Transparent, Lightweight, and High Strength Polyethylene Films by a Scalable Continuous Extrusion and Solid‐State Drawing Process

Abstract

The continuous production of transparent high strength ultra-drawn highdensity polyethylene films or tapes is explored using a cast film extrusion and solid-state drawing line. Two methodologies are explored to achieve such high strength transparent polyethylene films; i) the use of suitable additives like 2-(2H-benzotriazol-2-yl)-4,6-ditertpentylphenol (BZT) and ii) solid-state drawing at an optimal temperature of 105 °C (without additives). Both methodologies result in highly oriented films of high transparency (≈91%) in the far field. Maximum attainable modulus (≈33 GPa) and tensile strength (≈900 MPa) of both types of solid-state drawn films are similar and are an order of magnitude higher than traditional transparent plastics such as polycarbonate (PC) and poly(methyl methacrylate). Special emphasis is devoted to the effect of draw down and pre-orientation in the as-extruded films prior to solid-state drawing. It is shown that pre-orientation is beneficial in improving mechanical properties of the films at equal draw ratios. However, pre-orientation lowers the maximum attainable draw ratio and as such the ultimate modulus and tensile strength of the films. Potential applications of these high strength transparent flexible films lie in composite laminates, automotive or aircraft glazing, high impact windows, safety glass, and displays.

Stereocomplex Polylactide for Drug Delivery and Biomedical Applications: A Review

“…Numerous processing methods have been developed to improve the strength of the polymers. Many studies have demonstrated that solid-state drawing (SSD) can induce self-reinforcement through the maximization of macromolecular chain orientation in polymeric materials [ 80 , 81 , 82 ]. Im et al (2016, 2017) determined that the tensile strengths of PLLA monofilaments and films could be increased up to two- and nine-fold, respectively, by increasing the draw ratio using a directly designed processing machine for the SSD method ( Figure 17 a) [ 83 , 84 ].…”

State of the‐Art for Extrudate Swell of Molten Polymers: From Fundamental Understanding at Molecular Scale toward Optimal Die Design at Final Product Scale

“…In this technique, as shown in Figure 1a, polymer melts are forced through a (capillarity/slit) die or nozzle to obtain a final polymeric product with a certain 3D profile. [1][2][3][4][5][6][7] In general, the dimensions of the extrudate do not correspond well to the profile of the die or nozzle exit. This phenomenon, which is often denoted as extrudate swell, die swell, or the Barus effect, is considered as a flow instability of polymer melts.…”

Transparent semi‐crystalline polymeric materials and their nanocomposites: A review

“…[77,100] In addition, the scalable and continuous production of these highly oriented transparent HDPE films without additives could be accomplished on a continuous cast film extrusion and solid-state stretching line. [101] These films also possess a high transmittance of~91% in combination with a high Young's modulus of 33 GPa and tensile strength of 900 MPa. Furthermore, high performance transparent unidirectional and cross-ply composite laminates based on these transparent drawn HDPE films sandwiched between either glass or PC sheets were successfully fabricated with a good combination of high optical transparency, good tensile properties and penetration resistance.…”