MFGT 104
Materials and Quality
Chap 9: Composites
Professor Joe Greene
CSU, CHICO
MFGT 104
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Chap 9: Polymers Composites
• Objectives
– Define the components and difference types of composites.
– Explain the different types of composite construction and the
reasons behind them.
– Describe the various manufacturing methods used to produce
composites.
– List the different reinforcing materials used in composites.
– List the various matrix materials used in composites.
• Excellent Web sites
– Michigan State http://islnotes.cps.msu.edu/trp/
– U of Delaware http://www.ccm.udel.edu/publications/CU/99/
– Cornell University
http://www.engr.siu.edu/staff2/abrate/NSFATE/links.htm
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Composites
• Composite definition
– A composite is a material comprised of two or more physically distinct
materials with at least one material providing reinforcing properties on
strength and modulus.
• Natural Composites
– Bone
– Wood
– Bamboo: Natures fiber glass due to pronounced fibrillar structure which is
very apparent when fractured.
– Muscle and other tissue
• Engineering Composites
– Reinforced concrete beams
– Thermoset composites: Thermoset resins (polyurethanes, polesters, epoxies)
• Glass fibers, Carbon fibers, Synthetic fibers, metalfibers, or ceramic fibers
– Thermoplastic composites (polypropylene, nylon, polyester,TPU,polyimide)
• Glass fibers, Carbon fibers, Synthetic fibers, metalfibers, or ceramic fibers
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SMC
Sheet Molding
Compound
Automotive Applications of
Plastics and Composites
n
Composite Intensive Vehicles
RTM
Resin Transfer Molding
8-25 -98
M41_au 25
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Automotive Plastics and Composites Use
• Exterior Composite Panels
– doors
• Sheet Molded Compound (SMC): Camaro, Firebird and Corvette
• Resin Transfer Molding (RTM): Viper
– hoods
• Sheet Molded Compound (SMC): Camaro, Firebird, Corvette, Ford trucks
• Resin Transfer Molding (RTM): Viper, Heavy duty trucks)
– bumper beams
• Glass Mat Thermoplastic (GMT): Camaro, Firebird, Venture, Transport,
• Interior
– floor pan
• Resin Transfer Molding (RTM): Corvette
• Engine
– valve covers, intake manifolds, fluid containers, etc.
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Automotive Plastics and Composites Use
SMC
Sheet Molding
Compound
SMC
Sheet Molding
Compound
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Recreational Plastics and Composites Use
• Snow Equipment
– skis, snow boards, snow mobiles, etc.
• Water Sports Equipment
– water skis, water crafts, snorkel equipment, fishing gear
– diving equipment
• Land Sports Equipment
– shoes, roller blades, skate boards, tennis, golf
• Air Sports Equipment
– plane kits
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• Epoxy
Applications for Thermosets
– Protective coatings: maintenance coatings for industrial and marine,
tank linings, industrial floorings, beer and beverage can coatings,
food cans, appliance primers, hospital and laboratory furniture.
– Bonding and adhesives: Automotive and aircraft industries adhesive
to metals and composites.
– Molding, casting and tooling: Molding compounds in electrical and
electronic industries, casting resins, potting resins. Prototype and
master model tools.
– Laminating and composites: Binders in fiber reinforced laminates and
composites. Laminates are used in printed wiring boards. Composite
applications include filament winding (high performance pipes in oil
fields, pressure vessels, tank and rocket motor housings), pultrusion,
casting, and molding (graphite composites for aerospace applications)
– Building and construction: Flooring (seamless, self-leveling, or epoxy
terrazzo floors), repair of bridges and roads with glass and carbon
fiber wraps, concrete crack repair, coat reinforcing bars, binders for
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patios, swimming pool decks, and soil around oil-well drills.
