TAFE NSW -Technical and Further Education Commission ENMAT101A Engineering Materials and Processes Associate Degree of Applied Engineering (Renewable Energy Technologies) Lecture 19 – Plastics materials and rubbers

TAFE NSW -Technical and Further Education Commission Plastics materials and rubbers EMMAT101A Engineering Materials and Processes Reference TextSection Higgins RA & Bolton, Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann Ch 19 Reference TextSection Callister, W. Jr. and Rethwisch, D., 2010, Materials Science and Engineering: An Introduction, 8th Ed, Wiley, New York. Ch 4

TAFE NSW -Technical and Further Education Commission Plastics materials and rubbers EMMAT101A Engineering Materials and Processes Note: This lecture closely follows text (Higgins Ch19) Geomembrane liner:

TAFE NSW -Technical and Further Education Commission 19.2 Types of plastics (Higgins 19.2) EMMAT101A Engineering Materials and Processes READ HIGGINS Ch19.2 Thermoplastic materials, Thermosetting materials, Elastomers Raw materials Composition of plastics

TAFE NSW -Technical and Further Education Commission 19.2 Types of plastics (Higgins 19.2) EMMAT101A Engineering Materials and Processes (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.

TAFE NSW -Technical and Further Education Commission Alkanes Covalent 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 C0 2 + water. Bio-fuel (ethanol) is an alcohol, so it has oxygen in it. EMMAT101A Engineering Materials and Processes Ethanol above Oil refinery right Wikipedia

TAFE NSW -Technical and Further Education Commission Alkanes Increasing molecule size. Gas has 1 to 4 C. Petrol contains 5 to 12 C. EMMAT101A Engineering Materials and Processes Wikipedia AlkaneFormula Boiling point [°C] Melting point [°C] Density [g·cm 3 ] (at 20 °C) MethaneCH gas EthaneC2H6C2H gas PropaneC3H8C3H gas ButaneC 4 H gas PentaneC 5 H (liquid) HexaneC 6 H (liquid) HeptaneC 7 H (liquid) OctaneC 8 H (liquid) NonaneC 9 H (liquid) DecaneC 10 H (liquid) UndecaneC 11 H (liquid) DodecaneC 12 H (liquid) IcosaneC 20 H solid TriacontaneC 30 H solid TetracontaneC 40 H solid PentacontaneC 50 H solid HexacontaneC 60 H solid

TAFE NSW -Technical and Further Education Commission Alkanes Increasing 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. EMMAT101A Engineering Materials and Processes Fraction Composition of carbon chains Boiling range ( o C) Percent of crude oil Natural GasC 1 to C 4 Below 2010% Petroleum ether (solvent) C 5 to C 6 30 to 6010% Naphtha (solvent) C 7 to C 8 60 to 9010% GasolineC 6 to C to 20040% KeroseneC 12 to C to 30010% Fuel oils, mineral oil C 15 to C to 40030% Lubricating oil, petroleum jelly, greases, paraffin wax, asphalt C 16 to C 24 Over 40010%

TAFE NSW -Technical and Further Education Commission Plastics Unlike 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. EMMAT101A Engineering Materials and Processes Higgins 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 bin bcsplastics.com.au

TAFE NSW -Technical and Further Education Commission Van der Waals Forces Why 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. EMMAT101A Engineering Materials and Processes LDPE bottle promotionsonly.com.au HDPE bin bcsplastics.com.au This is why HDPE (garbage bin) is harder than LDPE (squeeze bottle).

TAFE NSW -Technical and Further Education Commission Gecko feet EMMAT101A Engineering Materials and Processes Biomimicry is when engineers copy ideas from nature. Velcro was copied from seed burrs in 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.

