Evaluation of graphene nanosheets influence on the physical properties of PVDF/PMMA blend

In this work, we report the preparation of PVDF/PMMA/graphene polymer blend nanocomposites via synthesis of PMMA/graphene as a masterbatch through in-situ polymerization. The PMMA/graphene masterbatch compounded with PVDF by solution mixing in different ratios. The compounding was followed by solution casting to form polymer blend nanocomposites. Solution cast films were subjected to thermal treatments at three different temperatures. ATR-FTIR results revealed the specific interaction between PVDF and graphene surface and also increasing the percentage of gamma-phase on the surface with rising the annealing temperature. SEM photographs of the top surface of casted films showed visible phase fluctuations with increasing the annealing temperature especially for 70: 30 which is induced by graphene sheets in the mixture of PVDF/PMMA. Also, presence of fiber pull-out in the fractured surface of 70: 30 was related to the increase in cohesive interface due to existence of PMMA. TGA analysis exposed the improvement in thermal stability of PVDF portion of the mixture due to preferentially adsorption of PVDF chains onto the graphene surface during of the heating. Decreasing in Yong's modulus was observed with addition of PMMA but presence of strong GNPs retrieve this negative effect and increases the tensile modulus. The melt-rheological studies illustrated the high interaction between PVDF, PMMA, GNPs and different status of dispersion in three different samples. As well, measuring MFI showed that PMMA caused to decline in melt flow of the polymer blend while the addition of graphene compensate it to some extent revealed lubrication effect of GNPs.