Relationship between the structure and thermal properties of polypropylene/graphene nanoplatelets composites for different platelet-sizes

Abstract

Polypropylene (PP) nanocomposites reinforced with different types of graphene nanoplatelets (GNPs) and their hybrid systems are prepared via melt extrusion. On the basis of experimental analysis and simulation, the factors of thermal property of the PP/GNPs nanocomposites, including GNPs size, weight filling ratio and proportion of various sizes, are systematically investigated. At high GNPs content (9,12 wt %), GNPs are widely distributed in PP matrix and the thermal paths are basically formed. The thermal conductivity of composites is determined by the size and thermal properties of GNPs. At low GNPs content (6 wt %), for single system, the larger diameter with moderate distribution would be more conducive to achieve the higher thermal conductivity, indicating the formation of thermal paths dramatically affects the thermal conductivity. For hybrid system, the PP filled with medium and small diameter GNPs obtains the highest thermal conductivity at the ratio of medium diameter GNPs to small diameter GNPs is 8:2, and is 23.8% higher than the single system of PP filled with small diameter GNPs. More precisely, the small diameter GNPs plays a role in connecting the scattered medium diameter GNPs, as mass thermal paths are formed. This shows that the distribution state by combining the synergistic effect of various GNPs significantly affects the thermal conductivity of PP/GNPs nanocomposites. Moreover, a numerical simulation dealing with the synergistic effect of different GNPs, is developed on the thermal conductivity of GNPs-reinforced PP matrix. The heat flux images demonstrate the existence of synergistic effect between different type of GNPs.

Extrusion of Polymer Nanocomposites with Graphene and Graphene Derivative Nanofillers: An Overview of Recent Developments

“…The effect of graphene nanoplatelets (GnP) size on PP nanocomposites processed by twin-screw extrusion and injection molding has been studied [51] to find that smaller size nanofillers are the most effective in improving tensile strength and thermal stabilities, due to their lower tendency to agglomeration. These findings agree with computational studies [63]. On the other hand, large size nanofillers reduce the percolation threshold and increase electrical conductivity [52].…”

Mechanical properties of in situ modified graphene nanosheets‐reinforced polypropylene

“…The addition of only 0.2 wt% graphene increased the thermal conductivity by approximately 29.5%, attributed to the graphene network formed in the composite, which provides a lowimpedance path for phonon motion. [33,34] The high thickness ratio of graphene, large contact area, and strong interfacial bonding with PP contribute to the heat transfer of PP/graphene composites. [35] The existence of graphene flakes improves the crystallization properties of PP to some extent and limits the movement or relaxation of polymer chains.…”

Graphene/graphene nanoplatelets reinforced polyamide nanocomposites: A review

“…GNPs can upgrade the thermal properties of the polymer matrix. [96][97][98][99] GNPs have a thermal conductivity up to *3000W/mK 88 at room temperature. The low content of GNPs can improve the thermal conductivity of PAs.…”