TAFE NSW -Technical and Further Education Commission Gecko feet. Van der Waals Forces! EMMAT101A Engineering Materials and Processes 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

TAFE NSW -Technical and Further Education Commission Copying Gecko feet. Velcro to Anything! EMMAT101A Engineering Materials and Processes Researchers have developed a robot that can climb vertical surfaces. Other teams are making gecko tape that sticks like 1 sided Velcro. Gecko Tape: Sticky gecko feet Space Age Reptiles BBC animals 2:25 min

TAFE NSW -Technical and Further Education Commission 19.2 Types of plastics (Higgins 19.2) EMMAT101A Engineering Materials and Processes READ HIGGINS Ch19.2 Thermoplastic materials, Thermosetting materials, Elastomers Raw materials Composition of plastics General properties of plastics materials Resist atmospheric corrosion Lightweight Reasonably tough and strong Cannot handle much heat Good finish, colours, some transparent Easy to process

TAFE NSW -Technical and Further Education Commission 19.3 Thermoplastics (Higgins 19.3) EMMAT101A Engineering Materials and Processes READ HIGGINS Ch Plasticisers Rigid PVC pipe: Wikipedia Plasticised PVC cable:

TAFE NSW -Technical and Further Education Commission 19.4 Thermoplastic materials (Higgins 19.4) EMMAT101A Engineering Materials and Processes READ HIGGINS Ch Vinyl plastics Polyethylene (PE) Polyvinyl chloride (PVC) Polyvinyl acetate (PVA) Polyvinyl acetate/chloride copolymers Polyethylene-vinyl acetate (EVA) Polypropylene (PP) Polypropylene-ethylene copolymers Polystyrene (PS) Acrylonitrile-butadiene-styrene (ABS) PVC boat: Wikipedia

TAFE NSW -Technical and Further Education Commission 19.4 Thermoplastic materials (Higgins 19.4) EMMAT101A Engineering Materials and Processes READ HIGGINS Ch Fluorocarbons Cellulose-base plastics (cellulose esters) Polyamides (PA) Polyesters Polyacetals Acrylics High-temperature thermoplastics Polyimides, Polysulphones, Polyether ether ketone (PEEK),

TAFE NSW -Technical and Further Education Commission 19.5 Thermosets (Higgins 19.5) EMMAT101A Engineering Materials and Processes Headlamp Housing READ HIGGINS Ch19.5

TAFE NSW -Technical and Further Education Commission 19.6 Thermoset Materials (Higgins 19.6) EMMAT101A Engineering Materials and Processes READ HIGGINS Ch Phenolics Phenol formaldehyde (PF) Urea formaldehyde (UF) Melamine formaldehyde (MF) Polyester resins Polyurethanes Epoxy resins Polyimides Silicones

TAFE NSW -Technical and Further Education Commission 19.7 Elastomers (Higgins 19.7) EMMAT101A Engineering Materials and Processes READ HIGGINS Ch Long chain molecules in rubber Vulcanisation Engineering elastomers Natural 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

TAFE NSW -Technical and Further Education Commission Recycling of plastics EMMAT101A Engineering Materials and Processes 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: Recycled Polyethylene: PET: wikipedia Plastic recycling

TAFE NSW -Technical and Further Education Commission Recycling of plastics EMMAT101A Engineering Materials and Processes Plastic recycling

TAFE NSW -Technical and Further Education Commission EMMAT101A Engineering Materials and Processes Wikipedia: Plastic Resources. Polymers

TAFE NSW -Technical and Further Education Commission EMMAT101A Engineering Materials and Processes Online Resources.

TAFE NSW -Technical and Further Education Commission Glossary EMMAT101A Engineering Materials and Processes Polymer Monomer Polymerisation Thermoplastic Thermosetting Elastomer Copolymer Cross linking Vulcanisation Branched polymer Mer Molecular weight

TAFE NSW -Technical and Further Education Commission QUESTIONS Higgins Ch19: Callister Ch4 Moodle XML: Some questions in Polymers 1.Define all glossary terms. 2.Attempt relevant questions from Quiz Polymers 3.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. EMMAT101A Engineering Materials and Processes