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In order to solve the safety problems that exist in traditional charging technology, a new visible light-curing 3D printing platform and energetic slurry formula were designed. Within them, the formula of light-curing slurry is 60.46% EA/PUA (prepolymer), 37.21% PETA/HDDA/BA (active diluent monomer), 0.47% CQ (visible light initiator), 0.93% DMT (curing accelerator), and 0.93% additive. The curing time of visible light-curing paste is 7.5 s, the viscosity is 22 6 mPa·s, the curing hardness is 2 H, the gel rate is 96.67%, the shrinkage rate is 98.35%, and the curing depth is 9.41 mm. The optimal formulation of energetic slurry is 20% visible light-curing slurry, 57.72% AP, 15.28% Al and 7% RDX. The 3D printing energetic powder column has a smooth surface, uniform filler distribution, a flat surface, no protrusions or other defects, and good matching. The average burning rate is 1.165 mm·s−1, the combustion is stable, and the maximum burning light intensity is 2.053 cd.

Resin content of composites is a dominant factor of macroscopic properties and essential to study. Taking carbon fiber/poly (ether ether ketone) (CF/PEEK) composites molded by various means as examples, a method for resin content calculation obtained along with thermogravimetric analysis (TGA) for thermal properties analyzation was introduced. According to results of resin mass contents, TGA curves and differential thermogravimetric analysis (DTG) curves were divided to four stages, including non-decomposition stage of 25–500 °C, rapid decomposition stage of 500–600 °C, transitional stage of 600–700 °C and the stable stage of 700–800 °C. And resin contents were accurate obtained from the transitional stage and stable stage. Results tested by acid digestion method, ignition loss method and TGA methods were compared and it was proved that the TGA method was suitable for resin fraction calculation with a slight difference below 3% compared to results from the other two methods. By comparing results of different composites, we found that TGA methods can also be applied to other composites including reinforcements not disintegrate such as graphite, carbon nanotubes and matrix of thermosetting and thermoplastic decompose under inert gas in testing condition.

In order to further improve the luminous intensity of illuminating flares, the technique of 3D printing of the combustible shell of the illuminating flare using DLP light-curing was proposed, and the combustion spectrum of the combustible shell was made consistent with the combustion spectrum of the illuminating agent. A combustible illuminating candle shell slurry formulation was designed, with light-curing resin, magnesium powder, and sodium nitrate as the main components, and was printed and molded by DLP light-curing 3D printing technology to test its luminescence properties, mechanical properties, compatibility, and moisture absorption. The results show that the optimal formulation mass fraction of energy-containing slurry for the 3D printing of the combustible lighting candle shell is 50% for light-curing resin, 41% for sodium nitrate (NaNO3), and 9% for magnesium powder (Mg). The mechanical properties of the shell are good, with tensile strength up to 9.82 MPa and compressive strength of 102.86 MPa, and the compatibility of the components of the formulation is good, with stable combustion, and can provide 4.73% of light intensity for the lighting candle.

In order to solve the problems of the complicated forming process, poor adaptability, low safety, and high cost of special-shaped energetic grains, light-curing 3D printing technology was applied to the forming field of energetic grains, and the feasibility of 3D printing (additive manufacturing) complex special-shaped energetic grains was explored. A photocurable resin was developed. A demonstration formula of a 3D printing energetic slurry composed of 41 wt% ultra-fine ammonium perchlorate (AP), 11 wt% modified aluminum (Al), and 48 wt% photocurable resin was fabricated. The special-shaped energetic grains were successfully 3D printed based on light-curing 3D printing technology. The optimal printing parameters were obtained. The microstructure, density, thermal decomposition, combustion performance, and mechanical properties of the printed grain were characterized. The microstructure of the grain shows that the surface of the grain is smooth, the internal structure is dense, and there are no defects. The average density is 1.606 g·cm−3, and the grain has good uniformity and stability. The thermal decomposition of the grain shows that it can be divided into three stages: endothermic, exothermic, and secondary exothermic, and the Al of the grain has a significant catalytic effect on the thermal decomposition of AP. The combustion performance of the grain shows that a uniform flame with a one-way jet is produced, and the average burning rate is 5.11 mm·s−1. The peak pressure of the sample is 45.917 KPa, and the pressurization rate is 94.874 KPa·s−1. The analysis of the mechanical properties shows that the compressive strength is 9.83 MPa and the tensile strength is 8.78 MPa.

Shear thickening fluid (STF), carbon nanotubes (CNTs) are both promising in body protection and anti-impact for the drastic viscosity change of STF and the extremely high tensile strength and elongation of CNTs. The excellent performance of the above two combined with traditional Kevlar fabrics can significantly improve the mechanical properties and reduce the number of layers used for body protection. This work reports a new method to prepare STF/CNTs/Kevlar with excellent tensile properties and anti-impact performance by spraying method with 1 wt% polyvinyl alcohol (PVA) solution as a binder for better integration between CNTs and Kevlar. Surface morphology changes in the preparation process indicate the combined structure of PVA binder, CNTs, and STF, presenting a uniform macroscopic and nonuniform microscopic surface of STF/CNTs/Kevlar composite. The tensile strength and anti-impact properties including punch residual velocity and energy absorbed were studied and results for STF/CNTs/Kevlar composite are 669.8 ± 18.1 MPa, 1.602 ± 0.045 m/s, and 21.683 ± 1.182 J in 12 ms, increased by 46.4%, 23.0%, and 240.2%, respectively, compared with neat Kevlar, owing to the improved tight bonding and friction between fabrics yarns caused by PVA adhesive and tangled CNTs, accompanied with the enhanced viscosity of STF under forces. Highlights • Composites were made by spraying PVA, CNTs, and STF onto Kevlar fabrics; • The tensile strength of the composite was 46.4% higher than Kevlar; • The energy absorbed in 12 ms in anti-impact tests was improved by 240.2%; • Tight bonding and friction between yarns are reasons to improve properties; • The raised viscosity of STF under forces is useful for mechanical properties. [ABSTRACT FROM AUTHOR]