Researchers Reveal the Multifunctionality of Polyurea Nanocomposites

A recent study published in the journal Smart materials in production focuses on producing smart, versatile and structurally robust nanocomposites by combining functionalized graphene nanoplates (F-GNPs) with polyureas.

Study: Smart multifunctional elastomeric nanocomposite materials containing graphene nanoplates† Image Credit: Saachka Pro/Shutterstock.com

Polyurea is an elastomeric material with remarkable mechanical properties. However, pure polyurea elastomers are often hampered by a lack of toughness and performance.

What Are Polyurea Materials?

Polyurea is one of the most important materials for structural shock absorption. The soft sections are usually composed of long carbon sequences, oligomeric polyols and other elastic sections with a wide variety of conformations. Isocyanates and chain extenders are used as mechanical crosslinks and reinforcing phases in the hard sections.

Polyurea has distinct viscoelastic properties that are significantly affected by pressure, heat and strain rates. The robust hydrogen bonding and intricate internal structures contribute to its remarkable defensive properties.

Polyurea polymers are limited in certain situations due to lack of utility or poor protective effectiveness. The nanocomposite technique could help to tackle these problems.

Functional conductive additives: the future of polymers

Functionalized polymer-based substances typically integrate polymers with certain functional additives to generate new or significantly improved capabilities, such as conduction, heat dissipation, barrier properties and sensing, especially self-detection, which is required for information-based advanced materials.

Fiber optics are often used to provide sensing capabilities to polymeric materials or concrete composites. This in turn causes errors in the composites and requires the use of large-scale testing equipment. Self-sensitive nanomaterials, which have appeared in recent years, are expected to overcome this limitation.

Under external stress, the conductive particle matrix deforms and breaks down, which can alter the network and alter the electrical resistance of the composites (the piezo-resistive power).

Graphene nanoplatelets (GNPs) as functional additives

Metals (eg flakes or strands), conductive foams, MXenes and activated carbon fillers such as carbon black, nanotubes and graphene nanoplatelets (GNPs) are all good considerations for conductive additives.

Metal-based compounds have the disadvantage of being heavier due to their large loads. Higher loads can result in a decrease in machinability and an increase in costs.

GNPs have become popular for their superior electromechanical properties. Efficient conductive networks can be built at low electrical percolation criteria due to their large aspect ratios. However, the homogeneous distribution of GNPs in polymeric materials remains a major challenge.

Schematics for (a) preparation of a polyurea/F-BNP nanocomposite and (b) the multichannel detection system. © Meng, Q. et al. (2022)

Highlights of the current research

While most previous polyurea research focused only on mechanical characteristics and capabilities, current work focuses on the multifunctionality of polyurea nanomaterials.

Functionalized graphene nanoplates (F-GNPs) were used in this study as fiber reinforcements to make versatile, self-sensitive polyurea composite materials with improved mechanical performance.

The researchers looked at the effect of F-GNPs on the mechanical properties and impact resistance of polyurea elastomers to see if the nanocomposites could be widely used as protective agents.

Key findings of the study

Polyurea nanocomposites, as a new type of multifunctional nanomaterials, not only provide continuous and safe stress detection and temperature measurement properties, but they can also monitor and locate the progress of their degradation, as shown by low-speed and cracking experiments.

The electrical conductivity of all nanocomposites produced increased as the nanofiller concentration increased, and the electrical percolation limit was set at 1.05 vol percent. The nanocomposite showed remarkable sensitivity in the stress range of 0-5%.

The findings show that the standardized resistance of the nanocomposite changes with temperature, and the sensitivities vary between the low and high temperature range. The nanocomposites showed good reliability and stability during cyclic load measurements up to 9100 cycles and showed a constant detection capacity between 20°C and 80°C.

Future Outlook and Outlook

This study describes a simple and efficient method for producing highly efficient, versatile polyurea nanocomposites. These functionalities are realized through the modification, degradation and recovery of the conductive system in the nanomaterials.

The self-sensing ability of functionalized polyurea composites to correctly detect and locate explosion damage and crack development as a new class of smart materials could open the door to many new industrial applications.

Reference

Meng, Q. et al. (2022). Smart multifunctional elastomeric nanocomposite materials containing graphene nanoplates. Smart materials in production† Available at: https://Researchers Reveal the Multifunctionality of Polyurea Nanocomposites

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