Recycling of the solid residue obtained from the pyrolysis of fiberglass polyester sheet molding compound

This paper is part of a project devoted to study the pyrolysis process as an alternative for recycling sheet molding compound (SMC), a thermoset composite of polyester and fiberglass. A standard SMC was pyrolyzed under nitrogen, at 300, 400, 500, 600, and 700°C, for 30 min in a 3.5-dm³ autoclave. This paper focuses on the possibilities of reusing the fibers and fillers contained in the solid residue obtained from SMC pyrolysis. The solid pyrolysis residue was recycled in another thermoset composite, bulk molding compound (BMC), of polyester and fiberglass. The mechanical properties of BMCs prepared with different proportions of the solid residue (fiber + CaCO₃ filler) from SMC pyrolysis were compared with those of BMCs prepared with the same proportions of virgin fiber and CaCO₃. In summary, pyrolysis can be an appropriate technique for recycling SMC, with 500°C, the most suitable temperature for the process. Solid residues of 75 wt%, composed of 65 wt% of powdery material (mainly CaCO₃) and 35 wt% of fiberglass, were obtained. Such solids can be recycled in a proportion of 6 wt% in BMC to replace virgin filler and fiberglass, with no detrimental effect on the BMC mechanical properties. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:141–149, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20150