Plastics are chemical substances derived from common materials, such as coal, air, water, wood, and crude oil. They are produced synthetically from organic polymers such as polyethylene, Polyvinyl chloride, nylon, natural from plants, animals, etc., and can be molded and hardened for a wide variety of uses.

Characteristics, Pros and Cons

Characteristics

Design explorations and technological advances, giving plastics a

• Strong for taking general loads, however it is not suitable for long-term loading.
• Tensile strength increases with fibrous reinforcement.
• Susceptible to heat and temperature
• Waterproof since they are impervious
• Gets brittle by ultra-violet radiation
• Resistant to acids and chemicals
• Low thermal expansion and low thermal conductivity

Pros

• Wide range of properties
• Reasonable/low cost
• Inherent design characteristics
• Lightweight and tough
• Resistant to corrosion and moisture
• Easily molded into complex shapes
• Durable
• replicate natural building materials, such as wood.

Cons

• They are mostly impervious in nature.
• Non-biodegradable hence hazardous

Uses

It is the general name for polymers. Plastics are useful for filler material, supporting material, but not as a structural material.

• Insulation (Foamed plastic, expanded plastic)
• Facades, exterior siding
• Vapor barriers
• Window and door frames
• Plumbing pipes
• Wall coverings and ceilings
• Floor coverings
• Furniture, Countertops, Tabletops, shower curtains, and accessories.

Types of Plastics

Plastics fall into two categories of thermoplastics and thermoset plastics.

• Thermoplastics and
• Thermoset Plastic

Thermoplastics

These are organic materials. Thermoplastics have high molecular weight. Their properties remain same.

• Soften when heated and harden when cooled.
• They can be reheated and molded over and over.
• Easier to mold into complex shapes, bends but does not break.
• exhibit higher impact strength than thermosets
• Many thermoplastics are flammable, which must be taken into consideration when using them in areas subject to fire.
• Dissolves and swells in certain solvents.
• Can be recycled and used gain by heating
• Some examples of thermo-plastics are polyethylene(plastic bags),acrylonitrile-butadiene-styrene’s(ABSs),vinyl’s, and polyvinyl chlorides (PVCs).

Types

• ABS
  • Acrylonitrite-butadiene-styrene) hard, tough; resistant to chemicals and abrasion.
  • Uses :Plumbing systems, furniture
• Acrylic
  • Lightweight; rigid; strong; good color and optical qualities; resistant to weather and temperature changes; scratches. Resembles glass.
  • Uses: Glazing, skylights, furniture, paints, accessories, countertops (Corian)
• Polystyrenes
  • Rigid, hard, resistant to chemicals, but not abrasion, breakable when bent, expanded to make Styrofoam
  • Uses: Furniture, kitchenware, insulation, tile
• PVC (Polyvinylchloride)
  • Rigid or made flexible with plasticizers; excellent resistance to wear and abrasion
  • Uses : Sheet form in hospitals, labs, etc. and pipes form for plumbing fixtures and fittings.
• Vinyl’s
  • Variable properties according to fillers and plasticizers used; foam and cellular; chemical resistant; stiffens at low temperature.
  • Vinyl floor coverings; upholstery wall and ceiling coverings; coatings for materials.
• Polyethylene’s
  • Made rigid or flexible; lightweight; resistant to chemicals and temperature extremes
  • used in thin films for water and vapor barriers

Thermosets

• They cannot be reshaped by heating because once formed in the manufacturing process, they become rigid.
• Chemically resistant
• High tensile strength
• Not recyclable
• A number of thermoset plastics are difficult to recycle; however, they can be ground up and used as a filler in other material processes.
• Cost effective compared to thermoplastics.
• Some common thermoset plastics are melamine, Bakelite, epoxies, phenolics, and polyesters.

Types

• Melamine
  • Tough, resistant to stains, scratching, heat, used in thin layers to make plastic laminates.
  • Uses : Cabinetry, furniture, countertops
• Phenolics
  • Strong, durable, resistant to heat and electricity
  • Electrical assemblies, paints, finish hardware
• Polycarbonates
  • Very durable, good options, high resistance to impact
  • Uses :Plastic glazing for shatterproof assemblies
• Polyesters
  • Often reinforced with fiberglass and made into thin sheets, flexible or rigid, resistant to weather, chemicals, translucent
• Urethanes
  • Cellular plastic available in many different properties, formed in place.
  • Uses: Insulation, cushions, fabrics, furniture

Plastic Fabrication

Plastics are formed in a variety of ways, such as foamed, molded, laminated, vacuformed, sprayed, injected, calendared(rolled),or blown. They can be produced in just about any weight, and almost any malleability from rigid to spongy, to create various forms and applications. Mineral or fabric fillers, such as mica, cotton, paper, sisal, and glass, are added strength, moisture, and thermal resistance.

Plastic Laminates

Plastic Laminates are used extensively for interior surfacing, such as wall treatments, furniture, cabinets, counter-tops, and tabletops. These are very durable materials available in a wide variety of colors, textures, and patterns. Plastic Laminates are impervious to many chemicals and are easy to maintain. Thermosetting plastics are used in the fabrication process of high-pressure laminating. This process is different from other manufacturing processes because it involves high heat and pressure.

Reinforcing materials, such as cloth, paper, wood, or fibers of glass that compose the body of the finished product are laminated between two sheets of plastic that hold them together. These added materials are impregnated with uncured resin or alternated with uncured plastic films, then pressed between two highly polished steel plates that are subjected to heat and high pressure. The plates squeeze the layers of material into a single sheet of the desired thickness. Textured or patterned steel pressing plates transfer these characteristics to the surface of the laminate.

Solid Surface materials

Many cabinetry countertops are made of an acrylic resign composite, commonly referred to as solid surface materials. They are manufactured of plastic and other combined materials to look like granite, marble, quartz, and many other types. Some of the most well-known brands are Corian and Avonite. These materials are resistant to stains and generally nonporous. They can be cast into shapes for integral sinks, and lavatories. A major feature of solid surface counters is that they can be made to look seamless, because they are joined and bonded together with no gaps.

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