Abstract: A process for increasing the solvent resistance of calendered paper consisting of poly(p-phenylene terephthalamide) short fibers and poly(m-phenylene isophthalamide) fibrids and the dimensional stability of laminates made therefrom.

Abstract: The present invention relates to an apparatus and a process for a half-cell structure to make a hexagonal-cell honeycomb core. The structure has a plurality of peaks and valleys and a diagonal surface between each consecutive peak and valley. The apparatus comprises a stack holder for stacking the structure so that as one sheet is placed on top of a stack comprising at least one sheet, the peaks of one sheet contact the peaks of an adjacent sheet. The apparatus also comprises an air blower disposed beneath the top of the stack for reducing the air pressure surrounding the stack to a pressure below the air pressure on the top of the stack, thereby pressing the layers together to form the core. The present invention also relates to a transfer head and a process for holding a half-cell structure.

Abstract: The present invention relates to an apparatus and a process for a half-cell structure to make a hexagonal-cell honeycomb core. The structure has a plurality of peaks and valleys and a diagonal surface between each consecutive peak and valley. The apparatus comprises a stack holder for stacking the structure so that as one sheet is placed on top of a stack comprising at least one sheet, the peaks of one sheet contact the peaks of an adjacent sheet. The apparatus also comprises an air blower disposed beneath the top of the stack for reducing the air pressure surrounding the stack to a pressure below the air pressure on the top of the stack, thereby pressing the layers together to form the core.

Abstract: Dimensionally stable resin impregnated laminates for printed wiring board applications are reinforced with from 43 to 57 weight percent of nonwoven aramid sheet having a coefficient of thermal expansion of less than 10 ppm per .degree. C, a basis weight of from 0.8 to 4.0 oz/yd.sup.2, a density of from 0.5 to 1.0 g/cc and a Gurley Hill Porosity of less than 10 sec.

Abstract: The present invention relates to an apparatus and a process for applying at least one adhesive component to a honeycomb half-cell structure. The half-cell structure has a plurality of peaks and valleys on each side thereof and a diagonal surface between each consecutive peak and valley. The apparatus comprises a first and second back-up roll and a first and second gravure roll. The first and second gravure rolls are disposed in a bath of a first adhesive component and a second adhesive component, respectively. Each of the first and second back-up rolls includes a plurality of spaced bars. The peaks of the half-cell structure face away from the bars of each respective back-up roll, and the peaks on the other side of the half-cell structure contact each respective first and second gravure roll, so that the first adhesive component contacts the peaks on the one side and the second adhesive component contacts the peaks to apply the first and second adhesive components to the half-cell structure.

Abstract: Papers with improved tensile strength and increased porosity are obtained by heat treatment of calendered sheets of poly(p-phenylene terephthalamide) short fibers and poly(m-phenylene isophthalamide) fibrids.

Abstract: A laminated fabric suitable for use in protective clothing is disclosed in which a layer of activated charcoal cloth is adhered to a layer of woven reinforcing fabric. The layer of reinforcing fabric has a weight less than about 100 g/m.sup.2 and contains sufficient high modulus aramid fiber to impart to the reinforcing fabric a tensile strength greater than about 44 newton/cm at an elongation of 3.5%.

Abstract: An improved heavy-weight, nonapertured, nonwoven fabric of hydraulically entangled synthetic organic staple fibers has a unit weight of 200 to 850 g/m.sup.2 [6 to 25 oz/yd.sup.2 ], a strip tensile strength of at least 0.26 (N/cm)/(g/m.sup.2) [5 (lb/in)/(oz/yd.sup.2)] and a resistance to disentanglement of at least 50 alternate extension cycles. The fabric is much stronger than such prior art heavy-weight nonwoven fabrics of hydraulically entangled staple fibers.

Abstract: Improved liquid-barrier properties are provided to spunlaced fabrics of woodpulp and synthetic organic fibers by employing closely spaced jets in a hydraulic entanglement treatment of the fibers. Additional improvement in barrier properties is provided by a finishing step which employs multiple passes under low pressure, closely spaced jets.

Abstract: The tensile strength of nonwoven fabric made by traversing a fibrous web on an apertured support with fine columnar streams of liquid is increased when the fine columnar streams are divided up into an array of a plurality of rows of streams, instead of a single row, with the streams in each row being staggered from one another and the rows being spaced 10 to 80 mils apart.

Abstract: The tensile strength of apertured nonwoven fabric can be increased by a change in the two-stage process of impinging fine columnar streams of liquid, first onto one face of a fibrous web and then onto the opposite face thereof, the change being that the asymmetrical woven wire screen on which the web is positioned during the second stage of the process is oriented with the wire forming the higher knuckle in the screen running in the direction of passage of the web beneath the fine columnar streams, with the area weight of the web being from 0.5 to 2.0 oz/yd.sup.2.