Polyethylene membrane acoustic assembly

Abstract

The assembly includes an acoustic device. The acoustic device can include a polyethylene film. The polyethylene film can have a first direction and a second direction, the second direction being perpendicular to the first direction. The polyethylene film can have a thickness of at least 39×10 6 / m. The polyethylene film may have a geometric mean tensile modulus of 250 to 750 MPa. The polyethylene film may have a maximum tensile modulus in a first direction of 440 to 915 MPa. The polyethylene film may have a maximum tensile modulus in a second direction of 275 to 515 MPa. The polyethylene film may be an oriented polyethylene film.

Description

[Technical Field] 【0001】 This disclosure relates to acoustic assemblies in general. More specifically, this disclosure relates to acoustic assemblies comprising polyethylene membranes. [Background technology] 【0002】 Acoustic membrane assemblies allow sound to pass through the membrane and enter and exit acoustic devices. Acoustic membranes can also prevent the intrusion of water, dust, and other contaminants. [Overview of the project] 【0003】 In some embodiments, the assembly includes an acoustic device. In some embodiments, the acoustic device includes a polyethylene film. In some embodiments, the polyethylene film has a first direction and a second direction, the second direction being perpendicular to the first direction. In some embodiments, the polyethylene film has a thickness of 0.5 μm to 14 μm. In some embodiments, the thickness defines the thickness direction, and the first and second directions are perpendicular to the thickness direction. In some embodiments, the polyethylene film is at least 39 × 10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film has a geometric mean tensile modulus of 250 to 750 MPa. In some embodiments, the polyethylene film has a maximum tensile modulus of 440 to 915 MPa in the first direction. In some embodiments, the polyethylene film has a maximum tensile modulus of 275 to 515 MPa in the second direction. 【0004】 In some embodiments, the acoustic device is a speaker, a microphone, or any combination thereof. 【0005】 In some embodiments, the acoustic device has a transmission loss (dB) that changes by less than 2.1 dB when tested using a WEP test 24 hours after an open hall challenge at 3 kHz and 1 bar. 【0006】 In some embodiments, the polyethylene film has a tensile modulus balance of 1 to 2.1. 【0007】 In some embodiments, the geometric mean tensile modulus is 350 to 650 MPa. 【0008】 In some embodiments, the polyethylene film has a porosity of 50% to 95%. 【0009】 In some embodiments, the polyethylene film has a porosity of 55% to 86%. 【0010】 In some embodiments, the % recovery after 1 hour of the 1 bar open hole challenge is at least 69%. 【0011】 In some embodiments, the polyethylene film has a bubble point of 7 psi to 200 psi. 【0012】 In some embodiments, the polyethylene film is 1×10 -15 m 2 ~8×10 -15 m 2 in permeability. 【0013】 In some embodiments, the polyethylene film is 3×10 -16 m 2 ~7.4×10 -15 m 2 in permeability. 【0014】 In some embodiments, the polyethylene film is a stretched polyethylene film. 【0015】 In some embodiments, the assembly includes an acoustic device. In some embodiments, the acoustic device includes a polyethylene film. In some embodiments, the % recovery after 1 hour of the 1 bar open hole challenge is at least 69%. 【0016】 In some embodiments, the acoustic device has a transmission loss (dB) that changes by less than 2.1 dB when tested using a WEP test 24 hours after an open hall challenge at 3 kHz and 1 bar. 【0017】 In some embodiments, the acoustic device is a speaker, a microphone, or any combination thereof. 【0018】 In some embodiments, the polyethylene film has a thickness of 0.5 μm to 14 μm. 【0019】 In some embodiments, the polyethylene film has a porosity of 50% to 95%. 【0020】 In some embodiments, the polyethylene film has a porosity of 55% to 86%. 【0021】 In some embodiments, the polyethylene film has bubble points between 7 psi and 200 psi. 【0022】 In some embodiments, the polyethylene film is 1 × 10 -15 m 2 ~8×10 -15 m 2 It has the following transparency. 【0023】 In some embodiments, the polyethylene film is 3 × 10 -16 m 2 ~7.4×10 -15 m 2 It has the following transparency. 【0024】 In some embodiments, the polyethylene film has a first direction and a second direction, where the second direction is perpendicular to the first direction and has a surface area of ​​at least 39 × 10⁻¹⁴ units per unit volume. 6 The coefficient of elasticity is / m, the geometric mean tensile modulus is 250-750 MPa, the maximum tensile modulus in the first direction is 440-915 MPa, and the maximum tensile modulus in the second direction is 275-515 MPa. 【0025】 In some embodiments, the polyethylene film has a tensile modulus balance of 1 to 2.1. 【0026】 In some embodiments, the geometric mean tensile modulus is 250 to 650 MPa. 【0027】 In some embodiments, the polyethylene membrane is a stretched polyethylene membrane. 【0028】 In some embodiments, the assembly includes an acoustic device. In some embodiments, the acoustic device includes a polyethylene membrane. In some embodiments, the acoustic device has a transmission loss (dB) that changes by less than 2.1 dB when tested using a WEP test 24 hours after an open-hall challenge at 3 kHz and 1 bar. 【0029】 In some embodiments, the polyethylene film has a first direction and a second direction, where the second direction is perpendicular to the first direction and the surface area per unit volume is at least 39 × 10⁻¹⁴ 6 The coefficient of elasticity is / m, the geometric mean tensile modulus is 250-750 MPa, the maximum tensile modulus in the first direction is 440-915 MPa, and the maximum tensile modulus in the second direction is 275-515 MPa. 【0030】 In some embodiments, the polyethylene film has a tensile modulus balance of 1 to 2.1. 【0031】 In some embodiments, the geometric mean tensile modulus is 250 to 650 MPa. 【0032】 In some embodiments, the surface area per unit volume is 39 × 10 6 / m~70×10 6 It is / m. 【0033】 In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is at least 69%. 【0034】 In some embodiments, the acoustic device is a speaker, a microphone, or any combination thereof. 【0035】 In some embodiments, the polyethylene film has a thickness of 0.5 μm to 14 μm. 【0036】 In some embodiments, the polyethylene film has a porosity of 50% to 95%. 【0037】 In some embodiments, the polyethylene film has a porosity of 55% to 86%. 【0038】 In some embodiments, the polyethylene film has bubble points between 7 psi and 200 psi. 【0039】 In some embodiments, the polyethylene film is 1 × 10 -15 m 2 ~8×10 -15 m 2 It has the following transparency. 【0040】 In some embodiments, the polyethylene film is 3 × 10 -16 m 2 ~7.4×10 -15 m 2 It has the following transparency. 【0041】 In some embodiments, the polyethylene membrane is a stretched polyethylene membrane. 【0042】 In some embodiments, the polyethylene film has a thickness, which defines the thickness direction, and the first and second directions are perpendicular to the thickness direction, respectively. 【0043】 In some embodiments, the maximum tensile modulus in the first direction is greater than the maximum tensile modulus in the second direction. 【0044】 In some embodiments, the first direction is one of the longitudinal and transverse directions of the polyethylene film, and the second direction is the other of the longitudinal and transverse directions of the polyethylene film. [Brief explanation of the drawing] 【0045】 Brief explanation of the drawing Refer to the accompanying drawings, which form part of this disclosure and illustrate embodiments in which the systems and methods described herein may be carried out. 【0046】 [Figure 1] Figure 1 shows a front view of an assembly including an acoustic device according to several embodiments. 【0047】 [Figure 2] Figure 2 shows a top view of the protective cover assembly of Figure 1 according to several embodiments. 【0048】 [Figure 3] Figure 3 shows cross-sectional views of the protective cover assemblies shown in Figures 1 and 2, according to several embodiments. 【0049】 [Figure 4] Figure 4 shows schematic diagrams of pressure test configurations according to several embodiments. 【0050】 Similar reference numbers represent the same or similar parts throughout the whole. [Modes for carrying out the invention] 【0051】 Further improvements to acoustic films are needed. Several embodiments described herein can advantageously achieve low acoustic loss and variability while providing mechanical protection in immersion applications. Several embodiments described herein can advantageously avoid excessive elongation of the film and provide consistent performance of the acoustic film over the long term. That is, by avoiding plastic deformation of the film, performance degradation over time can be mitigated. 【0052】 Some embodiments of this disclosure primarily concern reactive supported acoustic membranes. In the primarily reactive mode, sound is transmitted through a combination of vibrations of the membrane within the active region and vibrations in the gas phase within the open porous region of the membrane. 