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TAFE NSW -Technical and Further Education Commission

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ENMAT101A Engineering Materials and ProcessesAssociate Degree of Applied Engineering (Renewable Energy Technologies)Lecture 19 – Plastics materials and rubbers

www.tradenote.net


Plastics materials and rubbers

EMMAT101A Engineering Materials and Processes

Reference Text Section

Higgins RA & Bolton, 2010. Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann

Ch 19

Reference Text Section

Callister, W. Jr. and Rethwisch, D., 2010, Materials Science and Engineering: An Introduction, 8th Ed, Wiley, New York.

Ch 4


Plastics materials and rubbers


Note: This lecture closely follows text (Higgins Ch19)

Geomembrane liner: http://www.fabtech.com.au


19.2 Types of plastics (Higgins 19.2)


READ HIGGINS Ch19.2Thermoplastic materials, Thermosetting materials, Elastomers19.2.1 Raw materials19.2.2 Composition of plastics




(i) Linear polymers: These are polymers in which monomeric units are linked together to form linear chain. Tend to pack well and have high intermolecular forces of attraction, giving high densities, high tensile strength and high melting points. Some common example of linear polymers are HDPE, nylon, polyester, PVC, PAN, PS, PMMA. PTFE etc.

(ii) Branched chain polymers: These are polymers with side chains or branches of different lengths. These cause irregular packing and therefore, they have low tensile strength, low density, boiling point and melting points than comparable linear polymers. Examples include low density polythene, modified linear polymers.

http://www.lbl.gov/MicroWorlds/Kevlar/KevClue1Act1.htmlhttp://courses.chem.psu.edu/chem112/materials/polymers.html

http://www.lbl.gov/MicroWorlds/Kevlar/KevClue1Act1.html

http://www.lbl.gov/MicroWorlds/Kevlar/KevClue1Act1.html

http://courses.chem.psu.edu/chem112/materials/polymers.html


AlkanesCovalent bonding of C atoms with H atoms.

The most basic type of hydro-carbon, usually derived from fossil fuels (esp crude oil). They all burn with oxygen to produce C02 + water.

Bio-fuel (ethanol) is an alcohol, so it has oxygen in it.


Ethanol aboveOil refinery right

Wikipedia

http://www.3rd1000.com


AlkanesIncreasingmolecule size.

Gas has 1 to 4 C.

Petrol contains 5 to 12 C.


Wikipedia

Alkane Formula Boiling point [°C]

Melting point [°C]

Density [g·cm3] (at 20 °C)

Methane CH4 -162 -182 gasEthane C2H6 -89 -183 gas

Propane C3H8 -42 -188 gasButane C4H10 0 -138 gas

Pentane C5H12 36 -130 0.626 (liquid)

Hexane C6H14 69 -95 0.659 (liquid)

Heptane C7H16 98 -91 0.684 (liquid)

Octane C8H18 126 -57 0.703 (liquid)

Nonane C9H20 151 -54 0.718 (liquid)

Decane C10H22 174 -30 0.730 (liquid)

Undecane C11H24 196 -26 0.740 (liquid)

Dodecane C12H26 216 -10 0.749 (liquid)

Icosane C20H42 343 37 solid

Triacontane C30H62 450 66 solid

Tetracontane C40H82 525 82 solid

Pentacontane C50H102 575 91 solid

Hexacontane C60H122 625 100 solid

http://en.wikipedia.org/wiki/Methane

http://en.wikipedia.org/wiki/Ethane

http://en.wikipedia.org/wiki/Propane

http://en.wikipedia.org/wiki/Butane

http://en.wikipedia.org/wiki/Pentane

http://en.wikipedia.org/wiki/Hexane

http://en.wikipedia.org/wiki/Heptane

http://en.wikipedia.org/wiki/Octane

http://en.wikipedia.org/wiki/Nonane

http://en.wikipedia.org/wiki/Decane

http://en.wikipedia.org/wiki/Undecane

http://en.wikipedia.org/wiki/Dodecane

http://en.wikipedia.org/wiki/Icosane

http://en.wikipedia.org/wiki/Triacontane

http://en.wikipedia.org/wiki/Tetracontane

http://en.wikipedia.org/wiki/Pentacontane

http://en.wikipedia.org/wiki/Hexacontane


AlkanesIncreasing molecule size increases boiling point and viscosity (thickness or resistance to flow).

