Interface Research And Fabrication Of Aramid Fiber III/Polytriazole Matrix Composite

Aramid fiber reinforced composites with high modulus, high strength, and fatigue resistance, are widely used as aerospace materials.Poly-triazole (PTA) resin is a novel type of structural material, which is designed and synthesized by East China University of Science and Technology. In this paper, domestic aramid fiber Ⅲ (DAF-Ⅲ)/PTA composites were prepared, and a coupling agent (Al) containing isocyanate groups was employed to investigate the modifying effect onthecomposite materials. The interface modification mechanism was deduced. The main studies were as following:Firstly, four batches (05-88,02-49,02-177and04-103) domestic aramid fiber III/PTA composites were prepared. DAF-Ⅲ(02-49)/PTA possessed an optimal performance:ILSS is54.12MPa; flexural strength is668.85MPa; flexural modulus is57.98GPa. The performance differences of composite materials are derived from both the contents of the sizing agent and "activated carbon element" contents on the fiber surfaces via XPS, FTIR, and FE-SEM and other analysis methods.Secondly, DAF-Ⅲ (04-103) was selected to examine the content of sizing agent, the morphology and properties of the composites before and after extraction. The results proved: the ILSS and flexural strength of extracted DAF-Ⅲ/PTA increased by181.25%and56.20%, respectively. The value of flexural modulus decreased slightly. The sizing agent was a kind of aliphatic polyethers that weakened the bonding strength between aromatic DAF-Ⅲ fibers and aromatic PTA resins, which led to a decrease of the composite mechanical properties.Finally, the mechanical properties of four batches DAF-III/PTA composites were increased dramatically by Al modification. The ILSS andflexural strength of DAF-III (04-103)/PTA composite increased by187.34%and63.7%, respectively. The value of flexural modulus decreased slightly. In addition, the modification effect of Al on extracted DAF-III/PTA composite is inapparent. The experimental results of FE-SEM, FTIR, XPS and AFM proved that some of the-NCO functional groups reacted with-OH functional groups of the sizing agent. The interface layer of DAF-Ⅲ/PTA composite formed. Other-NCO groups were consumed by residual water. An active amino end group which can interact with PTA resin through hydrogen bonding is created. DSC is employed to trace the cure behaviors of PTA and Al/PTA resins. It is found that Al/PTA showed slightly lower curing temperature and higher activation energy. The result of DMA showed that the Tg of modified DAF-III/PTA composites raised.