Sleeve films

In all above- and below-cited publications in this field (e.g. 84 ) the problem was solved in order to calculate the tensors of strain velocity and stress, to prognosticate alteration of longitudinal viscosity, profile of alteration of the thickness of material over the height of the film sleeve (by coordinate on the central line of the sleeve counted from the outlet face of the extrusion head) and configuration of the sleeve ( bubble ) and also to solve thermal problems in order to determine the dependency of melt temperature upon height (or time) and to forecast the position of the crystallization... 

Okopack Film S is semi-transparent with properties similar to polyethylene. Okopack C and S can be used for production of flat films, sleeve films and bags and sacks, which can be used for fruit and vegetable packaging. 

Skin packaging is a combination of a pol3mier film sleeve with a bottom liner (cardboard or sheet polymer). The article is placed on the card liner and is wrapped into the inhibited shrinkage sleeve (Fig. 2.55a). The film ends are fixed on the card, which can also be made of an inhibited material. During heating the film shrinks skin tight around the article. Skin packaging is used for small-size machine parts, spares, tools etc. 

Large generators typically use Babbitt bearings, which are non-rotating, lined metal sleeves (also referred to as fluid-film bearings) that depend on a lubricating film... 

In normal operation, a sleeve bearing provides a uniform oil film around the supported shaft. Because the shaft is centered in the bearing, all forces generated by the rotating shaft, and all forces acting on the shaft, are equal. Figure 44.47 shows the balanced forces on a normal bearing. 

Lubricating-film instability is the dominant failure mode for sleeve bearings. This instability is typically caused by eccentric, or off-center, rotation of the machine shaft resulting from imbalance, misalignment, or other machine or process-related problems. Figure 44.48 shows a Babbitt bearing that exhibits instability. 

Rolling element bearings, based on factor recommendations, have an absolute fault limit of 0.01 ips-peak. Sleeve or fluid-film bearings should be watched closely. If the fractional components that identify oil whip or whirl are present at any level, the bearing is subject to damage and the problem should be corrected. 

Machine-trains that use sleeve bearings are designed based on the assumption that rotating elements and shafts operate in a balanced and, therefore, centered position. Under this assumption, the machine-train shaft will operate with an even, concentric oil film between the shaft and sleeve bearing. 

Many of the various techniques associated with metal film preparation have recently been reviewed by Klemperer (76). Much of the catalytic work with thick continuous films has used a cylindrical reaction vessel (Fig. 7a). This cylindrical geometry permits a cylindrical sleeve of mica sheet to be inserved and used as the film substrate for epitaxial film growth... 

Films and packaging with barrier properties, blister packaging, shrink caps, sleeves and... 

In particular, if a latex is to be used for coatings, adhesives, or film applications, no silicone-base stopcock greases should be used on emulsion polymerization equipment. Although hydrocarbon greases are not completely satisfactory either, there are very few alternatives. Teflon tapes, sleeves, and stoppers may be useful, although expensive. 

In blown film extrusion, the molten polymer enters a ring-shaped die either through the bottom or from the side. It is then forced around a mandrel inside llie die, shaped into a sleeve, and extruded through llie die opening in the form of a comparatively thick-walled tube. 

Experimentators managed to produce thin films from all polymers under investigation but their thickness differed with certain regularities despite the fact that the films were produced at different laboratories and on different equipment. The shape of sleeve and temperature profile over sleeve length also differed significantly, as well as the specific impact elasticity of films both along and transverse to the direction of extrusion. 

The approach to analysis of biaxial extension of melts in the simulation of the sleeve inflation process was developed by Pirson and Petrie in 1966-1970 with the use of ideas of the thin shell theory which allows to substitute sleeve film by flat film in analysis. The problem was formulated more accurately and completely and solved in works by Han et al. The author made several conclusion the velocity of material extension changes in the main direction of sleeve motion while effective longitudinal viscosity may increase, decrease, or remain constant depending on the nature of material and the range of strain velocities under consideration longitudinal viscosity of the material at fixed process parameters decreases with temperature rise (the behavior of longitudinal velocity is described more strictly above, in Sect, 2.2.6). 

The analysis indicates that presently quite adequate phenomenological models are available for description of the straining of commercial (polydisperse) polymers in the liquid state. A comparatively clear understanding of the mechanics of the processes of manufacturing of sleeve-type and flat films of molten thermoplastics also has been developed. So far, physical approaches have provided rheological models only for monodisperse polymers (the properties of which differ significantly from those of the ones used in industry). 

Plastic and elastomer packaging is used for bottles, jars, ampules, closures, plugs, films, sheets, labels, shrink sleeves, wads, cartons, and tubings. The barrier properties of plastics vary widely. Some detailed knowledge is required on the barrier of plastics to moisture, and to vapors and gases in order to make an optimum choice for a given product and application. 

Other applications include rotomolded tanks and containers for the storage of corrosive chemicals, such as nitric or hydrochloric acid. Extruded sheets can be thermoformed into various parts, such as battery cases for heart pacemakers.58 ECTFE film is used as release sheet in the fabrication of high-temperature composites for aerospace applications. Braided cable jackets made from monofilament strands are used in military and commercial aircraft as a protective sleeve for cables.59... 

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