Traditional tubular structures with multilayer annular structures (MAS) are limited in the number of layers; as a result of fewer layers, the layers are typically thick, rigid, and unsuitable for many tubular applications. An advanced technique to produce MAS with layer numbers up to 2048 and individual layer thickness remaining low to a few micrometers is successfully designed here. Planar multilayers with high layer numbers were first produced via a flat-die layer multiplication coextrusion, followed by being shaped into an annular structure by using a custom-made annular die that is designed with the aid of numerical simulation. Experimental verifications show that the microlayer pipes with layer numbers up to 2048 and uniform thickness on the circumference can be readily produced by using this advanced technique. Therefore, this work may provide a valuable solution to develop the processes and equipment for tubes with microlayer structures.

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Nanolayer films are monolithic films including 30−1000 periodic alternating layers, each layer having a thickness of 20−5000 nm. Owing to the superlattice multilayer configuration, nanolayer films usually show outstanding mechanical, barrier, and optical properties and thus have broad application prospects in the film industry. This work develops a nanolayer blown technology by combining a blown die and layer multiplication concepts, which can produce blown films with 1000+ layers and thickness below 10 μm. In detail, planar nanolayers were first produced via a flat-die layer multiplication coextrusion, wrapped into annular profiles by using a well-designed custom-made blown die, and then were blown up into the bubble to obtain the nanolayer films. Experimental verifications show that nanolayer films with 1000+ layers can be easily fabricated by using this technique. Consequently, this effort may be a breakthrough in blown film technology and thus provides some positive effects on the film industry.