Novel Expandable Epoxy Beads and Epoxy Particle Foam.
MATERIALS 2022;
15:ma15124205. [PMID:
35744266 PMCID:
PMC9228838 DOI:
10.3390/ma15124205]
[Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/09/2022] [Accepted: 06/10/2022] [Indexed: 02/06/2023]
Abstract
Expanded polymeric beads offer the advantage of being able to produce parts with complex geometries through a consolidation process. However, established polymeric beads are made of thermoplastics, deform and melt beyond their temperature services. In this manuscript, a new technique is proposed to fabricate expandable epoxy beads (EEBs), then expand and fuse them to produce epoxy particle foams (EPFs). This technique is called solid-state carbamate foaming technique. For production of EEBs, a mixture of epoxy, carbamate and hardener is prepared and poured into a 10 mL syringe. The mixture is manually extruded into 60 °C water to obtain a cylindric shape. The extrudate is then further cured to obtain an epoxy oligomer behaving rheological tan delta 3 and 2 at 60 °C. The extrudate is cut into pellets to obtain EEBs. The EEBs are then loaded into an aluminum mold and placed in an oven at 160 °C to expand, fuse to obtain EPFs of 212 kg/m3 and 258 kg/m3. The obtained EPFs provide a Tg of 150–154 °C. The fusion boundaries in EPFs are well formed. Thus, the produced EPFs exhibit a compressive modulus of 50–70 MPa, with a torsion storage modulus at 30 °C of 34–56 MPa.
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