1wileyonlinelibrary.com an extremely high graphene loading is required. For example, the fi rst graphene based EMI shielding composite exhibited an EMI SE of ≈21 dB with a graphene loading of 15 wt%. [ 5 ] Ling et al. reduced the graphene loading of a polyetherimide/ graphene composite to 10 wt%, while keeping EMI SE at 20.0 dB. [ 6 ] On the other hand, an improved EMI SE, 29.3 dB, of graphene/polystyrene (PS) composite was obtained at the cost of extremely high graphene loading of 30 wt%. [ 7 ] Graphene or reduced graphene oxide (rGO) composites based on poly (methyl methacrylate), [ 8 ] water-borne polyurethane, [ 9 ] phenolic [ 10 ] were also reported in published papers, nevertheless, satisfactory EMI SE always requires abundant nanofi llers due to the homogenous dispersion structure of these composites. High nanofi ller concentrations result in high production costs and poor composite processability. Preparing CPC materials with superior EMI SE at low nanofi ller loading remains a challenge.The formation of segregated architectures can reduce the electrical percolation threshold, and improve electrical conductivity. [11][12][13][14][15] In such architectures, electrical nanofi llers are distributed only at the interfaces of polymer granules not homogeneously distributed in the whole volume of the polymer matrix. Graphene was fi rst utilized to construct segregated conductive networks in ultrahigh molecular weight polyethylene (UHMWPE) matrix, exhibiting an electrical conductivity of 0.04 S m −1 at a rather low content of 0.6 vol%. 12] A comparative study of segregated and homogeneous graphene/polycarbonate composites showed that the percolation threshold of the former composite was one third of that for the latter, and electrical conductivity was also higher by 220% at the same graphene loading of 4 wt%. [ 13 ] Segregated architectures also provide enhanced EMI SE, for example, when Cu nanowires were used as an electrical nanofi ller in PS, the segregated composites exhibited EMI SE levels of 26 and 42 dB at 10 and 13 wt% Cu loading, respectively. [ 15 ] Very recently, our group reported an in situ thermally reduced graphene/ultrahigh molecular weight polyethylene composite with a segregated structure, revealing the EMI SE of 28.3-32.4 dB at an ultralow graphene loading. [ 16 ] Although the formation of such segregated architectures could improve electrical and EMI shielding performance, one major issue of segregated architectures is that the existence of nanofi ller agglomerates at polymer granule interfaces restricts molecular diffusion between granules, leading to poor Ding-Xiang Yan , Huan Pang , Bo Li , Robert Vajtai , Ling Xu , Peng-Gang Ren , Jian-Hua Wang , and Zhong-Ming Li * A high-performance electromagnetic interference shielding composite based on reduced graphene oxide (rGO) and polystyrene (PS) is realized via highpressure solid-phase compression molding. Superior shielding effectiveness of 45.1 dB, the highest value among rGO based polymer composite, is achieved with only 3.47 vol% rGO lo...

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The comparative study of rigid polyurethane foam (RPUF) nanocomposites based on graphene nanosheets (GNSs) and carbon nanotubes (CNTs) has been reported. A GNS content of 0.3 wt% in polyol turns to be optimal for its foamability with the isocyanate component, as verified by rheology measurements. Scanning electron microscopy and transmission electron microscopy observations reveal a homogeneous dispersion of GNSs and CNTs in the RPUF nanocomposites. Only 0.3 wt% loading of GNSs and CNTs led to 36% and 25% improvement respectively in the compressive modulus of the RPUF nanocomposites. Meanwhile, 16 °C and 14 °C improvements in the glass transition temperature confirm the important role of both the nanofillers in the heat resistance of RPUF nanocomposites. These results additionally indicate that GNSs work more effectively than CNTs in mechanical property and heat resistance enhancement of the RPUF nanocomposites. The superiority of GNSs over CNTs can be attributed to their wrinkled surface structure, unique two‐dimensional geometrical morphology and higher specific surface area, which results in stronger interaction and restriction of segmental motion at the interface between the GNSs and the RPUF matrix. In addition, changes in the thermal conductivity of the nanocomposites are negligible, indicating that incorporation of GNSs and CNTs will not hinder the application of RPUF nanocomposites as thermal insulators. On the contrary, the enhancement in mechanical properties and heat resistance will undoubtedly expand the application range of polyurethane foam materials. Copyright © 2012 Society of Chemical Industry

Polylactide (PLA) films with an excellent balance of toughness and stiffness were realized by extensional stress efficiently. For the relatively low extensional stress, gauche− gauche conformers that originated from the oriented amorphous chains lead to super-toughening behavior. Among higher extensional stress, strain-induced orientation and crystallization act as the driving force of reinforcement. This mechanism is evidenced by the pronounced enhancement in the elongation at break from 16.9 up to 294.9% accompanying the variation yield strength from 45.3 up to 135.5 MPa. The highest elongation at break results from the early stretching stages, whereas the highest yield strength is obtained from a high draw ratio. More impressively, PLA films show temperature-invariant super-ductility and reinforcement at low temperatures (0 and −20 °C). This work provides a preferable and scalable method to fabricate competitive PLA materials, expanding the practical application of sustainable polymers served at a wide temperature range or in harsh environments.