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  • PLASTIC

    BUILDING MATERIALS (BLD62003)

    BACHELOR OF QUANTITY SURVEYING (HONS.)

    BLD62003/MAK/PLASTIC

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  • 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

    BLD62003/MAK/PLASTIC

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  • WHAT IS PLASTIC?

    Derived from GREEK word

    PLASTIKOS = able to be shaped

    or molded.

    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.

    BLD62003/MAK/PLASTIC

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  • 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.

    BLD62003/MAK/PLASTIC

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    PLASTIC GRANULES

  • 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.

    BLD62003/MAK/PLASTIC

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  • 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.

    BLD62003/MAK/PLASTIC

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  • 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

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  • PROPERTIES OF PLASTIC

    Deforming capacity: Materials like iron cannot be

    deformed as easy as plastic. Hence plastic is more

    flexible.

    Atmospheric resistance: Resists to humidity, high and

    low temperatures.

    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.

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  • 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.

    BLD62003/MAK/PLASTIC

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  • CHEMICAL COMPOSITION

    The manufacture of plastic involves: polymerization of ethylene monomer (colorless gas) - @ high pressure 200 degree Celsius converted into clear polymer polyethylene or polythene

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  • ARRANGEMENT OF MONOMERS BLD62003/MAK/PLASTIC

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    LINEAR POLYMERS

    BRANCHED POLYMERS

    CROSS-LINKED POLYMERS

    NETWORK POLYMERS

  • CLASSIFICATION OF PLASTIC BLD62003/MAK/PLASTIC

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    THERMOPLASTICS

    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

    THERMOSETTING

    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.

    ELASTOMER

    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.

  • THERMOPLASTIC

    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

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  • THERMOSET

    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.

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  • THERMOPLASTIC vs THERMOSET

    BLD62003/MAK/PLASTIC

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  • ELASTOMER BLD62003/MAK/PLASTIC

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    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

  • COMPARISON BETWEEN

    THERMOPLASTIC &

    THERMOSET

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  • 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.

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  • THERMOPLASTIC vs THERMOSET

    THERMOPLASTICS

    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.

    THERMOSET

    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.

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  • HOW PLASTIC IS MADE OF? BLD62003/MAK/PLASTIC

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    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

  • PRODUCTION PROCESSES

    THERMOPLASTICS

    Raw materials (gas, liquid, powder, granules)

    Formed into extrusion or sheet.

    Reformed into finished product.

    THERMOSETTING PLASTICS

    Partially polymerized material; or

    Directly from resin and hardened mix.

    FOAMED PLASTICS

    Blown with internally generated gas; or

    Produced by a vacuum process.