Abstract: A testing apparatus for obtaining mechanical properties of a polymer composite extruded from a nozzle of a compounding extruder includes a plurality of pairs of roller units that roll the polymer composite along a first direction. Each of the pairs of roller units includes a first roller unit and a second roller unit disposed such that a center of the first roller unit and a center of the second roller unit are separated by a predetermined distance in a second direction that is perpendicular to the first direction. The pairs of roller units are disposed along the first direction such that the predetermined distance of each of the pairs of roller units increases stepwise along the first direction. The pairs of roller units strain a vulnerable portion of the polymer composite in the second direction. The testing apparatus further includes a sensor that measures stress in the vulnerable portion.

Abstract: A method for forming an article includes providing a sheet of material, optionally conditioning the sheet with a surface of a roller, forming the sheet to provide a web, and separating an article from the web to provide the article. An apparatus adapted to form the article from a sheet is provided.

Abstract: A blown film coextrusion line includes a support frame, a plurality of extruders each mounted to the support frame and extending upward at an angle, and a downward facing blown film coextrusion die connected to distal ends of each of the plurality of extruders and receiving individual polymer streams from them. The blown film coextrusion line is compact and sturdy and eliminates much of the floor space and towered mounting structure that was required for conventional blown film coextrusion lines.

Abstract: In examples, a microcatheter includes an enhanced inner liner that has a low coefficient of friction and improved toughness, which facilitates delivery of expandable vascular reconstruction devices. The microcatheter may include a stretched polytetrafluoroethylene (PTFE) liner, which may be stretched longitudinally and not circumferentially or radially over at least a portion of a length of the microcatheter. The stretched PTFE inner liner may result in the reduction of a delivery friction and improved toughness and resistance to scraping.

Abstract: A method for making a heater is provided. A support and a flexible substrate are provided. The flexible substrate is stretched along a first direction and is fixed on a surface of the support. An adhesive layer is coated on a surface of the flexible substrate. One end of a carbon nanotube film is attached on the flexible substrate via the adhesive layer. The carbon nanotube film is wrapped around the support by whirling the support to form a carbon nanotube structure. The flexible substrate is separated from the support and shrinks along the first direction. At least two electrodes are electrically connected with the carbon nanotube structure. A voltage is applied between the at least two electrodes to heat the carbon nanotube structure. The carbon nanotube structure heats and solidifies the adhesive layer.

Abstract: A universal adapter for use with a consumable assembly that is configured for use with an additive manufacturing system, the universal adapter comprising an inlet opening configured to receive a guide tube of the consumable assembly, and a connection member at the outlet end, which is configured interface with a mating panel of the additive manufacturing system.

Abstract: The invention relates to a method and an apparatus for producing a film web made of thermoplastic material in which the thermoplastic material is extruded in at least one layer as plastic melt from a wide-slit nozzle in an extrusion direction and subsequently led away over at least roller, wherein tensile forces are exerted in the extrusion direction and transversely to the extrusion direction in order to stretch the film web longitudinally and transversely, wherein during application of the tensile forces in and transversely to the extrusion direction the film web has a temperature at least corresponding to the melting temperature of the same.

Abstract: A method of manufacturing a polyimide film includes: extruding a polyimide film including polyimide and a solvent; first drying the extruded polyimide film; stripping the first-dried polyimide film; second drying the stripped polyimide film to remove a residual solvent in the polyimide film; and stretching the second-dried polyimide film, wherein an amount of the residual solvent in the second-dried polyimide film is equal to or less than about 10 weight percent.

Abstract: A pleatable nonwoven material is provided, including thicker form-giving fibers and thinner fibers determining the filter effect, wherein the thinner fibers are incorporated largely homogeneously in the thicker fibers running in the direction along the surface of the nonwoven material and a distribution density gradient of the thinner fibers is established perpendicular to the surface of the nonwoven material such that the highest concentration of thinner fibers is in the region of the center or on one of the two outsides, wherein the thicker and thinner fibers are bonded together by solidification from the melted condition and are made from the same material.

Abstract: There is provided a device, and related method and uses, for drawing a polymer fiber, the device comprising: a. at least two polymer compartments, wherein each polymer compartment is capable of retaining a polymer solution, and wherein adjacent compartments comprise different polymer solutions; and b. a slider comprising at least one prong, wherein the prong is capable of contacting the different polymer solutions, and wherein the slider is arranged in a retractable manner from the at least two polymer compartments. There is further provided a system and a related method for manufacturing a polymer fiber.

