Recycling Waste Fiberglass by Powder Grinding and Direct Molding of Powders

Direct molding is a compression molding process of thermoset particles without the addition of any linking agent or binder. It is suitable for recycling end-of-life fiberglass or other waste from the manufacturing of fiberglass products. In this study, for the first time, the feasibility of recycling waste fiberglass powder, collected from an industry, is shown in the case of a vinyl ester matrix. Powders have been directly molded, without any pre-treatment such as sieving, to manufacture small samples for four-point bending tests. Supplied powders have been characterized by microscopy and thermal analysis. Its size distribution has been evaluated by sieving, and the amount of resin by burning test. Samples have been compression molded in an eight-cavity mold and have shown good homogeneity and surface aspect. The average density of the recycled fiberglass is 1.23 g/cm³, the bending strength 28 MPa, the elongation at break 1.6%, and the elastic modulus 1.9 GPa, with low dispersion (7% at maximum). Surface analysis has shown a rough surface and the presence of embedded glass fibers into the agglomerated fiberglass. Results show that waste powders from secondary processes of fiberglass manufacturers, such as surface grinding, may provide secondary raw materials for the production of molded parts without mixing with virgin substances.