Reproducibility Study of the Thermoplastic Resin Transfer Molding Process for Glass Fiber Reinforced Polyamide 6 Composites

• Published in: Materials Vol. 16; no. 13; p. 4652
• Main Authors: Martins, Filipe P, Santos, Laura, Torcato, Ricardo, Lima, Paulo S, Oliveira, José M
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 28.06.2023; MDPI
• Subjects: Additives; Automobile industry; Crystallization; Emission standards; Emissions; Fiber composites; Fiber reinforced polymers; Filling; glass fiber; Glass fiber reinforced plastics; Homogeneity; Humidity; in situ polymerization; International organizations; Mechanical properties; Optimization; polyamide 6 composites; Polyamide resins; Polyamides; Polymerization; Process variables; Recyclability; Reproducibility; Resin transfer molding; T-RTM; Tensile strength; Thermodynamic properties; thermoplastic matrix; Thermoplastic resins; Thermoplastics; Viscosity; United Kingdom; Portugal; Japan; Germany; in situ polymerization; glass fiber; T-RTM; polyamide 6 composites; thermoplastic matrix
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16134652

Polyamide 6 (PA6) thermoplastic composites have higher recyclability potential when compared to conventional thermoset composites. A disruptive liquid molding manufacturing technology named Thermoplastic Resin Transfer Molding (T-RTM) can be used for processing composites due to the low viscosity of the monomers and additives. In this process, polymerization, crystallization and shrinkage occur almost at the same time. If these phenomena are not controlled, they can compromise the reproducibility and homogeneity of the parts. This work studied the influence of packing pressure, as a process variable, throughout the filling and polymerization stages. To assess the process reproducibility and parts' homogeneity, physical, thermal and mechanical properties were analyzed in different areas of neat PA6 and composite parts. This study showed that a two-stage packing pressure can be successfully used to increase parts' homogeneity and process reproducibility. The use of 3.5 bar packing pressure during the polymerization stage resulted in mechanical properties with lower standard deviations, indicating a higher degree of homogeneity of the manufactured parts and higher process reproducibility. These results will be used for establishing the actual state of the technology and will be a base for future process optimization.