【0053】 In some embodiments, the assembly includes an acoustic device. In some embodiments, the acoustic device is one of a speaker, a microphone, or any combination thereof. In some embodiments, the acoustic device includes a polyethylene membrane. In some embodiments, the polyethylene membrane is a stretched polyethylene membrane. In some embodiments, the polyethylene membrane has a fibrillated microstructure. 【0054】 As used herein, the term “membrane” refers to an article, such as a sheet, having three dimensions defined by three mutually orthogonal axes or directions, of which two dimensions are typically larger than the third dimension. For example, the two larger dimensions are at least one order of magnitude larger than the smallest third dimension. Thus, the smallest third dimension can represent the thickness of the membrane. This thickness can be measured along the third axis or direction, which is referred herein to as the thickness direction of the membrane. 【0055】 A film may have a first and second opposing surface, separated by the film's thickness, i.e., the shortest distance between the first and second opposing surfaces. This distance can be defined by lines perpendicular to the planes of both the first and second surfaces. Thus, the thickness direction can be parallel to the line defining the film's thickness. 【0056】 Both the first axis or direction and the second axis or direction are perpendicular to the thickness direction of the film. Therefore, the first and second directions define a plane perpendicular to the thickness direction of the film. Thus, the plane defined by the first and second directions is either parallel to or overlaps with the planar sheet of the film. 【0057】 In some embodiments, the first direction is selected from either the longitudinal or transverse direction of the film, and the second direction is selected from the other of the longitudinal or transverse direction of the film. In some embodiments, the first direction is selected from either the mechanical or transverse direction of the film, and the second direction is selected from the other of the mechanical or transverse direction of the film. 【0058】 In some embodiments, the maximum tensile modulus can be determined for each of the first and second directions. The first direction can be assigned to the direction having a larger maximum tensile modulus. The second direction can be assigned to the direction having a smaller maximum tensile modulus. 【0059】 Figure 1 shows an external front view of an electronic device 10 according to several embodiments. In the illustrated embodiments, the electronic device 10 is a mobile phone having an opening 12. The opening 12 can be a narrow slot or a circular aperture. Although one opening 12 is shown, it should be understood that the number, size, and shape of openings in the electronic device 10 can be changed. It should also be understood that the type of electronic device 10 can be changed to something other than a mobile phone. A protective cover assembly 14 is shown to cover the opening 12 to prevent moisture, debris, or other particles from entering the electronic device 10. The protective cover assembly 14 is suitable for openings of any size and is not particularly limited. The structures disclosed herein can be equally applied to sound-passing openings in protective covers for any equivalent electronic devices such as laptop computers, tablets, cameras, smartwatches, and portable microphones. In order to allow the protective cover assembly 14 to be fitted, the size of the protective cover assembly 14 is larger than the maximum diameter of the opening 12. 【0060】 Figure 2 shows a top view of the protective cover assembly 14 of Figure 1 according to several embodiments. In the illustrated embodiments, the protective cover assembly 14 includes an active region 16 surrounded by a support region 18. The active region 16 consists solely of a membrane, allowing sound to pass through it easily. The support region 18 includes a membrane sandwiched between external adhesive layers for connecting the protective cover assembly 14 to the electronic device 10. The specific structure for securing the membrane in place is not intended to be limiting. 【0061】 Figure 3 shows a cross-sectional view of a protective cover assembly 14 according to several embodiments. The layered assembly 20 is inserted into the casing 22 of the electronic device 10. The opening 12 defines an acoustic path 24, and the protective cover assembly 14 is positioned across the acoustic path 24, separating the external environment 26 of the casing 22 from the internal environment 28, and separating the external environment 26 from the acoustic cavity 30. The casing 22 is configured to be positioned and protect the electronic device 32 (e.g., a circuit board in a mobile device, cell phone, tablet, etc.) together with the layered assembly 20, and the layered assembly 20 is positioned to prevent water or debris from entering the internal environment 28, and in particular to protect the transducer 34. The transducer 34 is positioned below the active area 16 within the opening 12 for generating or receiving sound. 【0062】 The layered assembly 20 includes a membrane 36 and a support structure 38. Sound waves can travel along an acoustic path 24, through an acoustic cavity 30, and through the membrane 36 between the transducer 34 and the external environment 26. The acoustic path 24 is generally defined by an opening 12 within the casing 22. This opening 12 is generally approximately the same size as the unshielded portion of the membrane 36. 【0063】 The acoustic path 24 can also provide venting. Venting can provide pressure equalization between the acoustic cavity 30 and the external environment 26. Venting is useful when a pressure difference occurs between the acoustic cavity 30 and the external environment 26, which affects the ability of the layered assembly 20 to pass sound waves. For example, temperature changes within the acoustic cavity 30 can cause expansion or contraction of the air within the acoustic cavity, which tends to deform the layered assembly 20 and produce acoustic distortion. 【0064】 Surface area per unit volume 【0065】 In some embodiments, the polyethylene film is at least 39 × 10 6 It has a surface area per unit volume of / m. In some embodiments, the surface area per unit volume is 70 × 10 6 It is less than / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. 【0066】 In some embodiments, the polyethylene membrane is 40 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 41 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 42 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 43 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 44 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 45 × 10 6 / m~70×10 6It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 46 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 47 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 48 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 49 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 50 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 51 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 52 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 53 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 54 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 55 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 56 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 57 × 10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 58 × 10 6 / m~70×106 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 59×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 60×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 61×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 62×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 63×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 64×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 65×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 66×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 67×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 68×10 6 / m~70×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 69×10 6 / m~70×10 6 It has a surface area per unit volume of / m. 【0067】 In some embodiments, the polyethylene film is 39×10 6 / m~69×10 6has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 68×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 67×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 66×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 65×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 64×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 63×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 62×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 61×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 60×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 59×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 58×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 57×10 6 has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39×10 6 / m to 56×106 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~55×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~54×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~53×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~52×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~51×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~50×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~49×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~48×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~47×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~46×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~45×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~44×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 106 / m~43×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~42×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~41×10 6 It has a surface area per unit volume of / m. In some embodiments, the polyethylene film is 39 × 10 6 / m~40×10 6 It has a surface area per unit volume of / m. 