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WorksheetsT-Level Eng Materials Plastics Composites Smart-Materials
Total questions: 26
Worksheet time: 13mins
Which statement best distinguishes a thermoplastic from a thermoset?
Thermoplastics contain crosslinked molecular chains that prevent melting
Thermoplastics soften repeatedly on heating due to reversible behaviour
Thermoplastics have a lower glass transition temperature
Thermosets can be reshaped after curing
Which property explains why elastomers return to their original shape after deformation?
Highly crystalline polymer alignment
Loosely crosslinked long-chain molecular structure
Fully saturated polymer backbone bonding
Rigid covalent network
Which manufacturing process specifically relies on thermoplastic reversibility?
Wet lay-up lamination
Plastic Extrusion
Phenolic moulding
Resin-transfer curing
Which material is a thermoset commonly used for electrical insulation?
Polyethylene
Bakelite
Polycarbonate
PVC
What most strongly explains the rigidity of thermosets?
Weak intermolecular forces
Crystalline polymer alignment
Extensive strong crosslinking
High thermal conductivity
What is the primary role of the fibre reinforcement in composites?
To prevent thermal degradation
To provide tensile strength
To increase electrical resistance
To accelerate curing
Which term describes the directional variation of properties in composites?
Isotropy
Homogeneity
Anisotropy
Dilatation
Why is MDF classed as a composite?
It contains carbon fibres
It is made from compressed bonded wood fibres
It contains ceramic particles
It is electroplated
Dinner plates fall into which ceramic category?
Refractory ceramics
Whiteware ceramics
Engineering ceramics
Ferrous ceramics
Engineering ceramics differ mainly because they:
Contain organic binders
Are processed to high purity with superior properties
Conduct electricity
Exhibit ductile behaviour
Softwood originates from which botanical group?
Angiosperms
Deciduous trees
Gymnosperms
Broadleaf species
Engineered wood products are best described as:
Naturally modified hardwoods
Woods manufactured from manipulated wood materials
Moisture-resistant softwoods
Kiln-dried timber
Which smart material returns to its original form when reheated after deformation?
Piezoelectric crystal
Shape memory alloy
Quantum tunnelling composite
Epoxy laminate
Quantum tunnelling composites show a change in behaviour when:
Magnetised
Cooled
Compressed
Heated above 200°C
Piezoelectric crystals produce which effect when force is applied?
Increased thermal conductivity
Voltage across faces
Permanent strain
Uniform expansion
Which property is typically higher in composites than compressive strength?
Thermal emissivity
Tensile strength
Oxidation resistance
Electrical conductivity
Which behaviour describes thermosets when reheated?
They soften and reshape
They melt due to crystal breakdown
They remain solid due to permanent crosslinking
They vaporise at Tg
Pine, cedar and spruce belong to which group?
Hardwood
Engineered wood
Composite timber
Softwood
Smart materials are defined as those that:
Do not change properties
Are exclusively metallic
Respond reversibly and controllably to stimuli
Remain dimensionally fixed
Which materials are most associated with crucibles and furnace linings?
Whiteware ceramics
Refractory ceramics
Softwood laminates
Elastomeric resins
Which property is most characteristic of thermoplastics at their glass transition temperature?
They chemically crosslink
They become softer and more rubber-like
They undergo permanent setting
They combust
Which composite reinforcement orientation gives the highest tensile strength in one direction only?
Random fibre mat
Unidirectional fibre alignment
Cross-ply laminate
Woven bidirectional weave
Which feature of ceramics explains their brittleness?
Metallic bonding
Delocalised electrons
Ionic/covalent bonding with restricted slip
High ductility
Which category best describes wood-based boards made from sawmill waste bonded together?
Softwood timber
Engineered wood
Ceramic composite
Natural hardwood
Which smart material is most suitable for pressure-sensitive switching surfaces?
SMA wire
QTC polymer
GRP laminate
Epoxy tooling resin
Which statement best defines the glass transition temperature (Tg) in thermoplastics?
The temperature at which a thermoplastic begins to chemically crosslink and permanently harden
The temperature at which a thermoplastic combusts due to rapid thermal degradation
The temperature at which a thermoplastic transitions from a hard, glassy state to a softer and more rubber-like state
The temperature at which a thermoplastic melts into a fully liquid state suitable for casting
