CA2953375A1

CA2953375A1 - Device and method for the making of polymeric films with controlled thickness, and polymeric films thereof

Info

Publication number: CA2953375A1
Application number: CA2953375A
Authority: CA
Inventors: Ata TAGHIZADEH; Simon Gilbert St-Pierre
Original assignee: Solmax International Inc
Current assignee: Solmax International Inc
Priority date: 2017-01-03
Filing date: 2017-01-03
Publication date: 2018-07-03
Also published as: WO2018126309A1

Abstract

Described herein are polyethylene geomembrane liners having a peripheral longitudinal welding edge. The thickness of the any longitudinal strip at desired position is controlled with a method and a device in contact with the molten polymer that provides rapid cooling. This thickened strip can be in the peripheral longitudinal edges. The apparatus is positioned above the die of a blown film extrusion line and before the solidification point of molten polymer. The device and method of using it described herein can be used to control the thickness of any type of plastic films in blown film process to improve physical mechanical properties at some parts of the films or simply in the full width of the film.

Description

File number: 12391-006 Date: 01-03-2017 DEVICE AND METHOD FOR THE MAKING OF POLYMERIC FILMS WITH
CONTROLLED THICKNESS, AND POLYMERIC FILMS THEREOF
Field of the Invention [0001] The present invention belongs to the field of polymeric material, and generally relates to an apparatus and method for cooling a relatively thick polymer after die exit in blown film processing.
Background of the Invention

[0002] Polyethylene geomembranes are used extensively as a part of liquid containment systems in different applications such as in modem landfills or heap leach in mining industry. In all those applications the geomembrane is part of a system including geotextile and/or geosynthetie clay liner (GCL) as well as geomembranes. The integrity of this lining system is dependent on the cohesion between the different layers. Since the regular gluing mechanism cannot be used for this application with all the chemicals used and the big scale of the work, that integrity depends on the friction between the layers.
The surface of the geomembranes can be texturized to increase friction via different methods such as US4885201, US5403126 and US5258217.

[0003] There are different methods for producing polymeric films namely Cast film process and blown film process. In the latter process, the molten polymer is pushed into a die with annular die-exit where it forms a tube being pulled upward by the winders. The die exit is equipped with high efficiency high pressure air cooling system which blows cool air on the surface of the film from both sides to cool down the polymer and freeze the molecular structure as early as possible. The efficiency of the cooling system will determine the final properties of the film. The tube diameter and film thickness are controlled by blow-up and take-up ratios.

[0004] Today most of the Polyethylene geomembranes are made in three layers by co-extrusion, similar to the trend in food packaging film industry. Multilayer structure provides the possibility to customise the product for different applications.
One of the advantages of multilayer structure is using different materials in the core and skin layers to get the benefits of both materials such as HD/LL/HD combination (Cahpter 3, HDPE
Geomembranes; in A Guide to Polymeric Geomembranes, John Schiers, 2009, John File number: 12391-006 Date: 01-03-2017 Wiley & Sons). Another very important benefit of multilayer structure is the possibility of texturizing the skin layers without affecting the physical-mechanical properties of the thick core layer. JD Green (US5763047) introduces a method of texturizing the surface layer of the geomembranes with nitrogen or any other blowing agent. This dissolved blowing agent bursts into projections on the surface of the film at the die exit due to the sudden pressure drop. This phenomenon results in randomly textured surface.

[0005] Though textured surface brings a great advantage but it imposes some difficulty to the installations. In-field installations by fusion welding technic can be very problematic with textured surfaces. In order to solve that problem, a technique is provided to reduce texturizing the surface at the overlap edges where most of the welding is applied (US5804112). In this technique the flow of outer layers is simply blocked at the die to provide a peripheral edge. So at the peripheral edge a pretty easy welding can be performed.

[0006] When blocking the skin layers at the die exit, due to the lower thickness and higher stress concentration on the peripheral edge region a necking phenomenon (i.e.
reducing the thickness or Thinning) occurs at that part. Then the resulted thin areas act as weak points and cannot pass the norms of the industry (GRI GM 13) which specifies that minimum thickness should be 10% below the average thickness. This phenomenon is more pronounced in some specific surfaces such as the liners with electrically conductive layer (hereafter, "conductive liner") (US 5288168), where the necking problem becomes so pronounced that it can make the peripheral edges up to around 15% thinner than the nominal thickness of the geomembrane in both smooth and textured surfaces.
Consequently they have to trim the peripheral edge which brings the difficulty of welding afterwards. The conductive layer poses a lot of complexity to the welding process to a point that GSE Lining Inc. has introduced a very special welding machine for this kind of material (US9033620B2). And obviously it increases the cost of finished geomembranes lined systems considerably, plus the troubles of working with that machine for the welders.

