Fig. 13 shows the construction of a GRP (glass reinforced plastic) canoe hull. The polymer has been chosen for its specific properties including its ability...
Question 1 Report
Fig. 13 shows the construction of a GRP (glass reinforced plastic) canoe hull. The polymer has been chosen for its specific properties including its ability to be formed into shape. Modern manufacturing processes allow polymers to be produced in large quantities efficiently. The choice of polymer depends on the required properties of the finished product.
The base keeps it still. The lid lifts up and down.
The acrylic provides adequate hardness while keeping the overall weight low. Quality control checks are carried out at various stages of manufacture.
(a) Name the two main materials that make up GRP. [2]
(b) Describe one advantage of using GRP for the canoe hull. [1]
Answer Details
(a) The two main materials that make up GRP (glass reinforced plastic) are:
- Glass fibre (glass fibre mat) [1] - this is the reinforcement. It consists of fine strands of glass woven or matted together. It provides tensile strength, preventing the composite from cracking or tearing under load.
- Polyester resin (or epoxy resin) [1] - this is the matrix. It is a liquid that is applied over the glass fibre and hardens (cures) to form a rigid plastic. The resin binds the glass fibres together, transfers loads between them, and gives the composite its shape.
(b) One advantage of using GRP for the canoe hull is that it has a high strength-to-weight ratio, meaning the canoe is strong enough to withstand impacts and water pressure yet light enough for one or two people to carry to and from the water [1]. Other valid advantages include: GRP can be moulded into the complex curved shapes required for a hydrodynamic hull; it is resistant to water and does not corrode or rot like metals or timber; and it is relatively low cost compared to carbon fibre, making it suitable for recreational rather than competition use.
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