Eventually you get wax at a few hundred C atoms.

Then, at about 1200 C atoms, you have plastic: Polyethylene.


http://www.3rd1000.com

FractionComposition

of carbon chains

Boiling range (oC)

Percent of crude oil

Natural Gas C1 to C4 Below 20 10%

Petroleum ether (solvent) C5 to C6 30 to 60 10%

Naphtha (solvent)

C7 to C8 60 to 90 10%

Gasoline C6 to C12 75 to 200 40%

Kerosene C12 to C15 200 to 300 10%

Fuel oils, mineral oil

C15 to C18 300 to 400 30%

Lubricating oil, petroleum jelly, greases, paraffin wax, asphalt

C16 to C24 Over 400 10%


PlasticsUnlike metals where the outer-shell electrons can travel freely, the outer-shell electrons in covalently bonded substances (like plastics) are securely held to the atoms and cannot move away. So they make great electric insulators.

Polyethene was first used as an electrical insulator in electronics equipment used in radar during the Second World War.


Higgins 1.4.4 Fig 1.7

Why is it called Polyethylene? Poly-mer means “Many”– “mers”. In the case of Poly-ethylene, the mer (or base unit) looks like methane. The original name given in 1898 was polymethylene. However, it is made from polymerization of ethylene – which is a gas.

HDPE binbcsplastics.com.au


Van der Waals ForcesWhy do the alkanes get stiffer as the molecules get longer until eventually becoming a solid? The molecules are held together by weak electrical imbalances in adjacent molecules (caused by electron distribution).These forces are too weak to hold short molecules together, but when there are hundreds of Carbon atoms in the chains, the Van der Waal molecular forces increase.


LDPE bottlepromotionsonly.com.au

HDPE binbcsplastics.com.au

This is why HDPE (garbage bin) is harder than LDPE (squeeze bottle).


Gecko feet


http://www.sfu.ca

Biomimicry is when engineers copy ideas from nature.Velcro was copied from seed burrs in 1948.

Today we are trying to copy the feet of the gecko because they stick to anything – even glass, but not by suction.

The gecko can stick to any smooth surface and also friable sandstone.

A gecko can hold it’s entire weight on one toe.

No hooks, no slime, no suction.


Gecko feet. Van der Waals Forces!


The secret of the Gecko’s grip is Van der Waal’s forces. The forces are weak, but with enough surface area they become substantial.

The surface area is achieved by splitting the toes into smaller and smaller hairs – until there is about a billion hairs of nanometer size.

Wikipedia/CC BY 1.0


Copying Gecko feet. Velcro to Anything!


http://www.sfu.ca

Researchers have developed a robot that can climb vertical surfaces.

Other teams are making gecko tape that sticks like 1 sided Velcro.

Gecko Tape: http://news.sciencemag.org

Sticky gecko feet Space Age ReptilesBBC animals2:25 min

http://www.youtube.com/watch?v=IkV1zMh_GQk




READ HIGGINS Ch19.2

Thermoplastic materials, Thermosetting materials, Elastomers19.2.1 Raw materials19.2.2 Composition of plastics 19.2.3 General properties of plastics materialsResist atmospheric corrosion LightweightReasonably tough and strongCannot handle much heatGood finish, colours, some transparentEasy to process

http://www.dotmar.com.au

http://www.dotmar.com.au/


19.3 Thermoplastics (Higgins 19.3)


READ HIGGINS Ch19.3

19.3.1 Plasticisers

Rigid PVC pipe: WikipediaPlasticised PVC cable: www.diytrade.com


19.4 Thermoplastic materials (Higgins 19.4)


READ HIGGINS Ch19.4

19.4.1 Vinyl plasticsPolyethylene (PE)Polyvinyl chloride (PVC)Polyvinyl acetate (PVA)Polyvinyl acetate/chloride copolymersPolyethylene-vinyl acetate (EVA)Polypropylene (PP)Polypropylene-ethylene copolymersPolystyrene (PS)Acrylonitrile-butadiene-styrene (ABS)