【0068】 Geometric mean tensile modulus 【0069】 In some embodiments, the polyethylene film has a geometric mean tensile modulus of 250 MPa to 750 MPa. In some embodiments, the geometric mean tensile modulus is 300 MPa to 750 MPa. In some embodiments, the geometric mean tensile modulus is 350 MPa to 750 MPa. In some embodiments, the geometric mean tensile modulus is 400 MPa to 750 MPa. In some embodiments, the geometric mean tensile modulus is 450 MPa to 750 MPa. In some embodiments, the geometric mean tensile modulus is 500 MPa to 750 MPa. In some embodiments, the geometric mean tensile modulus is 550 MPa to 750 MPa. In some embodiments, the geometric mean tensile modulus is 600 MPa to 750 MPa. In some embodiments, the geometric mean tensile modulus is 650 MPa to 750 MPa. In some embodiments, the geometric mean tensile modulus is 700 MPa to 750 MPa. 【0070】 In some embodiments, the geometric mean tensile modulus is 250 MPa to 700 MPa. In some embodiments, the geometric mean tensile modulus is 250 MPa to 650 MPa. In some embodiments, the geometric mean tensile modulus is 250 MPa to 600 MPa. In some embodiments, the geometric mean tensile modulus is 250 MPa to 550 MPa. In some embodiments, the geometric mean tensile modulus is 250 MPa to 500 MPa. In some embodiments, the geometric mean tensile modulus is 250 MPa to 450 MPa. In some embodiments, the geometric mean tensile modulus is 250 MPa to 400 MPa. In some embodiments, the geometric mean tensile modulus is 250 MPa to 350 MPa. In some embodiments, the geometric mean tensile modulus is 250 MPa to 300 MPa. 【0071】 In some embodiments, the geometric mean tensile modulus is 350 MPa to 650 MPa. 【0072】 Tensile modulus balance 【0073】 In some embodiments, the polyethylene film has a tensile modulus balance of 1 to 2.1. 【0074】 In some embodiments, the tensile modulus balance is 1.1 to 2.1. In some embodiments, the tensile modulus balance is 1.2 to 2.1. In some embodiments, the tensile modulus balance is 1.3 to 2.1. In some embodiments, the tensile modulus balance is 1.4 to 2.1. In some embodiments, the tensile modulus balance is 1.5 to 2.1. In some embodiments, the tensile modulus balance is 1.6 to 2.1. In some embodiments, the tensile modulus balance is 1.7 to 2.1. In some embodiments, the tensile modulus balance is 1.8 to 2.1. In some embodiments, the tensile modulus balance is 1.9 to 2.1. In some embodiments, the tensile modulus balance is 2 to 2.1. 【0075】 In some embodiments, the tensile modulus balance is 1 to 2. In some embodiments, the tensile modulus balance is 1 to 1.9. In some embodiments, the tensile modulus balance is 1 to 1.8. In some embodiments, the tensile modulus balance is 1 to 1.7. In some embodiments, the tensile modulus balance is 1 to 1.6. In some embodiments, the tensile modulus balance is 1 to 1.5. In some embodiments, the tensile modulus balance is 1 to 1.4. In some embodiments, the tensile modulus balance is 1 to 1.3. In some embodiments, the tensile modulus balance is 1 to 1.2. In some embodiments, the tensile modulus balance is 1 to 1.1. 【0076】 In some embodiments, the tensile modulus balance is less than 2. 【0077】 Maximum tensile modulus 【0078】 In some embodiments, the polyethylene film has a maximum tensile modulus in the first direction of 440 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 900 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 850 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 800 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 750 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 700 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 650 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 600 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 550 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 500 MPa. In some embodiments, the tensile modulus in the first direction is 440 MPa to 450 MPa. 【0079】 In some embodiments, the tensile modulus in the first direction is 450 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 500 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 550 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 600 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 650 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 700 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 750 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 800 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 850 MPa to 915 MPa. In some embodiments, the tensile modulus in the first direction is 900 MPa to 915 MPa. 【0080】 In some embodiments, the polyethylene film has a maximum tensile modulus of 275 MPa to 515 MPa in a second direction perpendicular to the first direction. In some embodiments, the maximum tensile modulus in the second direction is 275 MPa to 500 MPa. In some embodiments, the maximum tensile modulus in the second direction is 275 MPa to 450 MPa. In some embodiments, the maximum tensile modulus in the second direction is 275 MPa to 400 MPa. In some embodiments, the maximum tensile modulus in the second direction is 275 MPa to 350 MPa. In some embodiments, the maximum tensile modulus in the second direction is 275 MPa to 300 MPa. 【0081】 In some embodiments, the maximum tensile modulus in the second direction is 300 MPa to 515 MPa. In some embodiments, the maximum tensile modulus in the second direction is 350 MPa to 515 MPa. In some embodiments, the maximum tensile modulus in the second direction is 400 MPa to 515 MPa. In some embodiments, the maximum tensile modulus in the second direction is 450 MPa to 515 MPa. In some embodiments, the maximum tensile modulus in the second direction is 500 MPa to 515 MPa. 【0082】 Please understand that the first and second directions can be reversed, as long as they are orthogonal to each other. 【0083】 thickness 【0084】 In some embodiments, the polyethylene film has a thickness of 14 μm or less. In some embodiments, the thickness is at least 0.5 μm. In some embodiments, the thickness is between 0.5 μm and 14 μm. 【0085】 In some embodiments, the thickness is 1 μm to 14 μm. In some embodiments, the thickness is 2 μm to 14 μm. In some embodiments, the thickness is 3 μm to 14 μm. In some embodiments, the thickness is 4 μm to 14 μm. In some embodiments, the thickness is 5 μm to 14 μm. In some embodiments, the thickness is 6 μm to 14 μm. In some embodiments, the thickness is 7 μm to 14 μm. In some embodiments, the thickness is 8 μm to 14 μm. In some embodiments, the thickness is 9 μm to 14 μm. In some embodiments, the thickness is 10 μm to 14 μm. In some embodiments, the thickness is 11 μm to 14 μm. In some embodiments, the thickness is 12 μm to 14 μm. In some embodiments, the thickness is 13 μm to 14 μm. 【0086】 In some embodiments, the thickness is 0.5 μm to 13 μm. In some embodiments, the thickness is 0.5 μm to 12 μm. In some embodiments, the thickness is 0.5 μm to 11 μm. In some embodiments, the thickness is 0.5 μm to 10 μm. In some embodiments, the thickness is 0.5 μm to 9 μm. In some embodiments, the thickness is 0.5 μm to 8 μm. In some embodiments, the thickness is 0.5 μm to 7 μm. In some embodiments, the thickness is 0.5 μm to 6 μm. In some embodiments, the thickness is 0.5 μm to 5 μm. In some embodiments, the thickness is 0.5 μm to 4 μm. In some embodiments, the thickness is 0.5 μm to 3 μm. In some embodiments, the thickness is 0.5 μm to 2 μm. In some embodiments, the thickness is 0.5 μm to 1 μm. 【0087】 porosity 【0088】 In some embodiments, the polyethylene film has a porosity of at least 50%. In some embodiments, the porosity is less than 95%. In some embodiments, the porosity is between 50% and 95%. 【0089】 In some embodiments, the porosity is 55% to 95%. In some embodiments, the porosity is 60% to 95%. In some embodiments, the porosity is 65% to 95%. In some embodiments, the porosity is 75% to 95%. In some embodiments, the porosity is 80% to 95%. In some embodiments, the porosity is 85% to 95%. In some embodiments, the porosity is 90% to 95%. 【0090】 In some embodiments, the porosity is 50% to 90%. In some embodiments, the porosity is 50% to 85%. In some embodiments, the porosity is 50% to 80%. In some embodiments, the porosity is 50% to 75%. In some embodiments, the porosity is 50% to 70%. In some embodiments, the porosity is 50% to 65%. In some embodiments, the porosity is 50% to 60%. In some embodiments, the porosity is 50% to 55%. 【0091】 In some embodiments, the porosity is 55% to 86%. 