A thermoplastic composite sheet may be composed of a polymer material matrix and a lightweight material that is disposed throughout the polymer material matrix. The polymer material matrix may extend continuously throughout a length, width, and thickness of the thermoplastic composite sheet. The polymer material matrix may be a fully polymerized thermoplastic material. The lightweight material may be fully saturated by the thermoplastic material of the polymer material matrix. The thermoplastic composite sheet may include between 50 and 99 weight percent of the thermoplastic material and between 1 and 50 weight percent of the lightweight material. The thermoplastic composite sheet may be free of reinforcing fibers.

Methods for forming vascular components include providing a composite sacrificial body comprising a first sacrificial material having an outer surface and a second sacrificial material applied to at least a portion of the outer surface, molding a solid substrate around the composite sacrificial body, removing the first sacrificial material by deflagration such that at least a portion of the second sacrificial material remains in the same orientation relative to the substrate as originally molded, and subsequently removing the second sacrificial material by a non-deflagration process to form a vascular component. The second sacrificial material can include a phase change material, a syntactic foam including hollow beads bound together with a polymeric binder or a sintered aggregation of hollow beads, a polymeric foam, a water-soluble resin, or an aerogel. The non-deflagration process can include mechanical pulverization, contacting the second sacrificial material with a solvent or chemical etching agent.

Methods for forming vascular components include providing a composite sacrificial body comprising a first sacrificial material having an outer surface and a second sacrificial material applied to at least a portion of the outer surface, molding a solid substrate around the composite sacrificial body, removing the first sacrificial material by deflagration such that at least a portion of the second sacrificial material remains in the same orientation relative to the substrate as originally molded, and subsequently removing the second sacrificial material by a non-deflagration process to form a vascular component. The second sacrificial material can include a phase change material, a syntactic foam including hollow beads bound together with a polymeric binder or a sintered aggregation of hollow beads, a polymeric foam, a water-soluble resin, or an aerogel. The non-deflagration process can include mechanical pulverization, contacting the second sacrificial material with a solvent or chemical etching agent.

A thermoplastic composite sheet may be composed of a polymer material matrix and a lightweight material that is disposed throughout the polymer material matrix. The polymer material matrix may extend continuously throughout a length, width, and thickness of the thermoplastic composite sheet. The polymer material matrix may be a fully polymerized thermoplastic material. The lightweight material may be fully saturated by the thermoplastic material of the polymer material matrix. The thermoplastic composite sheet may include between 50 and 99 weight percent of the thermoplastic material and between 1 and 50 weight percent of the lightweight material. The thermoplastic composite sheet may be free of reinforcing fibers.

A reduced vibration structure comprises honeycomb and a vibration damping coating on at least a portion of the internal surface of at least a portion of the cells of the honeycomb. The vibration damping coating is formed by curing a coating composition comprising acrylic polymer or copolymer emulsion and a vibration damping filler. The structure can include an adhesive coupled to both the upper surface and the lower surface of the honeycomb and two pieces of sheathing coupled to the adhesive, one on the upper surface and one on the lower surface of the honeycomb.

A reduced vibration structure comprises honeycomb and a vibration damping coating on at least a portion of the internal surface of at least a portion of the cells of the honeycomb. The vibration damping coating is formed by curing a coating composition comprising acrylic polymer or copolymer emulsion and a vibration damping filler. The structure can include an adhesive coupled to both the upper surface and the lower surface of the honeycomb and two pieces of sheathing coupled to the adhesive, one on the upper surface and one on the lower surface of the honeycomb.

A method of extruding filament comprises the steps of cutting a bulk source material into pieces having size S.sub.1, performing a first extrusion pass comprising the steps of melting the pieces in an extruding device at a temperature T.sub.1 and extruding a first filament at an extrusion speed V.sub.1, and performing at least one additional extrusion pass k comprising the steps of cutting the first filament into pieces having size S.sub.k, melting the pieces in an extruding device at temperature T.sub.k, and extruding a final filament at an extrusion speed V.sub.k. A system for extruding filament is also described.

An ink formulation for additive manufacturing of low density syntactic foams is described. The ink formulation can include a thermoset resin, a curing agent suitable for use with the thermoset resin, a plurality of hollow spheres, such as glass microballoons, one or more solvents, and one or more non-hollow, viscosity modifying filler. Also described are a method of preparing the ink formulation, a method of preparing three-dimensional objects comprising low density syntactic foams, and the three-dimensional objects prepared thereby.

Low-density thermoplastic expandable microspheres are disclosed. Various low-density structures, in particular, sandwich panels, based on foam prepared from the low-density microspheres, are also disclosed. Process of preparing low-density polymeric microspheres, per se, and the corresponding low-density structures, based on the microsphere foam, are also disclosed.

Low-density thermoplastic expandable microspheres are disclosed. Various low-density structures, in particular, sandwich panels, based on foam prepared from the low-density microspheres, are also disclosed. Process of preparing low-density polymeric microspheres, per se, and the corresponding low-density structures, based on the microsphere foam, are also disclosed.