polymer (plastics) 고분자재료 - manufacturing...
TRANSCRIPT
© GNU Su-Jin Kim
Plastics
Material Science
Polymer (Plastics)
고분자재료
Associate Professor Su-Jin Kim
School of Mechanical Engineering
Gyeongsang National University
© GNU Su-Jin Kim
Plastics
Material Science
OCW
Plastics and Polymers (Kids)
https://youtu.be/tAYPxxdIQQc
Polymers (BBC)
https://youtu.be/BgILS0UBUvA
The 7 Thermoplastics
https://youtu.be/29Az-dPwtg8?list=PLDE5A69832ECC4D26
Thermoset
https://youtu.be/-cyTDZmkbYc
© GNU Su-Jin Kim
Plastics
Material Science
OCW
Polymers (TED 5min)
Monomer, Polymer, Natural, Syntactic(Addition reaction, ) Bakelite, Rubber, Styropone
https://youtu.be/UwRVj9rz2QQ
LG Chemical http://www.lgchem.com
© GNU Su-Jin Kim
Plastics
Material Science
Contents
1. Plastics (Polymers, 고분자재료) • Thermoplastics (열가소성수지) • Thermoses (열경화성수지) • Rubbers (고무)
2. Physical Properties
© GNU Su-Jin Kim
Plastics
Material Science
Automotive Plastics and Composites Use Exterior
• doors, light, bumper covers
Interior
• instrument panels, door trim, seats, consoles
Engine
• valve covers, intake manifolds, fluid containers
© GNU Su-Jin Kim
Plastics
Material Science
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 and clothes
Land Sports Equipment
• shoes, roller blades, skate boards, tennis, golf, etc.
© GNU Su-Jin Kim
Plastics
Material Science
Commercial Plastics Usage
Packaging
• Wrapping, bags, bottles, foams, shrink wrap.
Textiles
• Clothing, carpets, fabrics, diapers, netting for sports
Furniture, Appliances, House wares
• Telephones and other communication equipment, computer housings and cabinets, luggage, seating, components for
• washers, dryers, etc.
• Musical instruments, CDs, VCRs, TVs, cases
© GNU Su-Jin Kim
Plastics
Material Science
Medical Plastics and Composites Use Containers
• Bottles, bags
Drug delivery
• IV bags, syringes
• tubing and tools for surgery
• Implants, artificial skins
© GNU Su-Jin Kim
Plastics
Material Science
Solid Materials
Metals Plastics Ceramic
Thermoplastics Thermosetts Elestomers
Plastic means to form or mold (from plastikos in Greek)
Polymer: Poly (many) + mer (structural unit)
Plastic = Polymer
© GNU Su-Jin Kim
Plastics
Material Science
Chemical Structure of Polymer
• A monomer is the basic building block of a polymer.
• Polymers are long-chain molecules.
• Monomers linked in repeating units by polymerization reaction.
Ethylene
/Monomer
Polyethylene-[C2H4]n-
/Polymer
Polymerization
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Plastics
Material Science
Chemical Structure of Polymer Monomer Polymer
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Plastics
Material Science
Degree of Polymerization
1. Molecular weight
- M = n M0 , n: degree of polymerization
2. Degree of polymerization, n
- the higher the n, the longer the chain and the higher polymer’s viscosity.
Ex) Polyethylene -[C2H4]n- plastic
© GNU Su-Jin Kim
Plastics
Material Science
Covalent (primary) bonding
• Occurs when two nonmetal atoms are in close proximity.
• Both atoms share outer electron shells.
• Strong Bond
Carbon 2C + hydrogen 4H
C
-
-
- -
H
-
H
-
H
-
H
-
Ethene C2H4
C
- -
- -
- -
H
H
C
- -
- -
- -
H
H
C
- -
- -
- -
H
H
Polyethylene -[C2H4]n-
C
-
-
- -
C
- -
- -
- -
H
H
C
- -
- -
- -
H
H
© GNU Su-Jin Kim
Plastics
Material Science
Van der Waals (secondary) bonding
• Due to the Interaction between molecules called intermolecular force. It is much weaker than covalent bonding.
C C
C C
C C
C C
C C
C C
C C
C C
C C
C C
C C
C C
C C
C C
C C
C C
Covalent bonding
Van der Waals bonding
© GNU Su-Jin Kim
Plastics
Material Science
Structure of Polymer
1. Linear
- Thermoplastic such as acrylics, nylons, polyethylene, polyvinyl.
2. Branched
- polyethylene.
3. Cross-linked & Network
- Thermosets; epoxis, phenolics silicones, rubbers, elastomers
© GNU Su-Jin Kim
Plastics
Material Science
Amorphous vs. Crystalline
• Amorphous region: polymer chains exist random. (Polyvinyl chloride, Polystyrene)
• Crystalline region: Uniform (regular) arrangement of molecules. It is stiffer, harder, less ductile. (Polyethylene, Polypropylene)
© GNU Su-Jin Kim
Plastics
Material Science
Thermoplastics(열가소성)
• little crosslinking, ductile
• soften with heating
ex) polyethylene, polypropylene, polycarbonate, polystyrene
Thermosets(열경화성)
• large crosslinking (10~50%), hard and brittle
• do not soften with heating
ex) rubber, epoxies, polyester resin, phenolic resin
Thermoplastics vs. Thermosets
© GNU Su-Jin Kim
Plastics
Material Science
Thermoplastics
• Linear and branched polymers will weaken secondary bonds.
