Mechanical properties of glass-fiber reinforced polyester composites manufactured by two different spray-up techniques

ABSTRACT

The study evaluates two methods for producing glass-fiber reinforced polyester (GFRP): the traditional spray-up process and a modified method named Resin Spraying with Vacuum Assisted Molding (RSVAM). Manufacturing processes for resin composites are briefly reviewed, with detailed description of RSVAM. Tensile, flexural, and Izod impact strength tests were conducted on GFRP samples containing 30 wt.% fiberglass from both methods. RSVAM yielded 120 samples (40 per test type), with results including average tensile strength (31 ± 3 MPa) and modulus (6.2 ± 0.2 GPa), flexural strength (157 ± 7 MPa) and modulus (7.2 ± 0.1 GPa), and Izod impact resistance (107 ± 2 J/cm). Comparison with 120 samples from the spray-up method revealed no significant difference in tensile and flexural strengths at a 5% significance level, but RSVAM samples showed 168% higher Izod impact resistance. Reliability curves, based on parametric and nonparametric statistics, predicted failure probabilities. For tensile and flexural tests, normal and Weibull distributions were analyzed, with similar outcomes favoring Weibull for flexural tests. Nonparametric analysis was suitable for Izod impact results, showing significant differences in failure probabilities between the two processes.

Keywords:
Fiberglass; Polyester; Spray-up technique; Weibull distribution; Kernel density estimation