Effect of molecular structure and rheology on the compression foam molding of ethylene-α-olefin copolymers

Foam 3D Printing of Thermoplastics: A Symbiosis of Additive Manufacturing and Foaming Technology

Due to their light-weight and cost-effectiveness, cellular thermoplastic foams are considered as important engineering materials. On the other hand, additive manufacturing or 3D printing is one of the emerging and fastest growing manufacturing technologies due to its advantages such as design freedom and tool-less production. Nowadays, 3D printing of polymer compounds is mostly limited to manufacturing of solid parts. In this context, a merged foaming and printing technology can introduce a great alternative for the currently used foam manufacturing technologies such as foam injection molding. This perspective review article tackles the attempts taken toward initiating this novel technology to simultaneously foam and print thermoplastics. After explaining the basics of polymer foaming and additive manufacturing, this article classifies different attempts that have been made toward generating foamed printed structures while highlighting their challenges. These attempts are clustered into 1) architected porous structures, 2) syntactic foaming, 3) post-foaming of printed parts, and eventually 4) printing of blowing agents saturated filaments. Among these, the latest approach is the most practical route although it has not been thoroughly studied yet. A filament free approach that can be introduced as a potential strategy to unlock the difficulties to produce printed foam structures is also proposed.

A Single-Use Microthruster Concept for Small Satellite Attitude Control in Formation-Flying Applications

In recent years, the maturation of small satellite technology has led to their adoption for a variety of space missions. The next generation of small satellite missions, however, will likely have the satellites operating in formations or “constellations” to perform missions that are not currently possible. A key enabling technology for constellation-based missions is a miniaturized propulsion system that is capable of delivering the extremely low impulse levels required for maintaining precise relative position and orientation. Existing propulsion solutions for this regime suffer from compromises on power, safety, and cost that have limited their adoption. In this work, we describe a new, low-power micropropulsion concept based on the thermal decomposition of an inert chemical blowing agent (CBA) as the propellant. A meso-scale prototype device is designed, fabricated, and tested. The experimental results indicate that this concept, when appropriately scaled, is capable of providing thrust levels (∼1 μ N) and impulse-bits (∼0.1 μ N·s) that are commensurate with the intended application.