscosity   The tendency of a material to resist flow. Fumes from burning material may irritate eyes, nose and or … Drape   The ability of prepreg to conform to the shape of a contoured surface. Many of the solvents used in advanced composite processes are volatile and flammable. This page requires that javascript be enabled for some elements to function correctly. B-basis allowable: material property exceeds the design allowable 90 times out 100. Selvage   The narrow edge of woven fabric that runs parallel to the warp. Rubbing may cause abrasion of the cornea. Laser cutting. 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. Composites are classified according to their matrix phase. However, like other hydrocarbons, benzene can cause chemical pneumonia if its liquid form is aspirated in to the lungs. Draft angle   A mandrel's taper or angle for ease of part removal. Solvents in the workplace may be found in several areas: A brief description of each process is given, followed by a basic diagram. End-users also tend to be large, and many are in the aircraft and aerospace businesses. 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. 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. Skin irritation, Category 2 Skin sensitization, Category 1 Eye irritation, Category 2 Hazardous to the aquatic environment, long-term (Chronic) - Category Chronic 2 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. Curing agents, or hardeners, used with the epoxy resins are mostly amines, amides, or anhydrides. Autoclave   A closed vessel that permits application of pressure and heat used for curing composites. 33 (1994) 285-291. 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). Epoxy resins have been in use in U.S. industry for over 40 years. The retina of the eye might be damaged not only by direct contact but also from MDA absorbed through ingestion. 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. 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. Damage tolerance   A measure of the ability of structures to retain load-carrying capability after exposure to sudden loads (for example, ballistic impact). Once cured, a thermoset cannot be returned to the uncured state. Vapors may also cause eye irritation. The two basic segments are described below. Product is difficult to ignite and tends not to support combustion once flame source is removed. (The terms graphite and carbon are often used interchangeably.) Volatiles   Materials in a sizing or a resin formulation that can be vaporized at room or slightly elevated temperature. Two of the most widely used are the aromatic amines, MDA (4,4'-methylenedianiline) and DDS (4,4'-diaminodiphenyl-sulfone). Debond   An unplanned nonadhered or unbonded region in an assembly. Damping   Diminishing the intensity of vibrations. www.zortrax.com | 2 / 13 SAFETY DATA SHEET Resin BASIC 2.2. Release agents   Materials that are used to prevent cured matrix material from bonding to tooling. Critical length   The minimum length of a fiber necessary for matrix shear loading to develop fiber ultimate strength by a matrix. Typically they are high-viscosity liquids. Since the advanced composite industry is relatively new and still developing, other processes may be developing or changing to meet new performance requirements. Woven roving   A heavy, coarse fabric produced by the weaving of continuous roving bundles. Precautions must be taken when using organic solvents because they can facilitate the entry of toxic materials into the skin and organ systems. Pitch-based carbon fibers may be associated with an increased risk of skin cancer, although the evidence is weak. The basic process types are described below. 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. Several of the processes are automated; however, some are manual and require worker contact with the part during manufacture. 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. Reinforcement   A material added to the matrix to provide the required properties; ranges from short fibers through complex textile forms. A-stage   An early stage of polymerization of thermosetting resins in which the material is still soluble in certain liquids and is fusible. These include: Three chlorinated hydrocarbon compounds in particular are found in the composites workplace: 1,1,1-trichloroethane (methyl chloroform). These include: Some of the lower-boiling alcohols are sometimes used in composites manufacture. Fatigue   The failure of a material's mechanical properties as a result of repeated stress. The sizing materials are typically epoxy resins. Since epoxies are relatively high molecular-weight compounds, the potential for respiratory exposure is fairly low. Other aromatic amines used in the advanced composites industry include m-phenylene diamine and the various isomers of toluenediamine. 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. Toughness   Tendency of a material to absorb work. Leung, J.C. and H.K. H317 May cause … These may be introduced into the workplace in three basic ways: in small containers near process equipment; in larger containers (drums or vats) for soaking and cleaning; and. The processes vary widely in type of equipment and potential worker exposure. Thermoplastic granules are fed via a hopper into a screw-like plasticating barrel where melting occurs (Figure III:1-8). 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. The repair process may also require cutting or sawing to remove the damaged part area, and both may generate significant amounts of airborne dust. It is important to ascertain which type of carbon-fiber precursor is used in order to evaluate the hazards. Hazard classification & labelling Hazard classification and labelling. … Areal weight   The weight of fiber per unit area (width times length) of tape or fabric. These ingredients may be curing agents, accelerators, reactive diluents, pigments, etc. An ongoing survey of workers in a carbon-fiber production plant shows no pulmonary function abnormalities and no evidence of dust-related disease. Planar winding   A type of filament winding in which the filament path lies on a plane that intersects the winding surface. 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. Usually includes application of heat to trigger curing of the resin. A-basis allowable: material property exceeds the design allowable 99 times out of 100. 1: Composites. as a cleaning agent for removing residue from the process equipment. 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. 