Overmolding Process Of Carbon Fiber Reinforced Poly Aryl Ether Ketone/Poly Ether Ether Ketone Thermoplastic Composites

In response to the demand for lightweight composite materials in the automotive and aerospace industries and the control of cost and manufacturing cycle,secondary molding technology is used to manufacture complex structural components due to its short manufacturing cycle,low cost,and integrated molding advantages.For the traditional preparation of thermoplastic composite structural elements such as reinforced wall panels,it is necessary first to use a molding process to shape the ribs and skin separately and then use secondary molding processes such as induction welding,resistance welding,and other connection processes to prepare the reinforced wall panel structure.Although the molding cycle has been shortened to some extent,the welding process requires specialized process equipment,and secondary molding can also lead to high manufacturing costs and other issues.Therefore,combining the secondary forming process of commonly used thermoplastic composite materials in the automotive industry,research on the secondary forming process of high-performance thermoplastic composite materials for aerospace applications has essential engineering significance.Firstly,the thermal,rheological,and mechanical properties of several resin matrices used in secondary molding were analyzed.The study showed that both poly(aryl ether ketone)(PAEK)and poly(ether ether ketone)(PEEK)had good thermal stability,and the melting temperature of PAEK(322 ℃)was lower than that of PEEK(343 ℃).Therefore,PAEK resin was selected as the resin matrix for continuous carbon fiber reinforced composite materials(CCF-PAEK)in overmolding;select high melting temperature PEEK resin to transfer heat to PAEK resin in secondary molding to promote interfacial bonding.Subsequently,continuous carbon fiber reinforced thermoplastic composites(CCF-PAEK)were prepared using hot pressing technology and cut to prepare prefabricated components.PEEK was used as an injection resin to prepare PEEK/CCF-PAEK composite materials.The effects of injection molding process parameters on the properties of overmolding composite materials were explored through mechanical property testing,microscopic morphology observation,and other methods.The results show a specific relationship between the properties of the overmolding composite and the injection process parameters.The shear strength first increases and then does not change with the rise of melt temperature,injection speed,and packing pressure;The increase in mold temperature can effectively increase the temperature at the interface,thereby improving the performance of PEEK/CCF-PAEK composite materials.Infrared heating preheating of prefabricated components can achieve an effect equivalent to mold temperature.Although surface polishing treatment of prefabricated components can increase the contact area between the prefabricated part and the melt,the poor surface resin is not conducive to resin bonding,resulting in decreased interfacial bonding strength.Then,this article uses short cut fiber reinforced polyether ether ketone(SCF-PEEK)as an injection resin to investigate the mechanical properties and interface bonding state of SCFPEEK/CCF-PAEK composite materials under the different mold and melt temperatures during overmolding.Dynamic thermal-mechanical properties and nanoindentation testing characterize the interface bonding state.The results indicate that the mold and melt temperatures positively affect the interfacial bonding strength of overmolding composite materials.The increase in mold temperature and melt temperature is conducive to forming a pinning effect at the interface of fibers,thereby improving the interfacial bonding strength.Finally,orthogonal experiments explored the optimal mechanical properties of secondary molded composite materials under different injection pressures,holding times,and cooling times.Finally,the PAEK/PEEK molecular model was established to study the interface diffusion mechanism.Molecular dynamics simulation was used to simulate the mold temperature,a significant factor affecting the interface temperature.The interface binding energy and diffusion coefficient were finally calculated by calculating the radius of gyration and the mean square displacement of PAEK/PEEK used to represent the self-motion ability and diffusion ability.The results showed that the binding energy and diffusion coefficient of the PAEK/PEEK interface gradually increased with the mold temperature,Matched with the experimental results.