【0092】 Recovery after the Open Hole Challenge 【0093】 In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is at least 69%. In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 99% or less. 【0094】 In some embodiments, the recovery rate after one hour of a 1-bar open hole challenge is 74% to 99%. In some embodiments, the recovery rate after one hour of a 1-bar open hole challenge is 79% to 99%. In some embodiments, the recovery rate after one hour of a 1-bar open hole challenge is 84% ​​to 99%. In some embodiments, the recovery rate after one hour of a 1-bar open hole challenge is 89% to 99%. In some embodiments, the recovery rate after one hour of a 1-bar open hole challenge is 94% to 99%. 【0095】 In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 69% to 94%. In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 69% to 89%. In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 69% to 84%. In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 69% to 79%. In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 69% to 74%. 【0096】 In some embodiments, the recovery rate after one hour of a 1-bar open hole challenge is 95% to 99%. In some embodiments, the recovery rate after one hour of a 1-bar open hole challenge is 96% to 99%. In some embodiments, the recovery rate after one hour of a 1-bar open hole challenge is 97% to 99%. In some embodiments, the recovery rate after one hour of a 1-bar open hole challenge is 98% to 99%. 【0097】 In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 94% to 98%. In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 94% to 97%. In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 94% to 96%. In some embodiments, the recovery percentage after one hour of a 1-bar open hole challenge is 94% to 95%. 【0098】 Bubble Points 【0099】 In some embodiments, the polyethylene film has a bubble point of 7 psi to 200 psi. In some embodiments, the bubble point is 10 psi to 200 psi. In some embodiments, the bubble point is 15 psi to 200 psi. In some embodiments, the bubble point is 20 psi to 200 psi. In some embodiments, the bubble point is 25 psi to 200 psi. In some embodiments, the bubble point is 30 psi to 200 psi. In some embodiments, the bubble point is 35 psi to 200 psi. In some embodiments, the bubble point is 40 psi to 200 psi. In some embodiments, the bubble point is 45 psi to 200 psi. In some embodiments, the bubble point is 50 psi to 200 psi. In some embodiments, the bubble point is 55 psi to 200 psi. In some embodiments, the bubble point is 60 psi to 200 psi. In some embodiments, the bubble point is 65 psi to 200 psi. In some embodiments, the bubble point is 70 psi to 200 psi. In some embodiments, the bubble point is 75 psi to 200 psi. In some embodiments, the bubble point is 80 psi to 200 psi. In some embodiments, the bubble point is 85 psi to 200 psi. In some embodiments, the bubble point is 90 psi to 200 psi. In some embodiments, the bubble point is 95 psi to 200 psi. In some embodiments, the bubble point is 100 psi to 200 psi. In some embodiments, the bubble point is 105 psi to 200 psi. In some embodiments, the bubble point is 110 psi to 200 psi. In some embodiments, the bubble point is 115 psi to 200 psi. In some embodiments, the bubble point is 120 psi to 200 psi. In some embodiments, the bubble point is 125 psi to 200 psi. In some embodiments, the bubble point is 130 psi to 200 psi.In some embodiments, the bubble point is 135 psi to 200 psi. In some embodiments, the bubble point is 140 psi to 200 psi. In some embodiments, the bubble point is 145 psi to 200 psi. In some embodiments, the bubble point is 150 psi to 200 psi. In some embodiments, the bubble point is 155 psi to 200 psi. In some embodiments, the bubble point is 160 psi to 200 psi. In some embodiments, the bubble point is 165 psi to 200 psi. In some embodiments, the bubble point is 170 psi to 200 psi. In some embodiments, the bubble point is 175 psi to 200 psi. In some embodiments, the bubble point is 180 psi to 200 psi. In some embodiments, the bubble point is 185 psi to 200 psi. In some embodiments, the bubble point is 190 psi to 200 psi. In some embodiments, the bubble point is 195 psi to 200 psi. 【0100】 In some embodiments, the bubble point is 7 psi to 195 psi. In some embodiments, the bubble point is 7 psi to 190 psi. In some embodiments, the bubble point is 7 psi to 185 psi. In some embodiments, the bubble point is 7 psi to 180 psi. In some embodiments, the bubble point is 7 psi to 175 psi. In some embodiments, the bubble point is 7 psi to 170 psi. In some embodiments, the bubble point is 7 psi to 165 psi. In some embodiments, the bubble point is 7 psi to 160 psi. In some embodiments, the bubble point is 7 psi to 155 psi. In some embodiments, the bubble point is 7 psi to 150 psi. In some embodiments, the bubble point is 7 psi to 145 psi. In some embodiments, the bubble point is 7 psi to 140 psi. In some embodiments, the bubble point is 7 psi to 135 psi. In some embodiments, the bubble point is 7 psi to 130 psi. In some embodiments, the bubble point is 7 psi to 125 psi. In some embodiments, the bubble point is 7 psi to 120 psi. In some embodiments, the bubble point is 7 psi to 115 psi. In some embodiments, the bubble point is 7 psi to 110 psi. In some embodiments, the bubble point is 7 psi to 105 psi. In some embodiments, the bubble point is 7 psi to 100 psi. In some embodiments, the bubble point is 7 psi to 95 psi. In some embodiments, the bubble point is 7 psi to 90 psi. In some embodiments, the bubble point is 7 psi to 85 psi. In some embodiments, the bubble point is 7 psi to 80 psi. In some embodiments, the bubble point is 7 psi to 75 psi. In some embodiments, the bubble point is 7 psi to 70 psi. In some embodiments, the bubble point is 7 psi to 65 psi. In some embodiments, the bubble point is 7 psi to 60 psi.In some embodiments, the bubble point is 7 psi to 55 psi. In some embodiments, the bubble point is 7 psi to 50 psi. In some embodiments, the bubble point is 7 psi to 45 psi. In some embodiments, the bubble point is 7 psi to 40 psi. In some embodiments, the bubble point is 7 psi to 35 psi. In some embodiments, the bubble point is 7 psi to 30 psi. In some embodiments, the bubble point is 7 psi to 25 psi. In some embodiments, the bubble point is 7 psi to 20 psi. In some embodiments, the bubble point is 7 psi to 15 psi. In some embodiments, the bubble point is 7 psi to 10 psi. 【0101】 Transparency 【0102】 In some embodiments, the polyethylene film is 3 × 10 -16 m 2 ~7.4×10 -15 m 2 It has a transmittance of 3 × 10⁻¹⁰. In some embodiments, the transmittance is 3 × 10⁻¹⁰. -16 m 2 ~7×10 -15 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~6×10 -15 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~5×10 -15 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~4×10 -15 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~3×10 -15 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~2×10-15 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~1 × 10 -15 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~9×10 -16 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~8×10 -16 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~7×10 -16 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~6×10 -16 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~5×10 -16 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -16 m 2 ~4×10 -16 m 2 That is the case. 【0103】 In some embodiments, the transmittance is 4 × 10 -16 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 5 × 10 -16 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 6 × 10 -16 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 7 × 10 -16 m 2 ~7.4×10 -15 m 2In some embodiments, the transmittance is 8 × 10 -16 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 9 × 10 -16 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 1 × 10⁻⁶. -15 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 2 × 10⁻⁶. -15 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 3 × 10⁻⁶. -15 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 4 × 10 -15 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 5 × 10 -15 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 6 × 10 -15 m 2 ~7.4×10 -15 m 2 In some embodiments, the transmittance is 7 × 10 -15 m 2 ~7.4×10 -15 m 2 That is the case. 【0104】 In some embodiments, the transmittance is 1.0 × 10⁻⁶ -15 m 2 ~8.0×10 -15 m 2 In some embodiments, the transmittance is 2.0 × 10⁻⁶. -15 m 2 ~8.0×10 -15 m 2In some embodiments, the transmittance is 3.0 × 10⁻⁶. -15 m 2 ~8.0×10 -15 m 2 In some embodiments, the transmittance is 4.0 × 10⁻⁶. -15 m 2 ~8.0×10 -15 m 2 In some embodiments, the transmittance is 5.0 × 10⁻⁶. -15 m 2 ~8.0×10 -15 m 2 In some embodiments, the transmittance is 6.0 × 10⁻⁶. -15 m 2 ~8.0×10 -15 m 2 In some embodiments, the transmittance is 7.0 × 10⁻⁶. -15 m 2 ~8.0×10 -15 m 2 That is the case. 【0105】 In some embodiments, the transmittance is 1.0 × 10⁻⁶ -15 m 2 ~7.0×10 -15 m 2 In some embodiments, the transmittance is 1.0 × 10⁻⁶. -15 m 2 ~6.0×10 -15 m 2 In some embodiments, the transmittance is 1.0 × 10⁻⁶. -15 m 2 ~5.0×10 -15 m 2 In some embodiments, the transmittance is 1.0 × 10⁻⁶. -15 m 2 ~4.0×10 -15 m 2 In some embodiments, the transmittance is 1.0 × 10⁻⁶. -15 m 2 ~3.0×10 -15 m 2 In some embodiments, the transmittance is 1.0 × 10⁻⁶. -15 m 2 ~2.0×10 -15 m2 That is the case. 