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Polymer Technology > Lecture 1: Design > Flashcards

Lecture 1: Design Flashcards

1
Q

A bag made of only Polyethylene will degrade in a few weeks. This doesn’t happen, why?

A

Additives

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2
Q

Polymer groups

A

Thermoplastics, thermosets, fibres, rubbers, bio based plastics

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3
Q

Thermoplastics

A

Bulk polymers: PE, PVC, PP, PS
Engineering plastics: PC, PA, PET, POM
High performance: PPO, PSU, PEEK

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4
Q

Thermosets

A

Matrix materials

Composites: including nanocomposites

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5
Q

Plastics

A

Polymers + additives

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6
Q

Additives

A

Fillers (to make the product cheaper, but can make it weaker)
Reinforcing agents (ex. reinforcement fillers)
Coupling agents (making polymer networks)
Plasticiser (ex. can handle heat better)
Antioxidants, stabilisers, flame retardants, nanofillers

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7
Q

Processing Methods

A

Injection moulding, extrusion, blow moulding, calendaring, rotational moulding, thermoforming

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8
Q

Rheology

A

Melt viscosity, shear- and elongation viscosity, shear thinning, die swell

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9
Q

Mechanical Properties

A

E-modulus, Tensile strength & elongation at break, Creep, Stress relaxation, Impact strength, Dynamical Properties, Time dependence, Fatigue

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10
Q

Life time

A

Degradation, Stabilization, Methods to estimate life time

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11
Q

Recycling

A

Reuse, Material recycling, Chemical Recycling, Energy Recycling

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12
Q

Material -> Processing -> Use

A

Materials: Polymers & Additives
Processing: Methods, Rheology, Design (recycling)
Use: Mechanical properties, life time (recycling)

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13
Q

Design 10 steps

A
  1. Definition of functions (function portfolio: colour, intended use), 2. Demand Profile (reflect light, strength etc.), 3. Coarse screening of material (challenge), 4. Property profile of possible materials (too good->too expensive), 5. Part design - recycling possibilities (might be in demand profile but not later than here), 6. Choice of processing methods, 7. Choice of material, 8. Tool preparation, 9. Prototype creation (verification of tool and product), 10. Adjusting of tool
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14
Q

Environmental aspects

A 
Feed stock consumption
Energy consumption
Environmental impact
Recycling
Bio based plastics
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15
Q

Solid Materials: Metals, Polymers (polymeric molecules), ceramics

A

Synthetic Polymers, Natural Polymers (wood, leather, cotton, hair)

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16
Q

Modified Natural Polymers

A

Celluloid, Cellophane

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17
Q

Synthetic Polymers

A

Do not occur naturally: Nylon, Polyester, Polyethylene

Occur naturally but made by non-natural process: synthetic rubber

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18
Q

Total annual production of synthetic polymers

A

250 million tons
60% Thermoplastics
15% Thermosets
20% Fibre

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19
Q

Most common thermoplastics

A
  1. Polyethylene
  2. PVC
  3. Polypropylene
  4. Polystyrene
  5. PET
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20
Q

Plastic 9 properties

A 
Low melting point
Large elongation
Low density
Low thermal conduction 
Electrical resistance
Optical clarity (some)
Easily coloured 
Solvent sensibility
Flammable
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21
Q

Low Melting Point

A

Advantage: Easy to process
Disadvantage: Lower temperature range

22
Q

Larg elongation

A

Less Brittle

Larger creep & lower yield strength

23
Q

Low density

A

Lightweight products

Low structural strength

24
Q

Low Thermal Conduction

A

Good thermal insulator

Low heat dissipation

25
Q

Electrical resistance

A

Good electrical insulator

Poor conductivity

26
Q

Optic Clarity

A

Optical applications

Influenced by sunlight (UV)

27
Q

Easily coloured

A

No need for painting

Hard to colour match

28
Q

Solvent Sensitivity

A

Can be dissolved (some)

Can be affected by solvents

29
Q

Flammable

A

Waste can burned

May cause fume, fire hazard

30
Q

Common mistakes designing plastic components

A
  • Wrong selection of materials
  • Ignorance of differences between polymers and metals
  • Not thinking of processing method and design of the mould
31
Q

Design Methodology

A

Inspiration, Concept, Prototype, Development, Final product

32
Q

Work Protocol when designing with polymers

A
  1. Recognise the needs, 2. Definition of function, 3. Establish a demand profile, 4. Coarse selection of materials, 5. Property profiles of possible materials, 6. Detailed design including recycling possibilities, 7. Choice of processing method, 8. Choice of material , 9. Tool preparation, 10. Production of test series: control of tool and product, 11. Revision and trimming of tool
33
Q

Establish a demand Profile

A

Mechanical load, thermal and chemical environment, fire risks, health risks, life time, recycling, standards; rules & laws, cost

34
Q

Coarse selection of materials

A
  • Eliminating impossible materials
  • Specific demands indicating special materials
  • Temperature region
  • Chemical environment
  • Contact with food
  • Is a plastic material possible
35
Q

Demand profile: Mechanical Properties

A

Shape preserving: E-modulus
Load bearing: E- & G- modulus
Cyclic load: Fatigue data, temperature increase?
Time of load: Creep and relaxation properties
Stress concentration: internal stress, brittleness at low T, anisotropy
Wear: wear strength, hardness, self lubrication, friction properties, need of lubricants
Heat: Expansion coefficient

36
Q

Demand Profile: Thermal environment

A

Maximal application T, vicat temperature, heat distortion temperature, expansion coefficients, specific heat, heat conduction, Tg

37
Q

Demand Profile: Chemical Environment

A

Chemical resistance for short and long time, corrosion, crack formation

38
Q

Demand Profile: Electrical environment

A

Volume and surface resistivity, break down strength, loss factor

39
Q

Demand Profile: Risk for fire

A

Fire class, ignition (electrical, heat) dripping, smoke formation

40
Q

Demand Profile: Radiation environment

A

Ageing properties (UV, high energy radiation)

41
Q

Demand Profile: Biological Environment

A

Toxicological recommendation, toxic properties

42
Q

Demand Profile: Optical properties

A

Opaque/transparent, light transmission, refractive index

43
Q

Demand Profile: Apperance

A

Shape, surface, colour

44
Q

Demand Profile

A

Mechanical parameters, thermal-, chemical-, Electrical-, Radiation-, Biological Environment, Risk for fire, Optical properties, appearance.

45
Q

Process Considerations

A

Processability, cutting ability, joining ability

46
Q

Processability

A
  • Tm & Tg
  • Viscosity
  • Heat of melting, cooling time
  • Mold and after shrink
47
Q

Cutting ability

A
  • cutting properties

- processing

48
Q

Joining ability

A
  • welding
  • adhesive bonding
  • riveting
  • snap joint
  • screwing
49
Q

Process consideration properties

A

Surface treatment, processing cost, mould cost, density, price per kg, price per component, number details, degree of automatisation, recycling; material, energy, landfill, material availability, merit values

50
Q

Detailed Design

A
  • Matching between demand profile and specific property profile
  • Design vs possible processing methods
  • Design with respect to recycling
51
Q

Choice of processing method

A
  • The processing method influence the design
  • The choice is influenced of ex. Material and number of details to be made
  • Injection Molding of thermoplastics if long series
  • Compression Molding is suitable for Thermosets and short series
  • Compromises
52
Q

Choice of materials from the pyramid

A

Top: High Performance Polymers
Middle: Mid-range polymers
Bottom: Common polymers

Right: Semi-crystalline
Left: Amorphous

Polymer Technology (2 decks)

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