148
5
Exercises
1. Predict and draw the curing cycle of a thermosetting resin having a gelation temperature and curing temperature of 70 °C and
160 °C, respectively. It has an initial viscosity and viscosity at
70 °C of 12,000 cps and 2000 cps, respectively.
2. Compare the fibre treatments on glass fibres, carbon fibres, and
Kevlar fibres. How is the role of sizing different in glass fibres
and carbon fibres?
3. What are the polyolefin fibres? Why are polyolefin fibres not
used in the fabrication of high-performance composites?
4. A composite and steel adhesive joint has a lap shear strength of
2.2 Kg/mm 2 . The surface free energy of bonding the steel and
composite is 0.7 J and 0.9 J, respectively. Calculate the interaction energy of the composite and steel joint in Joules.
5. How is interdiffusion different from mechanical locking?
6. What are the factors that influence the following in composites?
(a) Mechanical locking
(b) Chemical bonding
7. Why is the role of secondary chemical bonding important in the
bonding of fibres and matrices? What will happen if there is
only primary bonding?
8. Explain thermodynamic stability in cases of chemical bonding
and mechanical locking in the processing of polymeric composites.
9. What are the reasons for the popularity of prepregs in composite industries despite that the fabrication of composites using
prepregs is a two-step process causing a high cost of production?
10. How does the reinforcement from particles and whiskers in a
matrix differ in the performance of polymeric composites?
Which is better and why?
11. In thermoset composites, the temperature of the onset of the
gelation of a resin is 90 °C, and the temperature of the onset of
degradation of a resin is 270 °C. What is the likely curing temperature of this composite and why?
References
1. Hon, D. and Shiraishi, N., Eds., Wood and Cellulose Chemistry, 2nd Edition,
Marcel Dekker, New York, 2001.
2. Shaffer, G.D., “An Archaeomagnetic Study of a Wattle and Daub Building
Collapse,” Journal of Field Archaeology, 20 (1) (1993), p. 59.
3. Pukanszky, B., Tudos, F., Kolarik, J., and Lednicky F., "Ternary Composites of
Polypropylene, Elastomer, and Filler: Analysis of Phase Structure Formation",
Poly. Compos.,11 (1990), p. 98.
4. Brydson, J.A., Plastics Materials, Sixth Edition, Butterworth Heinemann,
USA, 1995.
5. Guth, E. and Smallwood, H., "Limiting Law of the Reinforcement of the Rubber", J. Appl. Phy., 15 (1944), p. 758.
6. Pludeman, E., Collins, N., Adhesion Science and Technology, Vol. 9a, Plenum
Press, New York, 1975.
7. Monte, S.J., Ken-React Reference Manual- Titanate, zirconate and aluminate
coupling agents, 1985.
Chapter 5 · Processability of Thermosetting Composites
5
Exercises
1. Predict and draw the curing cycle of a thermosetting resin having a gelation temperature and curing temperature of 70 °C and
160 °C, respectively. It has an initial viscosity and viscosity at
70 °C of 12,000 cps and 2000 cps, respectively.
2. Compare the fibre treatments on glass fibres, carbon fibres, and
Kevlar fibres. How is the role of sizing different in glass fibres
and carbon fibres?
3. What are the polyolefin fibres? Why are polyolefin fibres not
used in the fabrication of high-performance composites?
4. A composite and steel adhesive joint has a lap shear strength of
2.2 Kg/mm 2 . The surface free energy of bonding the steel and
composite is 0.7 J and 0.9 J, respectively. Calculate the interaction energy of the composite and steel joint in Joules.
5. How is interdiffusion different from mechanical locking?
6. What are the factors that influence the following in composites?
(a) Mechanical locking
(b) Chemical bonding
7. Why is the role of secondary chemical bonding important in the
bonding of fibres and matrices? What will happen if there is
only primary bonding?
8. Explain thermodynamic stability in cases of chemical bonding
and mechanical locking in the processing of polymeric composites.
9. What are the reasons for the popularity of prepregs in composite industries despite that the fabrication of composites using
prepregs is a two-step process causing a high cost of production?
10. How does the reinforcement from particles and whiskers in a
matrix differ in the performance of polymeric composites?
Which is better and why?
11. In thermoset composites, the temperature of the onset of the
gelation of a resin is 90 °C, and the temperature of the onset of
degradation of a resin is 270 °C. What is the likely curing temperature of this composite and why?
References
1. Hon, D. and Shiraishi, N., Eds., Wood and Cellulose Chemistry, 2nd Edition,
Marcel Dekker, New York, 2001.
2. Shaffer, G.D., “An Archaeomagnetic Study of a Wattle and Daub Building
Collapse,” Journal of Field Archaeology, 20 (1) (1993), p. 59.
3. Pukanszky, B., Tudos, F., Kolarik, J., and Lednicky F., "Ternary Composites of
Polypropylene, Elastomer, and Filler: Analysis of Phase Structure Formation",
Poly. Compos.,11 (1990), p. 98.
4. Brydson, J.A., Plastics Materials, Sixth Edition, Butterworth Heinemann,
USA, 1995.
5. Guth, E. and Smallwood, H., "Limiting Law of the Reinforcement of the Rubber", J. Appl. Phy., 15 (1944), p. 758.
6. Pludeman, E., Collins, N., Adhesion Science and Technology, Vol. 9a, Plenum
Press, New York, 1975.
7. Monte, S.J., Ken-React Reference Manual- Titanate, zirconate and aluminate
coupling agents, 1985.
Chapter 5 · Processability of Thermosetting Composites