【0106】 Transmission loss at 10kHz 【0107】 In some embodiments, the acoustic device has a transmission loss (dB) with a change of less than 2.1 dB (i.e., change in transmission loss, ΔTL(dB)) when tested using a WEP test 24 hours after a 1 bar open hall challenge at 10 kHz. In some embodiments, the transmission loss (dB) changes by less than 2 dB. In some embodiments, the transmission loss (dB) changes by less than 1.9 dB. In some embodiments, the transmission loss (dB) changes by less than 1.8 dB. In some embodiments, the transmission loss (dB) changes by less than 1.7 dB. In some embodiments, the transmission loss (dB) changes by less than 1.6 dB. In some embodiments, the transmission loss (dB) changes by less than 1.5 dB. In some embodiments, the transmission loss (dB) changes by less than 1.4 dB. In some embodiments, the transmission loss (dB) changes by less than 1.3 dB. In some embodiments, the transmission loss (dB) changes by less than 1.2 dB. In some embodiments, the transmission loss (dB) varies by less than 1.1 dB. In some embodiments, the transmission loss (dB) varies by less than 1 dB. In some embodiments, the transmission loss (dB) varies by less than 0.9 dB. In some embodiments, the transmission loss (dB) varies by less than 0.8 dB. In some embodiments, the transmission loss (dB) varies by less than 0.7 dB. In some embodiments, the transmission loss (dB) varies by less than 0.6 dB. In some embodiments, the transmission loss (dB) varies by less than 0.5 dB. In some embodiments, the transmission loss (dB) varies by less than 0.4 dB. In some embodiments, the transmission loss (dB) varies by less than 0.3 dB. In some embodiments, the transmission loss (dB) varies by less than 0.2 dB. 【0108】 Digital loss at 3kHz 【0109】 In some embodiments, the acoustic device has a transmission loss (dB) with a change of less than 2.1 dB (i.e., change in transmission loss, ΔTL(dB)) when tested using a WEP test 24 hours after a 1 bar open hall challenge at 3 kHz. In some embodiments, the transmission loss (dB) changes by less than 2 dB. In some embodiments, the transmission loss (dB) changes by less than 1.9 dB. In some embodiments, the transmission loss (dB) changes by less than 1.8 dB. In some embodiments, the transmission loss (dB) changes by less than 1.7 dB. In some embodiments, the transmission loss (dB) changes by less than 1.6 dB. In some embodiments, the transmission loss (dB) changes by less than 1.5 dB. In some embodiments, the transmission loss (dB) changes by less than 1.4 dB. In some embodiments, the transmission loss (dB) changes by less than 1.3 dB. In some embodiments, the transmission loss (dB) changes by less than 1.2 dB. In some embodiments, the transmission loss (dB) varies by less than 1.1 dB. In some embodiments, the transmission loss (dB) varies by less than 1 dB. In some embodiments, the transmission loss (dB) varies by less than 0.9 dB. In some embodiments, the transmission loss (dB) varies by less than 0.8 dB. In some embodiments, the transmission loss (dB) varies by less than 0.7 dB. In some embodiments, the transmission loss (dB) varies by less than 0.6 dB. In some embodiments, the transmission loss (dB) varies by less than 0.5 dB. In some embodiments, the transmission loss (dB) varies by less than 0.4 dB. In some embodiments, the transmission loss (dB) varies by less than 0.3 dB. In some embodiments, the transmission loss (dB) varies by less than 0.2 dB. 【0110】 transmission loss at 1kHz 【0111】 In some embodiments, the acoustic device has a transmission loss (dB) such that the change (i.e., change in transmission loss, ΔTL(dB)) is less than 2 dB when tested using a WEP test 24 hours after a 1-bar open hall challenge at 1 kHz. In some embodiments, the transmission loss (dB) changes by less than 1.9 dB. In some embodiments, the transmission loss (dB) changes by less than 1.8 dB. In some embodiments, the transmission loss (dB) changes by less than 1.7 dB. In some embodiments, the transmission loss (dB) changes by less than 1.6 dB. In some embodiments, the transmission loss (dB) changes by less than 1.5 dB. In some embodiments, the transmission loss (dB) changes by less than 1.4 dB. In some embodiments, the transmission loss (dB) changes by less than 1.3 dB. In some embodiments, the transmission loss (dB) changes by less than 1.2 dB. In some embodiments, the transmission loss (dB) changes by less than 1.1 dB. In some embodiments, the transmission loss (dB) varies by less than 1 dB. In some embodiments, the transmission loss (dB) varies by less than 0.9 dB. In some embodiments, the transmission loss (dB) varies by less than 0.8 dB. In some embodiments, the transmission loss (dB) varies by less than 0.7 dB. In some embodiments, the transmission loss (dB) varies by less than 0.6 dB. In some embodiments, the transmission loss (dB) varies by less than 0.5 dB. In some embodiments, the transmission loss (dB) varies by less than 0.4 dB. In some embodiments, the transmission loss (dB) varies by less than 0.3 dB. In some embodiments, the transmission loss (dB) varies by less than 0.2 dB. 【0112】 Test Procedure 【0113】 The following test procedure was used to generate the data in the "Non-Limited Examples" section. This test procedure is not intended to be limiting. 【0114】 Average surface area per unit volume: 【0115】 m 2The surface area per unit mass (SSA) of polyethylene membranes, expressed in units of / g, was first measured using the Brunauer-Emmett-Teller (BET) method with a Quantachrome NOVAtouch LX4 gas sorbent system (Quantachrome Instruments - Anton Paar - Boynton Beach, Florida). Samples were cut from the center of a polyethylene membrane sheet and placed in a Type B long cell, 9mm LG valve (reference number 193885). The mass of the polyethylene membrane samples was approximately 0.1–0.2 grams. The tubes were placed in a Coulter SA-Prep surface area outgasser (model SA-PREP, P / N 5102014) at Beckman Coulter Inc., Fullerton, California, and purged with helium at room temperature for 2 hours. The sample tubes were then removed from the SA-Prep outgasser and weighed. A glass filler rod (reference number 193900) was placed in a cell, and the assembly was placed in a NOVAtouch LX4 gas sorbent system. BET surface area analysis was performed using helium according to the instrument manual to calculate the free space and nitrogen as the adsorbed gas. One BET surface area (m²) was performed for each sample. 2 The measurement value ( / g) was recorded. 【0116】 Specific surface area (SSA) can be converted to surface area per unit volume (Sv) using the following formula: 【0117】 Sv = ρ(polymer) * SSA [10 6 / m] 【0118】 In the above formula, 【0119】 ρ (polymer) = 0.94 g / cc, 【0120】 SSA=Specific surface area [m 2 It is / g] 【0121】 Porosity: 【0122】 The sample was die-cut into circular sections with a radius of 5.64 cm (area = 100 cm²). 2 A sample was formed. The weight of each sample was measured using a Mettler Toledo analytical balance. Using the thickness calculated with a KEYENCE laser (see description below), the bulk density of the sample was calculated using the following formula: 【0123】 【number】 【0124】 In the above formula, 【0125】 ρ (bulk) = density (g / cc), 【0126】 m = mass (g), 【0127】 r = circular cut radius (5.64 cm), 【0128】 t = thickness (cm). 【0129】 Skeletal density is the density of a solid calculated by excluding all open pores and including the internal (or blind) pore volume. The density of polyethylene was assumed to be ρ(polymer) = 0.94 g / cc. 【0130】 Therefore, the porosity of the membrane or the total porosity within the substrate is simply the void volume of the sample divided by the total volume of the sample. The porosity of the membrane can be calculated using the following formula. 【0131】 %porosity=100%*{1-ρ(bulk) / ρ(skeleton)} 【0132】 Transparency: 【0133】 The ATEQ airflow test measures the laminar volumetric flow rate of air passing through a membrane sample. Each membrane sample is 2.99 cm across the flow path. 2The area was sealed and clamped between the two plates. An ATEQ® (ATEQ Corp., Livonia, Michigan) Premier D Compact Flow Tester was used to measure the airflow rate (L / hr) through each membrane sample by applying a differential pressure of 1.2 kPa (12 mbar) across the membrane. The instrument was operated using calibrated 30 L and 150 L flow tubes to measure airflow rates in the ranges of 0.5–30 L / hr and 3.8–150 L / hr, respectively. 【0134】 The Darcy transmission rate of air at room temperature can be calculated as follows for an ATEQ measurement at 12 mbar: 【0135】 Transparency (m 2 ) = 2.073 x 10 -17 *ATEQ*t 【0136】 In the above formula, 【0137】 ATEQ[@12mbar](L / h) 【0138】 t = thickness (μm). 【0139】 Thickness: 【0140】 The non-contact thickness of the film was measured using a KEYENCE LS-7600 laser system (commercially available from KEYENCE America). Optical measurements were performed by gently placing the sample film in a 1-inch diameter polished stainless steel cylinder and smoothing it with minimal applied tension. The sample thickness was determined by measuring the shadows created within the parallel optical paths at both ends of the KEYENCE laser micrometer. The average of three measurements was used. 