Effect of Polymer/Fiber Affinity on the Performance of Silk Composite Laminates

Abstract

Aerospace industry is intensely shifting towards the usage of composite materials, as the new Airbus and Boeing aircrafts, among others, comprise increasing percentages of these materials. Beyond their higher specific mechanical properties, fiber reinforced polymer composites are non-magnetic, and thus do not interfere with the magnetic compass of the aircraft, making them particularly suitable for the aircraft’s skin. Recent sustainability concerns and environmental awareness has led to the popularity of natural fibers as eco-friendly reinforcements in polymer composites. Among natural fibers with established potential applications, silk fibers have recently received considerable attention from researchers due to their remarkable properties. Strong, lightweight and flexible, silk is a viable natural reinforcement that can be repurposed for composite industrial use. However, silk composite laminates are hardly used in aerospace products due, in part, to a lack of affinity between the silk fibers and epoxy, the polymeric resin often used to manufacture silk composites. This paper investigates the effect of polymer/fiber affinity on the performance of silk composite laminates. To this effect, the silk/resin contact angle is measured for different resins, and correlated with the mechanical properties of the silk composite laminates fabricated by vacuum assisted resin transfer molding (VARTM). The ability of the resin to impregnate the woven silk fiber preform is observed to affect the mechanical performance of these laminates as well as their overall quality.