Study On High Surface Activity Aramid Fiber With UV Radiation Resistance

Aramid fiber?KF?is a typical representative of high performance organic fiber.Its excellent merits such as light weight,ultrahigh strength,high modulus and heat resistance make it suitable for many fields such as aerospace,safety protection,electronic information,goods,tire skeleton,etc.However,its low surface activity and poor UV resistance originated from its special chemical structure lead to poor manufacturability and low reliability of service.This paper seeks to improve KF's surface activity and UV resistance without sacrificing the original thermodynamic properties.The thesis contains two parts.The first part is the preparation of nano turbostratic boron nitride@cerium oxide?tBN@CeO₂?using a vapor deposition method,and tBN@CeO₂ was modified by the biomimetic material polydopamine?PDA?to prepare a double shell-core hybrid UV absorber?PDA@tBN@CeO₂?,in which CeO₂ is a core,nano-BN is the first shell and PDA as the second shell.The structure?crystal structure,surface element?and properties?heat resistance,Uv-vis and photocatalytic activity?of CeO₂,tBN@CeO₂ and PDA@tBN@CeO₂ have been systematically investigated.Results show that PDA@tBN@CeO₂ with size less than 100 nm were successfully prepared,which has double shell structure.The initial decomposition temperature?Tdi?of PDA@tBN@CeO₂ with active group of hydroxy and amino is higher than 700°C.In addition,the UV absorption wavelength 200-400 nm of PDA@tBN@CeO₂ is excellent,of which photocatalytic activity is simultaneously low.It can thus be seen that PDA@tBN@CeO₂ can serve as an effectively ultraviolet modifier for KF with excellent comprehensive performance.In the second part,KF was pretreated and then PDA@tBN@CeO₂ was grafted onto the surface of KF to construct a series of novel modified fibers?T-KF?,which possess of novel surface structure.The influence of the grafting amount of PDA@tBN@CeO₂ on the structure and comprehensive properties?surface activity,mechanical properties,thermal properties,and UV resistance?of T-KF fibers were systematically studied.Results show that the surface free energy of T-KF increased by 14-31%,tensile properties increased by 5%-20% than original KF,moreover,tensile strength and energy to break of T-KF2 are 1.14 and 1.21 times of those of original KF,which exhibits the best comprehensive property.The retention of tensile properties after 168 h UV radiation remained at 85-97%,which have increased by 11-20% compared to KF,especially,the retention of energy to break of T-KF2 is 1.62 times of that of KF.The excellent integrated performances of T-KF are proved to be attributed to the unique structure of PDA@tBN@CeO₂ and its interaction with KF?...