【0141】 Bubble points: 【0142】 Liquids whose surface free energy is lower than that of stretched porous polyethylene are pushed out of the structure when differential pressure is applied. This clearing first occurs through the largest passage. Next, a passage is formed through which bulk nitrogen flow can occur. The nitrogen flow appears as a steady flow of small bubbles through the liquid layer at the top of the sample. The pressure at which the initial bulk air flow occurs is called the bubble point and depends on the surface tension of the test fluid and the size of the largest opening. The bubble point can be used as a relative measure of the membrane's structure and often correlates with other types of performance criteria, such as filtration efficiency. 【0143】 The bubble point was measured using a capillary flow porometer (Quantachrome Instruments Model 3G zh) according to the general instructions of ASTM F316-03. The sample holder consisted of a porous metal plate with a diameter of 25.4 mm (part number: 196450, Anton Paar) and a plastic mask with an inner diameter of 18 mm and an outer diameter of 24.5 mm (part number ABF-300, Professional Plastics). The sample was placed between the metal plate and the plastic mask. The sample was then secured with a clamp and sealed using an O-ring (part number: 193798, Anton Paar). The sample was moistened with the test fluid (silicone fluid, 10 cSt, surface tension 19.75 dynes / cm). 【0144】 Transmission loss: 【0145】 Transmission loss and phase angle tests were performed using the Impedance Tube Transfer Matrix Test ("ITTMT"), a modified version of ASTM-E2611-09. ASTM-E2611-09 is a standard test method for measuring the transmission loss and phase of normally incident sound, based on the four-microphone transfer matrix method. All modifications to ASTM-E2611-09 are described here. The transfer matrix of the assembly is measured, and the T12 element of the transfer matrix is ​​used as the acoustic impedance value for all assemblies described in the example. 【0146】 Measurements were performed using an impedance tube over a frequency range of 500 Hz to 20,000 Hz. The inner diameter of the tube was 8 mm. The impedance tube was designed according to ASTM E1050-12 and ASTM E2611-09. A JBL 2426H compression driver was mounted on one end of the tube and driven by a Bruel & Kjaer Type 2735 amplifier connected to a 31-band ART 351 graphic equalizer. The measurement system used four Bruel and Kjaer Type 4138 microphones connected to a 4-channel Bruel and Kjaer Type 3160-A-042 LAN-XI front end with generator outputs. Data were acquired and processed using Bruel and Kjaer PULSE Labshop and Type 7758 acoustic material testing software version 21. 【0147】 The inner diameter of the tested sample assembly was 1.5 mm, which was smaller than the inner diameter of the impedance tube. Therefore, a pair of conical adapters were required to mount the sample assembly. The converging cone had an inlet diameter of 8 mm and an outlet diameter of 1.5 mm. The flared cone had an inlet diameter of 1.5 mm and an outlet diameter of 8 mm. 【0148】 When using conical adapters, additional data processing was required to account for the cone's convergence shape. Theoretical equations were derived to calculate the transmission matrix of the conical adapter and can be found in the literature (Hua, X. and Herrin, D., "Practical Considerations When Using the Two-Load Method to Determine Transmission Losses in Mufflers and Silencers," SAE Int. J. Passeng. Cars - Mech. Syst. 6(2):1094-1101, 2013 & Mechel, FP (2008). Formulas of Acoustics. New York, NY: Springer). 【0149】 Maximum tensile modulus: 【0150】 To determine the maximum tensile modulus, polyethylene membrane samples were cut longitudinally and transversely using an ASTM D412 Type F die (D412F). Tensile load as a function of displacement was measured using an INSTRON® 5565 tensile testing machine (Illinois Tool Works Inc., Norwood, Massachusetts) equipped with a flat grip and a 100N load cell. The grip separation distance was set to 8.26 cm, and a gauge length of 5.89 cm as specified by ASTM was used, with a strain rate of 0.847 cm / s or 14.4% / s. Data points were captured every 20 milliseconds. After placing the sample in the grip, the sample was reduced by 1.27 cm (to create slack in the specimen), and then the test was continued at the pre-specified strain rate. Once the slack in the sample recovered, the load cell recorded a baseline zero force with some noise in the signal, which was quantified by calculating the standard deviation. Three samples were tested individually for each condition in each orthogonal direction (e.g., longitudinal and transverse directions). In each test, the maximum tensile modulus was determined using the maximum linear fit, as further described below, and the average was reported. 【0151】 The maximum linear fit was determined by importing raw data from the tensile testing machine into a data analysis program. 【0152】 The zero strain point for each sample was established as follows: At each data point of the tensile test, it was determined whether the load exceeded twice the standard deviation of the baseline zero force measurement. A sample was determined to be under stress when a series of five data points met this criterion. The last data point preceding this series of data points was established as the zero strain point. 【0153】 The tensile modulus is the slope of the stress / strain plot. The tensile modulus was calculated by performing a series of linear fits of stress vs. strain for continuous groups of 5 data points collected by a tensile testing machine, starting from a strain of 0. A specific group of linearly fitted continuous data with the maximum slope was selected as the maximum tensile modulus. Three samples were tested in each orthogonal direction (e.g., longitudinal and transverse directions), and the average for each was reported. The larger of the two average maximum tensile moduli determined for the two orthogonal directions was assigned as the maximum tensile modulus for the first direction. The smaller of the two average maximum tensile moduli determined for the two orthogonal directions was assigned as the maximum tensile modulus for the second direction. 【0154】 Geometric mean modulus of elasticity: 【0155】 Next, the geometric mean of the maximum tensile modulus determined by the maximum linear fit described above for each membrane was calculated using the following formula. 【0156】 Geometric mean modulus = square root {(maximum tensile modulus in the longitudinal direction) * (maximum tensile modulus in the transverse direction)} 【0157】 Balance ratio of maximum tensile modulus 【0158】 The balance ratio of the maximum tensile modulus was calculated using the following formula. 【0159】 Elastic modulus balance ratio = (absolute maximum value of the maximum elastic modulus in one direction) / (value of the maximum elastic modulus in the direction perpendicular to the direction in which the maximum elastic modulus is maximized) 【0160】 Transmission loss testing before and after pressure testing: 【0161】 The sample assembly underwent the following pressure test procedure. The purpose of this test was to reproduce the pressure on the membrane assembly within the device submerged in a given depth of water for a given time. Transmission loss was measured before the pressure test and then remeasured 24 hours after the pressure test. The change in transmission loss (dB) due to the pressure test was calculated by subtracting the transmission loss before the test from the transmission loss after the test. 【0162】 Biaxial pressure test 【0163】 The biaxial out-of-plane displacement of the membrane caused by pneumatic or hydrostatic stress was measured by adding a single-point laser (Keyence CCD laser displacement sensor LK-G32) to track the vertical deflection at the center of the membrane, based on the test method described in ASTM D3786 / D3786M-13 Bursting Strength of Textile Fabrics. To measure the displacement of the membrane under applied challenge pressure, a flat sheet of composite material was inserted into an FR4-membrane-FR4 coupon sandwich with a 1.6 mm diameter orifice using pressure-sensitive adhesive (tesa® 4983), and the entire assembly was held in place by a metal fixture with a metal top plate having a 1.6 mm orifice. The top plate was secured with screws. The metal fixture was connected to a pressure vessel containing air. The pressure vessel was connected to a control box with programmable functions that allowed for pressure gradient and air pressure control. The control box was programmed to increase the inflow pressure at a rate of 1.0 psi / second until a maximum pressure of 14.5 psi was reached. This target pressure (e.g., 14.5 psi) represents the industry standard 10-meter water immersion depth grade. The sample is held at the target pressure for 30 minutes, followed by a 60-minute release of pressure. A single-point laser is positioned at the center of the material during the protocol to evaluate out-of-plane displacement both during the 30-minute pressurization phase at 14.5 psi and during the 60-minute recovery phase after the pressure has been released from the test sample. The ratio of the deflection value of the film at the center point at the end of the 60-minute relaxation phase to the maximum deflection value achieved under pressurization is defined as % elastic recovery. 