The present disclosure provides a die assembly for producing a microcapillary film. The die assembly includes a first die plate, a second die plate, a plurality of multi-jackbolt tensioners connecting the first die plate to the second die plate, a manifold, and a plurality of nozzles. The manifold is located between the pair of die plates and defines a plurality of film channels therebetween. The plurality of film channels converge into an elongate outlet, wherein a thermoplastic material is extrudable through the plurality of film channels and the elongate outlet to form a microcapillary film. The plurality of nozzles are located between the plurality of film channels. The plurality of nozzles are operatively connected to a source of channel fluid for emitting the channel fluid between layers of the microcapillary film, whereby a plurality of microcapillary channels are formed in the microcapillary film.