Study on improving the toughness of rapidly curing epoxy resin composite materials with a biobased microcrystalline cellulose

Abstract

Rapid solidification molding is one of the main low‐cost forming methods for composite materials, and the reasonable selection of the solidification molding process is the key to achieving material performance. The curing system used in this paper is the widely used, inexpensive, and readily available epoxy resin (WSR618) and the transparent, colorless, and less toxic 593 curing agent, which cures at room temperature. Through the study of various temperature formulations, a rapid curing system was determined that has a 10‐min cure at 80°C. The results showed that when the mass ratio of epoxy (EP) resin to curing agent was 5:1, the curing system was selected at 80°C for 10 min, and the bending strength could reach 100.19 MPa, and the impact strength could reach 12.82 kJ/m2. However, the difficulty caused by quick solidification was a reduction in mechanical characteristics, which required modification. Microcrystalline cellulose is cheap and readily available and widely available, so microcrystalline cellulose (MCC) was chosen for modification in this study. The experimental results showed that the addition of MCC reduced the fracture brittleness of EP composite materials. When 0.75% MCC was added, the bending and tensile strengths reached 116.88 and 52.53 MPa, respectively, which were 16.66% and 18.74% higher than unmodified EP. The elongation at break reached 11.57%, which is 14.13% higher than unmodified.