Practice Assignment 12
Paper properties: strength and impact resistance
. Ideally, use an expensive brand and a cheap brand, to facilitate and encourage ‘value for money’ discussion.
Half of the student groups might work on comparative tensile strength, and the other half on impact-failure energy.
Each student group should work initially with a single material. Where it is necessary to vary the width, masses or drop height in order to obtain meaningful measurements, students should record this and report it when results are collated.
The procedure requires some adaptation in the light of exploratory work, as described in the Standard Procedure. It is therefore a fairly demanding exercise.
Apparatus and Reagents
- Standard Procedure:
- SP 0012:2005 Methods of testing strengths of materials
- Part 1: Comparing the tensile strength of plastics, paper and board
- Part 2: Comparing the impact resistance of materials
For Part 1:
- SP 0012:2005 Methods of testing strengths of materials
- large pair of scissors, or surgical knife for cutting test pieces
- clear sticky tape
- metre rule
- clamp and stand
- wooden blocks
- strong thread
- dowel with a pin or pointer attached to one end
- 100 g mass hanger
- 100 g masses
- 10 g masses
For Part 2: - steel ball bearing, approximately 20 mm diameter
- Blu-Tak (or similar)
- two wooden blocks, approximately 40 x 40 x 40 mm
- two wooden blocks, approximately 40 x 40 x 8 mm
- mass hanger with 100 g and 10g masses
- tube, 500 mm long, with an inside diameter slightly larger than the diameter of the mass hanger.
- tube can be made of any suitable material, provided the inside edge is smooth.
- tube may need to be longer if the drop height is increased. (See NOTE in procedure.)
- clamp and stand
- thread
- metre rule
- 2 x G-clamp