Consumable filaments having reversible reinforcement for extrusion-based additive manufacturing

A method of building a three-dimensional part with an additive manufacturing system, the method comprising:

• providing a supply of feedstock material to a liquefier of the additive manufacturing system wherein the feedstock material comprises at least 50% by weight an elastomer and up to 50% by weight a reinforcing additive wherein the feedstock material has a flexural modulus greater than about 300 megaPascals (MPa);
• heating the feedstock material in the liquefier and extruding the molten feedstock material through a nozzle provided in an outlet of the liquefier;
• depositing the molten feedstock material in a layer by layer manner to build the three-dimensional part;
• and
• chemically treating the three-dimensional part to dissolve or weaken at least a portion of the reinforcing additive such that the flexural modulus of the three-dimensional part is less than the flexural modulus of the feedstock material.