bld62003 mak plastics
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BUILDING MATERIALS (BLD62003)
BACHELOR OF QUANTITY SURVEYING (HONS.)
• INTRODUCTION TO PLASTICS. • PROPERTIES & CHEMICAL COMPOSITION OF PLASTICS. • FORMING PROCESSES (Explanations & Videos) • TESTING PROCESSES. • APPLICATION OF PLASTIC MATERIALS IN CONSTRUCTION. • ONLINE QUIZ! SELF-ASSESSMENT • TUTORIALS
WHAT IS PLASTIC?
• Derived from GREEK word
“PLASTIKOS” = able to be shaped
• A PLASTIC material is any of a
wide range of synthetic or semi-
synthetic organic solids that can
be shaped or molded into any
form: some are naturally occurring,
but most are man-made.
WHAT IS PLASTIC MADE OF?
• The raw material is OIL.
• Produced from petrochemical products.
• There are some other raw materials that can be used:
coal, natural gas, various organic materials such as
sugar and oils.
WHAT IS PLASTIC?
• A substance that contains natural or synthetic high molecular organic material
• A petrochemical product-derived from petroleum
• Can be liquefied thus cast in specific molds
• Can imitate the appearance of wood, glass, metal etc
• Decorative items and accessories have been eventually being replaced by plastics instead of glass to lowered the manufacturing cost
• Appearances are similar to glass but there are great differences between their properties.
PROPERTIES OF PLASTIC
• Non-load bearing materials. • Not subject to corrosion. Therefore always be a replacement for
some other materials. • Degraded by sunlight exposure. Hence, reduce mechanical
strength. • Flammable unless treated. • Inexpensive to produce. • Lighter than other materials of comparable strength e.g wood,
metal (iron or steel) etc. • Low density materials: from 0.9-2.2g/cm. • Polythene & polystyrene are among the lightest. • Low tensile strength e.g the resistance to pulling force is weak. • 20% of plastic production used in building industry. E.g: 40%
PVC (Polyvinyl chloride – has high embodied energy content) used in pipes, cladding, electrical cable insulation, windows, doors and flooring.
PROPERTIES OF PLASTIC
• Elongate up to 500% without fracturing
• Low compressive strength yet glass-fiber-reinforced plastics resist compressive force more than steel
• Hardest plastic is softer than the softest metal yet the penetration resistant can be enhanced by reinforcing glass fibers
• Resistance impact varies e.g. rigid polymers i.e. polystyrene and acrylics are brittle and fracture easily
• Flexible plastic e.g polyvinyl and polyethylene have high impact strength
• Low melting temperatures but high coefficient of expansion
PROPERTIES OF PLASTIC
• Deforming capacity: Materials like iron cannot be
deformed as easy as plastic. Hence plastic is more
• Atmospheric resistance: Resists to humidity, high and
• Chemical resistance: Chemically inert, hence substances
like soap , water acid can be stored in plastic containers.
• Recyclability: Plastic can be re-used.
• Impermeability to light, water and gases.
• Composed of repeating units of short carbon compounds called ‘monomers’ that link together to form a larger molecule called a ‘polymer’
• Various types of monomers can be combined in many different arrangements to make infinite variety of plastic – which all have different chemical properties.
• The manufacture of plastic involves: polymerization of ethylene monomer (colorless gas) - @ high pressure 200 degree Celsius – converted into – clear polymer polyethylene or polythene
ARRANGEMENT OF MONOMERS BLD62003/MAK/PLASTIC
• LINEAR POLYMERS
• BRANCHED POLYMERS
• CROSS-LINKED POLYMERS
• NETWORK POLYMERS
CLASSIFICATION OF PLASTIC BLD62003/MAK/PLASTIC
• Can be heated and shaped many times.
• Will soften when is heated and can be shaped when hot.
• Will harden when cooled, but can be reshaped because it has no link between polymer chains.
• Example: ABS (acrylonitrile butadienestyrene), Nylon (polyamide), acrylic (polymethyl methacrylate), uPVC (polyvinyl chloride), polystyrene, polypropylene and cellulose acetate
• Can only be heated and shaped once.
• If re-heated they cannot soften as polymer chains are interlinked.
• Fixed molecular structure that cannot be reshaped by heat or solvents that are joined by adhesives.
• Example: Epoxy resin, melamine formaldehyde, polyester resin and urea formaldehyde.
• Elasticity • Plastic in which hellical /
zig-zag molecular chains are free to straighten when the material is stretched and recover when the load is taken away
• Example: natural rubber, neoprene.