[0007] To better control the thickness of the films, many attempts have been observed so far, especially in thin film industry. H.Upmeier (US4339404) proposed to install a thickness controlling sensors over the entire perimeter of the tube. These sensors will File number: 12391-006 Date: 01-03-2017 measure the thickness at each spot and then adjust the cooling capacity at the die exit (temperature and pressure of air jets) based on the film thickness profile.

[0008] In some other cases, some researchers have tried to impose some unbalanced thickness profile to the film due to the requirements in some specific applications such as tie bags (US6139186). This is achieved by increasing the cooling capacity of the air jets at the proper positions to freeze in earlier and get thicker material. But this is not always feasible for every film thicknesses (higher thicknesses would not be easily changed by air cooling capacity). Additionally, it requires permanent changes in the die and cooling capacity (air rings).

[0009] Another recent patent (US9193107) is on using an apparatus for differential cooling of the plastic film where they are using throttling valves to spray a fluid (water) on specific areas of the thin films (less than 20 mil). Obviously it has some advantages, such as not needing to modify the whole die structure and effective cooling as per their claims. But on the other hand, it involves some other disadvantages e.g. it would not be as efficient in thicker films such as geomembranes (20 to 100 mils).
Additionally, the amount of evaporated steam for an effective cooling is remarkable and may make a mess in the die exit to cool down that big diameter of a tube such as the geomembranes.

[0010] Another attempt has also been done to use a mandrel to cool down the film surface at the die exit. But since it is installed in the inner part, it is problematic to use this system. Since there is no access and/or direct control over the cooling piece or film surface structure until the film is out of the winders and inversed to observe the effect.

[0011] So there is obviously a need to adjust the thickness of the geomembranes in blown film process to be able to provide a thick enough of peripheral edge to pass the standards of the industry and fulfill the mechanical properties requirements at the welded edges.

[0012] It is also known in the industry that faster cooling of the films will cause less crystallinity and lower molecular orientation (more isotropic),and consequently, more isotropic mechanical properties and higher Environmental Stress Cracking Resistance (ESCR) in the geomembranes. Efficient cooling system will then be of various benefits to the industry of geomembranes.

File number: 12391-006 Date: 01-03-2017 Summary of the Invention

[0013] This invention is directed to multilayer geomembrane liner of N layers, N>2, where there is an accurate control of the film thickness at all parts, especially in the textured geomembranes and more specifically at the edges of the textured geomembranes.

[0014] The invention is directed to the multilayer polyethylene films having N
layers where N>2; where each layer can be made of different kind of polyethylene such as, but not limited to: High density Polyethylene (HDPE), Medium Density Polyethylene (MDPE), linear low density Polyethylene (LLDPE), Low density polyethylene (LDPE) and Polyethylene for Raised Temperature (PERT) as well as thermoplastic elastomers (TPEs) or thermoplastic olefins (TP0s).

[0015] It is disclosed a new method and apparatus of cooling down the temperature of the film between the die exit and the frost line in the blown film to address various problems in the thickness variation and mechanical properties of the geomembranes.

[0016] It is disclosed a device for cooling a molten plastic film and form a thickened part of the plastic film, the device comprising: at least one solid element with controlled temperature adapted to be installed at a die exit of a polymer processing extruder and having a surface configured to be in contact with a surface of said molten plastic film, the device allowing controlled cooling of at least one surface of the molten plastic, wherein said cooling is performed through conduction heat exchange between the surface of said solid element and the surface of said molten polymer film.

[0017] In one embodiment, the process involves a well-known process of blown film where the molten polymer is pushed upward through an annular die and includes air rings right at the die exit on one or both sides to cool down the liner. In a customized distance from the die exit and well before the frost line, a solid object is installed in a way that its surface is in contact with the liner surface. The temperature of the solid object is controlled by a cooling liquid from the other side of the solid surface in a way that cooling fluid is not in contact with the geomembrane.

[0018] In some embodiments, the solid object is in the form of solid curved plate with a curvature adjusted to the bubble of blown film.

File number: 12391-006 Date: 01-03-2017

[0019] In some other embodiments, the solid object is a curved pipe of certain diameter having a flow of a working fluid inside to control the temperature.

