Technical feasibility and variable optimization of pultruded fiberglass reinforced brominated-epoxy composites

Abstract

The technical feasibility and processing variables of fiberglass reinforced brominated-epoxy (BEP) composites produced via pultrusion were investigated. Based on the viscosity of the BEP matrix set 40°C–50°C after 3.66 h. The viscosity increase remained below 2000 mPa·s after 3.66 h. When the immersion tank was maintained at 40°C–50°C, the data indicate an operating time exceeding 3.66 h for the BEP matrices, it is ensured enough time for the following pultrusion process. Fourier Transform Infrared (FTIR) spectroscopy revealed that the absorption peak at 920 cm⁻¹, characteristic of the epoxy ring, completely disappeared when the BEP matrix was polymerized at 210°C for 120 s. At temperatures above 180°C, the BEP matrix showed a shorter gelation time (less than 60 s). FTIR spectroscopy and high-temperature gelation time measurements provided confirmation of the BEP matrix’s highly reactive nature. Glass fiber bundles are evenly distributed within the BEP matrix and a significant amount of BEP matrix remains adhered to the glass fiber surface after fracture testing by Scanning Electron Microscopy (SEM) images, it revealed excellent fiber impregnation by the BEP matrix. Investigating the BEP matrix’s extended operating time, highly reactive nature, and superior glass fiber wetting, this research confirms its robust technical feasibility for process. The investigated processing parameters encompassed mold temperature, pulling rate (speed), postcure duration (time) and temperature, filler content and type, and glass fiber content. Differential Scanning Calorimetry (DSC) analysis was used to determine the mold temperature, which should be above 180°C. The optimal pulling rates are determined to be 20 cm/min for mold temperatures of 190°C–210°C and 40 cm/min for 220°C–230°C. The optimal postcure temperature and duration were 120°C and 3 h. It was found that pultruded composites containing 2 phr of calcium carbonate or 4 phr of talc exhibited the optimal strength and thermal properties. This study determined the optimum glass fiber content to be 67.3 vol%.