Effects of the exposition of an autoclave prepreg to the processing environment on its properties, curing cycle and final composite behavior

• Published in: International journal of advanced manufacturing technology Vol. 106; no. 11-12; pp. 5129 - 5136
• Main Authors: de Andrade Raponi, Olivia, Barbosa, Lorena Cristina Miranda, Junior, José Everardo Baldo, Junior, Antonio Carlos Ancelotti, Guimarães, Alessandro
• Format: Journal Article
• Language: English
• Published: London Springer London 01.02.2020; Springer Nature B.V
• Subjects: Autoclaving; CAE) and Design; Computer-Aided Engineering (CAD; Curing; Engineering; Industrial and Production Engineering; Interfacial shear strength; Laminates; Mechanical Engineering; Media Management; Monitoring; Original Article; Prepregs; Rheological properties; Rheometry; Shear strength; Thermodynamic properties; Tracking; Tack; Autoclave prepreg; Composites manufacturing; Cure advancement
• ISSN: 0268-3768; 1433-3015
• DOI: 10.1007/s00170-020-05022-5

One of the major concerns when using prepreg materials for advanced composite manufacturing is the cure advancement. Although this type of prepreg curing is usually programmed to occur at high temperatures, the exposition to environmental conditions during processing, intrinsic to the industrial production, leads to the cure advancement and, consequently, to the detriment of prepreg’s processability. Therefore, techniques that provide accurate, relatively low-cost, and fast alternatives for tracking prepreg out-time are of great interest for composite industries. In this scenario, the present work aims to provide information on the use of thermal and rheological characterization techniques for monitoring the prepreg out-time. To do so, prepreg specimens were aged for pre-established periods (0 to 60 days) and characterized by differential scanning calorimetry (DSC) and dynamic shear rheometry techniques. Also, laminates were manufactured from aged prepregs, and their properties were characterized by ultrasound and volume fraction analyses and by interlaminar shear strength (ILSS) tests. The combination of the findings provides out-time tracking and properties monitoring alternatives for industries and points out to the possibility of extending prepreg out-time limits, reducing the waste on prepreg processing, one of the main challenges associated with composite manufacturing.