Application Of A Polyimide Glass Fiber Sizing Agent In PEEK/GF Composites

With the rapid development of China's aerospace industry,composite materials play an irreplaceable role in aircraft manufacturing because of its light weight and high strength.Therefore,the modification of composite materials has become an enduring research direction in recent ten years.Due to its excellent thermal properties,mechanical properties,solvent resistance,insulation properties and biocompatibility,peek can play a very important role in automotive industry,aerospace,mechanical and chemical industry,electronic circuit and medical consumables.But at the same time,the more stringent processing temperature and more expensive price of PEEK have become the factors restricting its development.The interface of composite material is a new phase with a certain thickness and unique structure,which exists in the contact between matrix phase and reinforcement phase.Throughout the theoretical and experimental results of interface research in modern composite materials,if the bonding between the matrix resin and the reinforcing phase is poor,and the modulus and strength of the matrix resin and the reinforcement are greatly different,when the composite is subjected to external force,the stress transfer between the two will become worse,and the interface layer will bear a greater degree of stress concentration It is easy to damage and fail.Therefore,the interface modification of composite materials is a method to improve the mechanical properties of composites with half the effortAt present,the surface sizing agent of glass fiber is mainly epoxy type,and the processing temperature of PEEK is as high as 380 ?.It can not provide effective interface bonding between fiber and resin,but also cause defects in the interior of the composite due to its decomposition to produce small molecules.Therefore,it is very important to find a high temperature resistant fiber sizing agent for peek processing industryIn this paper,a thermosetting polyimide containing phenylacetylene was selected as the sizing agent to coat the surface of the glass fiber,and the influence of the molecular weight of the sizing agent and the main chain group on the mechanical properties and interfacial bonding of the composite was investigated.We found that the tetramer PI sizing agent with p-methyl molecular structure in the main chain can provide better interface bonding between glass fiber and peek,and its tensile properties can be improved by 31% compared with the bare fiber PEEK composite;and we explored the optimal content of the wetting agent,and found that when its mass fraction is 1% of the fiber mass,its mechanical properties can be improved Furthermore,halloysite nanotubes grafted with small molecules of PEPA were introduced into the sizing agent to improve the mechanical interlock between the fiber and the resin matrix.The experimental results show that the introduction of nano particles can improve the comprehensive mechanical properties of the composites.At the same time,we explore the influence of nanotube concentration on the mechanical properties of the composites.It is found that the mechanical properties of the composites are the best when the mass fraction of nano particles is 5%,and the grafting of small molecules on the surface of nano particles can effectively combine the nano particles on the fiber surface At present,the mechanical properties have been improved,and the tensile properties have increased by 51% compared with the bare fiber.