Graphene-Enriched Agglomerated Cork Material and Its Behaviour under Quasi-Static and Dynamic Loading

Abstract

The use of cork for a variety of applications has been gaining significance due to environmental concerns and political agendas. Consequently, its range of applications is growing rapidly. In this work, aiming to improve its mechanical response for crashworthiness applications, cork agglomerates were enriched by small quantities of graphene oxide or graphene nanoplates in order to observe a resulting improvement of the mechanical behaviour during quasi-static and dynamic compressive loading cases. To produce homogenous cork agglomerates including graphene, the material was previously dispersed into granulated cork using stirrers to achieve a good distribution. Then, the typical procedure of compression and curing was carried out. Magnified images attest a good dispersion of graphene into the cork matrix. Mechanical testing was performed for a variety of graphene concentrations (0.1, 0.5 and 1.0 weight %), becoming clear that the beneficial effect of including graphene (either oxide or nanoplates) is related to a later densification stage while keeping the same stress plateau levels.

Method to Assess and Enhance Vulnerable Road User Safety during Impact Loading

“…It has been highlighted that in VRUs impacts, head injuries are one of the most common injury types. A number of publications noted that brain deformation or strain is a principal mechanism of the head injury [60,77]. From the biomechanical perspective, head injuries are regarded as the consequence of a series of mechanical interactions of the complex multi-layered scalp-skull-meninges-CSF-BVs-brain system; the CSF is cerebrospinal fluid and BVs is the abbreviation of bridging veins.…”

“…The last part of the presented authors' methodology is focused on safety gears and pro-active measuring systems. Moreover, the author presents, among others natural energy-absorbing materials-including cork-which, due to the adequate crashworthiness, may in the future replace commonly used polystyrene, for example, in motorcycle helmet liners [59][60][61].…”

Helmet Design Based on the Optimization of Biocomposite Energy-Absorbing Liners under Multi-Impact Loading

“…The continuous search for efficient and cost-effective materials to deal with crashworthiness applications has been driving many studies over recent decades [1][2][3][4][5][6][7][8][9][10][11][12]. However, recent self-consciousness and environmental responsibility are promoting the search for so-called green materials featuring good mechanical properties allied to recyclability and sustainability.…”

“…A material such as cork stands out to be employed as energy-absorbing liners in safety gear. Cork is a natural cellular material capable of absorbing great amounts of impact energy [10]. Jardin et al [14] performed quasi-static tests on different cork agglomerates and reported a value of 1.1 GJ/m 3 for a densified AC216 and 634 MJ/m 3 at the end of the stress plateau.…”

“…In particular, agglomerated cork, a by-product obtained from the scraps of wine-stoppers production, has been proving quite promising in terms of crashworthiness, showing nearly isotropic mechanical behavior and capacity to withstand extreme temperatures [15]. In addition, due to its viscoelastic behavior, cork recovers almost entirely after deformation, which is a desired characteristic in multi-impact applications [4,9,14,16] and its properties can be further tailored for specific applications [10,11].…”