• Linear or slightly branched molecules
• Do not chemically bond with each other when heated
• Can be heated, cooled, softened and hardened repeatedly like candle wax
• Can be remolded and reused
• Consists of chain molecules that chemically bonded, or cross-linked with each other when heated.
• Cannot be remolded once cured.
• Used to make heat-resistant products
• Example: a) phenol formaldehyde: decorative laminates; b) melamine formaldehyde: laminates for working surfaces and doors, molded electrical components, WC seats; c) urea formaldehyde: decorative laminates; d) glass-reinforced polyester (GRP): cladding & roofing panels, cold water tanks, spa baths, garage doors, decorative tiles and panels.
THERMOPLASTIC vs THERMOSET
• Natural rubber added with sulfur to ensure that elastomer materials return to its original form when applied stress is removed
• Also known as elastomeric • Example: a) Rubber: floorings, door seals,
anti-vibration beatings b) Neoprene: glazing seals, gaskets c) Elastomer: glazing seals,
gaskets, single-ply roofing systems
d) Butyl rubber: sheet liners to water features and land-fill sites
e) Nitrile rubber: tile & sheet flooring
THERMOPLASTIC vs THERMOSET
THERMOPLASTIC • These are made from polymers without
cross-linking between their chains. • The intermolecular forces between the
chains are relatively weak (compared to thermosets with covalent cross-links).
• The attractive forces in the thermoplastics can be broken down by warming.
• The chains are able to move over each other and the polymer can be deformed.
• On cooling, the weak forces between the polymer reform and the thermoplastic holds its new shape.
• Examples of thermoplastics are polythene and nylon.
THERMOSET • These polymers have lots of cross-
linking between the different polymer chains.
• These cross-links make the chains much stronger than in thermoplastics.
• The attractive forces cannot be broken by warming.
• The chains cannot move relative to each other and the polymer cannot change shape.
• If heated, the polymer just chars and burns. Bakelite is an example of a thermoset.
THERMOPLASTIC vs THERMOSET
• They will burn when excessive heat is applied because their melting point is simply too high to reach. • The materials degrade and decompose before they can reach temperatures high enough to melt. • Commonly utilized in automated equipment and high volume applications. • Thermoplastics are easier to work with than thermoset materials. • They can also be easily stripped if an application requires.
• Irreversibly molded. • Thermosets are great solutions
for high temperature applications or for circuits at risk for overload.
• High temperature ratings make them more likely to function if an application overheats suddenly.
HOW PLASTIC IS MADE OF? BLD62003/MAK/PLASTIC
• The melted plastic is poured into a mold. • When the plastic becomes cooler, it takes the shape. BLENCH
• Air or gas is injected into a plastic mass to form bubbles in order to make it lighter.
• Eg: mattresses, sponges, bike helmets. SKIM
• The plastic is passed through the rollers called calenders until it becomes into thin sheets.
• Eg: files CALENDER
• Plastic is given shape by introducing it into a mold by either high or low pressure. MOULDING
• Raw materials (gas, liquid, powder, granules)
• Formed into extrusion or sheet.
• Reformed into finished product.
• Partially polymerized material; or
• Directly from resin and hardened mix.
• Blown with internally generated gas; or
• Produced by a vacuum process.
TYPICAL MANUFACTURING PROCESS
• Conveys petroleum to a refinery • Refine raw oil and natural gas into ethane, propane & other
petrochemical products • Break ethane & propane into ethylene & propylene in a high
temperature furnace • Ethylene can be converted into clear polyethylene under high
pressure at 200 degree Celcius (polymerization process) • Combine ethylene or propylene with catalyst in a reactor to
produce “fluff”, a powdered material. • Combine “fluff” with additives in a continuous blender • Melt the polymer in an extruder • Cool the melted plastic • Cut the product into tiny pellets in a pelletizer • Send to customer
PLASTIC FORMING PROCESSES BLD62003/MAK/PLASTIC
EXTRUSION FORMING PROCESS
• Plastic pellets are placed in a feed hopper which feeds into the system.
• A turning screw pushes the plastic into the barrel where heaters increase the temperature and a melted polymer is obtained.
• The melted plastic is forced through a shaping die.
• Depending on the particular shape of this element, a continuous shape is formed and pulled out of the extrusion machine.
• Solidification by cooling.