【0164】 Figure 4 shows an example of a pressure test setup. The "pressure test" can be performed by placing the sample membrane 100 between two rigid supports 102 and 104. Then, either air or water pressure can be applied to the membrane at a selected level. The center height of the dome 106 produced by the applied pressure can be measured, for example, using a Keyence laser displacement meter. For example, the pressure test may include applying an air or water pressure of 1 bar to the membrane 100 for 30 minutes. Once this period is complete, no more pressure is applied, and the membrane 100 can return to its original state. [Examples] 【0165】 Non-restrictive examples 【0166】 One method for producing porous polyethylene membranes is by a wet or gel process. In this process, polyethylene is mixed with a hydrocarbon liquid and other additives. This mixture is heated over a polymer molten mass and extruded into a sheet. This sheet is then biaxially oriented before and / or after the hydrocarbon liquid is extracted to produce a microporous membrane. Details of various processes are known, for example, in U.S. Patents No. 5,248,461, No. 4,873,034, No. 5,051,183 and No. 6,566,012, each of which is incorporated herein by reference in its entirety. Additional discussions include "Casting and stretching of filled and unfilled UHMW-polyethylene films," Ir.FH Assinck, Centre for polymers and composites, Eindhoven University of Technology, Nov 1995, and "(Porous Biaxially, drawn UHMWPE Films), HM Fortuin, DSM Research BV, Department of Materials Technology - Fifth Int. Conf. of Environmental Ergonomics). 【0167】 Tables 1 and 2 below show the characteristics of the films from nine examples (Examples 1-9) and four comparative films (Comparative Examples 1-4). Examples 1-9 all utilized polyethylene films and showed low acoustic transmission loss after 24 hours of pressure testing (as shown in Table 3). Conversely, Comparative Examples 1-4 showed high acoustic transmission loss after 24 hours of pressure testing. 【0168】 The sample assemblies and comparative sample assemblies described and tested herein were prepared as follows: 【0169】 All example sample assemblies and comparative sample assemblies consist of a glass fiber sample carrier supported by two adhesives used to construct a sandwich containing a flat sheet membrane. Hereafter, this will simply be referred to as the glass fiber sample carrier. The glass fiber sample carrier was prepared by applying double-sided pressure-sensitive adhesive (tesa® 4983) to one side of a glass fiber sheet (commercially purchased from McMaster-Carr, product number 1331T37). The glass fiber / adhesive sheet was then laser-cut to create coupons. Next, a 1.5 mm diameter hole was created in the center, aligned with the lumen of the impedance tube, and the hole corresponds to the active region of the sample to be measured. 【0170】 A film piece placed within a four-sided rectangular cardboard frame is partially cut away from two adjacent sides of the frame to relieve residual tension, and the film is placed on a smooth, horizontal surface so that it is flat and wrinkle-free. An adhesive release liner was peeled from a precut glass fiber sample carrier to expose the adhesive. With the adhesive layer exposed, the sample carrier was gently placed on the film, and the excess film was cut away from around the sample carrier. Next, the sample carrier was placed on an alignment jig with the film side up. The release liner was removed from a second glass fiber sample carrier and placed on the alignment jig with the adhesive side down and facing the film. Light (i.e., manual) pressure was applied to bring the lower sample carrier and the upper sample carrier together to form an assembly having a stack structure of glass fiber sample carrier / adhesive / film / adhesive / glass fiber sample carrier. 【0171】 Example 1 【0172】 A gel-treated ultra-high molecular weight polyethylene (UHMWPE) membrane having a mass / area of 2.44 g / m 2 , a bubble point of 148 psi, an air flow rate of 4.9 L / hr (12 mbar, 2.99 cm 2 ), a thickness of 9.6 microns, a porosity of 73%, a surface area per volume of 65 [10 6 / m], a maximum tensile strength in the first direction of 280 MPa, a maximum tensile strength in the second direction (orthogonal to the first direction) of 241 MPa, a tensile modulus in the first direction of 623 MPa, and a tensile modulus in the second direction of 509 MPa. 【0173】 Example 2 【0174】 A gel-treated UHMWPE membrane having a mass / area of 2.63 g / m 2 , a bubble point of 148 psi, an air flow rate of 3.8 L / hr at 12 mbar and 2.99 cm 2 , a thickness of 9.6 microns, a porosity of 70.9%, a surface area per volume of 59.1 [10 6It has a maximum tensile strength of 240 MPa in the first direction, a maximum tensile strength of 216 MPa in the second direction (perpendicular to the first direction), a tensile modulus of elasticity of 452 MPa in the second direction, and a tensile modulus of elasticity of 386 MPa in the second direction. 【0175】 Example 3 【0176】 A gel-treated film having an oleophobic coating was applied by exposing the film of Example 2 to a mixture of 0.5% FluoroPel 800 perfluoroalkyl copolymer (supplier: Cytonix) and 3M Fluorinert Liquid FC-84 (supplier: 3M) and drying it in a convection oven at 80°C for approximately 15 minutes. The coated film had a mass / area of ​​2.60 g / m². 2 Bubble point 178 psi, 12 mbar and 2.99 cm 2 Airflow rate 1.7 L / hr, thickness 8.8 microns, porosity 68.6%, surface area per unit volume 47.8 [10 6 It has the following characteristics: a maximum tensile strength of 234 MPa in the first direction, a maximum tensile strength of 192 MPa in the second direction, a tensile modulus of elasticity of 578 MPa in the first direction, and a tensile modulus of elasticity of 420 MPa in the second direction. 【0177】 Example 4 【0178】 A gel-treated UHMWPE film with a mass / area of ​​2.63 g / m². 2 Bubble point 148 psi, 12 mbar and 2.99 cm 2 Airflow rate 3.8 L / hr, thickness 9.6 microns, porosity 70.9%, surface area per unit volume 59.1 [10 6 It has a maximum tensile strength of 240 MPa in the first direction, a maximum tensile strength of 216 MPa in the second direction, a tensile modulus of elasticity of 452 MPa in the first direction, and a tensile modulus of elasticity of 386 MPa in the second direction. 【0179】 Example 5 【0180】 A gel-treated UHMWPE film with a mass / area of ​​3.85 g / m². 2Bubble point 135 psi, 12 mbar and 2.99 cm 2 Airflow rate 3.8 L / hr, thickness 12.6 microns, porosity 67.4%, surface area per unit volume 62.9 [10 6 It has a maximum tensile strength of 267 MPa in the first direction, a maximum tensile strength of 225 MPa in the second direction, a tensile modulus of elasticity of 594 MPa in the first direction, and a tensile modulus of elasticity of 499 MPa in the second direction. 【0181】 Example 6 【0182】 A gel-treated UHMWPE film with a mass / area of ​​3.83 g / m². 2 Bubble point 135 psi, 12 mbar and 2.99 cm 2 Airflow rate 3.1 L / hr, thickness 12.6 microns, porosity 67.5%, surface area per unit volume 59.8 [10 6 It has a maximum tensile strength of 328 MPa in the first direction, a maximum tensile strength of 190 MPa in the second direction, a tensile modulus of elasticity of 442 MPa in the first direction, and a tensile modulus of elasticity of 279 MPa in the second direction. 【0183】 Example 7 【0184】 A gel-treated film having an oleophobic coating was applied by exposing the film of Example 6 to a mixture of 0.5% FluoroPel 800 perfluoroalkyl copolymer (supplier: Cytonix) and 3M Fluorinert Liquid FC-84 (supplier: 3M) and drying it in a convection oven at 80°C for approximately 15 minutes. The coated film had a mass / area of ​​2.60 g / m². 2 Bubble point 165 psi, 12 mbar and 2.99 cm 2 Airflow at 2.2 L / hr, thickness 13.6 microns, porosity 69.7%, surface area per unit volume 49.6 [10 6 It has the following characteristics: a maximum tensile strength of 277 MPa in the first direction, a maximum tensile strength of 150 MPa in the second direction, a tensile modulus of elasticity of 460 MPa in the first direction, and a tensile modulus of elasticity of 356 MPa in the second direction. 【0185】 Example 8 【0186】 A gel-treated UHMWPE film with a mass / area of ​​3.83 g / m². 2 Bubble point 135 psi, 12 mbar and 2.99 cm 2 Airflow rate 3.1 L / hr, thickness 12.6 microns, porosity 67.5%, surface area per unit volume 59.8 [10 6 It has a maximum tensile strength of 328 MPa in the first direction, a maximum tensile strength of 190 MPa in the second direction, a tensile modulus of elasticity of 442 MPa in the first direction, and a tensile modulus of elasticity of 279 MPa in the second direction. 【0187】 Example 9 【0188】 A gel-treated UHMWPE film with a mass / area of ​​2.5 g / m². 2 Bubble point 177 psi, 12 mbar and 2.99 cm 2 Airflow rate 2.5 L / hr, thickness 6.1 microns, porosity 57.1%, surface area per unit volume 64.7 [10 6 It has a maximum tensile strength of 306 MPa in the first direction, a maximum tensile strength of 155 MPa in the second direction, a tensile modulus of elasticity of 910 MPa in the first direction, and a tensile modulus of elasticity of 428 MPa in the second direction. 