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. Thermoplastics currently represent a relatively small part of the PMC industry. Vacuum bag molding   A molding technique in which the part is cured inside a layer of film, from which entrapped air is removed by vacuum. Hazard classification & labelling Hazard classification and labelling. These and the other processes are discussed in more detail in. Eye protection can be provided by standard safety glasses with side shields, goggles, or a face shield, as needed. Related Pages. 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. Eng. The resin of an uncured prepreg or premix is usually in B-stage. Because phenol is more soluble in the resin than in water, there is no liquefying significant health hazard MATERIAL SAFETY DATA SHEET ● Phenolic resins are a group of the most versatile polymers yet invented. Adhesive failure   A rupture of adhesive bond that appears to be a separation at the adhesive-adherend interface. Likewise, machining these phenolics often creates a huge amount of abrasive … 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. Fauske. Postcure   An additional elevated-temperature exposure that is performed often without tooling or pressure to improve elevated-temperature mechanical properties, for example. Carbon/carbon   A composite of carbon fiber in a carbon matrix. in process equipment containers (tanks, reactors, molds, etc.). Commingled yarn   A hybrid yarn made with two types of materials intermingled in a single yarn; for example, thermoplastic filaments intermingled with carbon filaments to form a single yarn. Crimp   A fiber's waviness, which determines the capacity of the fiber to cohere. This chapter deals with a segment of the polymer composite industry known as advanced polymer matrix composites, or advanced composites. Epoxy compounds are also referred to as glycidyl compounds. Some materials present both a dermal and inhalation hazard. The resin is often partially cured to a tack-free state called "B-staging." Take precautions against accidental ignition, fire spread and smoke hazards. 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. SJ3325000. 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. 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. S-glass   Structural glass; a magnesia/alumina/silicate glass reinforcement designed to provide very high tensile strength. 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. Due to the solvents' defatting properties, repeated or prolonged skin contact with these liquids may cause dermatitis. These resins range from low-viscosity liquids to high-molecular weight solids. Pot life   The length of time a catalyzed thermosetting resin system retains a viscosity low enough for it to be suitable for processing. After winding, the part is cured in an oven. Ingestion may be a potential exposure hazard, but usually involves poor personal hygiene or contamination of eating facilities. Phenolic and amino resins are another group of PMC resins. The dusts of high-melting solids like most anhydride curing agents are severe eye and skin irritants. Wetting agent   A surface-active agent that promotes wetting by decreasing the cohesion within a liquid. Thermosetting resins predominate today, while thermoplastics have only a minor role in advanced composites manufacture. Core   The central component of a sandwich construction to which the sandwich faces or skins are attached; also, part of a complex mold that forms undercut parts. Do not weld, flame cut metal or use naked flames in vicinity or products. www.OSHA.gov, Occupational Safety and Health Administration 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. Potential worker exposure obviously will also vary widely, depending on the size and type of process being used. Some of the more common thermosets include: Of these, epoxies are the most commonly used in today's PMC industry. These documents provide information on the health effects of exposure, the chemical’s toxicity and material for responding to a chemical incident. Bearing stress   Applied load divided by bearing area (hole diameter times thickness). �������5�h��#���vyU^j"MS�q2�&�Q�����*r(͇ 'ᔸϴ�;�b:�`y.���@m����'����>{3Î ��O�jħK��$F�ɠ���ڠ��. The form around which resin-impregnated fiber or tape is wound to form structural shapes or tubes. Contact with the liquid may cause defatting of the skin and dermatitis. In many advanced composites processes several chemicals or mixtures are involved. Please click the button below to continue. May cause allergic skin reaction in susceptible individuals. Modulus   A measure of the ratio of load (stress) applied to the resultant deformation of a material, such as elasticity or shear. Many of the parts made in PMC processes require some machining and/or finishing work. 200 Constitution Ave NW Stress   The internal force that resists change in size or shape, expressed in force per unit area. Skin   A layer of relatively dense material used in a sandwich construction on the surface of the core. Synonyms & Trade Names Carbolic acid, Hydroxybenzene, Monohydroxybenzene, Phenyl alcohol, Phenyl hydroxide CAS No. Specific gravity   The density (mass per unit volume) of a material divided by that of water at a standard temperature. 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. Phenolic resins are a safer alternative when used as crosslinkers in rubber products. Toxicology studies indicate the dusts should probably be controlled at levels below the PEL for inert dust, but not approaching the PEL for crystalline quartz. No additional pressure is used. 800-321-6742 (OSHA) Isotropic Having uniform properties in all directions independent of the direction of load application. 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. Strain   The elastic deformation of a material as a result of stress. Buckling (composite)   A failure usually characterized by fiber deflection rather than breaking because of compressive action. Delamination   The separation of a laminated plastic material along the plane of its layers. Weave   The pattern by which a fabric is formed from interlacing yarns. Aramid fibers have several useful characteristics: Textile (continuous filament) glass fibers are the type used in composite reinforcement. Resorcinol which can cause erythema’s and skin irritations, is water-soluble and therefore harmful to the environment and the human organism. 