This study suggests the novel thermoplastic toughening agent, which can be applied in the monomer forms without increasing the viscosity of the epoxy resin and polymerized during the resin curing. The diazide (p-BAB) and dialkyne (SPB) compounds are synthesized and mixed with the epoxy resin and the carbon fiber reinforced epoxy composites are prepared using vacuum infusion process (VIP). Then, flexural and drop weight tests are performed to evaluate the improvement in the toughness of the prepared composites to investigate the potential of the novel toughening agent. When 10 phr of p-BAB and SPB is added, the flexural properties are improved, maintaining the modulus as well as the toughness is improved. Even with a small amount of polytriazolesulfone polymerized, due to the filtering effect of the solid SPB by the layered carbon fabrics during the VIP, the toughening and strengthening effect were observed from the novel toughening agent, which could be added in monomer forms, p-BAB and SPB. This suggests that the novel toughening agent has a potential to be used for the composites prepared from viscosity sensitive process, such as resin transfer molding and VIP.

Abstract
 1. Introduction
 2. Experimental
  2.1. Materials
  2.2. Synthesis of the novel toughening agent
  2.3. Preparation of the carbon fiber-epoxycomposites
  2.4. Characterization and evaluation of theprepared toughening agents and composites
 3. Results and Discussion
  3.1. Chemical structure and reaction confirmationof the novel toughening agents
  3.2. Mechanical properties of the preparedcarbon fiber-epoxy composites with the noveltoughening agent
  3.3. Analyses of mechanical properties of theprepared composites
 4. Conclusions
 Conflict of Interest
 References

• Jin-Seok Bae(Department of Textile System Engineering, Kyungpook National University)
• Jihye Bae(Department of Textile System Engineering, Kyungpook National University)
• Heeju Woo(Department of Textile System Engineering, Kyungpook National University)
• Bumjae Lee(Department of Chemical Engineering and Applied Chemistry, Chungnam National University)
• Euigyung Jeong(Department of Textile System Engineering, Kyungpook National University) Corresponding Author