Plastic and Construction

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What is Plastic?

A PLASTIC material is any of a wide range of synthetic or semi-synthetic organic solids that

can be molded into shape while soft and then set into a rigid or slightly elastic form. The

name is derived from the fact that in the semi-liquid state, plastic is malleable, or have the

property ofplasticity. Plasticity is the deformation of a material undergoing non-reversible

changes of shape in response to applied forces. For example, a solid piece of metal being bent

or pounded into a new shape displays plasticity if permanent changes occur within the

material itself.

HistoryThe development of plastic has come from the use of natural plastic materials (e.g., chewing

gum, shellac) to the use of chemically modified natural materials (e.g., rubber, nitrocellulose,

collagen, galalite) and finally to completely synthetic molecules (e.g., bakelite, epoxy,

polyvinyl chloride, polyethylene).

Plastic material started in 1839, when an American inventor, Charles Goodyear was

experimenting with the sulfur treatment of natural rubber when, according to legend, he

dropped a piece of sulfur-treated rubber on a stove. The rubber seemed to have improved

properties, and Goodyear followed up with further experiments, and developed a process

known as "vulcanization" that involved cooking the rubber with sulfur. Compared to

untreated natural rubber, Goodyear's vulcanized rubber was stronger, more resistant to

abrasion, more elastic, much less sensitive to temperature, impermeable to gases, and highly

resistant to chemicals and electric current.

The first human-made plastic, parkesine had an inauspicious birth. An Englishman,

Alexander Parkes, looking for collodion in his medicine cabinet to staunch a wound,

discovered that it had gelled into a tough rubbery substance. He was an enterprising man who

saw the possibilities, if this substance could be molded. Unfortunately, molding required heat,

and heating always made the substance explode. Licking his wounds, Parkes worked on, and

finally produced a suitable mixture of collodion, camphor, and ethanol. Parkesine, the first

synthetic plastic, was launched in 1865, and the Xylonite company was formed a year later.

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The next major revolution of plastic is celluloid. Celluloid is derived from cellulose and

alcoholized camphor. John Wesley Hyatt invented celluloid as a substitute for the ivory in

billiard balls in 1868. He first tried using collodion a natural substance, after spilling a bottle

of it and discovering that the material dried into a tough and flexible film. However, the

material was not strong enough to be used as a billiard ball, until the addition of camphor, a

derivative of the laurel tree. The new celluloid could be moulded with heat and pressure into

a durable shape.

Next, the first plastic based on a synthetic polymer, was made from phenol and formaldehyde

by synthesis methods invented in 1907, by Leo Hendrik Baekeland, a Belgian-born

American. He called the new material Bakelite.

Bakelite was a purely synthetic material, not based on any material or even molecule found in

nature. It was also the first thermosetting plastic. Conventional thermoplastics can be

moulded and then melted again, but thermosetting plastics form bonds between polymers

strands when cured, creating a tangled matrix that cannot be undone without destroying the

plastic. Thermosetting plastics are tough and temperature resistant.

The next major thrust in the development of plastics took place in the 1920s with the

introduction of cellulose acetate (which is similar in structure to cellulose nitrate (celluloid),

but safer to process and use), ureaformaldehyde (which can be processed like the phenolics,

but can also be molded into light colored articles that are more attractive than the blacks and

browns in which phenolics are available), and polyvinyl chloride (PVC, or vinyl, as it is

commonly called). Nylon was also developed in the late 1920s through the classic research of

W.T. Carothers.

The decade of the 1950s saw the introduction of polypropylene and the development of acetal

and polycarbonate, two plastics that, along with nylon, came to form the nucleus of a sub-

group in the plastics family known as the "engineering thermoplastics." Their outstanding

impact strength and thermal and dimensional stability enabled them to compete directly and

favourably with metal in many applications.

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The Development of Plastic

1868 - Cellulose Nitrate

1909 - Phenol-Formaldehyde

1927 - Cellulose Acetate

1927 - Polyvinyl Chloride

1929 - Urea Formaldehyde

1935 - Ethyl Cellulose

1936 - Acrylic

1936 - Polyvinyl Acetate

1938 - Nylon

1942 - Polyester

1943 - Silicone

1947 - Epoxy

Types of Plastic

As of now, there exist hundreds of different types of plastics, in terms of its chemical formula.