[0020] In another embodiment of the invention, the plate is straight (not curved) and in contact with the film surface by pushing the film inward to achieve full contact.

[0021] A subset of the embodiments may include a second set of solid objects on top of the first set to stabilize the film temperature or to avoid a temperature shock and reduce residual stresses in the film for some sensitive materials or some specific thicknesses.

[0022] In some other embodiments, the cooling liquid is water to keep the temperature of the solid surface at a certain range. In some cases, this liquid can be an oil to avoid evaporation due to the heat exchange with the other side of solid surface being in contact with geomembrane hot surface.

[0023] Other and further aspects and advantages will be obvious upon an understanding of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.
Brief Description of the Drawings

[0024] The above and other aspects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which:

[0025] Figure 1 is showing the general simple concept of the blown film process cooled locally according to a preferred embodiment.

[0026] Figure 2 is a top view of the bubble and the plates according to a preferred embodiment..

[0027] Figure 3 is another setting for the solid object with two separate plates in contact with two parts of the film according to a preferred embodiment.

[0028] Figure 4 is another set up for the solid plate being a continuous plate in contact with the whole perimeter of the film acting equally on the whole surface of the film according to a preferred embodiment.

[0029] Figure 5 is a closer view of the cooling plate with the cooling liquid inlet and outlet according to a preferred embodiment.

File number: 12391-006 Date: 01-03-2017

[0030] Figure 6 is a view of the inside of the plate showing cooling channels and nuzzles plus the cooling liquid or gas flow-in and flow-out, according to a preferred embodiment.

[0031] Figure 7 is another set up the cooling plate where there are several cooling unit with different temperatures within one plate to control the temperature differentially according to a preferred embodiment.

[0032] Figure 8 is an illustrative representation of thick film product of this invention an its comparison with the existing products of the market.

[0033] Figure 9 is showing a few combinations of the thickened areas on the films that is possible via the method and device of this invention.
Detailed Description of the Preferred Embodiment

[0034] The films produced with this method may have an average thickness of preferably about 20 mils to about 120 mils. These films will be generally used in application related to, but not limited to, the geomembranes such as in primary and secondary containments of different liquids like water, leachate, slurry, sludge, tailings, pregnant solution, brine and similar or any other applications of geomembranes in the art.

[0035] The term "Peripheral Edge" means the parts of the film along the length of the film where is overlapped during installation to run fusion welding of two adjacent panels of films on or off the field. This can be from around 1 % to around 10% of the whole film width, and more specifically from 2% to 6% of the whole width of the film.

[0036] The surface texture of the films can be totally smooth or somehow textured. The film can be a monolayer or multilayer structure and each layer may or may not have the structure of the skin layer. In some cases, the skin layers are blocked in the die and the peripheral edges have the same structure and morphology as the core material.
In some other cases, it has the same structure as the rest of the film.

[0037] A novel product with accurate control on the peripheral edge thickness, a method and apparatus to adjust the thickness of the geomembrane film after the die exit and before the frost line will be described hereinafter. Although the invention is described in terms of specific illustrative embodiments, it is to be understood that the embodiments described herein are by way of example only and that the scope of the invention is not intended to be limited thereby.

File number: 12391-006 Date: 01-03-2017

[0038] A device for cooling a molten plastic film and form a thickened part of the plastic film is illustrated on Fig. 1.

[0039] The device 5 comprises at least one solid element with controlled temperature adapted to be installed at a die exit of a polymer processing extruder. The solid element has a surface configured to be in contact with a surface of said molten plastic film. The device allows controlled cooling of at least one surface of the molten plastic, wherein said cooling is performed through conduction heat exchange between the surface of said solid element and the surface of the molten polymer film.

[0040] Referring to Figure 1, the plastic is pushed out of the annular die 2 and blown to form a bubble or a tube 1 at a desired diameter. The air-rings 3 blow very high pressure air on the surface of the geomembrane from both sides (inside and outside).
There are various factors determining the thickness of the film including: the output of the die, air rings pressure inside and outside the bubble which forms the blow up ratio (BUP), pulling speed which produces take up ratio (TUR).

[0041] The cooling process is merely done by the high pressure air rings (air jets) blowing directly onto the film and cools down the film surface via convective heat transfer. Without introducing a permanent structural modification to the existing die and air ring structure, using any other convection method such as fluids or other gasses will not make a notable change in the efficacy of cooling due to the super high output rate of cooling air from the air-rings. So the main aspect of this invention is using the conduction heat exchange regime in order to quick drop of the film surface temperature to a desired temperature to avoid more necking at the specific spots or in the whole perimeter of the film tube.

