The Anti-Shock Wave Effect of Nanomaterial/Polymer Composites

Polymer composites lie at the heart of progress made in body armour. Their resilience to impact forces and their ability to effectively disperse energy away from single impact locations make them the go-to materials for personal protective equipment.

However, material scientists are still searching for ways to improve their protective capabilities, particularly in limiting the damage caused by blast-induced shockwaves which are a major contributor to brain damage in combat soldiers caught in explosions.

It is a problem that may have been solved with the application of nanomaterials in helmets and armoured vests to negate the intense, but short-lived, acoustic pressure waves that follow an artillery shell explosion or bomb detonation.

The breakthrough was made by a team from the China Academy of Engineering Physics and involved the application of surface modified silicon dioxide (SiO2) particles. This resulted in a SiO2/ poly-dimethylsiloxane (PDMS) composite with “agglomerate and monodisperse structures” which proved highly effective at energy dispersal.

The material science journal Azom reporting how the composite was “… prepared by dispersing SiO2 particles in a solvent, followed by sonication to ensure uniform distribution. Surface modification of the SiO2 particles was then carried out using Methyltriethoxysilan (MTES) to enhance particle-matrix compatibility.”

Following this the nanoparticles were mixed with a curing agent and the PDMS matrix to create a composite which could be moulded and cured into a desired shape.

Laser shock tests were conducted to evaluate how the material functioned under bomb-blast conditions. This involved inducing shock compression and then analysing the energy dissipation using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared spectroscopy (FTIR).

Through examination of the microstructures of the nanomaterial-polymer composite the researchers found that, “Composites with agglomerate structures showed increased strength and toughness compared to pure PDMS, with enhancements of 65 % and 280 %, respectively.” Additionally, the report notes, “… composites with monodisperse structures exhibited even greater improvements, with strength and toughness increasing by 90 % and 433 %, respectively.”

Adding that, “The shock wave peak pressure reduction was up to 43 % for composites with agglomerate structures and 75 % for composites with monodisperse structures, highlighting the impact of microstructure on energy dissipation efficiency.”

The discovery represents a significant breakthrough in protective material technology. As the study, now published in the journal Polymer Testing, reports, “Compared with agglomerate structure, homodisperse structure could endow composites with enhanced strength and toughness and better shock wave energy dissipation performance (at same particle content and sample thickness).” Specifically noting the materials suitability for use in the manufacture of combat helmets and blast protective padding, the report states that, “These composites with particle-controlled structure and performance are flexible, lightweight, easy manufacturing and low cost. They have great potential application in the preparation of energy-dissipating materials for personnel and equipment protection at high shock wave pressure.”

Over the last few years, nanomaterial composites have emerged as a practical and advancing area in the development of bulletproof vests, blast-proof safety gear, and military helmets. The integration of materials such as aramid fabric, poly(BA-a-co-PU) matrix, and multi-walled carbon nanotubes (MWCNTs) has led to the creation of lightweight and high-performance protective materials. These composites have shown enhanced ballistic impact resistance, reduced back face deformation (BFD), and have the ability to withstand high-velocity impacts, making them suitable for various protective applications.

Alongside this latest discovery, the continuous exploration of advanced technologies to create nanomaterial-polymer composites is proving to be crucial for further enhancing the safety and protection of individuals in various high-risk environments.

You may also like to read: Nanomaterials for Better Impact Protection or An Introduction to Nanomaterials as a Feedstock for Polymers

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