TITLE:
Progress in Recycling of Composites with Polycyanurate Matrix
AUTHORS:
Christian Dreyer, Dominik Söthje, Monika Bauer
KEYWORDS:
Polycyanurate, Composite Recycling, Thermoset, Cyanate Ester Resins, High Performance Polymers, Reinforcement Fiber, Carbon Fiber, Natural Fiber
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.4 No.2,
April
14,
2014
ABSTRACT:
Thermoset
based composites are used increasingly in industry for light weight applications,
mainly for aircraft, windmills and for automobiles. Fiber reinforced thermoset polymers
show a number of advantages over conventional materials, like metals, especially their better performance regarding their
strength-to-weight ratio. However, composite recycling is a big issue, as there
are almost no established recycling methods. The authors investigate the recyclability
of polycyanurate homo- and copolymers with different recycling agents under different
conditions. Also the influence of the recycling process on the most important reinforcement
fibers, i.e. carbon-, glass-, aramid-,
and natural-fiber is investigated. The authors find that: the recycling speed
is not only dependent on the temperature, but also is significantly influenced by
the particular recycling agents and the polycyanurate formulation. Hence, the stability
against the recycling media can be adjusted over a broad range by adjusting the polymer composition. Furthermore,
the authors find that the inorganic reinforcement fibers (carbon and glass) are
almost unaffected by neither recycling agent at either temperature. Aramid-fibers
degrade, depending on the particular recycling agent, from slightly up to extremely
strong. This leaves one with the possibility to find a combination of matrix resin
and recycling agent, which does not affect the aramid-fiber significantly. In the
case of natural fibers, the dependence on the particular recycling media is very
strong: some media do not affect the fiber significantly; others reduce the mechanical
properties (tensile strength and elongation at break) significantly, and still others
even improve both mechanical properties strongly. From the Recyclate, the authors
synthesize and subsequently characterize a number of new polyurethane thermosets
(foamed and solid samples) with different contents of recyclate, exhibiting Tg in the range of 60°C to 128°C.