Polyethylene slitting

The film is fibrillated mechanically by mbbing or bmshing. Immiscible polymers, such as polyethylene or polystyrene (PS), may be added to polypropylene to promote fibrillation. Many common fiber-texturing techniques such as stuffer-box, false-twist, or knife-edge treatments improve the textile characteristics of slit-film fibers. 

Figure 9. Polyethylene separator production process (IH) Slitting...

The alternative is hexane, which because of the explosion hazard requires a more expensive type of extractor construction. After the extraction the product is dull gray. The continuos sheet is slit to the final width according to customer requirements, searched by fully automatic detectors for any pinholes, wound into rolls of about 1 m diameter (corresponding to a length of 900-1000 m), and packed for shipping. Such a continuous production process is excellently suited for supervision by modern quality assurance systems, such as statistical process control (SPC). Figures 7-9 give a schematic picture of the production process for microporous polyethylene separators. 

The standard is made from Lupolen 1800, a branched low-density polyethylene with a very broad long period distribution. Therefore the slit-smeared SAXS peak is only a shoulder that starts with a plateau. 

A machine fitted with knives, spacer bars, let-off and take-up rollers, used for slitting rubber sheet, rubbered fabric, liner material, polyethylene film, etc., into narrower widths. 

XRD Characterization The powder x-ray diffraction of the mechano-chemically milled complex borohydride has been carried out by the Philips X pert diffractometer with Cu-Koi radiation of X= 5.4060 A. The incident and diffraction slit width used for the measurements are 1° and 2° respectively. The sample holder was covered with Polyethylene tape (foil) with an O-ring seal in an N2 filled glove box in order to avoid or at least minimize the 02/moisture pickup during the XRD measurements. The diffraction from the tape was calibrated without the actual sample and found to be occurring at 29 angles of 22° and 24°, respectively. The XRD phase identification and particle size calculation has been carried out using PANalytical X pert Highscore software, version l.Of. 

The principal use of LDPE and LLDPE in building products is as a film water barrier under below-grade floors as a wall vapor barrier, though PVC is typically preferred and as temporary enclosure film during construction. The film is made either by extruding a thin-walled tube, which may be slit or wound up direcdy, or by extmsion through a slot die and cast direcdy on to a cold roll, cooled, then wound up. The former method is more widely used. A much smaller use for low density polyethylene is in piping. 

Flow through a slit head has been studied also in polymers using the power-function flow principle (Ostwald-de Villes model). Some of the first works in this field were carried out in 1967-1968 by N. V. Tyabin et al.21,22). Tests were arranged with molten polyethylene in an extrusion head having a rotary conic core. The divergence between theory and experiment was comparatively significant which, apparently, is accounted for, primarily, by the basence of a necessary similarity between the conducted experiment and the theoretical description of the flow in a flat slit. 

Usually, for metallic surfaces such as steel and aluminum, most polymers adhere well due to adequate chain adsorption. Even polyethylenes apparently achieve sufficient chain adsorption on bare metallic walls for stresses up to 0.5 MPa. This means that only a coil-stretch transition may occur to produce disentanglement and to cause complete interfacial slip on metallic walls. Since the coil-stretch transition requires exertion of sufficient forces on each adsorbed or stagnant chain at the interface, it is not possible to observe on clean metallic surfaces in any geometry other than capillary (or slit) dies. It is well known [14]... 

In studies involving human exposure (Rengstorff and Mershon, 1969a, b), CS (0.1% or 0.25% in water 1.0% in triocyl phosphate) sprayed or administered as ophthalmic drops onto the eyes, caused apraxia of eyelid opening with blepharospasm upon eyelid closure for 10 to 135 s. It also caused a transient conjunctivitis but no comeal damage upon further inspection with a slit lamp. Rabbit eyes contaminated with CS as a solution (0.5-10% in polyethylene glycol), as a solid, or thermally dispersed as a smoke (15 min at 6,000 mg/m ) showed a greater toxicity with solution. CS in solution caused profuse lacrimation, conjunctivitis, iritis, chemosis, keratitis, and corneal vascularization at concentrations at or above 1%. 

After extrusion, blown-film is often slit and wound up as flat film, which is often much wider than anything produced by slot-die extrusion. Thus, blown-films of diameters 7 ft. or more have been produced, giving flat film ofwidths up to 24 ft. One example is reported [16] of a 10-in. extruder with 5-ft diameter and a blowup ratio of 2.5, producing 1,100 Ib/h, or polyethylene film, which when collapsed and slit in 40 ft wide. Films in thicknesses of 0.004-0.008 in. are readily produced by the blown-film process. Polyethylene films of such large widths and small thicknesses find extensive uses in agriculture, horticulture, and building. 

MAJOR APPLICATIONS Fiber, slit tape, cast and biaxially oriented film, containers and closures, automotive interior trim, appliance housings and components, component in elastomeric blends with polyethylene and olefinic rubbers. 

Polypropylene film fiber is becoming of great commercial interest in many applications such as carpeting and woven sacks. It consists of an extruded film that is slit along the machine direction into narrow, fiber-like ribbons. These ribbons are then woven to make strong fabrics, nets, and sacks. Low-density polyethylene (LDPE) is sometimes blended with PP in slit film applications in order to reduce fibrillation and improve processability. 

In this work uniaxially oriented specimens of polyethylene terephthalate were studied, most of which were from the first series used in the work of Nobbs et al. described in Section 5.3.1. The Raman intensity measurements were made using a Coderg PHO spectrometer and a CRL 52A argon ion laser tuned to 488 nm. The tape samples were mounted parallel to the spectrometer slit. The partially focused laser beam was incident normally on them and the scattered light was collected in directions making approximately 180° with the incident light direction. The incident and scattered light polarisation vectors could be chosen parallel or... 

After the stretching process the films may be annealed and are then slit into the desired number of tapes by rotating or stationary knives. Tapes for weaving or knitting polypropylene or high-density polyethylene are wound on bobbins, which are used in more or less conventional textile machinery. 

High density polyethylene CH3CF2CI 200 NR NR Pressure-driven slit die rheometer... 

Polypropylene and polyethylene microporous films obtained by this method are available from Celgard, [44, 46, 50, 51] and Ube [52]. The dry process is technologically convenient and environmentally benign because no solvents are required. However, biaxial stretching has been met with limited success to date and, as a result, the pores are slit-like in shape, and the mechanical properties of films are anisotropic. The tensile strength in the lateral direction is relatively low. 

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