Microwave‐assisted in situ polymerization of polycaprolactone/boron nitride composites with enhanced thermal conductivity and mechanical properties

• Published in: Polymer international Vol. 69; no. 7; pp. 635 - 643
• Main Authors: Tian, Hongli, Wu, Fangjuan, Chen, Peng, Peng, Xiangfang, Fang, Hui
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.07.2020; Wiley Subscription Services, Inc
• Subjects: Adhesion; Boron; Boron nitride; Compatibilizers; Copolymers; Dispersion; Field emission; Fillers; Fourier transforms; Graft copolymers; Heat conductivity; Heat loss; Heat transfer; in situ polymerization; Infrared spectroscopy; Mechanical properties; microwave‐assisted; Modulus of elasticity; Particulate composites; Polycaprolactone; Polymerization; Ring opening polymerization; Tensile strength; Thermal conductivity
• ISSN: 0959-8103; 1097-0126
• DOI: 10.1002/pi.6000

Polycaprolactone/boron nitride (PCL/BN) composites were prepared by microwave‐assisted ring‐opening polymerization of ε‐caprolactone (ε‐CL). In order to improve the dispersibility and interfacial interaction between BN fillers and PCL matrix, hydroxyl functional BN (mBN) was first prepared to be used as a macroinitiator for ε‐CL. Then BN grafted PCL (BN‐g‐PCL) copolymers were obtained via the in situ method, which acted as in situ compatibilizers in the PCL/BN composites. Various techniques were applied to characterize the mBN and PCL/BN composites. The Fourier transform infrared spectroscopy results confirm the structure of the BN‐g‐PCL copolymer. Field emission SEM graphs exhibit that, for the PCL/mBN composites, the mBN presents a homogeneous dispersion in the matrix and interfacial adhesion between the PCL and mBN is improved. These are beneficial for enhancing the thermal conductivity of the PCL/mBN composites. Notably, the PCL/mBN composite with 5 wt% mBN loading achieves the highest thermal conductivity of 0.55 W m−1 K−1, which is 2.75 times higher than that of pure PCL, 0.20 W m−1 K−1. This indicates that the excellent dispersion and interfacial adhesion could lead to the construction of continuous thermal conductive paths at a low BN loading and reduce the heat loss caused by phonon scattering in the interface. Furthermore, mBN could help to improve the mechanical properties of the composite. On adding 5 wt% mBN, the tensile strength and tensile modulus of the composite are 1.58 and 2.05 times higher, respectively, than those of PCL. © 2020 Society of Chemical Industry Boron nitride grafted polycaprolactone (BN‐g‐PCL), the compatibilizer in the PCL/mBN composite (mBN, hydroxyl functional BN), was formed in situ, and the thermal conductivity of the composite containing 5 wt% mBN is 2.75 times higher than that of PCL.