Abstract: The present invention provides a method for producing a long stretched film, including at least the steps of: forming a long film containing a thermoplastic resin; stretching the long film in an oblique direction; and winding the long film having been subjected to the oblique stretching. The oblique stretching is performed in a heating section including a preheating section, a stretching section, and a thermosetting section, the preheating section and the stretching section are separated from each other by a partition wall. The stretching section and the thermosetting section are separated from each other by a partition wall, each of the partition walls has an opening for permitting the long film to pass, and slide members independently movable on the opposite sides of the opening and in widthwise directions of the long film, the slide members can adjust the width of the opening and the widthwise position of the opening.

Abstract: A device and a method for extending a film web along its longitudinal direction are described and claimed, in which the film web is guided in a travel direction over several rollers, and in which the film web is extended in at least one straining gap which is limited by at least two rollers operated with different circumferential speeds. It is considered novel and inventive that the web is provided with a temperature gradient, which extends in the direction perpendicular in reference to the longitudinal axis of the film web.

Abstract: Disclosed is a dual tenter clip and table assembly for moving, by means of an endless chain consisting of alternating pairs of first chain links and pairs of second chain links rotatably connected by pins arranged in parallel to the plane of a rail and perpendicular to the direction of the endless chain's movement, a polymer material web on a stretching plant or stretching device for stretching said polymer material web at least in a transverse direction.

Abstract: A melt spinning apparatus has an apparatus body, and the apparatus body includes a spinning nozzle through which a molten resin is extruded into a filament, a primary air channel for directing primary airflow to the filament of the molten resin extruded from the spinning nozzle, and a secondary air channel for directing secondary airflow to the filament at a position downstream of the primary air channel. A part, which is closer to the spinning nozzle, of a wall of the secondary air channel that defines an air exit of the secondary air channel is chamfered to straighten the secondary airflow.

Abstract: A polymeric fiber for use in gas separation is formed from a spin dope which includes solvent and non-solvent materials. The fiber is passed through a quench bath, and then a leach bath, in which the solvent and non-solvent are removed. The quench bath and the leach bath include sets of rollers which transport the fiber through the system. Each set of rollers in the leach bath operates at a speed which is greater than or equal to the speed of the rollers which are immediately upstream. Thus, the fiber is stretched, in different amounts, at the same time that the solvent and non-solvent are being removed, and while the fiber is still wet. The resulting fiber has been found to exhibit superior flux and selectivity properties.

Abstract: The present invention provides apparatus and methods for growing fullerene nanotube forests, and forming nanotube films, threads and composite structures therefrom. In some embodiments, an interior-flow substrate includes a porous surface and one or more interior passages that provide reactant gas to an interior portion of a densely packed nanotube forest as it is growing. In some embodiments, a continuous-growth furnace is provided that includes an access port for removing nanotube forests without cooling the furnace substantially. In other embodiments, a nanotube film can be pulled from the nanotube forest without removing the forest from the furnace. A nanotube film loom is described. An apparatus for building layers of nanotube films on a continuous web is described.

Abstract: A film processing apparatus includes a film delivery section and a film stretching section. The film stretching section is positioned downstream of the film delivery section. The film stretching section defines a first inlet and a first outlet. The film processing apparatus includes one or more slitting devices positioned between the first inlet and the first outlet.

Abstract: A spinneret for producing nanofibers from a viscous liquid using electrostatic spinning in an electric field is described. The spinneret includes one or more narrow annular bodies radially centered about and axially spaced along a central axis. The annular bodies may be discs, rings, or coils.

Abstract: Process for manufacturing carbon fibres, includes a first spinning step of a fibre of PAN precursor and a second oxidation/carbonization step of the fibre and the plant thereof. The spinning and oxidation/carbonization steps are performed directly in line and continuously, and hence without any stocking buffer area of a PAN precursor between the two steps. The spinning step is performed at low speed, so that the output speed from the spinning step, downstream of the stretching operations, is a speed falling within the range of the suitable processing speeds in the subsequent oxidation/carbonization step. Moreover, the spinning step is performed in a modular way on a plurality of spinning modules aligned in one or more rows, each spinning module having a productivity not above 10% of the overall productivity of the spinning step. In any individual spinning module, the fibres downstream of the spinning area follow zig-zag, rectilinear paths.

