Fig 11 shows five material samples arranged on a workbench for a classification exercise. The samples are a section of copper pipe, a sheet of clear acrylic...
Question 1 Report
Fig 11 shows five material samples arranged on a workbench for a classification exercise. The samples are a section of copper pipe, a sheet of clear acrylic, a block of MDF, a length of mild steel bar, and a small piece of circuit board substrate removed from an old electronic device. Each sample displays standard material identification symbols. Part of the polymer housing structure from the electronic device is still attached to the circuit board piece. The fig shows all five samples with their symbols visible.
(a) Classify copper, acrylic, MDF, and mild steel into the correct material categories. [2]
(b) Name the international numbering system used within the recycling symbol to identify different types of polymer. [1]
Answer Details
(a) Classification of the four materials: [2]
| Material | Category |
|---|---|
| Copper | Non-ferrous metal - copper does not contain iron and is valued for its high electrical and thermal conductivity. |
| Acrylic | Polymer (thermoplastic) - acrylic (PMMA) softens when heated and can be remoulded; it is transparent and used for display cases and light fittings. |
| MDF | Manufactured board - MDF is made from processed wood fibres bonded with resin under heat and pressure; it is a sheet material, not a natural timber. |
| Mild steel | Ferrous metal - mild steel is an alloy of iron and carbon, making it a ferrous metal. It is magnetic and susceptible to rusting. |
(1 mark for any two correct, 2 marks for all four correct.)
(b) The international numbering system used within the recycling symbol to identify different types of polymer is the Resin Identification Code (RIC) system. [1] This system assigns a number (1 to 7) inside the chasing-arrows triangle to indicate the polymer type (e.g. 1 = PET, 2 = HDPE, 5 = PP). It is also known as the SPI codes or the numbered triangle system.
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