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In this study, graphene nanoplatelet (GNP) fillers were first mixed with a polyvinyl alcohol (PVA) aqueous solution under ultrasonication, and then glycerol was added as a plasticiser to enhance the thermal processability of the PVA/GNP mixture. The interactions among glycerol, GNP and PVA, rheological behaviour, crystallisation behaviour, electrical properties, and mechanical properties of the 3D printed parts were carefully investigated. The results show that the incorporation of glycerol can effectively decrease the melting temperature of PVA, thus improving the thermal FFF processability of the PVA/GNP nanocomposite. Besides, compared with the glycerol modified PVA (mPVA), the electrical conductivity of the mPVA/GNP nanocomposite 3D printed part with only 1.0 wt-% GNP loading could increase by ∼300 times (from 7.8 × 10−7 S m−1 to 2.4 × 10−4 S m−1). The obtained functional mPVA/GNP nanocomposite filaments were successfully used in fabrication of various 3D printed functional parts with complex geometry/structure and good dimensional accuracy.

In order to shield the massive electromagnetic perturbations and meet the more and more stringent requirement for advanced electronic equipment, development of diverse, lightweight and high-performance electromagnetic interference (EMI) shielding materials is urgent but still challenging. Herein, the facile and green method which combines fused deposition modeling (FDM) 3D printing, ball milling and microwave (MW) irradiation technology was proposed to fabricate exfoliated graphene nanoplatelets (GNPs) incorporated liner low density polyethylene (LLDPE) nanocomposite lightweight parts with porous and complex geometry structure. FDM 3D printing possesses high flexibility for structure design, which can significantly broaden the application of materials in various fields. Benefiting from design of a unique porous lamellar structure, the printed LLDPE/GNPs nanocomposite parts can achieve a prominent EMI shielding effectiveness (SE) of ~32.4 dB (with thickness-normalized specific EMI SE (SSE/t) of 318 dB cm2/g) in the range of 8.2–12.4 GHz. This remarkable characteristic is due to internal multiple reflections and absorption of electromagnetic (EM) waves. In addition, the specific FDM 3D-printed porous parts prepared by our strategy exhibit a relatively higher EMI SE at a lower density than those lightweight EMI shields in literatures. The use of MW irradiation technology improves mechanical properties, especially for the interfacial bonding strength between filaments. More importantly, this strategy is highly favorable for the fabrication of lightweight porous EMI shields with tailorable and optimized shape/structure, which could be expected to be applied in aerospace fields, portable electronic devices, smart devices and so on.

With booming development of 5G communications and electronic devices, electromagnetic waves (EMWs) radiation pollution has aroused much concern on public, and great efforts are being made to develop the high-performance electromagnetic interference shielding (EMI SE) materials. However, inherent deficiencies of traditionally processing technology restrain the current materials to fabricate desirable architectures for SE applications. Herein, taking full advantages of 3D printing in free-construction, architected honeycombs featuring lightweight and high-efficient EMI SE are designed with polylactic acid (PLA) as matrix, and graphene nanosheets and carbon nanotubes hybrids (GNs/CNTs) as functional fillers. The optimal printed material shows a high electrical conductivity up to 110.8 S/m and outstanding EMI SE property of 53.5 dB, far exceeding the standard of commercially shielding materials (20 dB). More encouragingly, this work makes a deep insight into the intrinsic connection of porous structure of 3D-printed components on shielding mechanism, which reveals that as the pore size is far less than a certain proportion of incident wavelength (λ/5), the components exhibit a good reconcilability on the lightweight (0.4–1.0 g/cm3) and high-performance EMI SE (35–45 dB). From fundamental materials to desirable components, this breakthrough lays a solid foundation for the free-construction of diversified architectures in EMI SE applications.