[0042] In a first embodiment, a curved plate 5 or two curved plates 10, 11 (curved to the curvature of the film as illustrated on Fig. 2 or 3), or simply straight plate as illustrated on Fig. 1, is pushed towards the outer surface of the film 1, via a holder rod 9 attached to each plate, in a way that the two surfaces are completely in contact with each other.

[0043] As illustrated in detail on Figure 6, the temperature of each plate is controlled by a flowing liquid circulating within the plate(s): flow-in 6 and flow-out 7, via some channels and nuzzles inside the plate(s) or other side of the plate(s) 14. Upon touching the surface of the solid surface, the film surface temperature will rapidly drop to a certain value due File number: 12391-006 Date: 01-03-2017 to the conduction heat transfer phenomenon. The temperature profile can be constant at all of its surface profile of the plate or be differentially controlled to adjust the thickness accordingly 15. Fig. 7 shows different temperatures of the plates identified as Ti to T4.
The temperature of the plate is adjusted based on the thickness of the film, temperature of the melt, the desired thickness of that section and type of the resin. If there is a type of resin showing surface instability then either a second plate 16 can be installed above the first plate 5 and before the solidification of the polymer melt 4 and the temperature of the first said plate is increased to a value that does not produce instability and the said second plate will have lower temperature to conduct the heat transfer in longer distance. The whole purpose is to find the right temperature profile of the plate to result in desired thickness (see example).

[0044] In another embodiment of the invention, the plates are installed and put in contact with the peripheral edge of a smooth or textured multilayer geomembrane liner, in order to increase the thickness of the peripheral edges to values up to around 10%
above the average thickness of the rest of the film. In a more specific case, smooth or textured surfaces are electrically conductive to be used in leak detection technic (US5288168).

[0045] In another embodiment of the invention, the plate is cooled differentially, i.e.
different temperatures are set on the plate in order to produce a differential temperature profile for the customized control of the film thickness. These temperature profile zones can be horizontal or vertical to the machine direction of the film.

[0046] In another embodiment of this invention illustrated on Figures 4 or 5, instead of using a plate to locally adjust the thickness, this plates is installed all around the bubble, in a continuous 12 or discontinues 13 manner, to help decreasing the height of the frost line to a desired height. This will, consequently, reduce the crystalline content of the film and increase the anisotropy in the film properties. The secondary effect would be, but not limited to, better environmental stress cracking resistance (ESCR) properties.

[0047] In another embodiment of the inventions some parts of the peripheral edge are optionally heated to reduce the thickening effect on those specific spots for various purposes such as ease of trimming down the line.

File number: 12391-006 Date: 01-03-2017

[0048] The invention can also be directed to lined containment systems comprising at least one multilayer polyethylene (PE) geomembrane liner as defined in this method or made using the methods as defined herein.

[0049] In accordance with a preferred embodiment, this method can be used in any type of geomembranes in any type of processes to locally adjust the thickness of the geomembranes of different materials such as PVC, CSPE, fPP and similar.

[0051] Two rectangular plates of 20mm thick and 0.1 m2 surface area were prepared. A
cold water of 5 C was passed through the coils inside the plates. The plates were put in the configuration shown in Fig. 3 right after the air rings and well below the solidification of the molten polymer with a 5 cm distance from the middle of the peripheral edges.
While the temperature of the polymer right after the air rings is around 155 C, the surface temperature of the liner after the plates were down to around 120 C. But in the middle of the film where there are no plates, the temperature at the same position is around 148 C.
This shows a 28 C difference which is a considerable reduction in temperature.
This reduction increases the cooled areas thickness increase of about 20% above the average thickness of the rest of the film.
[0052] Figure 8 is a typical comparison of the existing products in the market for geomembranes, and the products of this invention. As it is observed, the existing products do not have the thick strips.
[0053] In Figure 9, some examples of the location of the thickened strips on the plastic film. It has to be mentioned that these locations are merely illustrative and for the purpose of the example, however, the mentioned thickened strips can be anywhere in the widths of the film in a continuous or separate way.
[0054] While illustrative and presently preferred embodiments of the invention have been described in detail hereinabove, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.

