176
6
Exercises
1. Calculate the degree of autohesion in a glass- reinforced polypropylene composite having an experimental value of ILSS of
9 MPa. The ideal ILSS of this composite is 12 MPa.
2. The initial height and width of an undulation of fabric are
0.1 mm and 0.25 mm, respectively. The initial distance between
two undulations is 1 mm. After moulding the composite using
the same fabric, the final height of undulation is observed to be
0.05 mm. Calculate the degree of intimate contact.
3. Compare the modulus of a talc-filled polypropylene composite
with that of a glass fibre-reinforced polypropylene. The volume
fractions of talc and glass fibre are 0.4 and 0.5, respectively. The
moduli of polypropylene and glass fibre are 3 GPa and 70 GPa,
respectively.
4. Calculate Poisson’s ratio for filler-reinforced composites. The
volume fraction of filler is 0.25, and Young’s modulus is 70 GPa.
5. Why is a reinforcement with low thermal stability not preferred
in high-temperature thermoplastic composites?
6. Outline the challenges encountered in making natural fibrereinforced thermoplastic composites.
7. Why are ‘green composites’ generally thermoplastic but not
thermosetting in nature?
8. Which is the most common chemical group that makes a plastic
inherently fire resistant?
9. Calculate the load-bearing area of a cylindrical particulate composite. The length of the cylindrical portion of the particulate
filler is 3 mm and the Ф f value is 0.2. The dimension of a particle
may be taken in millimetres for the sake of calculation.
10. What are the post-processing operations in thermoplastic composites? Outline the significance of post-processing operations
also.
References
1. Shaffer, G.D., “An Archaeomagnetic Study of a Wattle and Daub Building
Collapse,” Journal of Field Archaeology, 20 (1) (1993), p. 59.
2. 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.
3. Brydson J.A., Plastics Materials, Sixth Edition, Butterworth Heinemann, USA,
1995.
4. Plastic Molding Tutorials: #107 Melt Flow Rate (MFR) of Plastics, http://www.
misumitechcentral. com/tt/en/mold/2012/01/107. html
5. Guth, E. and Smallwood, H. J., "Limiting Law of the Reinforcement of the
Rubber", Appl. Phy., 15 (1944), p. 758.
6. Hopgarten, H., Fibre Science and Technology, 11 (1978), p. 67.
7. Dwivedi, M., Alam, S., and Verma, G.L., “Effect of Nano-barium Titanate on
Mechanical, Electrical, and Solubility Performances of Ferrite-Filled Poly
(ether ether ketone) (PEEK) Composites,” Polymer International, 54 (2)
(2004), p. 401.
8. Varma, I.K., Gupta, A., Sangita, and Varma, D.S., "Addition Polyimides. I",
J. Poly Sci., 28 (1983), p. 191.
9. Varma, I.K., Sangita, and Varma, D.S., "Addition Polyimides. IV. Effect of
Structure on Thermal Characteristics", J. Poly Sci., 29 (1984), p. 2807.
Chapter 6 · Processability of Thermoplastic Composites
6
Exercises
1. Calculate the degree of autohesion in a glass- reinforced polypropylene composite having an experimental value of ILSS of
9 MPa. The ideal ILSS of this composite is 12 MPa.
2. The initial height and width of an undulation of fabric are
0.1 mm and 0.25 mm, respectively. The initial distance between
two undulations is 1 mm. After moulding the composite using
the same fabric, the final height of undulation is observed to be
0.05 mm. Calculate the degree of intimate contact.
3. Compare the modulus of a talc-filled polypropylene composite
with that of a glass fibre-reinforced polypropylene. The volume
fractions of talc and glass fibre are 0.4 and 0.5, respectively. The
moduli of polypropylene and glass fibre are 3 GPa and 70 GPa,
respectively.
4. Calculate Poisson’s ratio for filler-reinforced composites. The
volume fraction of filler is 0.25, and Young’s modulus is 70 GPa.
5. Why is a reinforcement with low thermal stability not preferred
in high-temperature thermoplastic composites?
6. Outline the challenges encountered in making natural fibrereinforced thermoplastic composites.
7. Why are ‘green composites’ generally thermoplastic but not
thermosetting in nature?
8. Which is the most common chemical group that makes a plastic
inherently fire resistant?
9. Calculate the load-bearing area of a cylindrical particulate composite. The length of the cylindrical portion of the particulate
filler is 3 mm and the Ф f value is 0.2. The dimension of a particle
may be taken in millimetres for the sake of calculation.
10. What are the post-processing operations in thermoplastic composites? Outline the significance of post-processing operations
also.
References
1. Shaffer, G.D., “An Archaeomagnetic Study of a Wattle and Daub Building
Collapse,” Journal of Field Archaeology, 20 (1) (1993), p. 59.
2. 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.
3. Brydson J.A., Plastics Materials, Sixth Edition, Butterworth Heinemann, USA,
1995.
4. Plastic Molding Tutorials: #107 Melt Flow Rate (MFR) of Plastics, http://www.
misumitechcentral. com/tt/en/mold/2012/01/107. html
5. Guth, E. and Smallwood, H. J., "Limiting Law of the Reinforcement of the
Rubber", Appl. Phy., 15 (1944), p. 758.
6. Hopgarten, H., Fibre Science and Technology, 11 (1978), p. 67.
7. Dwivedi, M., Alam, S., and Verma, G.L., “Effect of Nano-barium Titanate on
Mechanical, Electrical, and Solubility Performances of Ferrite-Filled Poly
(ether ether ketone) (PEEK) Composites,” Polymer International, 54 (2)
(2004), p. 401.
8. Varma, I.K., Gupta, A., Sangita, and Varma, D.S., "Addition Polyimides. I",
J. Poly Sci., 28 (1983), p. 191.
9. Varma, I.K., Sangita, and Varma, D.S., "Addition Polyimides. IV. Effect of
Structure on Thermal Characteristics", J. Poly Sci., 29 (1984), p. 2807.
Chapter 6 · Processability of Thermoplastic Composites