Fig. 3 shows two polymer samples. Sample P softens when heated and can be re-shaped. Sample Q chars and does not soften when heated. It can be used on its o...
Question 1 Report
Fig. 3 shows two polymer samples. Sample P softens when heated and can be re-shaped. Sample Q chars and does not soften when heated.
It can be used on its own. The shape is good. It is big and strong.
The parts fit well and look neat. It comes in many sizes and shapes. It is held in a vice while being cut.
This type of cast iron is chosen because of its rigidity. The product is intended for use in a industrial environment.
(a) State the classification of polymer P. [1]
(b) State the classification of polymer Q. [1]
(c) Give one named example of each type of polymer. [2]
Answer Details
(a) Polymer P is classified as a thermoplastic. [1]
Thermoplastics soften when heated and can be reshaped repeatedly. Their molecular chains are held together by weak intermolecular forces that break down when heat energy is applied, allowing the chains to slide past each other. When the material cools, it solidifies again in its new shape. This property makes thermoplastics recyclable, since they can be remelted and remoulded.
(b) Polymer Q is classified as a thermosetting plastic (thermoset). [1]
Thermosetting plastics undergo a permanent chemical change when first heated and moulded. Strong covalent cross-links form between the polymer chains, creating a rigid three-dimensional network. Once set, a thermoset cannot be softened or reshaped by further heating; it will char and decompose instead, exactly as described for Sample Q. This makes thermosets heat-resistant and dimensionally stable, but they cannot be recycled by remelting.
(c) Named examples: [2]
| Thermoplastic (Sample P type) | Thermosetting plastic (Sample Q type) |
|---|---|
| Acrylic (PMMA) | Epoxy resin |
| Polypropylene (PP) | Polyester resin |
| ABS | Melamine formaldehyde |
| High impact polystyrene (HIPS) | Urea formaldehyde |
| PVC | Phenol formaldehyde (Bakelite) |
| Nylon | |
| PET |
One valid example from each column is required for full marks.
Download The App On Google Playstore
Everything you need to excel in your exams