Abstract: An apparatus for a production of two-dimensional or three-dimensional fibrous materials of microfibers or nanofibers containing a set of spinning metal nozzles connected to a first potential, a set of electrodes of a collector facing the set of the nozzles, arranged at regular spacing and connected to a second potential, and a collecting plate or a collecting cylinder for collecting microfibers or nanofibers settled between couples of adjacent electrodes of the collector.

Abstract: Method for manufacturing an aerogel-containing composite, said method comprising the steps of: providing fibres, at least some of which are first fibres, such as mineral fibres, polymer fibres, cellulose fibres, or other types of fibres, in an amount of from 3 to 80 wt % of the total weight of starting materials, providing an aerogel particulate material in an amount of from 10 to 75 wt % of the total weight of starting materials, providing a binder in an amount of from 1 to 30 wt % of the total weight of starting materials, suspending the fibres in a primary air flow and suspending the aerogel particulate material in the primary air flow, thereby mixing the suspended aerogel particulate material with the suspended fibres, mixing the binder with the fibres and/or aerogel particulate material before, during or after mixing of the fibres with the aerogel particulate material, collecting the mixture of fibres, aerogel particulate material and binder and pressing and curing the mixture to provide a consolidated c

Abstract: A method and a device for producing a crimped multifilament thread are described. A multiplicity of filaments are extruded by means of a spinning machine, cooled and subsequently treated by a drawing device and a crimping device to form a crimped thread. Before the thread is wound up to form a bobbin, a multiplicity of intertwining knots is produced on the crimped thread by a treatment device. In order to obtain defined patterns of the intertwining knots within the thread, a pulse sequence of compressed air pulses at a predefined frequency is directed at the thread. The treatment device has a controllable blowing means.

Abstract: An injection nozzle for electrospinning including a first nozzle body and a second nozzle body detachably coupled with each other and nozzle members inserted in the first and second nozzle bodies and an electrospinning device using the nozzle. The electrospinning device basically performs air electrospinning wherein a source liquid for fiber is injected together with air while the source liquid for fiber is discharged through the nozzle members, and pure electrospinning without air injection can be efficiently carried out by separating the second nozzle body in such a manner that the lower ends of the nozzle members are exposed for a predetermined length or more. Therefore, according to the present invention, pure electrospinning, air electrospinning or hot air electrospinning may be selectively carried out.

Abstract: In an apparatus for the production of a non-woven fabric of filaments, where a plurality of filaments are extruded, cooled, stretched and collected on a mobile support, the means of collecting the filaments include furthermore, a gas permeable mobile support element (28), an aspirator (29) and one or more aspiration ducts (33C-36C), the collecting means being insulated from the environment air.

Abstract: A nonwoven fabric manufacturing apparatus has a spinning portion that spins fiber and an air delivery portion that blows air toward fiber spun out of the spinning portion. A roller is provided below the spinning portion. Fiber spun out of the spinning portion is blown onto the circumferential surface of the roller by the air blown out of the air delivery portion, so that nonwoven fabric is formed on the roller. A pair of guide plates is located below the roller. Entrained air flow is generated when the air blown out of the air delivery portion flows along the circumferential surface of the roller. Each guide plate interrupts and separates the entrained air flow from the circumferential surface of the roller.

Abstract: Provided is a method for manufacturing a high-quality porous film. Here, while the porous film is being manufactured through forming micropores by stretching, a raw film is prevented from slipping on the surfaces of the respective rolls as much as possible even though the raw film includes oil or liquid paraffin as a solvent. The method is for manufacturing a porous film through forming micropores by successive biaxial stretching. A tensile force applied to the raw film F transferring from the longitudinal stretching machine (10) to the transverse stretching machine (50) is set not less than a stretching force necessary for the longitudinal stretching, and thus the raw film is prevented from slipping on a contact surface between the raw film and each roll of the longitudinal stretching machine (10).

Abstract: The present disclosure relates to a method and use for immobilising Lepidopteran larvae and a method, device and use for forced silking from an immobilised Lepidopteran larva. A method for immobilising Lepidopteran larvae is disclosed which comprises paralysing the Lepidopteran larvae by at least one of transgenically expressing a polypeptide having paralytic effects in the Lepidopteran larvae, injecting hemolymph, wherein the hemolymph is drawn from Lepidopteran larvae and oxidised prior to the injecting, or injecting a natural or artificial polypeptide having paralytic effects.