【0189】 Comparative Example 1 【0190】 The same gel-treated film as in Example 1 was heated at 120°C for 180 seconds while constrained in both the longitudinal and transverse directions using a twin-axis pantograph machine. The sample was then shrunk in the transverse direction at a rate of 2% / second to 85% of its initial length. The final properties were a mass / area of ​​3.3 g / m². 2 , 12 mbar and 2.99 cm 2 Airflow rate 2.5 L / hr, thickness 8.4 microns, porosity 58.2%, surface area per unit volume 34.9 [10 6 It has a maximum tensile strength of 264 MPa in the first direction, a maximum tensile strength of 169 MPa in the second direction, a tensile modulus of elasticity of 511 MPa in the first direction, and a tensile modulus of elasticity of 254 MPa in the second direction. 【0191】 Comparative Example 2 【0192】 The same gel-treated film as in Example 2 was heated at 120 °C for 180 seconds while being constrained in both the longitudinal and transverse directions using a biaxial pantograph machine. Subsequently, the sample was contracted in the transverse direction at a rate of 2% / second to 85% of its initial length in that direction. The final properties were a mass / area of 3.24 g / m 2 , a bubble point of 118 psi, 12 mbar, an air flow rate of 4.7 L / hr at 2.99 cm 2 , a thickness of 9.8 microns, a porosity of 64.8%, a surface area per volume of 38.3 [10 6 / m], a maximum tensile strength of 289 MPa in the first direction, a maximum tensile strength of 196 MPa in the second direction, a tensile modulus of elasticity of 655 MPa in the first direction, and a tensile modulus of elasticity of 323 MPa in the second direction. 【0193】 Comparative Example 3 【0194】 The same gel-treated film as in Example 2 was heated to 120 °C for 180 seconds while being constrained in both the longitudinal and transverse directions using a biaxial pantograph machine. The final properties were a mass / area of 2.6 g / m 2 , a bubble point of 123 psi, 12 mbar and an air flow rate of 4.5 L / hr at 2.99 cm 2 , a thickness of 7.4 microns, a porosity of 62.9%, a surface area per volume of 36.3 [10 6 / m], a maximum tensile strength of 270 MPa in the first direction, a maximum tensile strength of 172 MPa in the second direction, a tensile modulus of elasticity of 787 MPa in the first direction, and a tensile modulus of elasticity of 752 MPa in the second direction. 【0195】 Comparative Example 4 【0196】 A mass / area of 10.7 g / m 2A commercially available gel-treated lithium-ion battery separator film (Gelon LIB Group, China) with a thickness of 16 microns, a longitudinal matrix tensile strength of 28,800 psi, and a transverse MTS of 23,600 psi was placed in a twin-axis pantograph machine. The starting film was heated to 125°C for 180 seconds while constrained in both directions. The sample was then expanded transversely and longitudinally at a rate of 1% / second to a ratio of 3:1 in each direction. The final properties were a mass / area of ​​1.63 g / m². 2 Bubble point 95 psi, 12 mbar and 2.99 cm 2 Airflow rate 16 L / hr, thickness 6.2 microns, porosity 72.1%, surface area per unit volume 48.4 [10 6 It has a maximum tensile strength of 394 MPa in the first direction, a maximum tensile strength of 317 MPa in the second direction, a tensile modulus of elasticity of 1265 MPa in the first direction, and a tensile modulus of elasticity of 890 MPa. [Table 1] [Table 2] [Table 3] 【0197】 As can be seen from Table 3, the transmission loss in Comparative Examples 1-4 was higher than that in Examples 1-9 of the present invention. 【0198】 Other purposes and advantages of this disclosure, among those disclosed, will become apparent from the following description made in conjunction with the accompanying drawings. While detailed embodiments of this disclosure are disclosed herein, the disclosed embodiments are merely illustrative of the various forms in which this disclosure may be embodied. Furthermore, the examples given with respect to various embodiments of this disclosure are illustrative and not limiting. 【0199】 Throughout this specification and the claims, the following terms have the meanings expressly associated herein unless the context clearly indicates otherwise. When used herein, the phrases “in one embodiment,” “in an embodiment,” and “in several embodiments” may refer to the same embodiment, but not necessarily the same embodiment. Furthermore, when used herein, the phrases “in another embodiment” and “in several other embodiments” may refer to a different embodiment, but not necessarily a different embodiment. All embodiments of this disclosure are intended to be combined without departing from the scope or spirit of this disclosure. 【0200】 All prior patents, publications, and test methods referenced herein are incorporated in their entirety by reference. 【0201】 The terms used herein are intended to describe, and not limit, embodiments. The terms “a,” “an,” and “the” include the plural form unless otherwise specified. The terms “comprises” and / or “comprising,” when used herein, specify the presence of the described functions, integers, processes, operations, elements, and / or components, but do not exclude the presence or addition of one or more other functions, integers, processes, operations, elements, and / or components. 【0202】 It should be understood that detailed modifications are possible, particularly with respect to the shape, size, and arrangement of the constituent materials and components used, without departing from the scope of this disclosure. The embodiments described herein and described herein are examples, and the true scope and spirit of this disclosure are shown by the following claims.

Claims

[Claim 1] Polyethylene membrane, An assembly comprising an acoustic device including, The polyethylene membrane has a first direction and a second direction, the second direction being perpendicular to the first direction. It has a thickness of 0.5 μm to 14 μm, where the thickness defines the thickness direction, and the first direction and the second direction are perpendicular to the thickness direction, At least 39 x 10 ６ Having a surface area per unit volume of / m, It has a geometric mean tensile modulus of 350 to 650 MPa. It has a maximum tensile modulus in the first direction of 440 to 915 MPa, and Having a maximum tensile modulus in the second direction of 275 to 515 MPa, assembly. [Claim 2] The assembly according to claim 1, wherein the acoustic device is one of a speaker, a microphone, or any combination thereof. [Claim 3] The assembly according to claim 1 or 2, wherein the acoustic device has an average transmission loss (dB) that changes by less than 2.1 dB when tested using a WEP test 24 hours after a 1-bar open hall challenge at 3 kHz. [Claim 4] The assembly according to claim 1 or 2, wherein the polyethylene film has a tensile modulus balance of 1 to 2.

1. [Claim 5] The assembly according to claim 1 or 2, wherein the polyethylene film has a porosity of 50% to 95%. [Claim 6] The assembly according to claim 1 or 2, wherein the polyethylene film has a porosity of 55% to 86%. [Claim 7] The assembly according to claim 1 or 2, wherein the recovery percentage after one hour of a 1-bar open hole challenge is at least 69%. [Claim 8] The assembly according to claim 1 or 2, wherein the polyethylene film has bubble points ranging from 7 psi to 200 psi. [Claim 9] The polyethylene film is 1 x 10 －１５ I understand ２ ~8 x 10 －１５ I understand ２ The assembly according to claim 1 or 2, having the transparency of the specified value. [Claim 10] The polyethylene film has a permeability of 3×10 －１６ m ２ to 7.4×10 －１５ m ２ and is the assembly according to claim 1 or 2. [Claim 11] The assembly according to claim 1 or 2, wherein the polyethylene membrane is a stretched polyethylene membrane. [Claim 12] The assembly according to claim 1 or 2, wherein the maximum tensile modulus in the first direction is greater than the maximum tensile modulus in the second direction. [Claim 13] The assembly according to claim 1 or 2, wherein the first direction is one of the longitudinal direction and the transverse direction of the polyethylene film, and the second direction is the other of the longitudinal direction and the transverse direction of the polyethylene film. [Claim 14] The tensile modulus is the slope of a stress / strain plot, where the tensile modulus is calculated by performing a series of linear fittings of stress versus strain on a continuous group of five data points collected by a tensile testing machine, starting from a strain of zero, and selecting a particular group of linearly fitted continuous data with the greatest slope as the maximum tensile modulus; testing three samples in each orthogonal direction (e.g., longitudinal and transverse), reporting the average of each, where the larger of the two average maximum tensile moduli determined for the two orthogonal directions is assigned as the maximum tensile modulus in the first direction, and the smaller of the two average maximum tensile moduli determined for the two orthogonal directions is assigned as the maximum tensile modulus in the second direction, according to claim 1 or 2.

Images