PLASTICS

PLASTICS

a product of synthetic origin which is capable of being shaped at some stage of its manufacture, but is not rubber, wood, leather or metal.

monomers

It is made from a number of common substances such as coal, salt, natural gas, cotton, wood and water, from which relatively simple chemicals known as

polymers

monomers are built up into chainlike molecules of high molecular weight

condensation polymerization, vinyl polymerization.

Polymers have low extensibility, can be molded, extruded, cut or worked into a variety of shapes and objects, rigid or non-rigid, relatively light, which are formed by _________________ and _____________________

hot water

Plastics can be hard, soft, clear, opaque, light, heavy, heat resistant or easily softened

Cellulose, Synthetic resin, from proteins and natural resins

three (3) types of Plastics

Thermoplastics, Thermosetting plastics

Synthetic resin plastics are subdivided into two (2) classes:

Thermoplastics

- soften when heated and harden when cooled (reversible and repeated)

-

linear or threadlike

Thermoplastics have a molecular structure which is essentially __________ or _____________ in form

Thermosetting plastics

- set into shape permanently when heat and pressure are applied during the forming stage

- They have a molecular structure in a 3-dimensional arrangement

thermocuring plastics

Thermosetting plastics, sometimes called

polyethyline (PE)

polystyrene

polyvinyl chloride (PVC)

polycarbonates

polypropylene

cellulosics

acrylic

nylons

fluoroplastics

acrylonitrile butadiene styrene (ABS)

EXAMPLES OF THERMOPLASTICS (10; PPPPPCANFA)

ACRYLIC

- Popular brands are "LUCITE" and "PLEXIGLASS"

- transparency of glass (but not scratchproof quality) with shatterproof quality

- Used principally for skylights, skydomes, paints, safety adhesives, finish hardware, & lighting fixtures

CELLULOSICS

- primarily cellulose acetate or butyrate

- used principally for paints and lacquers, and transparent sheeting

Ziegler PE, ICI PE

examples of POLYETHYLINE (PE)

Ziegler PE

a hard, strong, tough and rigid thermoplastic fo household and industrial applications.

ICI PE

- developed by Imperial Chemical Industries of Britain

- a high-pressure, low-density PE that is flexible, tough and slightly resilient thermoplastic used in construction as pond or lagoon lining, and watervapor barriers and dampproofing.

POLYSTYRENE

- sensitive to solvent action

- one of most important thermoplastics because of its excellent transparency and rigidity and its easy moldability.

- non- water absorbent, found in colorful, but brittle wall tiles.

- one of several plastics used in lighting fixture diffusers.

- In foam form, it has become an important thermal insulator. Also found in paint for concrete.

Polyvinyl Chloride (PVC)

- is a largely amorphous, rigid, tough, solvent-resistant, flameresistant thermoplastic.

- Used for resilient floor tile, films, pipes, and for paint lacquers, adhesives and safety glass.

POLYCARBONATES

- a family of linear polyesters

- a white, substantially amorphous, very tough and strong material

- with good heat resistance up to 150 deg C and excellent dimensional stability.

- It is injection-molded to produce plates, rods, gears, and other shaped parts that advantageously replace die-cast metal parts.

- Used for skylights.

POLYPROPYLENE

tough plastic with good resistance to heat and chemical action.

nylon

exceptionally strong, elastic, abrasion resistant, easy to wash, resistant to damage from oil and many chemicals, can be precolored or dyed in wide range of colors, and resilient

linear polyamides

The term nylon refers to a family of polymers called __________ ________

FLUOROPLASTICS

- are a class of paraffinic polymers that have some or all of the hydrogen replaced by fluorine.

- characterized by excellent chemical resistance, heat resistance, good electrical properties, and group is excellent excellent wear resistance.

- However, despite these attributes, perhaps the most desired characteristic of this group of plastics is their ability to resist abrasion

paraffinic polymers

FLUOROPLASTICS are a class of __________ _____________ that have some or all of the hydrogen replaced by fluorine.

ACRYLONITRILE BUTADIENE STYRENE (ABS)

- is a styrenic resin with improved toughness and heat resistance.

- ABS exhibits high gloss, low shrinkage, and good dimensional stability, is widely used in injection molding of appliances, furniture, and automotive parts.

- has high melt strength suitable for the production of extruded sheet, some of considerable size and thickness.

- Applications include panels for large appliances and thermoformed items such as hot tubs and recreational vehicle parts

styrenic resin

ABS is a __________ ___________ with improved toughness and heat resistance.

Melamine and Urea, Epoxy, Alkyds, Phenolics, Polyester, Urethanes, Silicones

EXAMPLES OF THERMOSETTING PLASTICS (6; MEAPUS)

Melamine and Urea

hard, durable and dimensionally stable, these similar plastics are resistant to chemicals, electric potential, and heat

Melamine

is well known for its use in molded dishes,

Urea

is useful for incandescent light diffusion and for baked enamels

EPOXY

- used in buildings for its remarkable adhesive qualities.

- It may also be used for special paints that are chemically resistant and for special caulking compounds

ALKYDS

appear chiefly as molded electrical parts, and as the vehicle in paints, lacquers, and enamels .

PHENOLICS

used for paints, baked enamels, adhesives, impregnating resins for paper and wood, and finish hardware

POLYESTER

- the plastic most used in large commonly glass-fiber reinforced translucent panels that are strong, rigid, and impact-resistant.

- Also used for impregnating paper and wood, as laminating material, and for contact adhesive

URETHANES

used in paint coatings, and as foams, are self-adhesive

SILICONE

used for clear, water repellant paint for surfaces and masonry above grade.

SHEETS

Usually made of acrylate, polyester, or polystyrene plastics, either plain or reinforced with glass-fiber, are available in flat or corrugated sheets and various deformed shapes

1.5mm to 2.38mm

Sheets thicknesses vary from ___________ to _________

Plastic sheets

can be used to replace glass in any type of windows or doors, skylights, shower enclosures, or in any area where a translucent, transparent or opaque material in a wide variety of colors are needed in the interior

corrugated sheet

As ____________ _________, plastics make good roofing material and other similar uses as sheet plastic

FILM SHEETS

As water barrier or dampproofing material, it is generally made of polyethylene and polyvinyl and come in thicknesses ranging from 1 to 10 mils

2, 4, 6

For building construction, ___, ____, & ______ mils are most commonly used

4 mil

Over tamped earth or sand fill, use ___ __________

6 mil

Over gravel and stone, use _____ ________

Foams

Used as flotation material, thermal insulators, and shock-resistant mountings. Offers possibilities for lightweight materials of high strength .

Lamination

is the process applied to paper or fabric impregnated with thermosetting resins.

LAMINATES

- Cotton cloth and paper are used as filler materials, usually in sheet forms, that are bonded together by heat and pressure to form an integral body

- The thickness is determined by the number of sheets placed between the two steel pans or platens of the press used in the process.

- extensively used for tabletops and wall facings