Claims

1. A plastic film having:
a. a main part formed of a film having an average thickness preferably of at least 0.254 mm thick across the width; and b. at least one area, preferably a longitudinal strip, having a thickness that is preferably at least about 5% higher than the average thickness of the main part.

2. A plastic film according to claim 1, wherein: the at least one longitudinal strip is located at a peripheral edge of the plastic film.

3. A plastic film according to claim 1 or 2, wherein both longitudinal peripheral edges of the film are oversized and have a thickness that is at least 5%
higher than the average thickness of the rest of the film.

4. A plastic film according to any one of claims 1 to 3, wherein the width of an oversized longitudinal peripheral edge ranges from about 1% to about 10% of the film width, preferably ranges from about 2% to about 6%.

5. A plastic film according to any one of claims 1 to 4, having two longitudinal peripheral oversized edges.

6. A plastic film according to any one of claims 1 to 5, wherein the shape of the peripheral edge, is such that the thickness reaches its maximum at the outer edge(s) of the smooth edges.

7. A plastic film according to any one of claims 1 to 6, wherein the at least longitudinal peripheral oversized edge is made of the same material of the sheet.

8. A plastic film according to any one of claims 1 to 7, wherein at least the thickness of one of the longitudinal strips is different from the other thickened strips.

9. A plastic film according to any one of claims 1 to 7, wherein the film is made from a natural or synthetic polymer, and is preferably made of at least one of the followings: High density Polyethylene (HDPE), Medium Density Polyethylene (MDPE), linear low density Polyethylene (LLDPE), Low density polyethylene (LDPE) and Polyethylene for Raised Temperature (PERT) as well as thermoplastic elastomers (TPEs) or thermoplastic olefins (TPOs), or any combination thereof.

10. A plastic film of any one of claims 1-8 wherein the plastic film is filled with any kind of fillers, micro-fillers or nano-fillers such as, but not limited to, short or long glass fibers, talk, fire retardants, Carbon black or conductive additives.

11. A plastic film of any one of claims 1-9, where the thickened areas are only in specific parts of the film, preferably on peripheral edges, more preferably in a discontinued way.

12. A plastic film of any one of claims 1 to 11, wherein the film is smooth at either or both sides of the film.

13. A plastic film of any one of claims 1 to 11, wherein the film is textured on one side or both sides of the film.

14. A plastic film of any one of claims 1 to 11, wherein the film is at least partly textured on at least one side of the film.

15. A plastic film of any one of claims 1 to 14, wherein the film is at least partially colored on at least one side of the film.

16. A plastic film of any one of claims 1 to 15, wherein the film is at least partially conductive on at least one side including or not the peripheral edges.

17. A plastic film, according to claims anyone of claims 1-16, wherein: the longitudinal strip is located anywhere in the width of the plastic film and/or in continuous or discontinuous manner.

18. A plastic film, according to anyone of the claims 1-17, wherein: the plastic film is a geomembrane liner, wherein the liner is used for waste containment, contaminated soil containment, fluid containment, mining containment, capping, secondary containment, dam, canal, fluid control.

19. A plastic film, according to anyone of the claims 1-18, wherein: the plastic film is composed of n layers where n>=2.

20. A plastic film, according to claim 19, wherein at least one layer is not conductive or partially conductive.

21. A plastic film, according to claim 19, wherein at least 2 layers are coextruded.

22. A plastic film, according to claim 19, wherein at least 2 layers are laminated on each other.

23. A plastic film, according to claim 19, wherein at least one layer is of a different thickness profile than the other layer(s).

24. A plastic film, according to claim 19, wherein at least one layer is made of a synthetic or natural polymer.

25. A plastic film, according to claim 24, wherein at least one layer is made of flexible non-polymeric material such as metallic films e.g. Aluminium or copper.

26. A plastic film, according to claim 25, wherein the film is a multilayer sandwich panel of one or more plastic layers and one or more metal layers like Aluminium to be used in construction applications, or laminated packaging film of similar structure in food packaging applications.

27. A roller made of a plastic film, according to any one of claims 1 to 26, rolled on a spool.

28. A device for cooling a molten plastic film and form a thickened part of the plastic film, the device comprising: at least one solid element with controlled temperature adapted to be installed at a die exit of a polymer processing extruder and having a surface configured to be in contact with a surface of said molten plastic film, the device allowing controlled cooling of at least one surface of the molten plastic, wherein said cooling is performed through conduction heat exchange between the surface of said solid element and the surface of said molten polymer film.

