Dynamic Mechanical and Thermal Properties of Phenylethynyl‐Terminated Polyimide Composites Reinforced With Expanded Graphite Nanoplatelets

Abstract

Summary: This article reports on the dynamic mechanical and thermal properties of thermosetting phenylethynyl‐terminated polyimide (PETI‐5) composites reinforced with expanded graphite (EG) nanoplatelets having various average particle sizes and content. The EG nanoplatelets with varying particle sizes were prepared by different pulverization techniques through intercalation and exfoliation of natural graphite flakes. The effect of the EG particle size and concentration of the thermal behavior of PETI‐5/EG composites was investigated with several thermal analysis methods (DMA, TMA, and DSC). The storage modulus dynamic mechanical properties and glass transition temperature significantly increased with increasing concentration of EG nanoreinforcements regardless of size. The coefficient of thermal expansion significantly decreased, especially in the glass transition region. magnified image

Graphitic nanofillers in PMMA nanocomposites—An investigation of particle size and dispersion and their influence on nanocomposite properties

“…Review of the nanocomposite literature provides many similar instances in which modulus changes but T g does not or the direction or relative magnitude of the changes are not the same 35,48,51,67,68 . However, it is also fair to say that this discrepancy has not yet been well studied and is still a subject of debate.…”

“…4,20,[25][26][27] While these clay nanocomposites can exhibit improved thermal and diffusion barrier properties, increased electrical conductivity cannot be achieved. In this respect, graphite is a more attractive alternative to clay due to its moderately high electrical conductivity, in addition to its substantially higher in-plane elastic modu- 18 Epoxy/EG Solution 0-9 N/A 5 1E-03 Xiao et al 22 PS/EG In-situ þ roll mill 0-61 N/A 2.5 6E-02 Li et al 30 GNP/epoxy Solution sonicate 2h 2 À16 N/A sonicate 8h 2 13 Chen et al 31 PS/EG In-situ 0-5 N/A 1.8 2E-06 Du et al 32 POBDS/GNP In-situ 0-15 81 c (15 wt %) 4 2E-02 Weng et al 33 Nylon 6/FG In-situ 0-3.5 N/A 1.5 a 1E-04 Chen et al 34 PS/GNP In-situ 0-16 N/A 1.5 1E-06 PS/UG 0-16 6 8E-05 Cho et al 35 PETI/EG In-situ 1 26 N/A 3 3 3 5 3 9 10 42 Chen et al 14 PMMA/GNP In-situ 0-6 N/A 0.5 3E-05 PMMA/UG 3 3E-05 Chen et al 36 PVC/PMMA/EG In-situ 0-10 N/A 3.5 2E-05 Weng et al 37 Nylon 6/FG In-situ 0-3.5 N/A 1.2 a 1E-05 Chen et al 38 PMMA/EG d In-situ 0-5 N/A 3.0 1E-02 Du et al 39 PANI/GNP In-situ 0-6 N/A 2 33 Yasmin et al 40 Epoxy Table 1. Graphite consists of stacked graphene sheets that are regularly spaced 0.335 nm apart and held together by van der Waals forces.…”

“…Cho et al 35 reported an increase in storage modulus with increased loading fraction of EG in phenylethynyl-terminated polyimide (PETI-5) as well as an increase in T g for 1-5 wt % loading. Notably, T g was reported to decrease at 10 wt % loading, and this result was attributed to poor dispersion at this high loading.…”

Graphite Nanosheet Exfoliation From Graphite Flakes Through Functionalization Using Phthalic Acid

“…Furthermore, the graphite lamellae or layers are bond through Van der Waals forces, which act along the common c-axis, and there happens to be a lot of interest currently in obtaining graphite nanosheets through exfoliation by overcoming these Van der Waals forces in graphite. Graphite nanosheets find several applications owing to their excellent electrical, mechanical, and thermal properties [3][4][5][6][7][8][9][10]. Aditionally, they are relatively inexpensive compared to carbon nanotubes and other carbon materials depending on the cost-effectiveness of their respective fabrication method/s [3,[13][14][15].…”

Effect of exfoliated graphite nanoplatelets on the fracture surface morphology and the electrical resistivity of phenylethynyl-terminated polyimide

“…Graphite nanoplatelets can be obtained from expandable graphite, which is composed of natural graphite flake intercalated with acids, by appropriate thermal or microwave processing. During the processing, expandable graphite can be expanded up to hundreds of times over its pristine graphene sheets at the nano-scale level along the c axis of graphene layers [1][2][3]. Recently, graphite or graphene nanoplatelets have attracted considerable attention in academia and a large number of papers have dealt with this material [4][5][6][7][8].…”