Chen-yu Li

Bio: Chen-yu Li is an academic researcher from Southwest Jiaotong University. The author has contributed to research in topics: Composite number & Ultimate tensile strength. The author has co-authored 1 publications.

Highly anisotropic thermal and electrical conductivities of nylon composite papers with the integration of strength and toughness

Abstract: The mechanical properties of thermally conductive composites are the key to realize their applications. Strength of materials is of significance, furthermore the toughness of materials also should attract more concern. Actually, few researchers have reported the simultaneous improvement of strength and toughness of anisotropic thermally and electrically conductive composites. Therefore, this study aims to obviously improve the in-plane thermal and electrical conductivities of nylon composites, which display superior tensile strength and toughness, compared to other thermally conductive composites. The nylon composite papers, prepared through a facile method involving vacuum-assisted filtration and compression molding processes, present a laminate structure and compact graphene nanoplatelet (GNP) stacks inside composites. On account of the special structure, the nylon composite papers show a super-high in-plane thermal conductivity of 16.0 W m−1 K−1 and electrical conductivity of 18.0 S cm−1 at a filler loading of 14.6 wt%. Surprisingly, the composite papers still exhibit a high strength of 48.3 MPa, which is comparable to that of a pure nylon film. In addition, the elongation at break of the composite paper with 14.6 wt% GNPs is as high as 34.2%, ultimately endowing the composite papers with a good toughness of 13.15 MJ m−3. The nylon composite papers successfully achieve the integration of excellent thermal and electrical conductivities, and superior strength and toughness, showing huge application values in the field of intelligent electronic device.

Construction of a 3D interconnected boron nitride nanosheets in a PDMS matrix for high thermal conductivity and high deformability

Abstract: With the electronic device advancing to miniaturization, higher integration and flexibility, flexible polymer composites with high thermal conductivity are desirable for efficient removal of accumulated heat to maintain normal operation of electronics. In this work, a polydimethylsiloxane/boron nitride nanosheets (PDMS/BNNS) foam scaffold was prepared by the sugar-templated method, and the corresponding PDMS/BNNS composites were manufactured with vacuum-assisted PDMS impregnation and curing. The PDMS/BNNS composites exhibit a three-dimensional (3D) BNNS interconnected network with curved BNNS pathways due to the intensive compression during hot-pressing curing, providing thermally conductive network and corresponding prestrains for deformable application. The PDMS/BNNS composites finally can achieve a high thermal conductivity of 7.55 W m−1 K−1 in the in-plane direction and 1.12 W m−1 K−1 in the through-plane direction with 25 vol% BNNS, which represent 153% and 78% increases over the composites prepared by randomly mixing method, respectively. In addition, the composite still maintains superior heat dissipation property under repeated stretching and bending conditions, which indicates a broad and bright application for thermal management in flexible electronic devices.

High performances of polyimide/boron nitride nanosheets composites via integrative interfacial decoration strategy

Abstract: With the rapid development of electrical equipment and integrated circuits, packaging materials with high heat dissipation capability are in great demand. Reducing the interfacial thermal resistance is still a great challenge in polymeric composites. Herein, surface-induced polyamide acid (PAA) polymerization on boron nitride nanosheets (BNNSs) was firstly achieved, and then the BNNS@PAA was introduced into the polymerization system of polyimide (PI). The dependence of microstructures and performances of the composites on imidization degree of BNNS@PAA was systematically investigated. The results show that there is an appropriate imidization temperature (120 °C), at which the composite with only 10 wt% BNNS@PAA exhibits high thermal conductivity (2.11 W/m·K), excellent mechanical properties (with tensile strength of 97.2 MPa and elongation at break of 19.8%), and good dielectric properties (with a discharged energy density of 3.67 J/cm 3 and a charge-discharge efficiency of 87.4% at the field of 300 MV/m).