Abstract: The present invention provides apparatus and methods for growing fullerene nanotube forests, and forming nanotube films, threads and composite structures therefrom. In some embodiments, an interior-flow substrate includes a porous surface and one or more interior passages that provide reactant gas to an interior portion of a densely packed nanotube forest as it is growing. In some embodiments, a continuous-growth furnace is provided that includes an access port for removing nanotube forests without cooling the furnace substantially. In other embodiments, a nanotube film can be pulled from the nanotube forest without removing the forest from the furnace. A nanotube film loom is described. An apparatus for building layers of nanotube films on a continuous web is described.

Abstract: A film stretcher that transports a film material in a predetermined transport direction while holding an end of the film material in a width direction of the film material to stretch the film material in the width direction includes a holding unit that includes a stretching roll having an annular groove formed on an outer periphery of the stretching roll and an endless wire fitted in the annular groove over a predetermined rotation angle range of the annular groove in a circular arc shape so that the end of the film material in the width direction of the film material is pinched. The stretching roll is inclined so as to open toward a downstream side in the transport direction of the film material. The holding unit transports the film material in the transport direction while pinching the film material using the stretching roll and the endless wire, whereby the film material is stretched in the width direction.

Abstract: An apparatus is configured to produce a spunbonded fabric. In order to achieve an airiness of the spunbonded fabric and ready adaptability to process parameters which are to be changed, a spinning beam together with a blowing apparatus is configured to be pivotable in a pivoting unit. A relatively high airiness is achieved by the filaments running obliquely onto the fabric belt below the spinning beam. Rotary leadthroughs or elastic feed lines to the spinning beam make the slight pivoting possible.

Abstract: The invention relates to an apparatus for treating a multifilament thread in a melt-spinning process, wherein a treatment channel is formed between a housing plate and an impact plate. The housing plate has a nozzle bore which opens into the treatment channel and is connected to a compressed-air connection. Together with the housing plate, the impact plate forms an inlet opening and an outlet opening at both ends of the treatment channel. In order to check the swirling effects which are produced on the thread by the eddying within the treatment channel, according to the invention the impact plate has a thread guiding element in the part piece of the treatment channel between the nozzle bore and the inlet opening, which thread guiding element is configured so as to protrude into the treatment channel in order to deflect the thread.

Abstract: The invention relates to a method and an apparatus for producing a film web made of thermoplastic material in which the thermoplastic material is extruded in at least one layer as plastic melt from a wide-slit nozzle in an extrusion direction and subsequently led away over at least roller, wherein tensile forces are exerted in the extrusion direction and transversely to the extrusion direction in order to stretch the film web longitudinally and transversely, wherein during application of the tensile forces in and transversely to the extrusion direction the film web has a temperature at least corresponding to the melting temperature of the same.

Abstract: An apparatus for manufacturing nonwoven fabric including a spinning nozzle, a fiber extension device, a receiver device and a sprinkler is provided. The spinning nozzle is filled with a spinning solution and has a plurality of spinners, where each of the spinners includes a spinning port and a main gas port surrounding the spinning port. The fiber extension device is disposed under the spinning nozzle and includes at least one secondary gas supply device. The secondary gas supply device has an arc gas distribution portion, such that the direction of gas ejected from the secondary gas supply device is the same as the direction of gas ejected from the main gas port. The receiver device is disposed under the fiber extension device. The sprinkler is disposed above the fiber extension device or the receiver device.

Abstract: An electrospinning apparatus for spinning polymer fibers from a fluid delivered by a jet supply device, which apparatus comprises at least one collector of a plurality of collectors in electrical communication with an electrode of the jet supply device. Collectors are insulated from each other. At least one collector comprises a stretcher adapted to stretch polymer fibers. The stretcher is an integral part of at least one collector. A controller controls sequence and time duration at which collectors are in electrical communication with the electrode of the jet supply device creating a non-woven polymer fabric or weaving polymer fibers into a fabric. The electrospinning apparatus comprises a rotator adapted to rotate the stretcher.