29. A device, according to claim 28, wherein the temperature of at least one part of the surface of the element in contact with the film is controlled in a way that the said heat exchange between said molten polymer surface and said surface of the solid element generates a thickening effect on at least one longitudinal strip.

30. A device, according to claims 28 and 29, wherein the surface of the solid element has a dimension of about a dimension of the thickened part of the molten plastic film to be obtained.

31. The device of any one of claims 28 to 30, wherein the solid element is a straight plate, preferably of the same size of longitudinal strip of a desired size or the whole perimeter of the film.

32. The device of any one of claim 28 to 30, wherein the solid element is a curved plate of a desired size.

33. The device of any one of claim 28 to 32, where there solid element is made of n sections, wherein each of the n sections are similar or different and connected or separated, the difference may be in surface temperature, in the size or in the form of the solid object to cover a strip or the whole perimeter of the film.

34. The device of any one of claim 29-33, wherein the device is static i.e.
not moving, or is moving or vibrating in any direction such as, but not limited to, rotating as in a calendar, moving up and down the machine direction (vertically) or moving in transverse direction (horizontally), in a continued or a discontinued manner.

35. The device of any one of claims 29 to 34, wherein the temperature of the solid object is controlled by a fluid or a gas flowing in the other side or inside the solid object to cool down the interface with the film.

36. The device of any one of claims 29 to 35, wherein the film has a thickness of <=
0.254 mm for different applications such as, but not limited to, food packaging, shopping bags, silage films, mulch film or shrink films.

37. The device of any one of claims 29 to 35, wherein the film has a thickness >=0.254 mm and preferably ranging from about 0.254 mm to 3 mm, and especially ranging from 0.5 mm to 2.5 mm used for various applications such as, but not limited to, geomembranes, caps and covers.

38. A method of adjusting the thickness of plastic film using the device of any one of claims 29 to 35, wherein the molten polymer, being pushed out of the die of a blown film process, comes in contact with the cooling surface of the said solid element, wherein the solid element is installed after the die exit and before the solidification of the molten plastic film and the temperature is adjusted in a way that it results in the desired thickness which is preferably at least 5%
higher in thickness than the average thickness of the film.

39. A method of claim 38, wherein both longitudinal peripheral edge being oversized and having a thickness that is at least 5% higher than the average thickness of the rest of the sheet.

40. A method of claim 38, wherein the width of an oversized longitudinal peripheral edge ranges from about 1% to about 10% of the film width, preferably ranges from about 2% to about 6%.

41. A method of claim 38, wherein the film has two longitudinal peripheral oversized edges.

42. A method of claim 38, wherein the shape of the peripheral edge, after cooling with the method mentioned in this invention, is such that the thickness reaches its maximum at about the outer edge of the smooth edges.

43. A method of claim 38, wherein the thickened strip of the molten polymer has undergone a morphological transformation resulting in different molecular structure such as different crystallinity and/or molecular orientation and/or density.

44. A method of claim 38, wherein the device is installed all around the perimeter of the film to affect the whole width of the final film.

45. A method of anyone of claims 38 to 44, wherein the film is made from a natural or synthetic polymer, and is preferably made of at least one of the followings:
High density Polyethylene (HDPE), Medium Density Polyethylene (MDPE), linear low density Polyethylene (LLDPE), Low density polyethylene (LDPE) and Polyethylene for Raised Temperature (PERT) as well as thermoplastic elastomers (TPEs) or thermoplastic olefins (TPOs), or any combination thereof.

46. A method of anyone of claims 38 to 44, wherein the thickened areas are only in certain spots of the film or peripheral edges in a discontinued way.

47. A method of anyone of claims 38 to 44, wherein the edges are characterized by a thickness of at least 5% higher than the average thickness of the rest of the film and with at least one edge which does not contain any conductive media.

48. A method of anyone of claims 38 to 44, wherein the film is smooth at either or both sides.

49. A method of anyone of claims 38 to 44, wherein the film is textured on one side or both sides.

50. A method of anyone of claims 38 to 44, wherein the film is colored on one or both sides.

51. A method of anyone of claims 38 to 44, wherein the liner is conductive on one side or both sides including or excluding the peripheral edges.

52. Any use of the polymeric film as defined in anyone of claims 1 to 26 or a polymeric film obtained by the device of any one of claims 28 to 37 or through the method defined in anyone of claims 38 to 44, in applications such as geomembrane liners, capping and covers, packaging films, shopping bags, shrink films, silage films and similar.