Graphite reinforced silane crosslinked high density polyethylene: The effect of filler loading on the thermal and mechanical properties

Abstract

Crosslinked polyethylene is a promising polymer regarding its mechanical properties and wear resistance, predominantly used in pipework systems. However, it suffers from low thermal conductivity, which limits its application in geothermal heating/cooling systems. In this work, crosslinked high‐density polyethylene (PEX) composites with spherical graphite (SG) as a reinforcing filler are examined in terms of their thermal and mechanical properties. Thermal conductivity measurements showed a significant improvement of the thermal conductivity of PEX with increasing filler content (40.6% augmentation for 5 wt% SG content), while the experimental data are in good agreement with the Chauhan theoretical model for spherical particles. Tensile tests revealed that the elastic modulus of PEX/SG composites presented a considerable improvement (23.6% augmentation for 5 wt% SG content). Various micromechanical models for the prediction of the composites' elastic behavior were applied to the experimental data, which present a satisfactory agreement with the Takayanagi I two‐phase model for low concentrations of SG, and the Takayanagi II two‐phase model for higher filler content.

Physico–mechanical properties of poly(ethylene‐co‐vinyl acetate)/acrylonitrile‐butadiene rubber/multi‐walled carbon nanotubes nanocomposites

“…T m is the melting temperature, S i is a measure of nucleation rate and it can be found by obtaining the slope of the linear part of the exotherm at high‐temperature side, X c is the degree of crystallinity and L c is the lamella thickness. [ 43 ] The value of L c was determined using the well‐known Thomson–Gibbs equation; [ 44,45 ] where is the equilibrium melting temperature of polyethylene (PE) and taken as 145.1°C, [ 46 ] is the density of completely crystalline PE and considered to be 1000 kg/m 3 , is the fold surface energy of PE (9.3 × 10 −2 J/m 2 ) [ 47 ] and is as defined earlier. The table shows that T onset slightly increases with the addition of the CNTs and even for the nanocomposite containing 7 wt% MWCNTs, it remains still higher than those of EVA and the blend.…”

“…T m is the melting temperature, S i is a measure of nucleation rate and it can be found by obtaining the slope of the linear part of the exotherm at high-temperature side, X c is the degree of crystallinity and L c is the lamella thickness. [43] The value of L c was determined using the well-known Thomson-Gibbs equation; [44,45]…”

On the Improved Mechanical Properties of Ball-Milled GNPs Reinforced Short Chain Branched-Polyethylene Nanocomposite: Micromechanical Modeling and Fractography Study

“…The Einstein model is also commonly used on the elastic moduli experimental data of nanocomposites [22]:…”

“…Many efforts have been made to predict the nanocomposites' tensile behavior using micromechanical models [21][22][23][24][25][26][27]. This has become a difficult task due to the nanocomposites' peculiar behavior, depending on the matrix's structure, filler's dispersion, as already stated, the particles' aspect ratio, the filler-filler and filler-matrix interactions etc.…”

Thermal Properties of Graphene Nanoplatelets Reinforced Crosslinked and Short Chain Branched Polyethylenes for Geothermal Pipe Applications

“…PEX presents improved properties regarding thermal degradation and chemical resistance and mechanical properties due to the crosslinks forming a three‐dimensional network structure. [ 1 ] PE‐RT has a characteristic molecular chain structure, where hexene or octene co‐monomers are introduced in the backbone of the polymeric chain, forming tie chains through the polymer's volume. This molecular structure contributes to improve processability and long‐term hydrostatic strength at higher temperatures without crosslinking.…”