Dramatic Effects of Scalable SNN‐Assisted Melt Dispersion on Thermal Conductivity and Coefficient of Thermal Expansion of Nanocomposites

Abstract

It is demonstrated that SNN‐assisted melt dispersion can lead to a significant improvement of the thermal conductivity of PC/MWCNT composites accompanied by a dramatic reduction in their linear CTE. The thermal conductivity of the SNN‐containing composites after the 2‐step process was about 95% higher than that of neat PC and 25% higher than that from 1‐step processing at same loading. The CTE below the glass‐transition temperature of composites with a 1.0 wt.‐% MWCNT loading is substantially reduced compared to the neat polymer. A reduction in the CTE of up to 60.8% is observed for composites from the 2‐step process. Simultaneous achievement of high thermal conductivity and low CTE is required for electronic packaging in microelectronics for device protection. magnified image

Probing the Role of Poly(3,4-ethylenedioxythiophene)/Poly(styrenesulfonate)-Coated Multiwalled Carbon Nanotubes in the Thermal and Mechanical Properties of Polycarbonate Nanocomposites

“…A considerable number of studies on improving the electrical conductivity − or the thermal conductivity − of nanocomposites has been conducted in the past few years. However, these studies usually use a single parameter optimization strategy (the most common parameter being the concentration of nanoparticles), whereas simultaneously optimizing and tailoring material behaviors for multifunctionality requires a multiparameter framework.…”

Graphite Oxide as a Dehydrative Polymerization Catalyst: A One-Step Synthesis of Carbon-Reinforced Poly(phenylene methylene) Composites

“…However, the incorporation of metastable additives such as graphene is often challenged by their propensity to aggregate and phase separate from the polymer matrix . From a processing perspective, the additive and matrix are typically combined via melt blending, extrusion, or other postpolymerization methods, − or through the in situ polymerization of a monomer in the presence of the carbon additive. , The latter of these approaches is generally more efficient as it minimizes or eliminates the need for extensive processing to ensure homogeneous dispersion of the additive in a preformed polymer. − In situ polymerizations are also preferred when interactions (either covalent or noncovalent) between an additive and its polymer matrix help stabilize the composite or provide enhanced mechanical, thermal, or electronic properties. − However, many of these in situ methods either require modification of the additive to ensure compatibility with the matrix or are not broadly applicable. Thus, simpler and more general in situ polymerization approaches are of high value.…”

An Efficient Quantified Stereological Macrodispersion Analysis Approach for Determining Microscale Influences on Nanocomposite Material Properties

“…This ultrasonication can affect the two‐step nanocomposite in two ways: (1) Due to the low viscosity of the SNN solution, the wetting of the polymer on the CNT may be improved compared to the one‐step composites; and (2) Ultrasonication has the potential to damage or shorten the CNT in addition to peeling them off the agglomerates, improving dispersion with the possibility of negatively affecting the CNT ability to assist with load transfer 3, 19. Interaction is difficult to quantify, but through field‐emission scanning electron microscopy (FESEM), wetting of the CNT can be observed, and similar wetting behavior was observed for all systems 15. Therefore, the only differences between the one‐ and two‐step systems are dispersion and CNT length/quality.…”

“…The purpose of the two different processes was to create different dispersion states within the composites. The two‐step process has shown to yield composites with better dispersion when compared to one‐step melt blended composites 15–17. Composites were produced with both methods at 0.5 and 1.0 wt% CNT in PC for comparison across processes and loadings.…”