Abstract: One embodiment of the present invention provides a method for producing a stretched cellulose acylate film with an in-plane retardation, Re, of 100 nm or more and a relationship between the thickness direction retardation, Rth, and Re which satisfies Rth<(Re/2), by longitudinally stretching an unstretched cellulose acylate film in a longitudinal direction by pulling by means of a difference in circumferential velocity between a pair of rollers, wherein the method is characterized in that the cellulose acylate film is subjected to free-end uniaxial stretching to a longitudinal stretch ratio of 1 to 2 while the film is being heated in a heating oven installed between the pair of rollers at a stretching temperature in the range of Tc?10° C. to Tc+70° C., Tc being the crystallization temperature of the film, and with the temperature difference in the film width direction maintained within 10° C.

Abstract: Provided is a method for manufacturing a high-quality porous film. Here, while the porous film is being manufactured through forming micropores by stretching, a raw film is prevented from slipping on the surfaces of the respective rolls as much as possible even though the raw film includes oil or liquid paraffin as a solvent. The method is for manufacturing a porous film through forming micropores by successive biaxial stretching. A tensile force applied to the raw film F transferring from the longitudinal stretching machine (10) to the transverse stretching machine (50) is set not less than a stretching force necessary for the longitudinal stretching, and thus the raw film is prevented from slipping on a contact surface between the raw film and each roll of the longitudinal stretching machine (10).

Abstract: A machine for manufacturing a nonwoven fabric includes a conveyer net, a spunbonding apparatus, and a container. In use, the spunbonding apparatus can project at least one fiber onto the conveyer net. The container can contain liquid, wherein the liquid level of the container is higher than at least a part of the conveyer net which the fiber is projected onto.

Abstract: A spunbonding apparatus includes at least one nozzle, a coagulating tank, a deformation region, a slit passage, and a drawing flow pump. The nozzle extrudes at least one spinning solution. The coagulating tank contains coagulating liquid to coagulate the spinning solution into at least one fiber. The deformation region is located between the coagulating tank and the nozzle. The slit passage is connected to the coagulating tank and allows the fiber to pass therethrough. The drawing flow pump provides a drawing flow to the slit passage.

Abstract: Disclosed is an evacuation system for use with plastic extrusion dies, in particular a contaminant evacuation system for removal of air borne contaminants generated at the die orifice of a plastics extrusion apparatus. The system includes an annular evacuation chamber and a suction source connected to the evacuation chamber for generating a vacuum in the evacuation chamber. The evacuation chamber has a radially inwardly directed annular air intake opening for placement about the die orifice, and a baffle structure in the evacuation chamber for equalizing suction pressure along the air intake opening and reduce or avoid localized pressure differences around the extruded product, which would lead to deformation of the product.

Abstract: An apparatus for continuous curing of a plurality of extruded strands can include a rigid frame structure formed by interconnecting a plurality of rigid frame members. A rigid top plate member and a rigid bottom plate member are attached to the rigid frame structure. A plurality of upper spindle units is rotatably attached to the rigid top plate member and a plurality of lower spindle units is rotatably attached to the rigid bottom plate member. A pair of drive motors is attached to the rigid frame structure. A gear assembly attached to the rigid frame structure is operably engaged to the pair of drive motors and a chamber is supported on the rigid frame structure for curing the plurality of extruded strands. The pair of drive motors drives the gear assembly to continuously pass the plurality of extruded strands through the chamber for continuous curing and post-curing.

Abstract: The present invention provides apparatus and methods for growing fullerene nanotube forests, and forming nanotube films, threads and composite structures therefrom. In some embodiments, an interior-flow substrate includes a porous surface and one or more interior passages that provide reactant gas to an interior portion of a densely packed nanotube forest as it is growing. In some embodiments, a continuous-growth furnace is provided that includes an access port for removing nanotube forests without cooling the furnace substantially. In other embodiments, a nanotube film can be pulled from the nanotube forest without removing the forest from the furnace. A nanotube film loom is described. An apparatus for building layers of nanotube films on a continuous web is described.

Abstract: In manufacture of a polyimide film, self-supporting film is heated with both ends in a width direction held and carried by the tenter apparatus. The tenter apparatus has a guide member placed on each side of a carry path for the self-supporting film and a pair of tenter chains each moved along the guide member and each including a film holding mechanism for holding an edge portion of the self-supporting film. The tenter chain has a rotating body supported rotatably around a shaft member extending in a direction in parallel with a carry face of the self-supporting film and perpendicular to a longitudinal direction of the guide member for movably supporting the tenter chain. The shaft member is directly or indirectly fixed to a member identical to a member to which the film holding mechanism is fixed.

