Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

Throughout the world there have been alarming concerns over the use of nonrenewable resources during manufacturing of goods and associated environmental legislations. Therefore, the use of natural materials and fabrication of composites therefrom, particularly, development of natural fiber reinforced polymer composites is gaining significant attention. Although natural fiber reinforced composites (NFRCs) show strong application prospects, various materials and processing related challenges needs to be addressed to achieve long-term stability and performance. In this review, we attempted to provide an overview of different types of natural fibers, their characteristics and properties enabling them to be used as reinforcing agents in different polymers. Then the unique requirement of fiber surface modification to achieve enhanced fiber-matrix bonding is discussed. The article also discusses conventional processing routes and critical issues associated with NFRCs processing. The use of different additive manufacturing (AM) technologies in processing polymer composites is also discussed. At the end, we have critically analyzed the challenges and opportunities associated with AM of NFRCs.

Additive manufacturing of natural fiber reinforced polymer composites: Processing and prospects

Graphene presents an extremely ultra-high thermal conductivity, well above other known thermally conductive fillers. However, graphene tends to aggregate easily due to its strong intermolecular π–π...

Reduced Graphene Oxide Heterostructured Silver Nanoparticles Significantly Enhanced Thermal Conductivities in Hot-Pressed Electrospun Polyimide Nanocomposites.

As a material possessing extremely high thermal conductivity, graphene has been considered as the ultimate filler for fabrication of highly thermally conductive polymer composites. In the past decade, graphene and its derivatives were demonstrated in many studies to be very effective in enhancing the thermal conductivity of various polymers. This paper reviews current progress in the development of graphene/polymer composites with high thermal conductivity. We began with the effects of isotopes, defects/doping, edges and substrate, polycrystallinity, functionalization, size and layer number, and folding/twisting on the thermal conductivity of graphene. We then modelled the thermal conductivity of graphene/polymer composites and, through molecular dynamics (MD) simulations, demonstrated its dependence on interfacial thermal conductance as well as size, dispersion and volume fraction of graphene. After a critique of recent studies on thermally conductive graphene/polymer composites and their potential applications, we identified several outstanding issues, new challenges and opportunities for future endeavours.

Thermal conductivity of graphene-based polymer nanocomposites

The burgeoning development of wearable electronic devices has resulted in urgent demands for electromagnetic interference (EMI) shielding films that feature excellent fireproof and heat dissipation...

Multifunctional MXene-Based Fireproof Electromagnetic Shielding Films with Exceptional Anisotropic Heat Dissipation Capability and Joule Heating Performance.

Ice-templated assembly strategy is an effective method to construct filler networks. The filler networks can be used to increase the thermal conductivity of polymer composites. Herein, silicon carbide nanowires, reduced graphene oxide and cellulose nanofiber were used as assembly units to construct vertically aligned filler networks by ice-templated assembly strategy. Polydimethylsiloxane grafted with poly(ethylene glycol) could enhance the interfacial interaction and improve the wettability between silicone rubber and the filler networks. Silicon carbide/reduced graphene oxide/silicone rubber composites were prepared by infiltrating the filler networks with silicone rubber. The thermal conductivity of the composites increased with increasing the contents of silicon carbide and reduced graphene oxide. The thermal conductivity of the composite with 1.84 vol% filler network was as high as 2.74 W/(m·K), exhibiting significant enhancement of thermal conductivity of 16 times compared with silicone rubber. This work provides an insight for preparing highly thermally conductive silicone rubber composites.