Applications for Thermosets
• Polyester
–
–
–
–
–
Boat hulls, shower stalls, electrical components, appliances
Recreation vehicles, automotive body panels, floor pans; SMC
Soft tooling, patterns
Cultured marble, buttons, corrosion resistant tanks and parts,
Corrugated and flat paneling, simulated wood furniture, bowling balls,
polymer concrete, and coatings
• Polyurethane
– Rigid foams: (MDI) Laminated board stock, Moldings, Bun, Foam in place
insulation, sprayed foam, packaging
– Semi-flexible foam: (MDI and TDI) Moldings, Integral-skin moldings
– Flexible foam:(TDI) Moldings, integral skin molding, carpet underlay
– Packaging: (TDI) Furniture cushioning
– Microcellular foam: (MDI) RIM parts, shoe soles
– Non-foam cast elastomers
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– Coatings, binders, thermoplastic elastomers, sealants, paints
Composite Classifications
• Reinforcement Type
– Discontinuous (fibers are chopped and dispersed in matrix resin)
• Short fibers: fiber lengths 3mm or less (most injection molded materials)
• Long fibers: fiber lengths greater than 6 mm. (Some injection molded materials
with 6mm fibers, Sheet Molding Compound (SMC) with 1” fibers, DFP
Directed Fiber Preforms for RTM and SRIM)
• Particulates: fibers is forms as spheres, plates, ellipsoids (some injection
molded materials reinforced with mineral fibers)
– Continuous (fibers are throughout structure with no break points)
• Glass roving: glass bundles are wound up in a packet similar to yarn.
• Roving is woven into several weaves using a loom machine like in apparel.
– Mat products: random swirl glass pattern.
– Woven product: roving is woven into machine direction (warp) and
cross direction (weft)
– Uni product: roving is woven in one direction with a cross thread given
to hold mat together.
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Composite Classifications
• Resin (or matrix) type
– Thermoset resins- those that undergo a chemical cross-linking reaction
• Epoxy: reaction of bisphenol A and epichlorohydrin
• Polyester: reaction of difunctional acid (or anhydride) and a difunctional
alcohol (glycol)
• Polyurethane: reaction of alcohol and isocyanate
• Phenolic
• Silicone
• Melamine
– Thermoplastic resins- those that are formed under heat
•
•
•
•
Polyamines (nylon) (short and long fibers)
Polyesters (short and long fibers)
Polypropylene (short, long fibers and continuous fibers)
Other thermoplastic resins (short and long fibers)
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Processing of Composites
• Open Mold processes
–
–
–
–
–
Hand lay-up
Spray-up
Vacuum bag, pressure bag, autoclave
Filament winding
Centrifugal casting
• Closed Mold Processes
– Compression molding
– Injection Molding [high pressure]
– Resin Transfer Molding (RTM), Structural Reaction Injection
Molding (SRIM) [low pressure]
– Pultrusion
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Properties of Materials
• Tensile modulus
–
–
–
–
–
Low alloy steel
Aluminum
Carbon fiber
Glass fiber
Aramid fiber
(Kevlar)
207GPa(30Mpsi)
72GPa (10Mpsi)
300GPa(40Mpsi)
76GPa (10Mpsi)
125GPa (20Mpsi)
• Tensile strength
–
–
–
–
–
Low alloy steel
Aluminum
Carbon fiber
Glass fiber
Aramid fiber
(Kevlar)
1500MPa(220Kpsi)
500MPa(75Kpsi)
2400MPa(360Kpsi)
2000MPa(300Kpsi)
3000MPa (450Kpsi)
Density
Spec Mod
7.85 g/cc
2.8 g/cc
1.8 g/cc
2.56g/cc
1.4g/cc
26spGPa
26spGPa
167spGPa
30spGPa
89spGPa
Density
Spec Str
7.85 g/cc
2.8 g/cc
1.8 g/cc
2.56g/cc
1.4g/cc
191spMPa
178spGPa
4320spGPa
781spGPa
2140spGPa
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Thermosets
• Thermosets are polymers that undergo a chemical reaction
during the polymerization.
• Thermosetting reaction is not reversible under heat.
• Epoxy
– Standard epoxy is based on bisphenol A and epichlorohydrin.
– Properties include good adhesion to many substrates, low
shrinkage, high electrical resistivity, good corrosion resistance, and
thermal.
– Processing is achieved without generation of volatiles.
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•
Polyester
and
Polyurethane
Polyester
– Thermoset reaction between a difunctional acid (or anhydride) and
a difunctional alcohol (glycol)
– Heat or radiation can trigger the cross linking reaction
– Accelerators (or promoters) speed up the reaction.
– Condensation Reaction results in CO2 and H2O.
