Enhanced Mechanical Properties Of Multi-layer Graphene/polymer Composites

Graphene materials are prominent fillers with typical 2D carbon atom planar structure,exhibiting excellent mechanical strength,extraordinary physical properties,good dispersion and compatibility with polymer matrix.In that case,combining graphene with polymer matrix has been an effective method for obtaining high performance composite materials.It is worth mentioning that the mechanical properties of composite materials is a key factor limiting practical application of graphene/polymer composites.In this work,we chose two kinds of the most widely used polymers which are poly(vinyl chloride)(PVC)and epoxy as matrix.We used multi-layer graphene(MLG)as reinforcing fillers and investigated enhanced mechanical properties of graphene/polymer composites.We prepared MLG filled PVC composites by using conventional melt-mixing methods.We found that a small amount of MLG loadings(0.36 wt.%)could greatly increase impact toughness of the MLG/PVC composites,which is mainly attributed to high flexibility and crumpled morphology of the MLG;the MLG plays an important role of soft elastomers in increasing strain at break and fracture toughness of the MLG/PVC composites.Furthermore,we also investigated the mechanical properties of MLG/PVC composite films.By taking full advantages of the large size and high integrity of the MLG,we found that a small amount of MLG loading can greatly increase the mechanical strength of the MLG/PVC composites.The tensile modulus of the 0.96 wt.%MLG/PVC composites is up to 40 MPa,increasing by 31.3%than that of neat PVC.Such significant mechanical reinforcement is mainly attributed to uniform dispersion of the large-size MLG,good compatibility and strong interactions between MLG and plasticizers and PVC.In order to obtain remarkable mechanical reinforcement of MLG/PVC composites with uniform MLG dispersion,we synthesized MLG/PVC blended resins by using in-situ polymerization method,and thereafter we prepared MLG/PVC composites through conventional melt-mixing technique.We found that a small amount of MLG loading(only 0.3 wt%)could greatly increase the tensile strength,tensile modulus and impact toughness of MLG/PVC composites,which is mainly attributed to the intrinsic high-strength of the used MLG,uniform MLG-dispersion throughout matrix,strong MLG-PVC interaction,and good MLG-PVC compatibility.In order to obtain uniform dispersion graphene throughout polymer matrix,we used 3D graphene/nickel foams as reinforcing materials and prepared graphene/Ni/epoxy composites by using resin transfer molding technique.Mechanical properties of the graphene/Ni/epoxy composites were investigated in details.We founded that the graphene-coated Ni foams exhibited higher compressive modulus and damping properties than the Ni foams,which is mainly attributed to strong interfacial bonding,confinement effect,and rich interfaces.On the other hand,we found that the graphene/Ni/epoxy composites exhibited higher storage modulus than the neat epoxy,the presence of graphene could greatly increase viscoelastic damping properties of the graphene/Ni/epoxy composites due to rich interface and interfacial sliding of the nanocomposties.Therefore,high-performance graphene/polymer composites can be obtained through structural design and optimal parameters,and they have great potential to be used in many fields.