EXTRUSION FORMING PROCESS BLD62003/MAK/PLASTIC
TYPICAL DIAGRAM OF EXTRUSION FORMING PROCESS
Using this processing it is possible to produce a wide range of different forms of plastic, such as tubes, sheets and films, structural parts, etc.
RESULT OF EXTRUSION PROCESS
INJECTION MOULDING PROCESS
• Plastics pellets flows, due to gravity, from the feed hopper onto a turning screw.
• It is converted into a melted plastic by the action of heaters situated along the barrel.
• The screw moves the molten plastic forward, forcing the plastic through a gate into the cooled mold.
• The mold is opened once the plastic has solidified and the piece is pushed from the mold by automatic ejector pins.
• After we get the manufactured piece, the mold is closed and clamped and the process begins again.
INJECTION MOULDING PROCESS BLD62003/MAK/PLASTIC
TYPICAL DIAGRAM OF INJECTION MOULDING PROCESS
• High production rates are possible.
• (A typical cycle time for a 3mm thick part would about 40 seconds)
• Injections molding allows you to produce products with a good finish to a good consistent quality
• Very expensive to set up - the tools (the dies or molds) are produced to a high degree of accuracy and surface finish
• In compression moulding, plastics pellets, sometimes called moulding powder, are placed in the feed hopper and pushed to the gate by the action of the turning screw.
• It is heated and compressed while it passes through the barrel.
• After the gate, the molten charge is quickly transferred to a press where it is moulded while still hot.
• The part is removed after sufficient cooling.
EXTRUSION BLOW MOLDING
• Plastic grocery bags, bottles and similar items are made using this processing.
• As in compression processing, plastic pellets are melted and the plastic is forced through a gate into the blow pin camera.
• The plastic substance is expanded and cooled by being made to flow around a massive air bubble.
• After a few seconds, the mould is opened and the manufactured product is ready.
• Vacuum forming is used to make simple moulds using thin sheets of thermoplastic.
• High impact polystyrene sheet is what is used in school (HIPS). PVC can also be used.
• A mould is created from wood or epoxy resin and this is placed on the table (platten) of the vacuum forming machine.
• The sheet plastic is heated until it becomes soft.
• The table with your mould on is lifted into position and a vacuum is used to draw the plastic over the mould.
• Vacuum forming only works with thin plastics and moulds with no undercuts.
• The plastic can then be trimmed to the required shape
• Vacuum forming is a popular deforming process.
• Vacuum forming works by removing air, thereby creating a partial vacuum underneath a soft and flexible thermoplastic sheet and allowing atmospheric pressure to push the plastic down onto a mold.
• The vacuum forming process may start with a ‘blow’ that stretches the plastic or it may be started by raising the mold, on the plate, to create a draping form.
SHORT VIDEO ON PLASTIC FORMING
TESTING OF PLASTIC BLD62003/MAK/PLASTIC
• Measures force to break a specimen, plastic and the extent to which specimen stretches or elongates to the breaking point.
• Produce a stress-strain diagram to determine tensile modulus.
• Depends on temperature
• Using extensometer
• Results are:
• A) tensile strength at yield and break
• B) tensile modulus
• C) strain
• D) elongation & % elongation at yield
• E) elongation & % elongation at break
• Determine rate of burning
• Used for production control, QC and materials comparison
• Cannot be used as a criterion for fire hazard
a) Place a specimen either horizontal or vertical in a test chamber
b) Apply a flame form a Bunsen burner for a specified time
c) Measure the time or distance the flame spreads.
• Hardness is tested by forcing a round rod into the plastic surface
• Conducted on a Rockwell hardness tester or a Shore durometer tester
• The test results in each case are a measure of how far the indenter penetrates into the sample
a) Place specimen on a hard flat surface
b) Indentor pressed into the specimen making sure it is parallel to the surface
c) Read the hardness within 1 second or as specified by customers
• IMR is a testing where few labs possess the capability to analyze both metals and plastics at one time.
• Produce testing and failure analysis.
OXYGEN INDEX TESTING
• Determines minimum concentration of oxygen in an oxygen/ nitrogen mixture that supports a flaming burn in specimen
COLD BEND TESTING
• Measures plastic resistance to cracking when being bent in a cold environment
• Evaluates plastics insulation on electrical wires
• Specimen is placed in a cold chamber i.e freezer for 4 hours then examined for cracks
• Evaluates surface irregularities or fracture
• Measures thickness
• Coats specimen with gold, place in vacuum chamber for computer monitor reviewing and take Polaroid photos for permanent record.
