Polycarbonate (PC)

Polycarbonate PC plastic is formed by a condensation polymerization resulting in a carbon that is bonded to three oxygens. The most common system for this polymerization is formed by a reaction of bisphenol A and phosgene. Applications of polycarbonate plastic are almost always those which take advantage of its uniquely high impact strength and its exceptional clarity. These unique properties of polycarbonate PC plastic have resulted in applications such as bulletproof windows, break resistant lenses, compact discs, etc. More recently however, additional interest has resulted because of the low flammability of polycarbonate plastic.

Transparency, excellent toughness, thermal stability and a very good dimensional stability make Polycarbonate (PC) one of the most widely used engineering thermoplastics. Compact discs, riot shields, vandal proof glazing, baby feeding bottles, electrical components, safety helmets and headlamp lenses are all typical applications for Polycarbonate plastic.

Polycarbonate is most commonly formed with the reaction of bis-phenol A (produced through the condensation of phenol with acetone under acidic conditions) with carbonyl chloride in an interfacial process. PC falls into the polyester family of plastics.

Polycarbonate remains one of the fastest growing engineering plastics as new applications are defined; global demand for PC exceeds 1.5 million tons.

Polycarbonate Plastic - PROPERTIES

Polycarbonates are strong, stiff, hard, tough, transparent engineering thermoplastics that can maintain rigidity up to 140oC and toughness down to -20°C or special grades even lower. The material is amorphous (thereby displaying excellent mechanical properties and high dimensional stability), is thermally resistant up to 135oC and rated as slow burning. Special flame retardant grades exist which pass several severe flammability tests.
Constraints to the use of Polycarbonate Plastic include limited chemical and scratch resistance and it's tendency to yellow upon long term exposure to UV light. However these constraints can be readily overcome by adding the right additives to the compound or processing through a co-extrusion process.

GRADES AVAILABLE

Polycarbonate plastic is available in a number of different grades dependent on the application and chosen processing method. The material is available in a variety of grades such as film, flame retardant, reinforced and stress crack resistant, branched (for applications requiring high melt strength) and other speciality grades. Also blends of Polycarbonate PC are available with e.g. ABS or Polyesters, widely used in automotive industry. Processing of Polycarbonate generally falls into:
• Injection Moulding
• Structural Foam Moulding
• Extrusion
• Vacuum Forming
• Blow Moulding

Polycarbonate Plastic - APPLICATIONS

In recent years Polycarbonate blends have become increasingly commercially important. PC is widely used in blends due to its excellent compatibility with a range of polymers. Typical blends include rubber modified Polycarbonate plastic, improving impact properties, PC/PBT blends, which allow toughness to be retained at lower temperatures and having improved fuel and weather resistance. Amongst the most significant are those incorporating ABS (Acrylonitrile Butadiene Styrene). PC/ABS blends exhibit high melt flow, very high toughness at low temperatures and improved stresscrack resistance compared to Polycarbonate plastic.
All Blends are produced using a compounding step to blend the polymers. This compounding technology is very important for creating the optimal morphology and interaction between the two phases. In combination with the right additive know-how (flame retardant, stabilisation, reinforcement) blends are obtained with an optimally balanced set of properties.
Polycarbonate plastic finds usage in a host of markets, notably in the automotive, glazing, electronic, business machine, optical media, medical, lighting and appliance markets.

Electrical & Electronics (E&E)

The largest application for Polycarbonate plastic is in the optical media market (i.e. usage in computer and audio compact discs). This is followed by an assortment of sheeting and glazing applications. The rest of the market consists of electrical and electronics (hosting applications in the business machine and telecommunications market), followed by transportation (including automotive), appliances, packaging, and other miscellaneous uses.

Miniaturisation fast product cycles make the E&E market one of the most demanding for Engineering Plastics. Demands include high service temperature, spike temperature resistance, ductility and toughness in thin sections, and flammability. All of this must be delivered consistently throughout the world, with co-ordinated engineering, market development, and technical service. In the E&E market our materials are well suited to internal components and current carrying devices.

Typical examples of Polycarbonate plastic applications are within:
• power distribution (covers and housings)
• connectors
• electrical household appliances
• mobile phones
• electrical chargers
• lighting
• battery boxes

Automotive

The use of Engineering Plastic Resins in automotive applications is nearing its fiftieth anniversary. Polycarbonate plastic has been part of this history and continues to bring innovation, which allows automakers to produce lighter, stronger, and more durable components.

Typical Polycarbonate and PC-blend applications include:
• automotive lighting
• head lamp lenses
• dashboards
• interior cladding
• exterior parts (bumpers, bodypanels)

General Industries / Packaging

While automotive and E&E markets tend to drive the technological breakthroughs in materials, other industries develop their own unique uses for Engineering Plastics like Polycarbonate.

In most of these industries durability, cost effectiveness, and appearance are the driving factors in material selection. The largest of these markets include:
• power tools
• baby bottles
• water dispensers
• garden equipment
• furniture (office & institutional)
• sporting goods
• medical applications

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