Chinese researchers have found a way to get rid of wrinkles in the graphene layers of paper. To do this, they immerse the material in the plasticizer, stretched, and then was taken out and dried under tension. As a result, scientists have been able to increase the tensile strength tensile 4.7 times in comparison with the source material, and the electrical conductivity of 1.62 times. Composites based on graphene paper can be used as structural materials for the aerospace industry. A study published in the journal Nature Communications.
Graphene has important properties: high conductivity, mechanical strength, softness and low resistance when bent. These properties make graphene attractive for the creation of durable composite materials with high thermal and electrical conductivity. However, the introduction of individual layers of graphene does not allow to give the end material required flexibility or sufficient strength. One possible solution is the creation of a graphene paper.
To create the graphene paper used today is either plasma-chemical deposition from the gas phase or recovery of the suspension of graphene oxide in water. However, in both cases the graphene sheets in this paper contain folds. This is the surface roughness that degrade the mechanical properties of graphene paper. Its bending stiffness, for example, is reduced more than 40 times compared to the conventional graphene, and the tensile strength — up to 453 megapascals.
Chinese scientists led by Professor Gao Chao (Chao Gao) from Zhejiang University have figured out how to deal with this problem. They made graphene paper long tape-like photographic film. Its ends wound on rotating rollers, and the Central part was placed in a solution of the plasticizer with the other rollers. The velocity are located at the edges of the tape rollers can be regulated. Depending on the velocity ratio of rollers the researchers had to regulate the tension force of the tape. Scientists stretched it to eight percent of the original length, while the tape was in the solution of the plasticizer. As the plasticizer, the researchers chose ethanol, the molecules of which are bound graphene layers via hydrogen bonds.