Fabrication of high-quality multilayer graphene using high-power ultrasonic vibration and testing its reinforcement application in several composite materials
In polymer composite systems, graphene acts as an effective reinforcing agent, significantly improving mechanical properties (such as tensile strength, hardness, impact resistance), thermal properties (enhancing thermal conductivity and thermal stability), and electrical properties (increasing electrical conductivity and antistatic resistance). Good dispersion of graphene within the polymer matrix helps create robust nanoscale networks, thereby forming nanocomposites with superior performance compared to traditional composites.
In addition, graphene is applied to improve the performance of technical polymers, functional coatings, anti-corrosion materials, conductive paints, thermal insulation materials, and high-tech products such as sensor membranes, energy storage devices, thermal conductive materials in electronics and industry. Therefore, research and development of efficient graphene fabrication processes and their application in polymer composite systems is an important direction to enhance utility value and expand the practical application potential of this strategic material.
The Institute of Materials Science is one of the first institutions in the country to carry out research on exfoliating graphite into graphene in liquid phase using advanced methods such as high-speed shear mixing and high-power ultrasonic vibration. Since 2018, the Institute of Materials Science has mastered the technology of exfoliating graphite into multilayer graphene using a dual-axis staggered shear mixer with a power capacity of 1–2 kW. Building upon that, the project titled “Fabrication of high-quality multilayer graphene using high-power ultrasonic vibration and testing its reinforcement application in several composite materials,” code: UDPTCN.04/21-23, led by Nguyen Thi Ngoc Tu, MSc, and Bui Hung Thang, PhD, along with their collaborators, was implemented to develop a liquid-phase exfoliation method using high-power density ultrasonic waves to produce few-layer graphene materials.
The project successfully designed and fabricated a high-power ultrasonic vibration device for exfoliating graphene from graphite. The device operates at an ultrasonic frequency of 40 kHz and a power density of up to 2.4 kW/litre—suitable for breaking the bonds between graphite layers in a liquid-phase environment. The graphene obtained after processing with this device has a sheet size smaller than 500 nm, a thickness of about 3 nm, a specific surface area over 60 m²/g, and high purity, with carbon content over 99%.
Figure 1. Image of the fabricated device
Figure 2. TEM image of the fabricated graphene material
The synthesised multilayer graphene was applied to reinforce two typical composite material systems, including natural rubber and epoxy. For natural rubber, the reinforced material achieved a tensile strength of 18.6 MPa, an elongation at break of 565.8%, and a hardness of 56.5 Shore A, showing a clear improvement compared to the base material. Meanwhile, the graphene-reinforced epoxy samples also demonstrated impressive mechanical-physical indicators, with an impact strength of 100 kg/cm, flexural strength and adhesion both rated at grade 1, and a relative hardness of 0.9.
Figure 3. Invention patent no. 44422 granted by the Intellectual Property Office
The project was highly rated by the Acceptance Council of the Vietnam Academy of Science and Technology in terms of scientific, technological, and application value and was classified as excellent. The project has completed invention patent no. 44422 granted by the Intellectual Property Office for the “High-power density ultrasonic vibration device and the process for exfoliating graphite into graphene”; submitted one patent application no. 1-2022-01007 currently under substantive examination for future granting; published one article in an international SCI-E-indexed journal (Materials Research Express), two articles in national scientific journals, delivered presentations at two national and international scientific conferences, and supported one PhD candidate in completing their doctoral dissertation.
Translated by Tuyet Nhung
Link to Vietnamese version
