*The definitions below have been adapted from the glossaries compiled by Composites One ® and NetComposites. For a more complete list please visit their websites.
- Activator/Accelerator: An oxidizing agent used to accelerate the chemical reaction (curing) between a catalyst and resin.
- Addition Polymerization: Chemical reaction in which monomers (chemical subunits) chemically bond to each other to form long-chain molecules (polymers) without forming chemical byproducts.
- Additive: A material incorporated into polymer resins to modify their physical properties.
- Amine Resin: A synthetic resin derived from the reaction of urea, thiourea, melamine or allied compounds with aldehydes, particularly formaldehyde.
- ASTM: American Society of Test Methods.
- Autoclave: A vessel capable of simultaneous application of heat and pressure, usually 50-200 psi, in order to compact the composite during curing.
- Bleeder: A cloth material (commonly non-woven) that provides a pathway for gas, resin, and volatiles to escape from a composite during vacuum bagging.
- Braid/Braider: A narrow tubular fabric produced by intertweaving yarns according to a controlled angle and pattern.
- Carbon Fiber: Fibers (~7-10 microns in diameter) produced by the pyrolysis of organic precursor fibers (commonly polyacrylonitrile (PAN) and pitch) under an inert atmosphere.
- Catalyst (Hardener): A chemical compound that facilitates the reaction of thermoset matrices via the production of free radicals.
- Composite: A material composed of two or more distinct phases. A composite contains a matrix and a reinforcement that is chemically or mechanically bonded to via an interface.
- Compressive Strength: The compressive load a material can sustain before buckling or crushing occurs.
- Condensation Polymerization: A chemical reaction between two or more monomers and which produces a molecular byproduct (commonly water).
- Continuous Reinforcement: Filaments or fibers that span a substantial fraction of the length of a composite.
- Copolymer: A polymer which is composed of two or more distinct monomer chemical subunits.
- Creep: The slow deformation of a material under sustained load over time.
- Cross-linking: The chemical links that form between polymers to create a 3D network in thermoset matrices.
- Cure Cycle: The combination of time, temperature, and pressure used to cure thermoset matrix composite.
- Curing Agent: A chemical molecule that reacts with a resin to form a cross-linked matrix.
- Deep-Draw Mold: A mold whose depth is large relative to the part thickness. Fabrics can wrinkle, tear, or exhibit other defects during deep-draw processes.
- Delamination: The debonding of neighboring composite layers.
- Density: The mass per unit volume of a material.
- E Glass: Electrical glass used in general-purpose composites. It is a borosilicate-based glass.
- Elasticity: The ability of a material to recover the original size and shape after the application of a load.
- Ejection (Demolding): Removing a composite part from its mold.
- Epoxy: An important composite matrix resin containing epoxide groups.
- Extruder: A machine that pushes molten plastic through a die.
- Fiber: Used as a reinforcement material within composites.
- Filler: An additive that is used to reduce plastics usage, improve properties, and lower cost.
- Flexural Strength: The maximum stress of a material in bending.
- Gelation: The point during resin cure when the material transitions from a liquid (flows) to a solid (no flow).
- Glass Transition Temperature (Tg): The temperature range over which polymers transition from partially crystalline to amorphous rubbery materials.
- Honeycomb: A cellular material manufactured from metal or resin-impregnated sheets and used as a lightweight core material in sandwich composites.
- Initiator: A chemical used to create free radicals.
- Instron: A mechanical testing machine to determine the mechanical properties of materials.
- Isotropic: Having uniform properties in all directions.
- Laminate: A composite material composed of layers, commonly fiber-based textiles infiltrated with a polymer matrix.
- Lay-up: The placement of layers of matrix and reinforcement at determined orientations prior to curing.
- Matrix: The continuous phase surrounding the reinforcement in a composite.
- Micron: One micron is 0.001 millimeter.
- Mold: The shaped tooling into or onto which the composite material is placed prior to curing.
- Monomer: A molecular unit capable of chemical reactions to form a polymer chain.
- Polymer: Chain molecule composed of many monomers.
- Polymerization: Chemical bonding of monomers during the curing reaction.
- Ply: A layer within a laminate.
- Prepreg: A fabric with the matrix material already present prior to lay-up.
- Release Agent: Chemical added to the mold surface to reduce adhesion of the composite part to the mold.
- Sandwich Composite: A composite composed of face materials that are attached to a lightweight core, commonly a honeycomb or plastic foam.
- Stiffness: The relationship of load to deformation.
- Stress-Strain Curve: The plot of the load per unit area on a sample versus the material strain.
- Surfactant: A chemical additive that modifies the surface properties of a material.
- Tensile Strength: The maximum stress a material can sustain prior to failure.
- Thermoplastic: A polymer matrix capable of being repeatedly heated to soften and cooled to harden the material.
- Thermoset: A polymer matrix that chemically crosslinks during curing and cannot be re-formed by heating.
- Ultimate Tensile Strength: The final stress sustained by a specimen under tensile loading.
- Vacuum Bag Molding: A fabrication method which pulls a vacuum on composite lay-up under an impermeable bag. Atmospheric pressure compresses the composite-lay-up to reduce voids and increase part quality.
- Viscosity: The resistance of a liquid to flow.
- Weave: The interlaced pattern of a fabric .