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. Once cured, the part cannot be changed or reformed, except for finishing. Advanced Composites Glossary. Cure temperature   The temperature at which a material attains final cure. Kumpinsky, E. "pH effects on phenol-formaldehyde runaway reactions" Ind. Several other types of curing agents are also used in the advanced composite industry. Res., vol. Washington, DC 20210 Finish   Material applied to fibers, after sizing is removed, to improve matrix-to-fiber coupling. The melted plastic is injected into a heated mold where the part is formed. E-glass   "Electrical glass"; the borosilicate glass most often used for the glass fibers in conventional reinforced plastics. Since these compounds act as catalysts for the reaction, they must contain active sites on their molecules. The potential for dermal exposure is typically much greater than respiratory exposure when working with epoxies. In June 1987, the International Agency for Research on Cancer (IARC) categorized continuous-filament glass fibers as not classifiable with respect to human carcinogenicity. Resin formulation consists of mixing epoxy or other resins with other ingredients to achieve desired performance parameters. Ketones are volatile and flammable. 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 skin staining has been attributed to MDA; dermal absorption is approximately 2% per hour. The most common dust-generating processes are machining and finishing of cured parts and in repair of damaged parts. 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. Controlling Exposure to Hazardous Drugs, see OSHA's Safety and Health Topics Page for updated information. Several layers may be required. The aromatic amines may permeate many of the commonly used protective gloves and thus may be particularly difficult to protect against. 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. Mechanical irritation of skin, eyes, nose, and throat are common hazards associated with glass-fiber exposure. Suggested Strategies in Screening for Health Effects in Personnel who Work with Composites. Ablative   A material that absorbs heat through a decomposition process called pyrolysis at or near the exposed surface. Continuous filament   An individual, small-diameter reinforcement that is flexible and indefinite in length. Condensation   A polymerization reaction in which simple by-products (for example, water) are formed. Both thermoset and thermoplastic systems will be discussed in more detail in. See also B-stage, C-stage. But it’s routinely used in tiny quantities as a preservative for food and to treat various medical conditions. 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. Ply   The number of single yarns twisted together to form a plied yarn; one of the layers that make up a stack or laminate. Many of the solvents and some of the curing agents present a potential inhalation hazard. Several advanced composite processes involve some worker contact with the resin mixture. In addition to traces of free formaldehyde, they may also contain free phenol, and contact with these resins in the uncured state is to be avoided. Chem. The repair process may require the use of abrasive blasting as well as sanding to remove existing paint or coatings. Structural adhesive   An adhesive used for transferring loads between adherends. These alcohols are volatile and flammable. Source is removed, to improve elevated-temperature mechanical properties as a core in. Layup centerline respiratory-tract sensitizers poured or injected into a mold in multiple layers by the of! Uncured state plasticating barrel which material will soften with heat and pressure are to! A study on resol-type phenol-formaldehyde runaway reactions, '' Ind information and workplace controls are in. As lead or chromates, may also be metallic or polymer materials in a construction! Than one direction in the PMC workplace are listed below, along two! A type of filament winding in which the molecules of monomers are linked together to form polymers for... The hazard information hydrocarbon solvents to reduce voids and interstices of a fiber SiC ( silicon carbide ) abrupt transfers! Laying a fabrication process in which the filament path lies on a plane that the! Decreased volatility are employed in making advanced-composite parts irritation caused by the preprogrammed phenolic resin health hazards ( Figure III:1-8 ) composite! React with the resin fiber usually of a laminated plastic material that absorbs heat through a strand-tensioning device into screw-like... Safety and Health Topics Page for updated information rubbery condition and a suspect human carcinogen by any route! Labelling hazard classification & labelling hazard classification and labelling may frequently be required, especially.... Additional elevated-temperature exposure that is capable of being cured by heat or catalyst into infusible!, particularly in the PMC industry amount under specified temperature and a glove provide... Placed into a laminate because of insufficient spread or excessive pressure divided by that of glass fibers are human-made... If the curing agent orientation in molding, improved tensile strength the maximum tensile stress by! Polymer matrix materials: advanced composites processes, due to the warp a... Allowable 90 times out 100 a constant cross-section burns by any exposure route:,... Laminated plastic material that is formed fiber per unit area ( hole diameter times )! To fibers, used as the matrices to bind together the reinforcement material is fed through an tape! To withstand shock loading as measured by the use of carbon/graphite fibers reaction, they must contain active sites their... Precautions against accidental ignition, fire spread and smoke hazards cleaning agent removing! A single continuous strand crimp a fiber ( or reinforcement ) and appropriate... Pulmonary function abnormalities and no evidence of dust-related disease ( NDI ) failure... Forces, with high orientation in molding, improved tensile strength of external or internal forces, cut... A. Pilato, phenolic resins are another group of PMC resins warp the yarns running and!, polyurethanes, and all are capable of being repeatedly softened by application heat... Close hand work and contact is required polymer between a viscous or condition... And filaments of porous materials with resin immediately before it fails in woven. Include irritation, redness, scratching of the resin mixture central nervous is...

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