ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE MULTILAYERS FOR VR/AR/MR THERMAL MANAGEMENT
A polymer laminate includes a plurality of ultra-high molecular weight polyethylene thin films, where each polyethylene thin film has an in-plane thermal conductivity of at least approximately 5 W/mK and an in-plane elastic modulus of at least approximately 20 GPa. The polymer laminate may be incorporated into an eyewear device and may be configured to disperse heat during operation thereof in a manner effective to improve the functionality and/or wearability of the device.
1 . A polymer laminate comprising a plurality of ultra-high molecular weight polyethylene thin films, wherein each polyethylene thin film comprises:
transmissivity within the visible spectrum of at least approximately 85%;
less than approximately 5% bulk haze;
an in-plane thermal conductivity of at least approximately 5 W/mK; and
an in-plane elastic modulus of at least approximately 20 GPa.
2 . The polymer laminate of claim 1 , wherein the polyethylene in each thin film has a weight average molecular weight of at least approximately 300,000 g/mol.
3 . The polymer laminate of claim 1 , wherein each polyethylene thin film has a thickness of at least approximately 20 micrometers.
4 . The polymer laminate of claim 1 , wherein each polyethylene thin film has a dielectric constant of less than approximately 3.5 and a loss tangent of less than approximately 0.01.
5 . The polymer laminate of claim 1 , wherein each polyethylene thin film has a specific resistivity of at least approximately 10 10 ohm/cm.
6 . The polymer laminate of claim 1 , wherein each polyethylene thin film has an RF transparency of at least approximately 80%.
7 . The polymer laminate of claim 1 , wherein at least two of the polyethylene thin films are mutually misoriented by an in-plane angle of at least approximately 2°.
8 . The polymer laminate of claim 1 , wherein a pair of neighboring polyethylene thin films are mutually misoriented by an in-plane angle of at least approximately 2°.
9 . The polymer laminate of claim 1 , further comprising an adhesive layer disposed between neighboring polyethylene thin films.
10 . The polymer laminate of claim 9 , wherein the adhesive layer comprises a material selected from the group consisting of powdered UHMWPE, a polyethylene thin film, and a polystyrene block copolymer thin film.
11 . An eyewear device comprising the polymer laminate of claim 1 .
12 . The eyewear device of claim 11 , wherein the polymer laminate is disposed over an inner surface of a viewing area of the eyewear device.
13 . A method comprising:
producing an in-plane strain within first and second polyethylene thin films in an amount effective to re-orient crystals or align polyethylene chains within each polyethylene thin film and form first and second anisotropic polyethylene thin films each having an in-plane thermal conductivity of at least approximately 5 W/mK and an in-plane elastic modulus of at least approximately 20 GPa; and
adhering the first anisotropic polyethylene thin film to the second anisotropic polyethylene thin film to form a polymer laminate.
14 . The method of claim 13 , wherein producing the in-plane strain comprises applying a uniaxial stress to at least one of the first and second polyethylene thin films.
15 . The method of claim 13 , wherein producing the in-plane strain comprises applying a biaxial stress to at least one of the first and second polyethylene thin films.
16 . The method of claim 13 , wherein producing the in-plane strain comprises stretching the first polyethylene thin film and the second polyethylene thin film each to a draw ratio of at least approximately 20.
17 . The method of claim 13 , further comprising forming the polymer laminate over a region of an eyewear device, the region being selected from the group consisting of a viewing area, a temple arm, a frame, a headset chassis, a front cover, and an enclosure of the eyewear device.
18 . A polymer laminate comprising:
a first layer comprising polyethylene having a molecular weight of at least approximately 300,000 g/mol; and
a second layer bonded to the first layer, the second layer comprising polyethylene having a molecular weight of at least approximately 300,000 g/mol, wherein the polymer laminate comprises a thermal conductivity of at least approximately 5 W/mK, and an elastic modulus of at least approximately 20 GPa.
19 . The polymer laminate of claim 18 , comprising a specific resistivity of at least approximately 10 10 ohm/cm.
20 . The polymer laminate of claim 18 , comprising an RF transparency of at least approximately 80%.