高分子材料与应用(英文版) Chapter 4 ThermosetsPPT资料53页
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• Wiring devices • Switch gear • Circuit breakers • Insulators • Gears • Wear guides • Pulleys • Rollers
Amino Resins (UF and MF)
• Formaldehyde + -NH2(amine group)
Thermosets
• Resin
– Phenolics – Epoxies – Melamines – Silicones – Polyesters – Composites
• Thermoset vs. thermoplastic
General Properties of Thermosets
Three active sites
H
H
N
C
N
N
Plus
Formaldehyde
O
H N
H
C
C
N
Melamine
H N
H
C
H
H
Crosslinking as Polymers are Formed
Melamine Formaldehyde
Water
Crosslinking as Polymers are
• 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.
Injection Molding Glass Reinforced Composites
Application of melamine plastics
• Melamine Plastics
Polyester Thermosets (TS) or Unsaturated Polyesters (UP)
• Largest group of thermosets • Most like to be reinforced with fiberglass
Crosslinking of Phenolics
• Reactive Groups—Phenolics
H
O Phenol
H
C
H
C
C
Plus
O
Formaldehyde
C
H
H
C
C
H
C
H
H
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.
Crosslinking
• Reactive Groups—Unsaturated polyesters
H
C
R
C
H
Plus
R1
Carbon-carbon Double bond
O
R1
R
O
Initiator (usually peroxide)
Applications:
• wood particleboard, plywood, • boat hulls • flooring • furniture assemblies
Cellulose-filled urea compound: Electrical wall plates, receptacles, • knobs, handle Cellulose-filled melamine compound: dinnerware, buttons, control buttons, knob
– (1) Urea-formaldehyde – (2) Melamine-formaldehyde
Crosslinking
• Reactive Groups—Amino plastics
O
H
R
H
Formaldehyde
N
N
C
Amine
Plus
H
H
H
H
Urea formaldehyde
Crosslinking as Polymers are Formed
• Strength • Flexibility • Thermal • Creep • Ability to reinforce • Ability to cure at room temperature
Formaldehyde Resins
• Phenolics • Urea formaldehyde • Melamine formaldehyde
H
H
C
H
Formed
N
H
C
H
H
N
N
H
H
H
N
H
H
H
C
N
C
C
N
C
N
C
C
N
C
H
H
N
H
H
N
N
C
Melamine Formaldehyde
N
H
H
C
H
Water
HH
N
H
O
C
N
N
H
H
N
H
H
H
H
H
H
C
N
C
C
N
C
N
C
C
N
C
H
H
H
N
N
N
H
ห้องสมุดไป่ตู้
C
N
H
H
C
H
Amine plastics – clear adhesive
Chipboard
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.
• Plastic pellets with glass fibers are melted in screw, injected into a cold mold, and then ejected.
Glass filled resin pellets
Application of Phenolics
Amino Resins (UF and MF)
• Formaldehyde + -NH2(amine group)
Thermosets
• Resin
– Phenolics – Epoxies – Melamines – Silicones – Polyesters – Composites
• Thermoset vs. thermoplastic
General Properties of Thermosets
Three active sites
H
H
N
C
N
N
Plus
Formaldehyde
O
H N
H
C
C
N
Melamine
H N
H
C
H
H
Crosslinking as Polymers are Formed
Melamine Formaldehyde
Water
Crosslinking as Polymers are
• 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.
Injection Molding Glass Reinforced Composites
Application of melamine plastics
• Melamine Plastics
Polyester Thermosets (TS) or Unsaturated Polyesters (UP)
• Largest group of thermosets • Most like to be reinforced with fiberglass
Crosslinking of Phenolics
• Reactive Groups—Phenolics
H
O Phenol
H
C
H
C
C
Plus
O
Formaldehyde
C
H
H
C
C
H
C
H
H
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.
Crosslinking
• Reactive Groups—Unsaturated polyesters
H
C
R
C
H
Plus
R1
Carbon-carbon Double bond
O
R1
R
O
Initiator (usually peroxide)
Applications:
• wood particleboard, plywood, • boat hulls • flooring • furniture assemblies
Cellulose-filled urea compound: Electrical wall plates, receptacles, • knobs, handle Cellulose-filled melamine compound: dinnerware, buttons, control buttons, knob
– (1) Urea-formaldehyde – (2) Melamine-formaldehyde
Crosslinking
• Reactive Groups—Amino plastics
O
H
R
H
Formaldehyde
N
N
C
Amine
Plus
H
H
H
H
Urea formaldehyde
Crosslinking as Polymers are Formed
• Strength • Flexibility • Thermal • Creep • Ability to reinforce • Ability to cure at room temperature
Formaldehyde Resins
• Phenolics • Urea formaldehyde • Melamine formaldehyde
H
H
C
H
Formed
N
H
C
H
H
N
N
H
H
H
N
H
H
H
C
N
C
C
N
C
N
C
C
N
C
H
H
N
H
H
N
N
C
Melamine Formaldehyde
N
H
H
C
H
Water
HH
N
H
O
C
N
N
H
H
N
H
H
H
H
H
H
C
N
C
C
N
C
N
C
C
N
C
H
H
H
N
N
N
H
ห้องสมุดไป่ตู้
C
N
H
H
C
H
Amine plastics – clear adhesive
Chipboard
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.
• Plastic pellets with glass fibers are melted in screw, injected into a cold mold, and then ejected.
Glass filled resin pellets
Application of Phenolics