202
7
7. Low hardner content leads to under curing or no curing of
the composite, affecting its glass transition temperature
and mechanical properties.
8. Improper curing causes residual stresses in the composites.
9. Core materials are used in composite manufacturing in
order to increase thickness. This is a common practice in
vacuum infusion technology.
10. Thermoforming is predominantly a process for short
fibre- reinforced thermoplastic composites.
11. Prepreg is a reinforcement pre-impregnated with resin.
12. Preforms are pre-shaped reinforcement that ensures the
firm positional placement of reinforcement.
Exercises
1. The viscosity of polyester resin (processability constant = 0.5)
goes up from 2000 to 70,000 cps in 30 minutes at room temperature. How much time will this resin take to wet and percolate
through the reinforcement to get a good composite?
2. Why does fuzzing takes place in carbon fibres and not in glass
fibres?
3. How does the tension in glass roving affect the filament winding
process? Why will high tension cause a resin- starved filament
wound structure? Explain.
4. What makes a contact layup process most popular for composites?
5. Calculate the wettability time for glass fibre- reinforced polyester
composites. The gelation time for polyester resin is 5 minutes,
and the processability factor of polyester resin is 0.5.
6. The viscosity of resin reaches 50,000 cps in 20 minutes at 100 °C
during the processing of a composite. What will be the wettability
time for fibres in this composite? (Processability constant is 0.5)
7. Outline the filament winding process for thermosetting and
thermoplastic composites. Also, compare the major difference in
their processing.
References
1. Murphy, J., The Reinforced Plastics Handbook, Elsevier Advanced Technology, Oxford, 1994.
2. Bader, S., Crystic Polyester Handbook, Scott Bader Co., Ltd, Wellingborough,
1980.
3. Monk, J.F., Thermosetting Plastics - Practical Moulding Technology, George
Goldwin, London, 1981.
4. Kia, Hamid G., “Sheet Moulding Compound,” Science and Technology, Hanser, USA, 1993.
5. The Use of Epoxy, Polyester and Similar Reactive Polymers in Construction,
Vols. 1, 2, and 3, CIRIA, London, 2000.
6. Open Moulding, Moulded Fiber Glass Companies, http://www.
moldedfiberglass. com/processes/open-molding-process.
7. Sigg, A., De Oliveira, R., Hochman, L., Cazes, T., and Michaud, V., “Process
induced defects in thick composite laminates,” Laboratoire de Technologie
Chapter 7 · Processability in Open Mould Processing of Polymeric Composites
7
7. Low hardner content leads to under curing or no curing of
the composite, affecting its glass transition temperature
and mechanical properties.
8. Improper curing causes residual stresses in the composites.
9. Core materials are used in composite manufacturing in
order to increase thickness. This is a common practice in
vacuum infusion technology.
10. Thermoforming is predominantly a process for short
fibre- reinforced thermoplastic composites.
11. Prepreg is a reinforcement pre-impregnated with resin.
12. Preforms are pre-shaped reinforcement that ensures the
firm positional placement of reinforcement.
Exercises
1. The viscosity of polyester resin (processability constant = 0.5)
goes up from 2000 to 70,000 cps in 30 minutes at room temperature. How much time will this resin take to wet and percolate
through the reinforcement to get a good composite?
2. Why does fuzzing takes place in carbon fibres and not in glass
fibres?
3. How does the tension in glass roving affect the filament winding
process? Why will high tension cause a resin- starved filament
wound structure? Explain.
4. What makes a contact layup process most popular for composites?
5. Calculate the wettability time for glass fibre- reinforced polyester
composites. The gelation time for polyester resin is 5 minutes,
and the processability factor of polyester resin is 0.5.
6. The viscosity of resin reaches 50,000 cps in 20 minutes at 100 °C
during the processing of a composite. What will be the wettability
time for fibres in this composite? (Processability constant is 0.5)
7. Outline the filament winding process for thermosetting and
thermoplastic composites. Also, compare the major difference in
their processing.
References
1. Murphy, J., The Reinforced Plastics Handbook, Elsevier Advanced Technology, Oxford, 1994.
2. Bader, S., Crystic Polyester Handbook, Scott Bader Co., Ltd, Wellingborough,
1980.
3. Monk, J.F., Thermosetting Plastics - Practical Moulding Technology, George
Goldwin, London, 1981.
4. Kia, Hamid G., “Sheet Moulding Compound,” Science and Technology, Hanser, USA, 1993.
5. The Use of Epoxy, Polyester and Similar Reactive Polymers in Construction,
Vols. 1, 2, and 3, CIRIA, London, 2000.
6. Open Moulding, Moulded Fiber Glass Companies, http://www.
moldedfiberglass. com/processes/open-molding-process.
7. Sigg, A., De Oliveira, R., Hochman, L., Cazes, T., and Michaud, V., “Process
induced defects in thick composite laminates,” Laboratoire de Technologie
Chapter 7 · Processability in Open Mould Processing of Polymeric Composites