Vertically aligned silicon carbide nanowires/reduced graphene oxide networks for enhancing the thermal conductivity of silicone rubber composites

Thermally conductive silicone rubber composites used for heat removal from electronic devices have attracted great attention. A facile spin-assisted layer-by-layer assembly approach was used to fabricate highly thermally conductive multilayered silicone rubber/graphene films. The films exhibit highly ordered lamellar structure with the high orientation of graphene which provides continuous thermally conductive pathways in horizontal direction. A multilayered film with 40 assembly cycles has the thermal conductivity of 2.03 W/(m·K) in in-plane direction. Moreover, the film can be highly twisted to any angle and has the elongation at break of 325%, which is rarely achieved in previously reported graphene-based multilayered films. Even up to 500 stretch-recovery cycles at 50% strain, the change of the thermal conductivity was negligible, indicating the high durability, excellent flexibility and stretchability of the film. The films with high thermal conductivity and stretchability have potential applications in flexible electronics, wearable devices and electronic skin.

High thermal conductivity and stretchability of layer-by-layer assembled silicone rubber/graphene nanosheets multilayered films

Synergistic enhancement of fillers in the polymer matrix has emerged as a subject of scientific and industrial interest. A hybrid with the silica decorating on GO surface (SiO2@GO) was fabricated by an electrostatic self-assembly method, and its morphology, structure and composition were characterized. GO, silica, silica/GO mixture (SiO2-GO), and SiO2@GO were separately filled in styrene-butadiene rubber (SBR) to obtain composites. SBR/SiO2@GO (100/20) composite exhibited the best performance, and its tensile strength increased by 308% compared with that of SBR. This is due to SiO2@GO was uniformly embedded in the SBR matrix brought by the synergistic dispersion of silica and GO. SiO2@GO acted as the barrier in SBR composites, and increased the temperature at 50% weight loss for SBR/SiO2@GO (100/20) by 13.1 °C compared to SBR. Anchoring silica on GO surface is an effective way to develop various high-performance rubber composite materials with good potential in industrial applications.

Enhanced mechanical and thermal properties of SBR composites by introducing graphene oxide nanosheets decorated with silica particles

The invention relates to a non-black appearance conductive silicon rubber material and a preparation method thereof. The silicon rubber material comprises the following components in parts by weight:100 parts of methyl vinyl silicone rubber, 20-45 parts of white carbon black, 1-5 parts of hydroxyl silicone oil, 2-6 parts of dimethyl diethyoxyl silane, 30-150 parts of conductive packing, 2-15 parts of an anti-electrostatic agent and 1-2 parts of 2,5-dimethyl-2,5-di(tert-butyl peroxide) hexane. The preparation method specifically comprises the following steps: mixing the methyl vinyl silicone rubber, the white carbon black, the hydroxyl silicone oil, the dimethyl diethyoxyl silane, the conductive packing and the anti-electrostatic agent, further uniformly mixing with the 2,5-dimethyl-2,5-di(tert-butyl peroxide) hexane, and performing vulcanization, thereby obtaining the non-black appearance conductive silicon rubber material. Compared with the prior art, the silicon rubber material provided by the invention is relatively high in tension strength, excellent in electric property, excellent in high-temperature resistance and excellent in flame retardancy and has a non-black appearance.

Non-black appearance conductive silicon rubber material and preparation method thereof

The invention relates to an environmental-friendly adhesive for adhering a metal onto rubber and the application of the environmental-friendly adhesive. The environmental-friendly adhesive comprises the following components in parts by weight: 100 parts of alkoxy silicon ended polybutadiene, 1-5 parts of a silane coupling agent, 0.1-0.5 part of a catalyst and 0-400 parts of a diluent. Compared with the prior art, the environmental-friendly adhesive provided by the invention is free of solvents and is environmental-friendly, in addition, effectively bonding of a metal reinforced part with a rubber substrate can be promoted in a reaction cross-linking mode.

Yong Zhang

Papers

Vertically aligned silicon carbide nanowires/reduced graphene oxide networks for enhancing the thermal conductivity of silicone rubber composites

High thermal conductivity and stretchability of layer-by-layer assembled silicone rubber/graphene nanosheets multilayered films

Enhanced mechanical and thermal properties of SBR composites by introducing graphene oxide nanosheets decorated with silica particles

Non-black appearance conductive silicon rubber material and preparation method thereof

Environmental-friendly adhesive for adhering metal onto rubber and application of environmental-friendly adhesive