β-polypropylene (β-PP) demonstrating both increased toughness and strength was prepared by simultaneously adding montmorillonite (MMT) and a melt-soluble β-nucleating agent (β-NA). The MMT functioned as a “micro-stirrer” to promote the dissolution of β-NAs in the β-PP melt due to an increased shear rate around the existing particles. A subsequent recrystallization on cooling triggered a transition from dot-like to fibrous β-NAs, and leaf-like β-crystals were obtained via epitaxial crystallization on the fibrous β-NAs formed in situ. Accordingly, the strength and toughness of β-PP were enhanced simultaneously, suggesting that MMT improved the toughness of the β-PP. For example, when the MMT fraction was 2%, the β-PP/MMT composite exhibited an increase of 90% in elongation at break and 60% in impact strength in comparison to pure β-PP. This study provides a valuable guide to achieving an outstanding combination of strength and toughness in PP composites by tailoring the morphology of β-NAs, which is also applicable to other β-PP composites.

The prevalent way to enhance interface interaction of immiscible polymer blend is adding some low molecular weight compatibilizers with “soft” nature, unfortunately throwing negative effects on the final mechanical strength. Here, an interfacial interlocking design strategy for immiscible polypropylene (PP)/polyamide (PA) blend is proposed. The formation process involves aryl amide-based compounds firstly were selectively enriched in PA phase, followed by controlled release and recrystallization at the subsequent annealing process, into fiber-like crystals at the interface. Accordingly, the blend featuring mechanical interlocking was successfully prepared, where the interfacial grown fibers functioned as interlocks to integrate the two immiscible components via large interfacial friction. Furthermore, the density and dimension of the interfacial fibers were tailored by adjusting the annealing temperatures. Specially, at the elevated temperature, the large and dense fibers were generated at the interface to offer stronger interfacial friction, which in turn strengthened the interfacial interaction. The interfacial topological regulation can effectively solve the interfacial problems and also can extend broadly to the other immiscible bi-phase systems.

Herein, a novel local enrichment strategy (LES) was proposed to fabricate functional polylactic acid (PLA)/graphene nanoplatelet (GNP) nanocomposites for fused deposition modeling (FDM) three-dimensional (3D) printing by precisely manipulating the selective distribution of fillers. Experimental results showed that the PLA/GNP nanocomposites prepared using the LES method exhibited higher electrical conductivity and electromagnetic interference (EMI) shielding properties than those prepared using the conventional melt-compounding method. Particularly for EMI properties, the shielding efficiency (SE) of an LES sample prepared at 6 and 10 wt % GNPs reached 21.7 and 34.7 dB, respectively, which is an improvement of over 45% compared with the conventional ones. In addition, based on the theoretical analysis of shear field and the experimental verification of filler distribution after printing, a functional 3D printed honeycomb-like part with a porous structure, light weight, and highly efficient EMI shielding properties was successfully fabricated using the FDM 3D printing technology. A new strategy was accordingly established by manipulating the filler distribution to prepare functional filaments and parts for EMI shielding applications in this innovative study.

In this paper, a local enrichment strategy was adopted to prepare carbon nanotube (CNT) enriched polylactic acid (PLA) composite filaments, which were used to fabricate the corresponding conductive 3D-printed parts by fused deposition modeling (FDM) technology. Combined with computer simulation, the carbon nanotubes (CNTs) were found to be successfully kept and supported on the surface of filaments after 3D-printing. With this strategy, the prepared 3D-printed parts showed a remarkably enhanced electrical conductivity, which was approximately eight orders of magnitude higher than that of the conventional 3D-printed parts at the same loading of CNTs. This encouraging result provided a new method for fabricating the high-performance parts through FDM printing, and also opened up new routes for 3D-printing technologies to prepare other advanced binary or multicomponent polymer composites.

Interfacial properties govern effective transfer of load from a polymer matrix to a reinforced fiber, dictating the mechanical performance of the composite. This paper reports a facile and controlled strategy of preparing root-like natural fibers (NFs) in polypropylene (PP), where the two components are integrated via mechanical interlocking provided by the interfacial grown fiber. Specifically, driven by hydrogen bonding between amide groups of the self-assembling molecules (NAs) and abundant hydroxyl groups existing in the NF, the former selectively diffuses and aggregates on the latter and then self-assembles into branched fibers, which can be tailored finely by the annealing temperature and time as well as cooling rate. This study opens up an interfacial manipulation without preliminary surface modification and holds great potential in preparing NF-reinforced polymer composites.

