Enhancement of interfacial interactions in fiber-reinforced Polymeric composites with multifunctıonal carbon Nanomaterials

Official URL: https://risc01.sabanciuniv.edu/record=b3400648

Fiber-reinforced polymeric composites (FRPCs) continue to replace conventional materials including metals in many fields because of their prominent features such as high strength-to-weight ratio and tunable mechanical properties, especially in structural engineering applications requiring lightweight. In addition, FRPCs display notable in-plane features, durability, and corrosion resistance. Although FRPCs have such superior properties, they also suffer from many disadvantages, including poor out-of-plane properties resulting in fiber matrix cracking, fatigue and delamination, and limited fracture toughness. Therefore, a better understanding and tailoring of the interactions between the micro-scale fiber and the polymer matrix is crucial in addressing the needs for stronger, more durable, and lighter-weight composite materials for various industries including the aerospace. In this dissertation, multifunctional carbon nanomaterials (CNMs) decorated with ionic and urea groups were designed and incorporated into the fiber-matrix interface, in an effort to enhance these interactions in carbon fiber reinforced, epoxy-based composites. For this purpose, a novel, ultrasonic spray deposition method was used for the homogeneous and uniform introduction of multifunctional CNMs from their aqueous dispersions onto carbon fiber fabric surface prior to the manufacturing of FRPCs. The multi-functionalization strategy utilized in this dissertation not only allowed a homogeneous dispersion of CNMs in water for their ultrasonic spray deposition in an environmentally friendly manner by eliminating the use of organic solvents, but also offered a high degree of secondary interactions (i.e. hydrogen bonding) at the fiber-matrix interface of FRPCs manufactured by the prepregging method followed by autoclave curing. To further enhance the fiber-matrix interfacial interactions in FRPCs, waterborne, hyperbranched polyurethane dispersions (HBPUD) with a multitude of functional end-groups were designed and synthesized, which were deposited onto the carbon fiber fabric surface in the presence of CNMs by ultrasonic spray deposition. The effect of HBPUD:CNM ratio during the ultrasonic spray deposition, the total amount of CNM deposited onto the carbon fiber, and the type of functional end-groups on HBPUDs on the mechanical properties of resulting FRPCs was systematical investigated in this dissertation.