1.13 Enhancement of Materials Flashcards
(27 cards)
Define material enhancement
the process of improving a material’s properties—such as strength, durability, flexibility, conductivity, flame resistance, or appearance—by modifying its structure or adding substances (called additives or reinforcements).
Polymer Enhancement
State the reason for adding lubricants
Adding wax or calcium stearate reduces the viscosity of the molten polymer, making it less ‘sticky’ and allowing more intricate shapes to be formed.
Lubricants also allow the moulding temperature to be lowered, saving energy
Polymer Enhancement
State the reason for adding thermal antioxidants
Thermal antioxidants are added to polymers to prevent degradation caused by heat during processing and use. High temperatures can break polymer chains and create free radicals, leading to discoloration, brittleness, and loss of strength.
Thermal antioxidants:
Stabilise the polymer by neutralising free radicals
Protect properties like flexibility and colour
Extend the lifespan of products exposed to heat (e.g. in automotive, electrical, or packaging applications)
They are especially important in processes like extrusion, injection moulding, and high-temperature end use.
Polymer Enhancement
State the reason for adding pigments
Pigments are added to polymers to give color and improve the appearance of the final product. They can also:
Protect against UV light, helping prevent fading or degradation from sunlight
Provide opacity, making the polymer less transparent
Enhance branding or aesthetic appeal by offering consistent and vibrant colors
Pigments help make plastics more attractive and suitable for a wide range of applications, from packaging to automotive parts.
Polymer Enhancement
State the reason for adding antistatics
Entistatics are added to polymers to reduce the buildup of static electricity on the polymer surface. This is important because static charges can attract dust, cause handling issues, interfere with electronic components, and pose a risk of sparks in flammable environments.
Polymer Enhancement
State the reason for adding flame retardants
Flame retardants are added to polymers to reduce their flammability and slow the spread of fire. They work by interfering with the combustion process by releasing flame-inhibiting gases.
(car engine components) or potential electrical fires such as plug sockets.
Polymer Enhancement
State the reason for adding plasticiser
Plasticisers are additives used to increase the flexibility, softness, and workability of polymers by reducing the forces between polymer chains. This makes the material easier to shape and less brittle, especially at low temperatures.
They are commonly used in products like PVC cables, synthetic leather, flexible hoses, and packaging films.
Plasticisers also help in processing because they allow polymers to be easily formed at higher temperatures
Polymer Enhancement
State the reason for adding fillers
Sawdust and wood flour provide bulk to the product, meaning that less polymer is required.
Mineral fillers such as chalk, clay and calcium carbonate help increase the thermal conductivity of the polymer, meaning it will heat up and cool down more quickly, which gives shorter mould cycle times.
Polymer Enhancement
State the reason for adding biodegradable plasticisers
plasticising additives that not only soften and improve the flexibility of polymers but also break down naturally in the environment over time. They are designed to reduce environmental impact compared to traditional plasticisers like phthalates, which can persist and cause pollution.
They are often derived from natural or renewable sources, such as glycerol (from fats and oils)
Biodegradable plasticisers are commonly used in bioplastics and eco-friendly packaging, where both flexibility and sustainability are key.
Polymer Enhancement
State the reason for adding bio-batch additives
Bio-batch additives are concentrated mixtures of biodegradable or bio-based materials added to plastics to promote environmental sustainability. They are typically used in the production of biodegradable or compostable plastics.
These additives can serve various functions, such as:
Enhancing biodegradability (e.g., making traditional plastics break down faster)
Acting as natural fillers or plasticisers
Improving compostability or recyclability
Reducing the use of petroleum-based raw materials
Oxy-degradable, photodegradable and hydro-degradable additives help reduce the degradable time from hundreds of years to a few years or even months.
Polymer Enhancement
State the reason for adding antioxidants
Antioxidant polymer additives are added to polymers to prevent or slow down degradation caused by oxidation. Oxidation can occur during processing (like heating or extrusion) or over time due to exposure to air, heat, and UV light. It can lead to discoloration, brittleness, and loss of mechanical properties.
The main purpose is to extend the life and performance of polymer products. Often used in polymer garden furniture.
Polymer Enhancement
State the reason for adding UV light stabilisers
Prevent the polymer chains being broken down by sunlight. UV attack causes colour loss and brittleness. Used in outdoor toys and play equipment, garden furniture, sports stadium seats and synthetic grass playing surfaces.
Wood Enhancement
State the use of resins and laminations
Used in engineered wood (e.g. manufacture boards) to enchance the properties of the useable parts of trees such as sawdust, wood chips and fibres.
Resins and laminations are used in wood enhancement to improve strength, durability, moisture resistance, and appearance.
Resins (like urea-formaldehyde, phenolic, or epoxy resins) are used to:
Bind wood fibers in products like MDF or plywood.
Increase hardness and water resistance.
Fill gaps or seal surfaces for better finish and protection.