Generally, plastics can be classified into two, namely thermosetting and thermoplastic. The

thermosetting plastics are those that cannot be soften again, after being exposed to heat and

pressure. On the action of heat and pressure, the molecular chain of thermosetting plastics

become cross-linked and therefore forbids the slippage when pressure & heat are reapplied.

On the other hand, the thermoplastic are those that can be soften again and again & remade

by the action of heat and pressure. On the action of heat and pressure, the molecular chain ofthermoplastics undergoes change and the polymers slide past each other, which result in the

property of plasticity.

Thermosetting materials are generally stronger than thermoplastic materials due to this 3-D

network of bonds (cross-linking), and are also better suited to high-temperature applications

up to the decomposition temperature. However, they are more brittle. Many thermosetting

polymers are difficult to recycle.

Some examples of thermosetting materials are:

Polyester fibreglass systems: Vulcanized rubber Bakelite, a phenol-formaldehyde

resin

Duroplast Urea-formaldehyde

Melamine resin Epoxy resin Polyimides Cyanate Esters or Polycyanurates Mold or Mold Runners

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Some examples ofthermoplastic materials are:

Acrylonitrile butadiene styrene(ABS)

Acrylic (PMMA) Celluloid Cellulose acetate Fluoroplastics (PTFE, alongside

with FEP, PFA, CTFE, ECTFE,

ETFE)

Kydex Liquid Crystal Polymer (LCP) Polyacrylonitrile (PAN or

Acrylonitrile)

Polyamide (PA or Nylon) Polyamide-imide (PAI) Polyaryletherketone (PAEK or

Ketone)

Polybutadiene (PBD) Polybutylene (PB) Polybutylene terephthalate (PBT) Polycaprolactone (PCL) Polychlorotrifluoroethylene

(PCTFE)

Polyethylene terephthalate (PET) Polycarbonate (PC)

Polyhydroxyalkanoates (PHAs) Polyketone (PK) Polyester Polyethylene (PE) Polyetheretherketone (PEEK) Polyetherketoneketone (PEKK) Polyetherimide (PEI) Polyethersulfone (PES) Polyimide (PI) Polylactic acid (PLA) Polymethylpentene (PMP) Polyphenylene oxide (PPO) Polyphenylene sulfide (PPS) Polyphthalamide (PPA) Polypropylene (PP) Polystyrene (PS) Polysulfone (PSU) Polytrimethylene terephthalate

(PTT)

Polyurethane (PU) Polyvinyl acetate (PVA) Polyvinyl chloride (PVC) Polyvinylidene chloride (PVDC) Styrene-acrylonitrile (SAN)

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Material properties of some Thermoplastics

Name Symb

ol

Density

[g/cm^3

]

Tensile

strength

[MPa]

Flexural

Strengt

h

[MPa]

Elastic

Modul

us

[GPa]

Elongati

on at

rupture

[%]

Thermal

stability

[C]

Expansi

on at

20C

[10^-

6/C]

High Density

PolyethyleneHDPE 0.95 31 40 1.86 100 120 126

Low Density

PolyethyleneLDPE 0.92 17 14 0.29 500 90 160

Polyvinyl

ChloridePVC 1.44 47 91 3.32 60 80 75

Polypropylene PP 0.91 37 49 1.36 350 150 90

Polyethylene

terephthalatePET 1.35 61 105 1.35 170 120 70

Polymethylmet

hacrylate

PMM

A1.19 61 103 2.77 4 100 65

Polycarbonate PC 1.2 68 95 2.3 130 120 66

Acrylonitrile

butadiene

styrene

ABS 1.05 45 70 2.45 33 70 90

PolyamideNylon

61.13 60 91 2.95 60 110 66

Polyimide PI 1.38 96 143 3.1 7 380 43

Polysulfone PSF 1.25 68 115 2.61 75 160 56

Polyamide-

imide,

electrical grade

PAI 1.41 138 193 4.1 12 260 30

Polyamide-

imide, bearing

grade

PAI 1.46 103 159 5.5 6 260 25

Polytetrafluoro PTFE 2.17 24 33 0.49 300 260 95

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ethylene

Polyetherimide PEI 1.27 105 151 2.9 60 210 31

Polyether ether

ketonePEEK 1.32 100 3.6 50 343

Polyaryletherk

etone (strong)PEAK 1.46 136 213 12.4 2.1 267

Polyaryletherk

etone (tought)PEAK 1.29 87 124 3 40 190

Self-reinforced

polyphenyleneSRP 1.19 152 234 5.52 10 151

Polyamide-

imide

PAI 1.42 152 241 4.9 15 278

Apart from this classification, plastics have also been divided into seven different types by

the plastic industry. These seven types of plastics are:

Polymer

TypesExamples of applications Symbol

Polyethylene

TerephthalateFizzy drink and water bottles. Salad trays.