PVC boat: Wikipedia


19.4 Thermoplastic materials (Higgins 19.4)


READ HIGGINS Ch19.4

19.4.2 Fluorocarbons19.4.3 Cellulose-base plastics (cellulose esters)19.4.4 Polyamides (PA)19.4.5 Polyesters19.4.6 Polyacetals19.4.7 Acrylics19.4.8 High-temperature thermoplasticsPolyimides, Polysulphones, Polyether ether ketone (PEEK),

http://www.dotmar.com.au

http://www.dotmar.com.au/


19.5 Thermosets (Higgins 19.5)


Headlamp Housinghttp://www.withermoset.com

READ HIGGINS Ch19.5


19.6 Thermoset Materials (Higgins 19.6)


READ HIGGINS Ch19.6

19.6.1 PhenolicsPhenol formaldehyde (PF)Urea formaldehyde (UF)Melamine formaldehyde (MF)

19.6.2 Polyester resins19.6.3 Polyurethanes19.6.4 Epoxy resins19.6.5 Polyimides19.6.6 Silicones

http://www.glowpaint.com.au

http://en.wikipedia.org/wiki/Silicone


19.7 Elastomers (Higgins 19.7)


READ HIGGINS Ch19.7

19.7.1 Long chain molecules in rubber19.7.2 Vulcanisation19.7.3 Engineering elastomersNatural rubber (NR) and polyisoprene (IR)Styrene-butadiene rubber (SBR)Butadiene rubber (BR)Polychloroprene rubber (CR)Acrylonitrile-butadiene rubbers (NBR)Butyl rubber (IIR)Ethylene-propylene rubber (EPM)Silicone rubbers (SI)

news.alibaba.com

news.alibaba.com

http://news.alibaba.com/article/detail/industry-news/100037148-1-teknor-apex-establishes-automotive-programme.html


Recycling of plastics


Only thermoplastics can be re-melted.Identification is needed to prevent mixing.Food grade must be virgin (new) – not recycled material.Common plastics can be collected (PET), but specialist polymers are too rare.Product must be simple enough to sort. Recycling Misconceptions: http://www.ecologycenter.org/ptf/misconceptions.html

Recycled Polyethylene: http://www.replas.com.auPET: wikipedia

Plastic recycling

http://www.ecologycenter.org/ptf/misconceptions.html

http://en.wikipedia.org/wiki/Plastic_recycling


Recycling of plastics


http://learneasy.info/MDME/MEMmods/MEM30007A/polymers/polymers.html

Plastic recycling

http://en.wikipedia.org/wiki/Plastic_recycling



Wikipedia: Plastic

Resources.

Polymers

http://en.wikipedia.org/wiki/Plastic

http://learneasy.info/MDME/MEMmods/MEM30007A/polymers/polymers.html



Online Resources.

http://www.dotmar.com.au/engineered-plastics-products.html

http://www.adelaideplastics.com.au/glossary.htm


Glossary


PolymerMonomerPolymerisationThermoplasticThermosettingElastomerCopolymerCross linkingVulcanisationBranched polymerMerMolecular weight


QUESTIONSHiggins Ch19: Callister Ch4Moodle XML: Some questions in 10104 Polymers

1. Define all glossary terms. 2. Attempt relevant questions from Quiz 10104 Polymers3. Which elastomer is used for car tyres? What are the strong and weak points of this

polymer?4. Explain the different uses of the terms vulcanisation and cross-linking.5. Using their molecular features, explain the physical differences in the range of

polyethylenes. What type of molecular force is responsible for this change?6. Make comparisons of thermoplastic and thermosetting polymers (a) on the basis of

mechanical characteristics upon heating, and (b) according to possible molecular structures.

7. Some of the polyesters may be either thermoplastic or thermosetting. Suggest one reason for this.

8. (a) Is it possible to grind up and reuse phenol- formaldehyde? Why or why not? (b) Is it possible to grind up and reuse polypropylene? Why or why not?

9. Compare the general properties of the four classes of polymeric structures: Linear, branched, cross-linked and network. Gives 2 examples in each type.


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