A method of molding a tubular laminate comprising joining flows of a plurality of thermoplasticized resins together to prepare a laminated composite flow having two side edges, and then passing the composite flow having two side edges through an annular extrusion die to abut both side edges of the respective layers to each other in the die, thereby forming an integrated tubular flow.

Multilayer coextruded piezoelectric/pyroelectric elements and method for manufacturing these elements are disclosed. The layer configuration of the element permits easy application of conductive material to two separate faces and thus prevents short-circuiting.

An all-polymeric ultraviolet light reflective film which is lower in cost than previously used reflector materials, is weather resistant, and which does not absorb significant amounts of solar ultraviolet energy is provided. The film includes a sufficient number of alternating layers of at least first and second diverse polymeric materials which have an average percent transmission of greater than about 50% between wavelengths of 300-400 nm. A substantial majority of the individual layers of the film have optical thicknesses in the range where the sum of the optical thicknesses in a repeating unit of the polymeric materials is between about 0.15 .mu.m to about 0.228 .mu.m, and the first and second polymeric materials differ from each other in refractive index by at least about 0.03 in the wavelength range of from about 300-400 nm. The reflective film is useful as a reflective material in solar detoxification systems, as a protective material in indoor and outdoor lighting systems, as a UV mirror in the fields of medical imaging, astronomical telescopes, and microscopy or in chemical reactions using UV radiation.

An extrusion die for the extrusion of a multilayer thermoplastic foil or plate in which a stack of die plates is provided and each plate has an inlet fitting on a respective side of the rectangular outline of the die connected to a respective extruder and a broadening channel opening at an outlet along another edge of the respective plate. The outlets are located on the same side of the stack and open into a common die lip from which the multilayer extrusion emerges at an elongated slit for the broad-mouth die. The broadening channels of the upper and lower plates are sickle shaped and extend inwardly from the respective inlets mirror-symmetrically to receive a median plane along which the inlet of the broadening channel of the central plate is provided.

Method and apparatus for generating interfacial surfaces in a fluid mass which: (a) divide a first stream of the fluid mass into a plurality of branch streams, redirect or reposition the branch streams, expand and contract the branch streams in a symmetrical fashion, and recombine the branch streams to form a second stream of the fluid mass; or (b) divide a first stream of the fluid mass into a plurality of branch streams, redirect or reposition the branch streams, recombine the branch streams to form a second stream of the fluid mass, and expand and contract the second stream in a symmetrical fashion.