Dynamic mechanical analysis for assessment of carbon fillers in glass fiber epoxy composites

The effect of incorporation of micron sized aluminum trihydrate, multi-walled carbon nanotubes, and graphene nano platelets into glass fiber reinforced epoxy matrix is investigated using dynamic mechanical analysis. The objective of the investigation was to develop polymer central core of high temperature low sag transmission conductor. The effect of individual and hybrid carbon fillers on the viscoelastic properties of the epoxy composites is investigated and discussed. The storage modulus of the glass reinforced epoxy increases by 20% at room temperature due to incorporation of carbon nanofillers. In glass transition region, the increase is higher between 40% and 60% and it varies up to 90% in the rubbery region. Key attributes of carbon filler addition are limited enhancement of storage modulus at room temperature, higher enhancement over glassy, glass transition, and rubbery regions. The carbon fillers extend the temperature range of the glassy region. The cross-link density, filler efficiency, and degree of entanglement of fibers are estimated to understand the implications of the carbon fillers on the viscoelastic properties. The loss modulus peak of glass epoxy composite increases from 2800 to 3900 MPa with carbon fillers and the increase in glass transition temperature is 47?. Incorporation of carbon fillers leads to increase of damping factor peak from 0.2 to 0.28. Cole-Cole plots have established the inherent heterogeneity of epoxy systems due to the presence of carbon fillers. Prediction models for storage modulus and damping factor have been proposed to highlight the influence of geometry and size of carbon filler.