Study On Microwave-Assisted Synthesis Of Polycaprolactone/Boron Nitride Composites And Their Properties

Polycaprolactone?PCL?exhibits excellent electrical insulation,good processability,and biodegradability,which make it considered as a bio-based electronic packaging materials.However,the low melting point and thermal conductivity limit the application of PCL.In this paper,we choose hexagonal boron nitride?h BN?as a high mechanical strength,high thermally conductive but electrically insulating reinforcing filler to prepare the highly thermally conductive PCL/BN composites by incorporating hydroxyl-functional BN?m BN??three-dimensional oriented scaffolds into PCL matrix by microwave-assisted in situ polymerization.And then we carried out a series of characterizations of PCL/BN composites,and the main contents are as follows:?1?The hydroxyl-functional BN?m BN?was first prepared by hydrothermal reaction of h BN.And then the polycaprolactone/boron nitride?PCL/BN?composites with different BN contents were prepared by microwave-assisted polymerization of?-CL.The structure,morphology,and performance of the sample were analyzed,and the results show that:the surface treatment can effectively promote the interfacial compatibility between h BN filler and PCL matrix,and also improve the thermal properties and mechanical strength of the composite.When the m BN content is 5wt%,the thermal conductivity of the composites reaches 0.55 W m^-1K^-1,which is2.75 times that of pure PCL(0.2 W m^-1K^-1).Besides,the tensile strength and elastic modulus of composites were increased by 1.58 and 2.05 times compare to pure PCL,respectively.?2?The three-dimensional oriented 3D-BN scaffold was prepared by the ice-templated assembly technique,and then the PCL/3D-BN composite was prepared by vacuum-assisted impregnation and microwave-assisted polymerization.The structure,morphology,and thermal conductivity of the composites were analyzed,and the results show that:the ice-templated method can effectively promote the orientation of h BNs in the z and x directions.With the increase of h BN content,the thermal conductivity of the composites tend to increase first and then decrease.When the h BN filling amount is 13.41 vol%,the k_zand k_xof PCL/3D-BN composite reach1.42 and 1.01 W m^-1K^-1,respectively,which is 7.10 and 5.05 times than that of pure PCL(0.20 W m^-1K^-1).According to the analysis of the multi-orientation model,when the content of h BN is higher than 13.41 vol%,the volume fraction of randomly oriented h BN in the PCL/3D-BN composite increased,resulting in a decrease in the thermal conductivity of the composite.?3?The oriented 3D-C-BN scaffolds were prepared by ice-templated assembly technique and high temperature sintering.And then PCL/3D-C-BN composite was prepared by vacuum-assisted impregnation and microwave-assisted polymerization.The morphology,structure,and performance of 3D-C-BN and PCL/3D-C-BN composites were analyzed,and the results show that:carbonized CS can be used as thermally conductive filler to improve the thermal conductivity of the composite with h BN,and also act as a carbon skeleton support material which promotes the 3D-C-BN scaffolds to form a long-range ordered interconnection networ.When h BN content is17.69 wt%,the thermal conductivity of PCL/3D-C-BN reaches 1.73 W m^-1K^-1,which is 1.22 times than the highest thermal conductivity of PCL/3D-BN composites(1.42W m^-1K^-1,23.73 wt%).