– Monomer required to polymerize, e.g., Styrene at 30% to 50% in
commercial polyester systems
• Polurethane
– Reaction between isocyanate and alcohol (polyol). Condensation
Reaction results in CO2 and H2O.
– Crosslinking occurs between isocyanate groups (-NCO) and the
polyol’s hydroxyl end-groups (-OH)
– Thermoplastic PU (TPU) have some crosslinking, but purely by
physical means. These bonds can be broken reversibly by raising
the material’s temperature, as in molding or extrusion.
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Polyurethane Chemistry
• Reaction between isocyanate and alcohol (polyol).
• Crosslinking occurs between isocyanate groups (-NCO)
and the polyol’s hydroxyl end-groups (-OH)
• Thermoplastic PU (TPU) have some crosslinking, but
purely by physical means. These bonds can be broken
reversibly by raising the material’s temperature, as in
molding or extrusion.
• Ratio between the two give a range of properties between
a flexible foam (some crosslinking) to a rigid urethane
(high degree of crosslinking).
• In PUR foams density can range from 1 lb/ft3 to 70 lb/ft3.
• Foams are produced by chemical blowing agents.
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• Catalyst are used to initiate reaction.
Processing of Composites
• Open Mold processes
–
–
–
–
–
Hand lay-up
Spray-up
Vacuum bag, pressure bag, autoclave
Filament winding
Centrifugal casting
• Closed Mold Processes
– Compression molding
– Injection Molding [high pressure]
– Resin Transfer Molding (RTM), Structural Reaction Injection
Molding (SRIM) [low pressure]
– Pultrusion
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Processing of Composites
• Open Mold processes
– Hand lay-up and Spray-up
– Filament winding
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Processing of Composites
• Open Mold processes
– Vacuum bag, pressure bag, SCRIMP
– autoclave: Apply Vacuum Pressure and Heat in an oven which can
be 5 feet to 300 feet long
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Thermoset Reacting Polymers
• Process Window
– Temperature and pressure must be set to produce chemical reaction
without excess flash (too low a viscosity), short shot (too high a
viscosity), degradation (too much heat)
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Processing of Composites
• Closed Mold Processes
– Compression molding [moderate pressure]
– Injection Molding [high pressure]
– Resin Transfer Molding (RTM), Structural Reaction Injection
Molding (SRIM) [low pressure]
– Pultrusion [low pressure]
Injection
Molding
Annual Part 30K – 200K
Production
Volume
Part Size
Small
< 2 lbs
Compression
Molding
30K – 200K
Structural
RIM
5K – 200 K
Medium
2 lbs – 20 lbs
Fixed
Assets
Tooling
Cost
Cycle Time
$500K-$2M
Medium
Medium to large 5 lbs
2 lbs – 20
– 50 lbs
lbs
$300K-$1M $10K - $150K
Materials
$300K -$2M
$50K -$500K
$150K-$500K $50K$300K
1 sec –
30 sec –
30 sec –
30 sec
90 sec
120 sec
Thermoplastic Thermoplastic Thermoset
Thermoset
Resin Transfer
Molding
0.5K –5 K
$20K - $300K
5 min – 30 min
Thermoset
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Injection Molding
Glass Reinforced Composites
• Plastic pellets with glass fibers are melted in screw,
injected into a cold mold, and then ejected.
Glass filled resin pellets
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Composites Have a Fiber Preform
• Fiber type
– Roving form that can be sprayed into a 3-D preform
– Roving form that is woven into a glass sheet and then formed to
shape (preform)
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Compression Molding
• Compression molding was specifically developed for replacement of metal
components with composite parts. The molding process can be carried out with
either thermosets or thermoplastics. However, most applications today use
thermoset polymers. In fact,compression molding is the most common method
of processing thermosets.
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Resin Transfer Molding
• In the RTM process, dry (i.e.,unimpregnated )
reinforcement is pre-shaped and oriented into skeleton of
the actual part known as the preform which is inserted into
a matched die mold.
• The heated mold is closed and the liquid resin is injected
• The part is cured in mold.
• The mold is opened and part is removed from mold.
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Structural RIM
• Fiber preform is placed into mold.
• Polyol and Isocyanate liquids are injected into a closed
mold and reacted to form a urethane.
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