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Continuous carbon fiber reinforced polymer composites (CFRPCs) exhibiting superior mechanical properties have emerged as high-performance engineering materials for various industrial applications. Additive manufacturing (AM) of CFRPCs enables production of customized structures with superior mechanical properties at a low cost and has gained tremendous popularity. In the present study, a novel AM technique namely laser-assisted laminated object manufacturing (LA-LOM) is proposed for producing CFRPCs using prepreg sheets with continuous carbon fiber reinforcement. The interfacial properties of the bonded prepreg sheets are critical for the performance of the additively manufactured CFRPCs. We further introduce graphene as a modifier between the prepreg sheets to improve the mechanical properties of the CFRPCs. It is shown that low porosity (0.38%), high concentrations of continuous carbon fibers (63 wt. %), and improved interfacial bonding strength contribute to excellent mechanical properties. For the composite structure ([0 ]s fiber arrangements), in which 0.5 mg/ml graphene is introduced as interface modifier, the lap shear strength, tensile strength, and tensile modulus are 18 MPa, 2940 MPa, and 170 GPa, respectively, and the flexural strength and modulus are 1310 MPa and 140 GPa, respectively.The tensile strength and modulus outperform all AM-produced structures reported in literature, including carbon fiber composites and metals and metal alloys. Meanwhile, the increases are observed in the lap shear strength by 25%, flexural strength by 10%, and flexural modulus by 27%, as well as tensile strength by 7% and modulus by 6%, compared to specimens without graphene reinforcement. This composite architecture design, involving laminated continuous carbon fiber reinforced prepreg sheets and graphene-modified interfaces, provides a readily scalable manufacturing method toward excellent properties and this method can be further explored in industrial applications.

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Electrostatic adsorption is an important complement to the mechanical filtration for high-efficiency air filtering. However, the electrostatic charge decays with time, especially in humid conditions. In this work, a self-charging air filter is presented to capture airborne particles in an efficient and long-lasting manner without the need of external power sources. Leveraging the triboelectric effect between the electrospun poly(vinylidene fluoride) nanofiber film and nylon fabric, the self-charging air filter-based mask excited by breathing can continuously replenish electrostatic charges. As a result, its effective lifespan is up to 60 hours (including 30 hours of wearing), with a minimum filtration efficiency of 95.8% for 0.3-μm particles. The filtration efficiency and lifespan are significantly higher than those of a commercial surgical mask. Furthermore, we uncover the quantitative relation between filtration efficiency and surface electrostatic potential. This work provides an effective strategy to significantly prolong the electrostatic adsorption efficacy for high-performance air-filtering masks.

Additive manufacturing (AM) of continuous fiber-reinforced thermoplastic composites (CFRTPCs) has drawn increasing interest and great attention in academic and industrial communities due to its capability of manufacturing complex lightweight structures with high strength at a low cost. In this study, we proposed a novel AM technique to fabricate CFRTPCs using carbon fiber prepreg sheets based on a novel method: ultrasonic-assisted laminated object manufacturing (UA-LOM). The prepreg sheets were first cut into 2D shapes, then every eight layers of the sheets were successively consolidated by an ultrasonic-vibration roller to fabricate one 3D composite part at a faster speed than conventional AM processes where materials are deposited layer by layer. Samples with controlled fiber alignments were prepared for mechanical tests. The post-processing hot press was carried out to further improve mechanical properties of the additively manufactured components. Results showed that the unidirectional composite samples displayed an ultra-high tensile strength of 1760.2 (±71.7) MPa and a tensile modulus of 105.7 (±7.2) GPa. The proposed method exhibited superior mechanical performance compared to state-of-theart AM techniques. The hot-press-treated AM composite parts in this work approached the benchmark mechanical properties provided by the prepreg manufacturing company using traditional fabrication methods. Overall, the proposed AM methods of CFRTPCs show great potential applications in aerospace and transportation industries.

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