Thermosetting polymer

A thermosetting resin is a prepolymer in a soft solid or viscous state that changes irreversibly into an infusible, insoluble polymer network by curing.[1] Curing is induced by the action of heat or suitable radiation, often under high pressure. A cured thermosetting resin is called a thermoset or a thermosetting plastic/ polymer.

Process

Curing transforms the resin into a plastic or rubber by crosslinking individual chains of the polymer. The crosslinking is facilitated by energy and catalysts at chemically active sites, which may be unsaturated sites or epoxy sites, for example, linking into a rigid, three-dimensional structure. This yields molecules with a large molecular weight, resulting in a material that usually decomposes before melting. Therefore, a thermoset cannot be melted and re-shaped after it is cured. This implies that thermosets cannot be recycled for the same purpose, except as filler material.[2]

Some methods of molding thermosets are:

Properties

Thermosetting plastics are generally stronger than thermoplastic materials due to the three-dimensional network of bonds (crosslinking), and are also better suited to high-temperature applications up to the decomposition temperature. However, they are more brittle.

Examples

See also

References

  1. http://old.iupac.org/goldbook/TT07168.pdf
  2. The Open University (UK), 2000. T838 Design and Manufacture with Polymers: Introduction to Polymers, page 9. Milton Keynes: The Open University
  3. Fortman, David J.; Jacob P. Brutman; Christopher J. Cramer; Marc A. Hillmyer; William R. Dichtel (2015). "Mechanically Activated, Catalyst-Free Polyhydroxyurethane Vitrimers". Journal of the American Chemical Society. doi:10.1021/jacs.5b08084.
  4. Roberto C. Dante, Diego A. Santamaría and Jesús Martín Gil (2009). "Crosslinking and thermal stability of thermosets based on novolak and melamine". Journal of Applied Polymer Science. 114 (6): 4059–4065. doi:10.1002/app.31114.
  5. Enrique Guzman; Joël Cugnoni; Thomas Gmür (2014). "Multi-factorial models of a carbon fibre/epoxy composite subjected to accelerated environmental ageing". Composite Structures. 111 (4): 179–192. doi:10.1016/j.compstruct.2013.12.028.
This article is issued from Wikipedia - version of the 12/1/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.