Abstract: An apparatus and method for depositing synthetic fibers to form a non-woven web includes guiding the synthetic fibers by a blowing stream through a drawing unit for depositing on a deposit belt. Multiple guidance elements are arranged inside the guidance distance between a blast opening of the drawing unit and the deposit belt, and form a guidance channel above the deposit belt. The guidance elements form a channel opening at a distance from the blast opening of the drawing unit. In order to achieve constant strength in the deposition of the fiber strands, the distance between the outlet of the drawing unit and the channel opening of the guidance channel is larger than half the guidance distance, and the guidance width of an open space formed between the outlet of the drawing unit and the channel opening of the guidance channel is larger than the guidance channel.

Abstract: A method that includes producing a strand by extruding a textile pulp at an extrusion rate that correlates with a first removal speed of the strand to generate a hollow fiber membrane, transporting the hollow fiber membrane at the first removal speed, and elongating the hollow fiber membrane by transporting the hollow fiber membrane at a second removal speed that is 0.5 to 50% higher than the first removal speed.

Abstract: A blown film extrusion line has an annular die gap, from which a film tube can be extruded, a flatness unit or nip rolls, which fold the film tube, a calibration basket, which is disposed between the die gap and the flatness unit or nip rolls, and which has at least two film-guide elements that guide the film tube such that the film tube retains its round cross-section, with the diameter of the film tube being adjustable by changing the relative position of the two film-guide elements. The calibration basket includes a coupling device that couples the movement of the two film-guide elements to each other.

Abstract: A device for drawing melt-spun filaments for forming a spunbonded fabric includes at least one guide member. The filaments are guided through a slot-shaped nozzle, onto which compressed air is applied, and which conveys the filaments through the drawing nozzle. Guide members are provided on both sides of the slot on the base of the slot-shaped outlet, which cause a uniform structure of the fabric due to their shaping. This is achieved when a guide member has a plurality of notches parallel to the conveying direction, and the opposite guide member has a plurality of bores, which passively connect the space between the guide member with the environment.

Abstract: The invention resides in enabling biodegradable filament of polylactic acid, polyglycolic acid and the like to manufacture biodegradable micro-filament by simple and convenient means without needing special, high-accuracy and high-level apparatus; it is characterized in that highly molecular oriented micro-filament those of 12 ?m or less and generally from 2 ?m to 3 ?m can be obtained by heating biodegradable filament by infrared beam and the heated original filament is drawn to 100 times or more by tension of 10 MPa or less.

Abstract: An apparatus and method suitable for producing a polymer film, particularly a polyimide film, perform drying and heat treatment using a tenter type feeding apparatus that suppresses the problems of deformation of film in the vicinity of pore into which the pins bite and breakage of the pores to form long pores in the width direction. The apparatus includes a device to suppress deformation of the film in the vicinity of the tenter pins at the time point when the both ends of the film is pierced with the pins and cools the pin temperature to less than 180° C. at the time when the film is pierced with the pins. Individual pins can be arranged on the innermost side of the pin sheets so that they are all disposed at the same distance both in the film feeding direction in the individual pin sheets and between other pin sheets.

Abstract: The present invention provides apparatus and methods for growing fullerene nanotube forests, and forming nanotube films, threads and composite structures therefrom. In some embodiments, an interior-flow substrate includes a porous surface and one or more interior passages that provide reactant gas to an interior portion of a densely packed nanotube forest as it is growing. In some embodiments, a continuous-growth furnace is provided that includes an access port for removing nanotube forests without cooling the furnace substantially. In other embodiments, a nanotube film can be pulled from the nanotube forest without removing the forest from the furnace. A nanotube film loom is described. An apparatus for building layers of nanotube films on a continuous web is described.

Abstract: A film stretcher utilizes a spring bias to clamp the film. The film stretcher may include a stretch head having one or more clamps positioned about the film in locations necessary to clamp the film for stretching in one or more axes. The clamp may utilize a spring to provide the clamping force. The stretch head may include structures that operate to counter the spring bias to move the clamp to one state and then to allow the spring bias to move the clamp to another state. Thus, the stretch head may effectively clamp and unclamp the film.