Graphene nanoplatelets (GNP) filled epoxy composites ranged from 0.2 to 5 vol.% were prepared in this study using simple heat assisted bath sonication for better GNP dispersion and exfoliation. The effects of GNP filler loading via heat assisted bath sonication on the mechanical properties and thermal deformation behaviour were investigated. Improvements on flexural strength and fracture toughness up to 0.4 vol.% filler loading were recorded. Further addition of GNP filler loading shows a deteriorating behaviour on the mechanical properties on the composites. The bulk electrical conductivity of the epoxy composites is greatly improved with the addition of GNP filler loading up to 1 vol.%. The thermal expansion of epoxy composites is reduced with the addition of GNP; however poor thermal stability of the composites is observed.

A new approach of mimicking the selective localization mechanism of conductive filler into one phase of immiscible polymer blend system is proposed here, where a moderate fine of polymethylmethacrylate (PMMA) powder is prepared and used as the spacer in the carbon black (CB) filled epoxy adhesives system that can be applied at room temperature. The main purpose of PMMA‐spacer is to promote the formation of conductive networks via aiding the 3D self‐assembly of CB filler, selectively in the continuous phase of epoxy. PMMA‐spacer content ranged from 10, 20, 30, 40, and 50 vol.% were investigated under electrical, mechanical, and thermal properties for both unfilled and 15 vol.% CB filled system. With the incorporation of 10 vol.% PMMA‐spacer, the filled system shows promising improvement in electrical conductivity, with three order of magnitude increment at 15 vol.% CB loading. Toughening mechanism of epoxy was observed, where crack deflection upon the PMMA‐spacer is observed under scanning electron microscopy characterization and agreed by fracture toughness calculation. Thermal stability and coefficient of thermal expansion were improved at the minimum addition of PMMA‐spacer content, at 10 vol.%, while a small reduction in flexural strength is observed because of the poor interface interaction between the PMMA‐spacer and epoxy matrix. Interestingly, a limited interaction between the PMMA‐spacer with epoxy at the curing temperature of 100°C is observed, indicating the solubility of PMMA‐spacer in epoxy before crosslinking process occurred. Copyright © 2016 John Wiley & Sons, Ltd.

Polymer blend consist of epoxy and polymethylmethacrylate (PMMA) was prepared via two different blending methods. Conventional blending method which required solvent to obtain polymer blend of PMMA and epoxy. However, due to the high consumption of solvent and environmental issue, a new approaching method: direct mixing method was used to prepare the polymer blend without the usage of solvent. The PMMA pellets are grinded and sieved into fine powders and incorporated into epoxy. Comparison between the conventional and new method was done through the investigation based on the morphology and mechanical behaviour, with different PMMA content (0, 10, 20, 30, 40 and 50 vol.%) between two blending methods. In overall, the polymer blend system prepared via direct mixing methods exhibited better mechanical properties as compared to conventional solvent dissolution method. Improvement on fracture toughness was observed in direct mixing method.

Abstract A comparison study between carbon black (CB) filled thermoset (epoxy) and thermoplastic, polymethylmethacrylate (PMMA), was done in this research. CB was introduced as the conductive filler in epoxy and PMMA at different filler loading, which ranged from 5 vol.% to 20 vol.%. The physical, mechanical, electrical and thermal stability properties were investigated. The incorporation of CB into both epoxy and PMMA increased the density, improved the thermal stability and electrical conductivity of the composites, reduced the coefficient of thermal expansion and weakened the flexural and fracture toughness properties of the composites.

A blend system between two different thermoset polymer, epoxy and unsaturated polyester at ratio 80/20 weight percentage (wt. %) with 10, 20, 30 and 40 volume percentage (vol. %) of recycled copper powder as conductive filler was investigated. The conductive polymer blend composites were undergone some characterization and testing which include flexural properties, hardness, thermal stability, electrical properties and scanning electron microscopy (SEM). The flexural strength of the unfilled system decreased as increasing of the recycled copper powder content. With the increase of recycled copper, from 0 vol.% to 40 vol.%, a total 350% of increment in flexural modulus was observed. The thermal stability of the blend polymer increased with the filler loading, from 140°C to 300°C, which was the 5% weight loss onset degradation temperature. The electrical conductivity properties of the blend composite shown the percolation threshold at 30 40 vol.% of recycled copper powder filler content, where the conductive blend composites change from insulator to conductor.