Plastics: Additives, Consumption and Transformation

• Additives are incorporated into plastics to enhance their properties during processing and in their final state

World Plastic Consumption (2010)

• Europe accounted for 24% of the world's plastic consumption
• The USA consumed 23%
• Japan used 23%
• China used 11%
• Taiwan used 5%
• Korea consumed 3%
• Russia accounted for 3%
• Other regions accounted for the remaining 8%
• Total world plastic consumption in 2010 was 111,500 tons

Plastic Transformation in Mexico (2008)

• Injection molding comprised 34% of plastic transformation
• Extrusion accounted for 30%
• Blowing was 15%
• Lamination comprised 6%
• Rotomolding was 4%
• Foaming accounted for 4%
• Compression was 2%
• Other methods accounted for the remaining 5%

Additive Requirements

• Must easily disperse within the plastic material
• Must improve the properties of the plastic product
• Must facilitate the manufacturing process
• Should exhibit no toxicity
• Should not produce any adverse side effects

Process Additives

• Lubricants: Aid in processing
• Antioxidants: Prevent degradation
• Stabilizers: Enhance stability
• Viscosity Modifiers: Alter the flow characteristics
• Release Agents: Assist in demolding

Additive Functions and Types

• Stabilizers and lubricants facilitate processing
• Plasticizers, reinforcing loads, and impact modifiers change mechanical properties
• Fillers, diluents, and extenders reduce formulation costs
• Antistatic, anti-slip, and wear additives, along with adhesion promoters modify superficial properties
• Pigments and dyes and nucleating agents modify optical properties
• UV stabilizers and fungicides are used as additives against aging
• Foaming agents and flame retardants are used as other additives

Stabilizers (Antioxidants)

• Oxidation, leading to polymer degradation, can occur during manufacturing, affecting the polymer structure
• They inhibit or retard oxidation during manufacturing
• Free radicals in polymers attract oxygen, leading to unstable hyperoxides and chain reactions
• High processing temperatures and speeds promote material degradation
• Polymer degradation can manifest as discoloration/yellowing, loss of mechanical properties, rigidity, and weight loss

Plasticizers

• Improve processability and flexibility by reducing viscosity in the molten state
• Lower the elastic modulus and glass transition temperature of polymers

Anti-UV Additives

• Ultraviolet light absorbers/stabilizers increase the lifespan of plastic products
• Hularo® is a polyethylene-based, vat-dyed synthetic fiber from Germany, used in furniture

Antistatic Additives

• These additives prevent the build-up of static charges
• Used to manufacture flexible food containers

Antibacterial Additives

• Inhibit bacteria from growing within the material

Microceramic Fillers

• Consist of 12, 23 and 42 micron fillers
• Increase hardness, abrasion resistance, and can serve as a thermal barrier because of their low density

Fiber Glass Fillers

• Reinforces the material

Fluorescent Pigments

• Add fluorescent properties to plastics

Opague Pigments

• Adds opacity to the materal

Foam Additives

• Foaming agents create an insulating foam structure
• Reduces density, fuel consumption, and transport costs

Foams

• Two-phase materials consist of a solid matrix and gas phase
• Have a density of approximately 1.6 - 960 kg/m³
• Have a density of approximately 3 - 700 kg/m³

Coupling Agents

• Coupling agents enhance material compatibility

Laser Marking Additives

• Enables laser marking on plastics

Flame Retardant Additives

• Reduce flammability and slow flame spread

Specific Additives and Their Functions

• Antioxidants prevent oxidative degradation during plastics processing
• Oxidative degradation can deteriorate physical and mechanical properties
• UV stabilizers protect polymers from UV light degradation
• Antimicrobials prevent contamination and resulting issues (staining, odor, etc.)
• AA reducers lower acetaldehyde levels in polyethylene terephthalate (PET)
• Flame retardants prevent ignition/flame propagation
• Oxygen barriers extend product shelf life by reducing oxygen permeation

Other Additives and Their Functions

• Additives reduce/eliminate scratching on polymer surfaces
• Sliding agents alter surface characteristics and improve preform compaction
• Antistatic agents prevent static charge build-up during processing/handling
• Optical brighteners enhance material whiteness/brightness
• Chemical foaming agents introduce a gas-releasing compound to thermoplastics when heated
• Nucleating agents improve polymer properties like brightness, optical clarity, and reduce warping