Laminations (like plywood) involve bonding layers of wood (veneers) or other materials together, which:
Increases structural strength and reduces warping.
Allows for decorative surface finishes.
Enables the use of lower-grade wood inside, with high-quality veneers on the outside.
Wood Enhancement
State the use of resins with fire retardants
resins with fire retardants are used to improve the fire resistance of wood-based products while maintaining structural strength and stability.
Binding fire retardant chemicals into the wood structure so they don’t leach out over time.
Distributing fire-resistant properties evenly throughout composite materials like MDF or plywood.
Forming a protective char layer when exposed to heat, which slows down combustion.
This combination is especially useful in construction, furniture, and public building interiors where fire safety is critical.
Wood Enhancement
State the use of laminations
Laminations are used in wood enhancement to improve the strength, stability, and appearance of wood products. By bonding multiple thin layers of wood or materials together, laminations:
- Reduce warping, twisting, and splitting by alternating grain directions
- Increase structural strength, making the material suitable for load-bearing uses
- Allow decorative surfaces to be applied over lower-quality cores (e.g. melamine-coated chipboard)
- Enhance durability and resistance to wear in furniture and flooring
Common applications include plywood, laminated veneer lumber (LVL), and laminated worktops.
Wood Enhancement
State the use of preservatives
Protect wood (especially for outdoor use) form fungal and insect attack.
Wood can be pre-treated with a copper-based preservative, which penetrates the wood to protect the whole plank.
Copper has excellent fungicidal properties.
Wood Enhancement
State the use of pigments
Added to the preservative to give different coloured shades to enhance the aesthetics, e.g. outdoor decking.
Can also be used on cheaper softwoods to make them look like hardwoods.
Wood Enhancement
State the use of fire-retardant preservatives
Fire-retardant preservatives are used in wood enhancement to reduce the wood’s flammability and slow the spread of fire. They work by:
Chemically altering the combustion process, producing less flammable gases
Forming a protective char layer on the surface when heated, which insulates and slows burning
Reducing smoke production and delaying ignition
These preservatives are often used in construction timber, cladding, public buildings, and transport applications where fire safety is essential.
Wood Enhancement
State the use of modified natural polysaccharides
Modified natural polysaccharides are used in wood enhancement to improve durability, moisture resistance, and dimensional stability. These are naturally derived compounds (like starch or cellulose) that are chemically altered to enhance their performance.
Their uses include:
Reducing water absorption, which helps prevent swelling, warping, and decay
Improving resistance to biological attack, such as mould and insects
Sustainably enhancing wood without relying on synthetic chemicals
They are particularly useful in eco-friendly wood treatments and biocomposite materials. (often added to hardwood floor panels)
Wood Enhancement
State the use of structural composite lumber (SCL) and laminated veneer lumber (LVL)
Made by layering strands (SCL) or veneers (LVL) of wood with resins such as urea formaldehyde, pressing and heat curing them to produce a stable wood billet.
SCL and LVL are less prone to defects such as warping, splitting or shrinking.
Used in structural applications including beams, joists and rafters.
Metal Enhancement
Define work hardening
Work hardening, also known as strain hardening, is the process where a metal becomes stronger and harder as it is plastically deformed through processes like hammering, rolling, or bending.
When you deform the metal (like hammering or bending), its internal structure changes—tiny defects called dislocations build up. These dislocations make it harder for the metal to move and stretch further, so it becomes tougher but less flexible.
This is useful because it can improve the strength of metal parts without heating them, but if worked too much, the metal might become brittle and crack.
eg. Sheet metal forming: When metal sheets are bent or stamped into shapes (like car panels or appliance casings), work hardening makes them stronger and more durable.
Metal Enhancement
Define annealing
Annealing is a heat treatment process where a metal is heated to a specific temperature and then slowly cooled. This process:
Softens the metal
Relieves internal stresses
Improves ductility and toughness
Restores the metal’s ability to be shaped or worked
annealing is often used after work hardening to make metals easier to cut, bend, or form again without cracking.(less brittle and more ductile).
Metal Enhancement
Define case hardening
Case hardening is a surface hardening process where the outer layer of a metal is made hard and wear-resistant, while the inner core remains softer and tougher.
This is done by adding carbon or nitrogen to the metal’s surface through heating in a carbon- or nitrogen-rich environment, followed by cooling. It improves the metal’s wear resistance and fatigue strength without making the whole piece brittle.
It’s commonly used for parts like gears, cams, and tool tips that need a hard surface but a strong, shock-absorbing core.
Metal Enhancement
Define carburising
Carburising is a type of case hardening process where steel or iron is heated in a carbon-rich environment to allow carbon atoms to diffuse into the surface layer of the metal.
This increases the carbon content on the surface, making it harder and more wear-resistant, while the inner core remains softer and tougher.
Carburising is commonly used to strengthen parts like gears, shafts, and camshafts that require a hard surface to resist wear but need a tough core to absorb impact.
