Preparation And Thermal Conductive Property Of Composites Based On Polyvinyl Alcohol/polyimide/Ti₃C₂T_x

With the development of electronic packaging and flexible wearable products,the requirements for heat dissipation of devices are increasing.Polymer composite materials have the advantages of light weight and simple preparation,but they do not have good thermal conductivity.Studies have shown that adding high thermal conductivity fillers to polymers to construct two-dimensional and three-dimensional composite frameworks is an effective way to improve the thermal conductivity of composite materials.In this paper,polyvinyl alcohol(PVA)is used as the base polymer,and polyimide(PI)of different structures is compounded,and a two-dimensional transition metal carbide(Ti₃C₂T_x)with a graphene-like structure is further added to improve the thermal conductivity.The specific research content is as follows:1.Preparation and performance research of PVA/PI/Ti₃C₂T_x thermally conductive composite material.PVA and two polyimides of different structures(PI-1,PI-2)were mixed with different proportions of Ti₃C₂T_x and dissolved in three different solvents(DMAc,H₂O,DMF)to prepare composite films.The composite film prepared under the system showed the best performance.The structure of Ti₃C₂T_xwas characterized by infrared spectroscopy,XRD,XPS and other testing methods.Thermal infrared imager,tensile testing machine and thermogravimetric analyzer were used to investigate the thermal conductivity,mechanical properties and thermodynamic stability of the composite film.The results show that the thermal conductivity of the composite is the best when Ti₃C₂T_x is added at 1 wt%,that is,the temperature reaches 85.2°C when heated for 20 s,the highest thermal conductivity is0.15 W·m^-1·K^-1;when PI-1 is mixed with 0.4 wt%Ti₃C₂T_x,the tensile strength reaches the highest The tensile strength is 8.22 MPa;the PI-2-based composite film has better flexibility,the elongation at break is 75.97%;after adding Ti₃C₂T_x,the thermal stability of PI-1-based composites is improved.2.Preparation and performance study of PVA/PI/KH550-Ti₃C₂T_x thermally conductive composite film.KH550-Ti₃C₂T_x was prepared by surface modification of Ti₃C₂T_x by aminopropyltriethoxysilane(KH-550).Test methods such as infrared,XRD,XPS,SEM and TEM showed that KH550-Ti₃C₂T_x was successfully prepared.PVA and two polyimides with different structures(PI-1,PI-2)were added into the DMF solution,and KH550-Ti₃C₂T_x in different proportions were mixed to prepare a thermally conductive composite film.Thermal infrared imager,tensile testing machine and thermogravimetric analyzer were used to investigate the thermal conductivity,mechanical properties and thermodynamic stability of the composite film.The results show that the thermal conductivity of the composite is best when the KH550-Ti₃C₂T_x is added at 0.4 wt%,that is,the temperature reaches 73.5°C when heated for 20 s,the highest thermal conductivity is 0.19 W·m^-1·K^-1;the tensile strength is when PI-1 is mixed with 0.4 wt%of KH550-Ti₃C₂T_x reached the highest tensile strength of 7.01 MPa;PI-2-based composite film has more excellent flexibility,the elongation at break is 71.52%;after adding KH550-Ti₃C₂T_x,the thermal stability of PI-1-based composites is improved.3.Preparation and performance study of PVA/PI/Ti₃C₂T_x three-dimensional thermally conductive composite material.The three-dimensional foam structure was prepared by freeze-drying to remove the ice template,and the foam was immersed in PI DMF solution to obtain a soft ternary composite material.SEM characterization confirmed that the composite material has an obvious three-dimensional foam structure.Thermal infrared imager and thermogravimetric analyzer were used to test the thermal conductivity and thermodynamic stability of the composite material.The results show that when the addition amount of KH550-Ti₃C₂T_x is 1 wt%,the thermal conductivity of the PI-2-based three-dimensional composite material is the best,that is,the highest temperature reaches 75°C when heated for 20 s,the highest thermal conductivity is 0.24 W·m^-1·K^-1;after adding KH550-Ti₃C₂T_x,the thermal stability of PI-2-based composites is improved.