GCSE Chemistry revision

Ceramics, polymers and composites

Using materials (chemistry only)

AQA 4.10.3.3 Foundation & Higher

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Revision summary

Read on screen, then print for Cornell-style active revision.

LDPE is produced using very high pressure and trace oxygen, resulting in highly branched polymer chains that cannot pack tightly together, creating a flexible material (e.g., carrier bags and cling film).

HDPE is manufactured using moderate pressure, lower temperatures, and a specialized catalyst, yielding straight, unbranched polymer chains that pack closely into a dense, rigid structure.
The tightly packed polymer chains in HDPE give it high strength and a higher melting point, making it ideal for rigid containers like milk bottles, water pipes, and wheelie bins.

2. high density poly(ethene) (HDPE) AQA

HDPE is manufactured using moderate pressure, lower temperatures, and a specialized catalyst, yielding straight, unbranched polymer chains that pack closely into a dense, rigid structure.
The tightly packed polymer chains in HDPE give it high strength and a higher melting point, making it ideal for rigid containers like milk bottles, water pipes, and wheelie bins.

Thermosoftening polymers consist of individual polymer chains held together by weak intermolecular forces that easily break when heated, allowing the chains to slide past one another so the plastic melts and can be remoulded.
Example: Poly(ethene) and PVC soften when heated and harden upon cooling, allowing them to be melted down and recycled into new products like plumbing pipes or plastic packaging.

3. Thermosoftening Polymer AQA

Thermosoftening polymers consist of individual polymer chains held together by weak intermolecular forces that easily break when heated, allowing the chains to slide past one another so the plastic melts and can be remoulded.
Example: Poly(ethene) and PVC soften when heated and harden upon cooling, allowing them to be melted down and recycled into new products like plumbing pipes or plastic packaging.

Thermosetting polymers contain polymer chains linked together by strong covalent cross-links that do not break upon heating, keeping the structure rigid so the polymer does not melt or soften when heated.
Example: Vulcanised rubber and melamine-formaldehyde feature extensive covalent cross-links, meaning items like electrical plugs, saucepan handles, and kitchen countertops retain their shape and decompose rather than melt at high temperatures.

4. Thermosetting Polymer AQA

Thermosetting polymers contain polymer chains linked together by strong covalent cross-links that do not break upon heating, keeping the structure rigid so the polymer does not melt or soften when heated.
Example: Vulcanised rubber and melamine-formaldehyde feature extensive covalent cross-links, meaning items like electrical plugs, saucepan handles, and kitchen countertops retain their shape and decompose rather than melt at high temperatures.

Composition of Composites: Composites are made of two distinct materials—a matrix (binder) that surrounds and binds together fragments or fibers of a reinforcement material.
Reinforced Concrete: Matrix of cement and sand reinforced with steel rods or mesh, combining high compressive strength with high tensile strength for construction work.
Fibreglass (Glass-Reinforced Plastic): Polymer resin matrix reinforced with embedded glass fibers, producing a lightweight, strong material used for boat hulls, kayaks, and surfboards.
Carbon Fibre Reinforced Polymer (CFRP): Polymer resin matrix reinforced with woven carbon fiber threads, providing an exceptional strength-to-weight ratio for race cars, aerospace components, and sports equipment.
Wood: A natural composite consisting of a lignin polymer matrix binding together tough cellulose fibers.

5. Examples of Composite Materials AQA

Composition of Composites: Composites are made of two distinct materials—a matrix (binder) that surrounds and binds together fragments or fibers of a reinforcement material.
Reinforced Concrete: Matrix of cement and sand reinforced with steel rods or mesh, combining high compressive strength with high tensile strength for construction work.
Fibreglass (Glass-Reinforced Plastic): Polymer resin matrix reinforced with embedded glass fibers, producing a lightweight, strong material used for boat hulls, kayaks, and surfboards.
Carbon Fibre Reinforced Polymer (CFRP): Polymer resin matrix reinforced with woven carbon fiber threads, providing an exceptional strength-to-weight ratio for race cars, aerospace components, and sports equipment.
Wood: A natural composite consisting of a lignin polymer matrix binding together tough cellulose fibers.