High Density

PolyethyleneMilk bottles, bleach, cleaners and most shampoo bottles.

Polyvinyl

Chloride

Pipes, fittings, window and door frames (rigid

PVC). Thermal insulation (PVC foam) and automotive

parts.

Low Density

PolyethyleneCarrier bags, bin liners and packaging films.

Polypropylene

Margarine tubs, microwaveable meal trays, also

produced as fibres and filaments for carpets, wall

coverings and vehicle upholstery.

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Polystyrene

Yoghurt pots, foam hamburger boxes and egg cartons,

plastic cutlery, protective packaging for electronic goods

and toys. Insulating material in the building and

construction industry.

Unallocated

References

Any other plastics that do not fall into any of the above

categories - for example polycarbonate which is often

used in glazing for the aircraft industry

Manufacturing of Plastic

In the process of manufacturing plastic, there are two major types; manufacturing of

thermoplastics and manufacturing of thermosetting plastics.

Thermoplastics

In the making of thermoplastics, there are several techniques that can be used:

- Extrusion

- Moulding

- Thermoforming

- Recycling

- Coating

Extrusion

Extrusion has 7 types:

- Sheet extrusion

- Co-extrusion

- Profile extrusion

- Cast extrusion

- Pipe extrusion

- Foam extrusion

- Blown film extrusion

Profile extrusion is the process to manufacture plastic products with a continuous cross-

section such as, drinking straws, plastic eves roughing, and a wide variety of other products.

The polymer melts into the hollow mould cavity under high pressure. Steps of the process are

as follows:

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1) Plastic is fed into the extruder machines and being softened by friction rotating screwinside a heated barrel and heat.

2) The softened plastic then is forced out through a die and directly into cool water wherethe product solidifies.

3) It is conveyed onwards into the take-off rollers.4) The die is a metal plate placed at the end of the extruder with a section cut out of its

interior, this cut out, and the speed of the take-off rollers, determines the cross-section

of the product being manufactured.

Typical Materials for Profile Extrusion

- HDPE (High Density Polyethylene)

- LDPE (Low Density Polyethylene)- LLDPE (Linear Low Density

Polyethylene)

- PETG

- Flexible PVC

- Butyrate- Polypropylene

- Polystyrene

- ABS

Moulding

Moulding has 8 types:

- Injection moulding- Blow moulding

- Rotational moulding

- Compression moulding

- Insert moulding- Dip moulding

- Transfer moulding

- Structural foam moulding

There are two types of gas assist injection moulding; Internal Gas Injection (most widely

used) and External Gas Injection (used to improve surface details). Gas-assist injection

moulding is a process that utilizes an inert gas (normally nitrogen) to create one or morehollow channels within an injection-moulded plastic part. Steps of the process are as follows:

1) At the end of the filling stage, the gas (N2) is injected into the still liquid core of themoulding. The gas will follow and create the shape of the product.

2) Gas pressure packs the plastic against the mould surface until the part solidifies.3) The gas is vented to atmosphere or recycled.

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Benefits of Gas Assist Injection Moulding:

Lower cost The use of the gas transmits the pressure

uniformly throughout the moulding.

Elimination of sink marks. Avoidance of plastic packing from the

moulding machine.

Reduce in-mould pressures by up to 70%and therefore reduce press lock forces

enabling larger mouldings on smaller

machines.

Reduce power consumption. Reduce moulded in stress, and therefore

improves dimensional stability with no

distortion.

Typical Materials for Gas Assist Injection Moulding

- Polypropylene (PP)- ABS

- HIPS

- Polycarbonate (PC)- PPC

- Nylon (including glass filled grades).

