Crystallization behavior of polypropylene/graphene nanoplatelets composites

Abstract

Interest in graphite fillers has grown since the separation of graphene from graphite by micromechanical cleavage. The object of the article is to understand the influence of graphene nanoplatelets (GNPs) with different sizes on the crystallization behavior of a polyolefin matrix such as polypropylene (PP), after elaboration by melt mixing and compression molding. Composites with volume fractions of graphene nanoplatelets ranging from 0.3 to 2 vol% were prepared. The particle dispersion states in the composites were characterized at different scales using Scanning and Transmission Electron Microscopies (SEM and TEM). Polypropylene crystallization and orientation were investigated using optical microscopy, Differential Scanning Calorimetry (DSC) and X‐ray diffraction. This article discusses the strong acceleration of crystallization kinetics because of the presence of GNPs. The micrometric flake‐shaped GNPs act as nucleating agent and induce an epitaxial growth of alpha (α) crystalline phase of PP. The nucleating effect is related to the surface of the particles available for heterogeneous nucleation. Radial spherulitic growths are observed from the smallest micrometric particles. The coarsest GNPs, easily oriented by flow, favor PP transcrystallinity, in such a way that (010) plane of PP is parallel to (001) plane of graphene nanoplatelets.

Melt-Mixed 3D Hierarchical Graphene/Polypropylene Nanocomposites with Low Electrical Percolation Threshold

“…Instead, relatively large amounts of γ phase are obtained as visible from the [117] γ peak in Figure 9. Most of these findings are in agreement with the results by Beuguel et al [65], who showed epitaxial growth of crystals from graphene nanoplatelets. This is also shown in the SEM micrograph of Figure 8b, and in particular transcristallinity from the oriented agglomerates, however no γ phase was observed in that work.…”

“…130 °C, as typical of the best nucleating agents commercially available [63]. This behavior has been reported in the past for a number of fillers including clay, nanotubes and graphitic platelets [35,55,64], and most recently by Beuguel et al [65]. The crystallization temperature, taken as a proxy for nucleation efficiency, increases with increasing filler loading.…”

Development of waste tire‐derived graphene reinforced polypropylene nanocomposites with controlled polymer grade, crystallization and mechanical characteristics via melt‐mixing

“…12 A similar trend of increase in the crystallization onset temperature was also reported in the literature. [24][25][26][27] In addition, a higher increase in crystallization onset temperature for nanocomposites based on Homo-PP compared to Copo-PP means that the Homo-PP structure is more prone to crystallization than Copo-PP. In addition, considering the crystallization enthalpy, ΔH c showed a higher crystallinity level of Homo-PP in comparison with Copo-PP as anticipated from their molecular structures.…”

Tailoring Multifunctional and Lightweight Hierarchical Hybrid Graphene Nanoplatelet and Glass Fiber Composites

“…Furthermore, the GnP c -axis would merge with the PP b -axis in such a way that the (002) GnP plane is matched with the (010) α PP planes, specifically the (040) α and (060) α planes. The effect of the reinforcements to induce epitaxial growth is quantified by considering the ratio of (040) α and (110) α intensities (i.e., I (040) α / I (110) α ). ,, For instance, I (040) α / I (110) α increases to 7.92 and 3.18 for PPGnP0.5 and PPGnP0.5GF10, respectively, relative to Neat PP (1.28). However, for the GF-reinforced biphasic counterpart (i.e., PPGF10), this ratio is equal to 1.25, indicating that GF has no effect on epitaxial growth of PP.…”