Fabrication of graphite/MgO-reinforced poly(vinyl chloride) composites by mechanical activation with enhanced thermal properties

In situ generated gas bubble-directed self-assembly of multifunctional MgO-based hybrid foams for highly efficient thermal conduction, microwave absorption, and self-cleaning

Developing multifunctional materials with superior thermal conductivity and microwave absorption is an effective means to address the increasingly serious electromagnetic (EM) compatibility and heat dissipation problems in modern electron devices. Here, multifunctional MgO/Mg(OH)2/C, MgO/M/C (M = Co, Ni, Cu), and MgO/NOx/C (N = Fe, Mn) hybrid foams were synthesized using a facile one-step gas-bubble-assisted combustion method, and their texture, composition, and properties were regulated by tuning salt type and feeding ratio. Our results show that the MgO/Co/C foams have high thermal conductivity (3.40-4.09 W m-1 K-1) with a filler load of 20-50 wt% at the Co2+ molar content of φ = 70 mol% and excellent EM wave absorption (EABW = 11.44 GHz), with a thickness of 2.1 mm and a minimal reflection loss of -59.42 dB at φ = 90 mol%. The enhanced properties are ascribed to the construction of foams with 3D interconnected networks and the synergistic effect of magnetic Co, insulating MgO, and dielectric C, which provide a continuous pathway for electron/phonon relay transmission and magnetic/dielectric dual losses. Moreover, the MgO/Co/C foams possess strong mechanical/hydrophobicity performance, tunable magnetic properties, and electrical conductivity, and can be applied in self-cleaning, electromagnetic interference, and heat management. Overall, this study offers a novel understanding of preparing multifunctional heat conductive-EM wave absorptive foam materials in modern electronic devices.

Effects of Coupling Agent and Thermoplastic on the Interfacial Bond Strength and the Mechanical Properties of Oriented Wood Strand-Thermoplastic Composites

Wood-plastic composites (WPC) with good mechanical and physical properties are desirable products for manufacturers and customers, and interfacial bond strength is one of the most critical factors affecting WPC performance. To verify that a higher interfacial bond strength between wood and thermoplastics improves WPC performance, wood veneer-thermoplastic composites (VPC) and oriented strand-thermoplastic composites (OSPC) were fabricated using hot pressing. The effects of the coupling agent (KH550 or MDI) and the thermoplastic (LDPE, HDPE, PP, or PVC) on the interfacial bond strength of VPC, and the mechanical and physical properties of OSPC, were investigated. The results showed that coupling agents KH550 and MDI improved the interfacial bond strength between wood and thermoplastics under dry conditions. MDI was better than KH550 at improving the interfacial bond strength and the mechanical properties of OSPC. Better interfacial bonding between plastic and wood improved the OSPC performance. The OSPC fabricated using PVC film as the thermoplastic and MDI as the coupling agent displayed the highest mechanical properties, with a modulus of rupture of 91.9 MPa, a modulus of elasticity of 10.9 GPa, and a thickness swelling of 2.4%. PVC and MDI are recommended to fabricate WPCs with desirable performance for general applications.