Traditional Composites 125

This class covers the materials commonly used to create resins and reinforcements for traditional composites. It also describes the basic characteristics of polymers.

  • Difficulty Beginner

  • Format Online

  • Number of Lessons 15

  • Language English


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Course Outline
  • Objectives
  • Traditional Composite Materials
  • E-glass Fibers
  • What Is a Polymer?
  • Polymer Arrangements
  • Temperature Transitions for Polymers
  • Thermoplastic Polymers
  • Polypropylene
  • Nylon
  • Acrylonitrile-Butadiene-Styrene
  • Thermoset Polymers
  • Unsaturated Polyester
  • The Pros and Cons of Polyester
  • Vinylester
  • Summary
  • Describe the materials used to make commercial composite parts.
  • Describe E-glass fibers for composite reinforcements.
  • Describe polymers for composite resins.
  • List the basic structures of polymer molecules.
  • Describe temperature transitions for polymers.
  • Describe polymers for thermoplastic resins.
  • Describe polypropylene thermoplastic resin.
  • Describe nylon thermoplastic resin.
  • Describe ABS thermoplastic resin.
  • Describe polymers for thermoset resins.
  • Describe unsaturated polyester thermoset resin.
  • List the pros and cons of using polyester resin.
  • Describe vinylester thermoset resin.
Vocabulary Term


A monomer used as one of the three ingredients in ABS thermoplastic resin.


A thermoplastic polymer used as a resin for traditional composites. ABS is strong, stiff, and resistant to abrasion and impact.


An organic compound that reacts with organic acid to create unsaturated polyester.


A carbon compound used as one of the three ingredients in ABS thermoplastic resin.


A glass fiber that provides greater resistance to chemicals and is used in advanced composites. Fiberglass is generally classified as E-glass, S-glass, and C-glass.


A material made by combining a binding resin with small filaments of solid material. Composites have the strength of metal, the light weight of plastic, and the rigidity of ceramics.


A type of material deformation resulting from stress over time. Composites made from thermoplastics are vulnerable to creep.


The development of primary bonds between polymer molecules. Thermosets are heavily cross-linked, while thermoplastics are not cross-linked or are cross-linked to a weaker degree.


The process of flowing molten glass through tiny holes in a metal plate to form filaments. Drawing is part of the process for creating fiberglass.


A glass fiber with good general properties used for traditional composites. Fiberglass is generally classified as E-glass, S-glass, and C-glass.


The most common polymer used for advanced thermoset resins. Epoxies are very tough and heat-resistant.


Reinforcement material made from extremely fine strands of glass. Traditional composites primarily use E-glass fibers.

fiberglass reinforced plastic

A composite made from unsaturated polyester and fiberglass. FRPs make up a large portion of the traditional composites market.


An inert substance added to polymers to fill up space. Unsaturated polyester resin is low in cost because it has a high percentage of fillers.

freezing point

The temperature at which a liquid resin becomes solid. The molecules in a hardened resin are frozen, or locked, in place and cannot move.

glass transition temperature

The temperature at which a rigid solid becomes pliable and can be formed, shaped, or molded. The glass transition temperature is slightly below the melting point.

high-performance composite

A composite made from specially formulated resins and high-performance fibers. High-performance composites are often used in applications requiring parts with high strength, stiffness, and resistance to heat.


Having little or no tendency to react chemically with other materials. A filler is an inert substance that is added to polymers to fill up space and reduce cost.


A substance that slows or stops chemical activity. Inhibitors are added to polyester resin to extend its storage life.


A state of matter that is cohesive and has the ability to flow. Liquid resin hardens into a solid when it cools.


A large molecule that consists of repeating molecular units. Polymers consist of long chains of multiple macromolecules.


The material that binds together the reinforcing fibers of a composite. The matrix in traditional composites is usually a polymer.

melting point

The temperature at which resin becomes liquid. When a hardened resin melts to a liquid, the molecules can move about freely.


A basic molecular unit that consists of a collection of atoms. Polymer molecules contain thousands of repeating mers bonded in a long chain.


The smallest unit into which a material can be divided without changing its properties. A molecule consists of a group of atoms held together by strong primary bonds.


A small molecule that joins with other molecules to form a polymer. Acrylonitrile-butadiene-styrene is composed of monomers acrylonitrile, butadiene, and styrene.

multiple chains, loosely bonded

A polymer arrangement in which cross-linking occurs to a weaker degree than in a tightly bonded multiple chain. Loose cross-linking, or no cross-linking, produces a more flexible part.

multiple chains, tightly bonded

A polymer arrangement in which cross-linked molecules form strong primary bonds that connect multiple molecule chains together. Heavy cross-linking produces a stronger, more rigid part.


A thermoplastic polymer used as a resin for traditional composites. There are many types of nylon, and all nylons are strong and flexible.

organic acid

An organic compound that reacts with alcohol to create unsaturated polyester.


The most widely used thermoset polymer in the composite industry. Fiberglass reinforced plastics are made with unsaturated polyester and fiberglass reinforcement.


A lightweight thermoplastic polymer used to create high-performance reinforcement fibers in composites. Polyethylene is stronger than polypropylene.


A long chain of very large molecules made up of many parts. Traditional composites use polymers for matrix resins.


A thermoplastic polymer used as a resin for traditional composites. Polypropylene is economical, versatile, and very lightweight.

pot life

The period of time after mixing during which a resin remains suitable for use. Polyester resin has a long pot life.

primary bond

A bond that forms between atoms and that involves the exchange or sharing of electrons. Primary bonds form strong connections within molecules.


The part of the composite that provides strength, stiffness, and the ability to carry a load. In traditional composites, E-glass fibers are the most commonly used reinforcement.


A substance made from either synthetic or natural polymers and used for composite matrices. In essence, a resin is a polymer that has not yet been processed into its final form.

secondary bond

A bond that involves attraction between molecules but has no transfer or sharing of electrons. Secondary bonds are not as strong as primary bonds.


A glass fiber that provides greater strength and can withstand higher temperatures than E-glass. Fiberglass is generally classified as E-glass, S-glass, and C-glass.

single chain

A polymer arrangement in which the molecule chains are held together by relatively weak secondary bonds.

single chain with branches

A polymer arrangement in which smaller chains of mer units attach themselves to a longer polymer chain.


A basic non-flowing form of a substance. A solid is the room temperature form of some substances, such as plastic, or the frozen form of others, such as water.

strength-to-weight ratio

The relationship between a material's strength and its weight. To find the ratio, the strength of a material is divided by its density.


A monomer used as one of the three ingredients in ABS thermoplastic resin.


The descriptive term for a polymer in which the molecules are not cross-linked or cross-linked to a weaker degree. Thermoplastics can be melted and hardened repeatedly without changing their chemical structure.


The descriptive term for a polymer that cannot be remelted or reformed once it has cured. Thermosets have higher rigidity and better thermal stability than thermoplastics.

traditional composite

A composite that uses a relatively consistent combination of resin and fiberglass reinforcement. Traditional composites are low-cost and are processed by traditional methods.


A thermoset polymer that shares common qualities with both polyester and epoxy. Vinylester is tougher and more expensive than polyester, but not as tough or expensive as epoxy.