In this paper, the crystalline structures of polypropylene (PP)/montmorillonite (MMT)/β-nucleating agent (TMB-5) composites were investigated at the different heating temperatures. The experimental results showed that MMTs had the negligible effect on the formation of β-PP in the composites, whose morphologies and content were governed by TMB-5 due to its high β-nucleating efficiency and the self-assembling character. However, MMTs amplified the flow strength to promote the dissolution of TMB-5 in the PP melts. As a result, more TMB-5 self-assembled at lower temperature compared to the sample without MMTs. Depended on the solubility related to the temperature and MMTs content, various topological aggregations of TMB-5 were formed to direct the epitaxial crystallization of PP into needle-like and dendritic β-crystals. The special morphological β-crystals combined with the reinforcing MMTs is expected to endow PP product with higher strength and toughness.

Polymer-based thermal conductive composites (PTCs) with both excellent thermal and mechanical properties are highly desirable in the thermal management of modern microelectronic industry. However, the enhancement efficiency for fillers loaded polymer composite is actually lower than the theoretically predicted value. The significant reasons could be due to the restriction of interfacial thermal resistance at filler-polymer matrix interfaces as well as the thermal conductive orientation dependence of anisotropic fillers. In the present study, solid-state shear milling (S3M) strategy and FDM 3D-printing aligning technology were combined to synergistically improve thermal conductivity of linear low-density polyethylene (LLDPE)/graphene nanoplatelet (GNPs) nanocomposites. The fabricated FDM 3D-printed parts exhibit a significantly enhanced through-plane thermal conductivity up to 3.43 W m−1 K−1 along printing direction compared to that of neat LLDPE (0.40 W m−1 K−1) and also that of traditionally melt-compounded LLDPE/GNPs composites (1.98 W m−1 K−1) at the same GNPs loading of 15.0 vol%. The enhanced thermal conductivity is attributed to the long-range aligned bridge-connected network structure of GNPs constructed in the PE matrix along printing direction due to the shear-inducing effect of FDM 3D-printing. Simultaneously, the S3M technology we adopted also reduces the interfacial thermal resistance and thus increases the thermal conductivity of the obtained nanocomposite, which was further demonstrated by the way of theoretical effective medium approximation (EMA) models we applied. The achieved high thermal conductivity and mechanical properties of the FDM 3D-printed LLDPE/GNPs thermal conductive parts suggest promising applications in the heat diffusion of some advanced electronic devices.

In this paper, a local enrichment strategy was adopted to prepare carbon nanotube (CNT) enriched polylactic acid (PLA) composite filaments, which were used to fabricate the corresponding conductive 3D-printed parts by fused deposition modeling (FDM) technology. Combined with computer simulation, the carbon nanotubes (CNTs) were found to be successfully kept and supported on the surface of filaments after 3D-printing. With this strategy, the prepared 3D-printed parts showed a remarkably enhanced electrical conductivity, which was approximately eight orders of magnitude higher than that of the conventional 3D-printed parts at the same loading of CNTs. This encouraging result provided a new method for fabricating the high-performance parts through FDM printing, and also opened up new routes for 3D-printing technologies to prepare other advanced binary or multicomponent polymer composites.

A facile methodology was developed to induce a core-pompon structure in the PA66/iPP system. By controlling the diffusion and self-assembly behavior of β-nucleating agents (NAs), we successfully localized the self-assembly and heterogeneous nucleation of NAs in the near interface region of PA66 spheres. The PA66-core/β-PP-pompon structure exhibited promising and applicable functionalities as toughening components.

How to control the architectures of the 3D printed cellular parts so as to achieve the electromagnetic interference (EMI) shielding protection is a challenging issue. In this paper, by combining FD...