A graded-index optical element may include a nanovoided material including a first surface and a second surface opposite the first surface. The nanovoided material may be transparent between the first surface and the second surface. Additionally, the nanovoided material may have a predefined change in effective refractive index in at least one axis due to a change in at least one of nanovoid size or nanovoid distribution along the at least one axis. Various other elements, devices, systems, materials, and methods are also disclosed.

This disclosure relates to an article that includes a nonwoven substrate, a first film supported by the nonwoven substrate, and a second film such that the first film is between the nonwoven substrate and the second film. The first film includes a first polymer and a pore-forming filler. The difference between a surface energy of the first film and a surface energy of the nonwoven substrate is at most about 10 mN/m. The second film includes a second polymer capable of absorbing and desorbing moisture and providing a barrier to aqueous fluids.

A multilayer film having Machine Direction Orientation (MDO) is prepared by first co-extruding a multilayer film, then stretching the multilayer film in the machine direction at a temperature lower than the melting point of the polyethylene resin that is used to prepare the film. At least one layer of the film is a first polyethylene composition having a density of from about 0.94 to about 0.97 g/cc and at least one second layer is prepared from a polyethylene composition having a lower density than the first polyethylene composition. This disclosure enables the manufacture of films having outstanding barrier properties (low Water Vapor Transmission Rate, WVTR, and low Oxygen Transmission Rate, OTR) and good physical properties.

The invention relates to a process for the production of a high strength transparent high density polyethylene article comprising the steps of (i) heating a high density polyethylene (HDPE) to a temperature above the melting temperature (T.sub.m) of the HDPE; (ii) molding the heated HDPE obtained in step (i) to form a hot molded HDPE article; (iii) cooling the hot molded HDPE article to a temperature below T.sub.m to form a melt-crystallized HDPE article; (iv) stretching the melt-crystallized HDPE article to a total draw ratio of at least 5 comprising at least one stretching step of the article at a temperature T.sub.1 below the melting temperature T.sub.m to a draw ratio (DR.sub.1) of at least 2 to form an oriented HDPE article, wherein the HDPE has a melt flow index (MFI) measured at 21.6 kg and 190° C. according to ASTM D1238 of at most 1.5 g/I Omin, an isotropic density measured according to ISO 1 183-1 A of at most 0.955 g/cm3 and a T.sub.m measured according to ISO 1 1357-3 of greater than 130° C. The invention also relates to high strength transparent HDPE articles and products comprising the high strength transparent HDPE article such as ballistic resistant articles, visors, car parts, train parts, plane parts, windshields, windows and radomes.

A nanovoided polymer-based material may include a bulk polymer material defining a plurality of nanovoids and an interfacial film disposed at an interface between each of the plurality of nanovoids and the bulk polymer material. The interfacial film may include one or more layers of material. A method of forming a nanovoided polymer-based material may include (1) forming a bulk polymer material defining a plurality of nanovoids and (2) forming an interfacial film at an interface between each of the plurality of nanovoids and the bulk polymer material. Various other methods, systems, and materials are also disclosed.

A semi-aromatic polyamide film having a thermal shrinkage factor in the longitudinal direction of the film, S.sub.MD, of −1.0 to 1.5% and a thermal shrinkage factor in the width direction of the film, S.sub.TD, of −1.0 to 1.5% as measured under the conditions of 250° C. and 5 min, a tensile breaking elongation of 70% or more in the longitudinal direction and the width direction, and a haze of 14% or less.

The present disclosure is directed to a film formulation that resulted in a substantially non-migratory cold seal release film with improved blocking resistance. Specifically, the multilayered biaxially oriented polypropylene film can include a core layer of polypropylene homopolymer; a first outer layer on one side of the core layer that can be suitable for sealing, printing, or coating; and a second outer layer on the opposite side of the core layer that is a blocking resistant layer comprising thermoplastic polymers which reduce blocking tendency.

In some examples, a method includes forming a material layer on a substrate, partially polymerizing a component of the material layer, to form fluid-filled droplets within a partially polymerized matrix, deforming the material layer to form anisotropic fluid-filled droplets, and further polymerizing the partially polymerized matrix to form an anisotropic voided polymer, including anisotropic voids in a polymer matrix. The anisotropic voids may include anisotropic nanovoids. Example methods may further include depositing electrodes on the anisotropic voided polymer so that at least a portion of the anisotropic voided polymer is located between the electrodes. Examples may include forming electroactive elements including an anisotropic nanovoided polymer, and devices (such as sensors and/or actuators) including electroactive elements.

In some examples, a method includes forming a material layer on a substrate, partially polymerizing a component of the material layer, to form fluid-filled droplets within a partially polymerized matrix, deforming the material layer to form anisotropic fluid-filled droplets, and further polymerizing the partially polymerized matrix to form an anisotropic voided polymer, including anisotropic voids in a polymer matrix. The anisotropic voids may include anisotropic nanovoids. Example methods may further include depositing electrodes on the anisotropic voided polymer so that at least a portion of the anisotropic voided polymer is located between the electrodes. Examples may include forming electroactive elements including an anisotropic nanovoided polymer, and devices (such as sensors and/or actuators) including electroactive elements.

In some examples, a device includes a multilayer structure, a first electrode, and a second electrode, where the multilayer structure is located at least in part between the first electrode and the second electrode, and the multilayer structure includes a nanovoided polymer layer, and a solid layer. The solid layer may include a non-nanovoided layer. The nanovoided polymer layer may be an electroactive layer. The device may further include a control circuit configured to apply an electrical potential between the first electrode and the second electrode, which may induce a mechanical deformation of the multilayer.