Microstructure and properties of poly(butylene terephthalate)/poly(ethylene terephthalate) composites based on carbon nanotubes/graphene nanoplatelets hybrid filler systems

Abstract

This work describes the preparation of poly(butylene terephthalate) (PBT)/poly(ethylene terephthalate) (PET) composites using carbon nanotubes (CNTs)/graphene nanoplatelets (GNPs) hybrid fillers by melt blending process. The effects of CNTs/GNPs hybrid fillers on the thermal conductivity, electrical conductivity, electromagnetic interference shielding effectiveness (EMI SE) and mechanical properties of composites with varying CNTs/GNPs weight ratios were investigated. Scanning electron microscopy showed that the CNTs/GNPs hybrid fillers had better dispersion in PBT/PET matrix, they could effectively cooperate to build filler network structure. The excellent synergistic effects of hybrid fillers could significantly improve the mechanical properties and thermal conductivity. When adding 2 phr CNTs and 8 phr GNPs simultaneously, the thermal conductivity reached 0.84 W m−1 K−1 and Young's modulus was 1.2‐fold compared with PBT/PET blends. In addition, all hybrid composites with higher CNTs/GNPs weight ratios showed better electrical conductivity and EMI SE. The measurement of EMI SE and study of shielding mechanism indicated that absorption loss was the main mechanism for the attenuation of incident electromagnetic waves in hybrid composites over X‐band frequency.

Conductive Plastics from Al Platelets in a PBT-PET Polyester Blend Having Co-Continuous Morphology

“…Gao et al [ 15 ] combined a hybrid filler of 10 phr of graphene + CNTs with a 70/30 PBT/PET blend. They cited an electrical conductivity of 9.61 × 10 −12 S/m for their 70/30 PBT/PET (resistivity of 1.04 × 10 11 Ω/m) but with 10 phr of CNTs, the electrical conductivity increased to 3.03 × 10 −3 S/m (resistivity of 3.3 × 10 −4 Ω/m); this put it into the EMI shielding range.…”

“…The values range from about 10 −5 S/m (ESD range) to 3.89 × 10 2 S/m (EMI shielding range), depending on filler content and processing methods. To get a perspective on where our Al-PBT-PET fits, Table 3 shows a selection of materials that span the five ranges of electrical conductivities [ 15 , 27 , 28 , 29 ].…”

“…They used a lower magnification and, according to us, the co-continuous structure cannot be seen as the phase domains are small in size ( Figure 14 b). Gao et al [ 15 ], who used a 70/30 PBT/PET blend with hybrid graphene + CNT fillers, stated that there was no observable phase separation of the polymers and they concluded there was ‘good compatibility’ between the PET and PBT.…”

“…Where an Al platelet protrudes (arrow in Figure 15 a), it is coated with polymer. This can be contrasted with Al platelets in a PP matrix [ 37 ] or graphene in PBT/PET [ 15 ], where platelets are pulled out and show no polymer coating. The bold arrow in Figure 15 a indicates polymer covering a platelet, indicating the adhesion between the particles and the blend is good.…”

“…Gao et al [ 15 ] combined both concepts, where a hybrid filler (up to 10 parts per hundred (phr) of graphene + CNTs) was placed in a polymer blend of 70/30 PBT/PET. However, there was a reduction in mechanical properties (the notched Izod impact was about 30–50% lower) compared to the unfilled blend.…”