The elastic modulus and Poisson's ratio are determined as E = 381–385 N/m and ν = 0.456 ± 0.008, respectively. They are close to the upper limit of the reported ranges of the elastic modulus of graphene (E = 312–384 N/m) and Poisson's ratio (ν = 0.16–0.46 [18,21,34,35,47,48,56–58
Dear Mukesh Pandey many thanks for your interesring technical question. I'm certainly not a proven expert in this field. However, I can recommend to you the following useful article which might help answering your question:
Poisson’s Ratio of Layered Two-dimensional Crystals
https://arxiv.org/pdf/1507.07324.pdf
This paper can be freely downloaded as public full text. Also please see the following relevant RG links:
The Size- and Chirality-Dependent Elastic Properties of Graphene Nanofilms
Article The Size- and Chirality-Dependent Elastic Properties of Grap...
and
Probing the Young’s modulus and Poisson’s ratio in graphene/metal interfaces and graphite: a comparative study
Article Probing the Young's modulus and Poisson's ratio in graphene/...