Factors affecting thermal conductivities of the polymers and polymer composites: A review

Polymers for additive manufacturing and 4D-printing: Materials, methodologies, and biomedical applications

As biodegradable thermoplastics are more and more penetrating the market of filaments for fused deposition modeling (FDM) 3D printing, fillers in the form of natural fibers are convenient: They have the clear advantage of reducing cost, yet retaining the filament biodegradability characteristics. In plastics that are processed through standard techniques (e.g., extrusion or injection molding), natural fibers have a mild reinforcing function, improving stiffness and strength, it is thus interesting to evaluate whether the same holds true also in the case of FDM produced components. The results analyzed in this review show that the mechanical properties of the most common materials, i.e., acrylonitrile-butadiene-styrene (ABS) and PLA, do not benefit from biofillers, while other less widely used polymers, such as the polyolefins, are found to become more performant. Much research has been devoted to studying the effect of additive formulation and processing parameters on the mechanical properties of biofilled 3D printed specimens. The results look promising due to the relevant number of articles published in this field in the last few years. This notwithstanding, not all aspects have been explored and more could potentially be obtained through modifications of the usual FDM techniques and the devices that have been used so far.

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FDM 3D Printing of Polymers Containing Natural Fillers: A Review of their Mechanical Properties

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

Advances in 3D printing of thermoplastic polymer composites and nanocomposites

High through-plane thermal conductivity of polymer based product with vertical alignment of graphite flakes achieved via 3D printing

Three‐dimensional printing of poly(lactic acid) bio‐based composites with sugarcane bagasse fiber: Effect of printing orientation on tensile performance

Preparation of a new filament based on polyamide-6 for three-dimensional printing

Enhanced through‐plane thermal conductivity of polyamide 6 composites with vertical alignment of boron nitride achieved by fused deposition modeling

Based on the rapid development of three-dimensional (3D) printing, the fabrication of the 3D printed products which can change their shapes over time has been termed as four-dimensional (4D) printing. Since the functionality is generally limited by available materials, especially for fused deposition modeling (FDM, a trendy technology of 3D printing), it has aroused widespread requirements to develop a novel filament with excellent properties and functionalities. In this study, polypropylene/nylon 6 (PP/PA6) alloy was fabricated as a candidate for FDM and maleic anhydride-grafted poly(ethylene–octene) (POE-g-MAH) was used as a modifying agent as well as a compatibilizer. The results showed that the PP/PA6 alloy with 30 wt% of PA6 on the basis of the certain mass ratio of PP and POE-g-MAH (1.5:1) exhibited a high dimensional stability and appropriate mechanical properties in FDM. In addition, the possibility of PP/PA6 alloy as a shape memory polymer blend and the mechanism of shape memory effect (SME) were investigated. The 3D printed product with 30 wt% of PA6 fabricated by the infill orientation of 45°/− 45° and 100% infill density exhibited a great SME with the deformation temperature (Td) of 175 °C. This simple method for preparation of a novel filament with shape memory performance based on PP/PA6 alloy has a vast potential for the development of 4D printing technology.

Xiaodong Peng

Papers

High through-plane thermal conductivity of polymer based product with vertical alignment of graphite flakes achieved via 3D printing

Three‐dimensional printing of poly(lactic acid) bio‐based composites with sugarcane bagasse fiber: Effect of printing orientation on tensile performance

Preparation of a new filament based on polyamide-6 for three-dimensional printing

Enhanced through‐plane thermal conductivity of polyamide 6 composites with vertical alignment of boron nitride achieved by fused deposition modeling

Shape memory effect of three-dimensional printed products based on polypropylene/nylon 6 alloy