The incorporation of graphene into autopolymerising acrylic resin is an innovative strategy to improve its mechanical properties, simultaneously increasing the elastic modulus as well as the tenacity, reducing the appearance of cracks and/or the spreading of them as well as decreasing the shrinkage rate during polymerisation.
Graphene is the ideal candidate to improve the performance of autopolymerising acrylic resins for dental use, not only due to its high traction resistance, coefficient of thermal expansion, high capacity for absorption and lubrication, flexibility and high surface area, but also for its high weight to resistance ratio.
Acrylic resins are hard, fragile and crystalline polymers, which are used as thermostable materials, given that, after they have been cured, they cannot be changed or moulded.
The autopolymerising resins based on polymethyl methacrylate (PMMA) are the materials most used in dental laboratories. However they present low resistance to impact and a low transversal and flexion resistance, derived from the formation and the spread of cracks when they are put through mechanical stress.
One of the principal advantages of graphene is that even in small quantities its inclusion can cause big changes in the mechanical and physicochemical properties to the material to which it is added, as long as it is well dispersed and produces a good reaction with the original material.
Given that graphene is a good thermal conductor and that the process of post-polymerisation of the acrylic resin requires heat to be completed, the addition of graphene allows for a higher polymerisation conversion rate.
Compared with conventional polymer materials, polymers reinforced with graphene have a higher modulus and specific resistance thanks to the distribution of tension between the structures, meaning that they are capable of withstanding tensions practically without suffering deformations. The union between the Nano reinforcements and the original polymer is one of the main aspects that explains the increase in mechanical properties in this type of compound material.
Graphene, a last generation nanotechnological material, is one of the allotropic forms in which carbon can be found, just as graphite or diamond, and therefore, it is abundant in nature.
Graphene is one of the most investigated nanomaterials at the moment, due to the incredible mechanical, optical and electrical properties that it presents, as well as the many improvements it provides to other materials.
It is the most resistant material known, about 200 times harder than structural steel with the same thickness, and at the same time, is as light as carbon fiber and even more flexible than this, among many other properties. In addition to greater flexibility, graphene provides a high elasticity to materials and less chance of breakage.
Graphene is waterproof and, unlike most water-resistant surfaces, is a great thermal and electrical conductor, better than copper, diamond and silver. In turn, graphene effectively acts as an antibacterial agent, preventing the growth of bacteria and mold.
All these improvements mean an increase in the durability of graphene materials and a reduction of both raw material and final costs, as well as promoting improvements in the environment thanks to its use in specific technologies.