Effect of steady shear deformation on electrically conductive PP/PS/MWCNT composites

This study investigates the evolution of morphology and electrical properties of polypropylene (PP)/polystyrene (PS) blend nanocomposites under controlled steady shear flow. These nanocomposites contain either few-layer graphene (FLG) or a mixture of FLG and multi-walled carbon nanotubes (MWCNT), prepared via a conventional melt-mixing. Composites were created by premixing FLG or FLG/MWCNT with either PP [PP/PS/FLG or PP/PS/(FLG+MWCNT)] or PS [PS/PP/FLG or PS/PP/(FLG+MWCNT)] at a PP/PS ratio inducing co-continuous morphology. Results showed a significant reduction in the percolation threshold (PT) for PS/PP/FLG composites, with an 81% decrease compared to PS/FLG. When FLG was premixed with PS, PT required only 2 wt. % FLG, compared to 5.9 wt. % in PP/PS/FLG. Steady shear deformation disrupted the electrical network in both PP/PS/FLG and PS/PP/FLG composites. However, the PS/PP/FLG composites exhibited greater stability in electrical conductivity at lower FLG concentrations (above 3 wt. %) compared to the PP/PS/FLG composites (above 6 wt. %). The applied shear did not affect the co-continuous morphology of the blend-based composites containing 1 wt. % or more of FLG. Additionally, the synergistic effects of the hybrid FLG/MWCNT mixture on the electrical conductivity and rheological properties of both PP/PS/(FLG+MWCNT) and PS/PP/(FLG+MWCNT) composites were evaluated. The incorporation of MWCNT into both PP/PS/FLG and PS/PP/FLG composites significantly enhanced the formation of a hybrid electrical network structure, leading to a further reduction in the percolation threshold concentration of FLG. Specifically, in PP/PS/FLG composites, PT decreased from 5.9 to 1–3 wt. % of FLG, while in PS/PP/FLG composites, PT dropped from 2 to 1 wt. % of FLG.

show abstract

Quantifying electron transport in aggregated colloidal suspensions in the strong flow regime

Hipp,

Ramos,

Liu

et al. 2024

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Electron transport in complex fluids, biology, and soft matter is a valuable characteristic in processes ranging from redox reactions to electrochemical energy storage. These processes often employ conductor–insulator composites in which electron transport properties are fundamentally linked to the microstructure and dynamics of the conductive phase. While microstructure and dynamics are well recognized as key determinants of the electrical properties, a unified description of their effect has yet to be determined, especially under flowing conditions. In this work, the conductivity and shear viscosity are measured for conductive colloidal suspensions to build a unified description by exploiting both recent quantification of the effect of flow-induced dynamics on electron transport and well-established relationships between electrical properties, microstructure, and flow. These model suspensions consist of conductive carbon black (CB) particles dispersed in fluids of varying viscosities and dielectric constants. In a stable, well-characterized shear rate regime where all suspensions undergo self-similar agglomerate breakup, competing relationships between conductivity and shear rate were observed. To account for the role of variable agglomerate size, equivalent microstructural states were identified using a dimensionless fluid Mason number, Mn f , which allowed for isolation of the role of dynamics on the flow-induced electron transport rate. At equivalent microstructural states, shear-enhanced particle–particle collisions are found to dominate the electron transport rate. This work rationalizes seemingly contradictory experimental observations in literature concerning the shear-dependent electrical properties of CB suspensions and can be extended to other flowing composite systems.

show abstract

Effect of steady shear deformation on electrically conductive PP/PS/MWCNT composites

Cited by 4 publications

References 81 publications

Recyclability of Carbon Nanomaterials-Based Conductive Polymer Composites

Recyclability of Carbon Nanomaterials-Based Conductive Polymer Composites

Evolution of morphology and electrical properties under controlled flow in polypropylene/polystyrene co-continuous blends containing interfacially localized carbonaceous nanoparticles

Quantifying electron transport in aggregated colloidal suspensions in the strong flow regime

Contact Info

Product

Resources

About