PLASTIC IN CONSTRUCTION
• Plastics are used in a growing range of application in the construction industry.
• Can be designed and engineered to respond to particular design conditions. For instance they may especially require to be durable, strong or waterproof to suit a particular project.
• The possibility of these materials are ever growing and our natural resources are in short supply, and hence they could increasingly be important in reducing the amount of raw materials used.
EDEN PROJECT BLD62003/MAK/PLASTIC
• The Eden Project is a visitor attraction situated in Cornwall United Kingdom.
• These artificial biomes house thousands of plant species collected from all over the world.
• This structure consists of hundreds of hexagonal and pentagonal cells that are made by plastic (ETFE – Ethylene tetrafluoroethylene) that are supported by steel frames.
• These plastic cells help the dome withstand high temperature and also allows light into the spaces.
WATER CUBE BLD62003/MAK/PLASTIC
• Was built in 2008 to house the water events for the Olympics games in Beijing.
• Cells are plastic, framed with steel and concrete.
• The material is transparent, and fills the space with light.
KUNSTHA, US BLD62003/MAK/PLASTIC
• This is an art museum located in Austria.
• Its formwork is reinforced concrete box that is covered in blue plastic, creating an organic shape.
• At night the lights are carefully lit to exaggerate the unusual shape.
• The EcoArk building is a movable fashion pavilion.
• The structure features walls made entirely of plastic bottles called POLLI-Bricks.
• Just a small amount of silicone is used to make a bond between the bottles.
XILE TUNNEL BLD62003/MAK/PLASTIC
• Xile is a plastic tunnel that connects two dark, industrial halls in Belgium.
• The tunnel is strikingly bright, foldable, expandable and environmentally friendly which can be used indoors or outdoors.
PLASTIC HOUSE POLAND BLD62003/MAK/PLASTIC
• This is a house situated in Poland that is clad entirely in Thermopian – a plastic material typically used in roofing applications and favored for its high thermal and insulating properties.
IN JAPAN BLD62003/MAK/PLASTIC
• The architect who designed this house does not believe that we should allow the choice of modern materials to mislead us, and hence this house features two materials commonly used in traditional japanese archirecture –bamboo and rice paper.
• The plastic urethane panels used were chosen for their flexibilty and visual qualities which are similar to the traditional rice paper.
EXHIBITION BOOTH – PVC PIPES
• This exhibition design was showcased at the Danish design centre, Copenhagen.
• It was constructed using PVC pipes and acted as a stage for the exhibits.
THERMOPLASTIC - PRODUCTS
• Soft polythene (low density): DPC (damp proof course), DPM (damp proof membrane), vapor checks, roof DPM
• Rigid polythene (high density): cold water tanks, cold water plumbing
• Polypropylene: pipework and fittings, drainage systems, water tanks, WC cisterns, DPCs, fibers in fiber-reinforced concrete
• Polybutylene: hot & cold water pipework & fittings • Rigid polyvinyl chloride (PVC-U): rainwater good,
drainage systems, pipe and fittings, underground services, window and door frames, conservatories, garage doors, translucent roofing sheets
• Medium rigid polyvinyl chloride (PVC-UE): claddings, soffits, fascia, window boards
THERMOPLASTIC - PRODUCTS
• Soft polyvinyl chloride (PVC): tile & sheet floor coverings, single-ply roofing, cable insulation, electrical trunking systems, tensile membrane structures, glazing to flexible doors, door seals, handrail coatings, vinyl-film finishes to timber products
• Chlorinated polyvinyl chloride (CPVC): hot water systems, door and window frames
• Ethylenetetrafluoroethylene (ETFE): inflated systems for translucent wall and roof membranes
• Polymethyltetrafluoroethylene (PTFE): sealing tape for plumbing, tensile membrane structures, low-friction movement joints
THERMOPLASTIC - PRODUCTS
• Polymethylene methacrylate: baths, shower trays, kitchen sinks, glazing, roof lights, luminaires
• Polycarbonate: vandal – resistant glazing, spa baths, kitchen sinks
• Polystyrene: bath and shower panels, decorative expanded polystrene tiles
• Copolymer: pipe and fittings, rainwater goods, drainage systems, shower trays
• Nylons: electrical conduit and trunkings, low-friction components: hinges, brush strips for sealing doors and windows, carpet tiles & carpets, shower curtains
PUSH-FIT PLASTIC FITTINGS BLD62003/MAK/PLASTIC
• Whilst the bulk of the materials used are thermoplastics, such as PVC (polyvinyl chloride), ABS (acrylonitrile butadiene styrene terpolymer) and polypropylene, without the use of rubber O-rings and compression gaskets push-fit systems would be impractical.