• When above glass-transition temperature, polymers is easier to mold into shapes.
• Small increasing in temperature drops strength and increase ductility.
© GNU Su-Jin Kim
Plastics
Material Science
Thermoplastics
PET Polyethylene terephthalate (high toughness, transparent )
Water & sports drink bottle
HDPE High density polyethylene (hard)
Milk, water, juice bottle; yogurt tub; retail bag
LDPE Low-density polyethylene (squeezable)
Bread and frozen food bag and squeezable bottle
PP Polypropylene (-110°C, high strength, transparent)
Flip-top bottle, plastic bag
PS Polystyrene (low strength, low elongation, transparent)
Yogurts cup, styrofoam
PVC Polyvinyl chloride
Flexible cables ; pipe
© GNU Su-Jin Kim
Plastics
Material Science
Thermoplastics
PC Polycarbonate (high toughness, transparent)
Baby bottle, Phone, Laptop, Safyglass, Canopy
ABS Acrylonitrile Butadiene Styrene (high strength & toughness)
Electric, Home, Automotive
0.523" Polycarbonate
0.190" Spall Polycarbonate
0.025" TPU Interlayer
Abrasion Resistant Coating
Abrasion Resistant Coating
© GNU Su-Jin Kim
Plastics
Material Science
Properties
Max usage Temperature°C
Optical Features
Mechanical properties
PS 60-70 Transparent Low strength & elongation
PE 60-80 Translucent to opaque
Low strength, Soft to rigid
PP 100-110 Translucent High strength & rigidity
PC 115-125 Transparent High strength
© GNU Su-Jin Kim
Plastics
Material Science
Thermosets
• Polymerization: linear chain(liquid) +(heat, pressure)-> cross-linking(cured permanently, no recycled)
• Epoxy resins - coating, adhesive
• Phenolic resins - tool handles, billiard balls
• Polyester resins - FRP
• Epoxy or Polyester +Fiberglass = FRP
© GNU Su-Jin Kim
Plastics
Material Science
Thermosets
• Acrylic: transparent
• Melamine
• Polyimide(PI): high temperature
• Teflon(PTFE): non-stick coating
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Plastics
Material Science
Elastomers (Rubbers)
• An elastomer is capable of recovering substantially in shape and size after its load has been removed.
• Rubber is capable of quickly recovering from large deformations(<500%).
• Elastomers encounter hysteresis loss in stretching or compression. During the deformation energy is lost.
Elongation
Load
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Plastics
Material Science
Elastomers (Rubbers)
• Natural rubber
• SBR(styrene butadiene rubber)
• Silicone
• Polyurethane: insulating foams
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Plastics
Material Science
Polymer Additives(첨가제)
Improve mechanical properties, processability, durability, etc.
• Fillers (충진제)
– Added to improve tensile strength & abrasion resistance, toughness & decrease cost
– ex: carbon black, silica gel, wood flour, glass, limestone, etc.
• Plasticizers (가소제)
– Added to reduce the glass transition temperature Tg
– commonly added to PVC - otherwise it is brittle
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Plastics
Material Science 27
Polymer Additives
• Stabilizers (안정화제)
– Antioxidants
– UV protectants
• Lubricants (윤활제)
– Added to allow easier processing
– “slides” through dies easier – ex: Na stearate
• Colorants (색소제)
– Dyes or pigments
• Flame Retardants (방염제)
– Cl/F & B
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Plastics
Material Science 28
Stress-strain curve (응력-변형율)
Strain >10 possible (metals < 0.1)
brittle polymer
plastic
elastomer
Str
ess 1
0%
of m
eta
l
Network linked
Amorphous chain
• Stress 0.1xmetal, Strain 10xmetal
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Plastics
Material Science 29
Stress-strain curve (응력-변형율)
• Strength: PMMA>ABS>PP>PE
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Plastics
Material Science 30
↑Temperature
↓Elastic modulus, ↓ Tensile strength
↑Ductility
Sensitive to Temperature
0 0 0.1 0.2 0.3
4°C
20°C
40°C
60°C to 1.3
str
ess
strain
© GNU Su-Jin Kim
Plastics
Material Science
Viscoelastic (점탄성)
Stress relaxation(응력이완)
strain to ε0 and hold stress decrease with time.
Relaxation modulus(이완계수) Er(t) = σ(t)/ ε0
time
str
ain
, str
ess
Strain ε0
Stress σ(t)
© GNU Su-Jin Kim
Plastics
Material Science
Glass-transition(유리천이) temperature
• Relaxation modulus drop large at Glass-transition temperature, Tg.
glassy
(rigid, brittle)
Tg Tm
rubbery
E
G
elastic solid
(탄성고체)
viscous liquid
(점성유체)
dy
dv
Viscoelastic
(점탄성체)
leathery viscous
mC
Log R
ela
xation m
odulu
s E
r
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Plastics
Material Science 33
Drawing
• Drawing (ex: monofilament fish line) - stretches the polymer prior to use - aligns chains in the stretching direction • Results of drawing: - increases the elastic modulus (E) in the stretching direction - increases the tensile strength (TS) in the stretching direction - decreases ductility (%EL) • Annealing after drawing - decreases alignment - reverses effects of drawing.
© GNU Su-Jin Kim
Plastics
Material Science
Injection molding (사출성형)
Hopper
Barrel
Mold
• Plastics are melted in a heated cylinder and forced into a mold by hydraulic plunger of rotating screw.