4.2d Plastics Flashcards

1
Q

What are the raw materials for plastics?

A

Derived from petro-chemicals (crude oil, coal, natural gas)
Plastics are polymers in which the different types of bonds determine the physical/ mechanical properties

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2
Q

What is the molecular structure of thermoplastics?

A

Linear chain molecules
Weak secondary bonds between chains
ductile
low stiffness
easily injected into a mold
reshaped after heating
low production cost

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3
Q

What is the molecular structure of thermosetting plastics and its properties?

A

Linear chain molecules
Strong primary bonds between adjacent polymer chains
high stiffness
high strength
can not be reheated / remolded
heat resistant

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4
Q

What are the types of thermoplastics?

A

PP (Polypropylene)
PE (Polyethylene)
HIPS (High Impact Polystyrene)
ABS
PET (Polyethylene terephthalate)
PVC (Polyvinyl Chloride)

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5
Q

What are the properties of PP (Polypropylene)?

A

High temperature resistance

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6
Q

What are the properties of PE (Polyethylene)?

A

Flexible

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7
Q

What are the properties of HIPS (High Impact Polystyrene)?

A

Easy to shape

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8
Q

What are the properties of ABS?

A

Heat resistance

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9
Q

What are the properties of PET (Polyethylene terephthalate)?

A

Impact resistant

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10
Q

What are the properties of PVC (Polyvinyl Chloride)?

A

High hardness

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11
Q

What are the types of thermoset plastics?

A

Polyurethane
Urea-formaldehyde
Melamine resin
Epoxy resin

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12
Q

What are the properties of Polyurethane?

A

Good insulator, and high tensile/compressive strength

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13
Q

What are the properties of Urea-formaldehyde?

A

High tensile strength

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14
Q

What are the properties of melamine resin?

A

High electrical resistance

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15
Q

What are the properties of epoxy resin?

A

High mechanical strength (tensile/compressive)

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16
Q

What is the recovery and disposal of plastics?

A

It is recyclable (the degree of recyclability depends on type, economic factors, logistics)
Thermoplastics are easily recycled, while thermosets are not easy (often sent to landfills)

17
Q

What is the impact of temperature on recycling thermoplastics?

A

Thermoplastics soften when heated, and harden/ strength after cooling
Can be heated, shaped, and cooled without causing a chemical change (weak secondary bonds break, but not the primary ones)
Allows it to be readily recycled