• With potable water distribution, polyethylene pipes are now widely used.
• Pipes are available in diameters from a nominal 8 mm bore up to 1000 mm and above, made from specially developed grades of MDPE (medium density polyethylene) which meet a range of water industry specifications .
• One advantage of plastic pipes over more traditional materials is that in the smaller diameter sizes they are available in continuous lengths of up to 100m or even 250m in some cases.
• This reduces the number of joints needed and hence the number of potential leaks.
PLASTIC PIPES BLD62003/MAK/PLASTIC
• Plastic pipes have a smoother bore than their metal counterparts, flow rates can be increased and scale formation is reduced.
• Plastic pipes also offer advantages in corrosion resistance.
THERMOPLASTIC - PRODUCTS BLD62003/MAK/PLASTIC
• For underground potable water distribution pipes are coloured blue.
• This enables the contents of a buried pipe to be immediately identified on a construction site.
• Above ground black coloured polyethylene is used to ensure adequate UV stability.
• Cross-linked polyethylene (PEX) is made from normal polyethylene by, for example, crosslinking it using a peroxide catalyst.
• The cross-linking raises the thermal stability of the material under load. Thus, the resistance to environmental stress cracking, creep, and slow crack growth are greatly improved over polyethylene.
• PEX pipe is approved for potable hot- and cold-water plumbing systems and hot-water (hydronic) heating systems in all model plumbing and mechanical codes across the U.S. and Canada.
• PEX piping systems are durable, provide security for safe drinking water, and use reliable connections and fittings. There are currently about ten domestic producers of quality PEX piping.
ROOFING SYSTEM BLD62003/MAK/PLASTIC
• Corrugated plastic sheeting has been used for roofing in conservatories and buildings where transparent panels have been required.
• However, in more recent times double and triple walled polycarbonate sheeting has become increasingly used.
• This provides not only diffuse daylight for illumination but also heat insulation and hence reduced heating costs.
• EPOXY RESIN
• MELAMINE LAMINATED BOARDS
ELASTOMER - PRODUCTS BLD62003/MAK/PLASTIC
Neoprene rubber flange gaskets
Butyl rubber sheet liner
EXAMPLE: ELASTOMER MODIFIED ASPHALT
• Both have the reliability of original asphalt waterproof, and also have elasticity of the rubber
• Good resistance to high and low temperature performance, it can adapt to all the year round;
• Waterproof layer with high strength, durability, resistance to chromium, tear resistance, fatigue resistance;
• With good extensibility and high ability to bear cracks at the base plane;
• Remain good performance at low temperatures, even in cold weather;
• The lap joint can use hot melting method, the seam sealing is reliable.
• Scope of application • Applicable to industrial and civil architecture
roofing and underground waterproofing engineering, the paint is suitable for low temperature environment of building waterproof project.
ADVANTAGES OF PLASTIC
• Corrosion resistance
• Good thermal and electrical insulators (has high
resistance to heat & protects electric cable cores etc)
• Easily mold into desired shapes
• Variety of choices: appearances, colors &
DISADVANTAGES OF PLASTIC
• Non-biodegradable – Take long time to decay. (Biodegradation of plastic takes up to 500-1000 years)
• Cost of recycling – It can be very costly.
• Environmental damage – release toxic gases over time and after burning.
• Less dimensional stability over a period of time – Creep effect : the deformation under load over time of plastic makes them not suitable for heavy equipment yet some reinforced plastic resins are sued for light-machine bases
• Aging effect – Becomes brittle over time.
PLASTIC RECYCLING • Convert waste or reused plastic into reusable useful products. • There are 4 types of recycling
•Primary Recycling •Secondary Recycling •Tertiary Recycling & •Quaternary Recycling
• Products are recycled into products of the same type.
• Eg: aluminum cans to aluminum cans.
• Also known as closed-loop recycling.
• The reused products are converted to different end products.
• Eg: tyres into other rubber products.
• The structural breakdown of the material into their raw core components and then turning it into a completely new products
• The plastic is burnt in order to use the heat it produces as an energy source.
PLASTIC IN INDUSTRY
• Plastics are classified into thermoplastics, thermosetting plastics and elastomers. With the aid of a diagram, explain the extrusion forming process of plastics (10 marks).
• Describe 3 different characteristics of thermosetting plastics and thermoplastics (9 marks).