A form birefringent optical element includes a structured layer and a dielectric environment disposed over the structured layer. At least one of the structured layer and the dielectric environment includes a nanovoided polymer, the nanovoided polymer having a first refractive index in an unactuated state and a second refractive index different than the first refractive index in an actuated state. Actuation of the nanovoided polymer can be used to reversibly control the form birefringence of the optical element. Various other apparatuses, systems, materials, and methods are also disclosed.

Disclosed is a method of coating fertilizer particles with a coating, the method comprising providing fertilizer particles in a coating unit, one or more steps of applying a coating layer by applying one or more coating components to the fertilizer particles in the coating unit, and at least, partially curing or hardening the coating layer, wherein said curing or hardening involves a chemical reaction of said one or more coating components, discharging the coated fertilizer particles from the coating unit, optionally after a final cure or hardening step, wherein the coating unit comprises a stationary frame and at least two movable elements.

A modified polyamic acid, a preparation method thereof, and a preparation method of a composite film are provided. The modified polyamic acid includes polyamic acid and polyvinylidene fluoride. The modified polyamic acid is formed by introducing polyvinylidene fluoride having good thermal stability, high dielectric constant, excellent piezoelectric, and ferroelectric properties, so the dielectric constant and structural adjustability of the modified polyamic acid are improved.

A free radical curable automotive body primer is provided that has a color change corresponding to the progress of the cure process until a dry to sand condition has been attained and an internal colored guide coat that does not change color given its exposure to ambient air and as a result, has a different color on the surface of the primer than when in bulk, allowing for the detection and removal of low spots or other imperfections from a vehicle body by additional sanding of the inventive primer to remove oxidized guide coat colorant surface regions. The cure color change is achieved through resort to at least one color changing dye that reacts with a free radical cure initiator during the vehicle body priming process and changes color to indicate when the primer composition has achieved a level of cure so as to be dry enough to sand.

Conductive films comprising epoxy materials doped with graphene, and combined with a metal component to form a hybrid conductive surfacing film for use as lightning strike protection surfacing films for composite structures are disclosed, along with their methods of manufacture.

One variation of a method for fabricating a dermal heatsink includes: fabricating a substrate defining an interior surface, an exterior surface opposite the interior surface, and an open network of pores extending between the interior surface and the exterior surface; activating surfaces of the substrate and walls of the open network of pores; applying a coating over the substrate to form a heatsink, the coating comprising a porous, hydrophilic material and defining a void network; removing an excess of the coating from the substrate to clear blockages within the open network of pores by the coating; hydrating the heatsink during a curing period; heating the heatsink during the curing period to increase porosity of the coating applied over surfaces of the substrate; and rinsing the heatsink with an acid to decarbonate the coating along walls of the open network of pores in the substrate.

A modified polyamic acid, a preparation method thereof, and a preparation method of a composite film are provided. The modified polyamic acid includes polyamic acid and polyvinylidene fluoride. The modified polyamic acid is formed by introducing polyvinylidene fluoride having good thermal stability, high dielectric constant, excellent piezoelectric, and ferroelectric properties, so the dielectric constant and structural adjustability of the modified polyamic acid are improved.

Technologies are generally described for hybrid acoustic damping materials that may be used in noise, vibration, and harshness mitigation. In some examples, solvated acrylic, silicone, and/or urethane materials may be blended in selected proportions to form a hybrid acoustic damping material. Characteristics of the components of the hybrid acoustic damping material such as viscosity and proportions may be selected for a desired composite loss factor vs. temperature characteristic of the material. In some examples, a broad temperature range of damping or a targeted temperature region may be achieved based on the composition of the hybrid acoustic damping material. To achieve a uniform stable blend with a consistent viscosity, individual component materials may be selected with similar molecular weight/viscosity. Compatible solvents may be added during blending of the components. In various example applications, the hybrid acoustic damping material may be used in vehicle brake applications to reduce brake noise/vibration.

The disclosure relates to a thermoset omniphobic composition (such as an omniphobic polyurethane or epoxy composition) which includes a thermoset polymer with first, second, and third backbone segments. The first, second, and third backbone segments can correspond to urethane or urea reaction products of polyisocyanate(s), amine-functional omniphobic polymer(s), and polyol(s), respectively, for omniphobic polyurethanes. Similarly, the first, second, and third backbone segments can correspond to urea or beta-hydroxy amine reaction products of polyamine(s), isocyanate-functional omniphobic polymer(s), and polyepoxide(s), respectively, for omniphobic epoxies. The thermoset omniphobic composition has favorable omniphobic properties, for example as characterized by water and/or oil contact and/or sliding angles. The thermoset omniphobic composition further has favorable barrier properties, for example with respect to water vapor and oxygen transmission as well as water absorption. The thermoset omniphobic composition can be used as a coating on any of a variety of substrates to provide omniphobic properties to a surface of the substrate. Such omniphobic coatings can be scratch resistant, ink/paint resistant, and optically clear.

A cure promoter composition is disclosed, including an accelerator which may include a thiocarbamate, a hydrated thiocarbamate, a dithiocarbamate, a thiazole, a mercaptothiazole, a sulfenamide, a thiazolesulfenamide, a metal salt of thiocarbamate, sulfur chloride, or combinations thereof. The cure promoter composition also includes a compatibilizing carrier, one or more organic solvents, a catalyst, an optional reducing agent, an optional reactive silane, an optional reactive organometallic, an optional gelling agent, and an optional aqueous component. A method for applying the cure promoter composition is disclosed, including contacting the organic solvents, the accelerator, the carrier, the reactive silanes, the reactive organometallics, the reducing agents, and the catalyst with one another to prepare the cure promoter composition, homogenizing the cure promoter composition, pausing after homogenizing to allow the cure promoter time to react, applying a sealant onto a substrate, and applying the cure promoter composition to a surface of the sealant.