Thermosetting plastics

In the making of thermosetting plastics, there are several techniques that can be used:

- Pultrusion

- Resin transfer Moulding

- SMC and DMS Moulding

- Other GRP Moulding Techniques

Pultrusion

Pultrusion is a manufacturing method for obtaining high quality composite profiles with

consistently repeatable mechanical properties. It is mainly used for the production of solid or

hollow cross-section products. Pultrusion process can use a wide range of materials to

provide a large type of composite properties. Pultruded products are essentially composed of

high performance fibres such as glass, carbon, or aramide, individually or in combination,

combined with a polymer matrix such as polyester, vinyl-ester, epoxy. Steps of the process

are as follows:

1) Pulling continuous reinforcements through a resin impregnation system. Each fibre is

coated with a specially formulated resin which is to ensure a good condition of the fibre

reinforcement.

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2) Excess resin is then removed to expel any trapped air and to compact the fibres. The

coated fibres are passed through preforming guides to align reinforcement and preform

the part to the desired shape before entering the heated die.

3) The shape and dimensions of the end product are ultimately determined by the die cross

section. The temperature of the die is carefully controlled to ensure that the composite

is fully cured; the rate of reaction is controlled by heating and cooling zones in the die.

4) The fully cured section can be cut to the length according to the size and shape.

Typical Materials for Pultrusion

- Polyester is suitable for most industrial applications.

- Vinyl-ester affords improved corrosion resistance and physical properties.

- Epoxy offers superior thermal stability and corrosion resistance.- Modar improves fire performance and smoke emissions.

- Phenolic maximises fire performance and is offered as an alternative to Modar

Benefits of Pultrusion

Consistent quality Low weight High strength & stiffness Good surface finish Continuous length Excellent corrosion properties Electrical and thermal insulation

Maintenance free Non magnetic attraction Fire retardant properties Excellent creep and fatigue performance Transparent to radio frequencies Pigmentability

Why do we need different kinds of plastics?

Copper, silver and aluminium are all metals, yet each has unique properties. We do not make

a car out of silver or a beer can out of copper because the properties of these metals are not

the best choice for final product. Likewise, while plastics are all related, each resin has

attributes that make it best suited to a particular application. Plastics make this possible

because as a material family they are so versatile.

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Plastics in Building and Construction

From the construction of new homes to the retrofit and renovation of commercial buildings,

and from hospitals to schools, civil engineers, architects and designers rely on plastics to help

maximize energy efficiency, durability and performance. In addition to potentially lightening

a structures environmental footprint, properly installed plastic building products can help

reduce energy and maintenance costs, improve aesthetics and safety over many years.

A one-year study found that the use of plastic building and construction materials saved

467.2 trillion Btu of energy over alternative construction materials. Thats enough energy

saved over the course of a year to meet the average annual energy needs of 4.6 million U.S.

households. Savings vary by material and products. (Source: Franklin Associates, Ltd., U.S.DOE and U.S. Census Bureau).

Below are some examples of plastic building products that promote the efficient use of

energy and other resources:

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1) Plastic Pipes and Fittings

2) Plastic Structural Insulated Panel

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3) Plastic Pipe Radiant Floor Heating

4) Plastic Trims and Wall Coverings

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5) Plastic Decking, Fencing & Railings

6) Plastic Roofing

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Latest Technology of Plastic used in

Construction

We are on the verge of a technology and materials revolution that promises lower

construction costs and a solution to problems such as global warming, waste and housing for

the masses. Construction techniques and materials that have not changed much since the time

of the Romans are all set to change. With the rapid development of technology, new materials

are designed to meet the demand of the construction. Plastic or polymer materials have

developed so much since its invention in the 19th

century. Composite materials which

combine polymer and other building materials such as ceramics, glass and concrete are a

norm and a must in this 21

st

century.

1) TiO2 (Titanium Dioxide) Photocatalytic Membrane

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Applications

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2) ETFE Film

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Applications

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Conclusion

The future of plastic or polymer materials are very promising. In the 20th

century, many

people would not have thought about what plastic can become nowadays. With rapid

development of technology, such as nanotechnology, plastics that once used only for items

that do not require much strength, have changed. Plastics can now become the main structure

of a building, and can be used more dynamically especially in the civil engineering field.

Plastic will truly someday become the main material in our daily life.