Co-extrusion method

Co-extrusion methods are especially desirable. Multilayer laminates formed by co-extrusion are advantageous economically and generally exhibit improvements in cohesion and adhesion relative to the various layers making up the multilayer laminate. 

Multilayered and combined inhibited hose films are mainly produced by co-extrusion methods. Apart from these, original procedures for obtaining adherence to the hose base functional layers (coats) are employed. In one of these [50] a barrier coating is formed on the outer surface of the hose film filled by Cl using one of aforementioned methods. 

In most cases there is insufficient adhesion between the basic polymers and so it is necessary to have an adhesive film between each of the layers. Recent investigations of co-extrusion have been centred on methods of avoiding the need for the adhesive layer. The most successful seems to be the development... 

All molten-state processing methods are usable extrusion, injection, compression, blown film, blow moulding, thermoforming, foam, co-extrusion, machining for high hardness grades, welding. 

All the molten-state processing methods can be used, mainly extrusion, injection, blow moulding, co-extrusion, foaming, welding, crosslinking. 

All the molten-state methods are usable but extrusion, injection, calendering, thermoforming, welding and co-extrusion are the most used. 

Thin-film composite mixed-matrix membranes can be made by a coating method or by a dual-layer co-extrusion technology, as discussed in Section 11.5.2.2. 

The polymer compound and components moulded from it usually are coloured uniformly throughout (that is, the colours of the surface and the interior are the same). However, with a view to reducing costs of colouring and of compounding, methods have been developed for colouring only the surface, by sandwich moulding or by co-extrusion of product and surface layer. 

Norrish Type I cleavage reactions dominate in the gas phase photochemistry of many acyclic aldehydes and ketones, whereas in the liquid phase this process is less common and alternative pathways (ii, iii, v) dominate. When no suitable C-H bonds are present to allow hydrogen abstraction reactions, however, this process will also constitute an important synthetic method for the cleavage of a-C-C bonds in solution. One important subsequent reaction of the resulting acyl and alkyl radicals is carbon monoxide formation and radical combination. Overall CO extrusion results which represents a versatile method for the formation of C-C single bonds from ketones. When cyclic substrates (cycloalkanones but not conjugated cycloalkenones which exhibit a different photochemistry) are used, ring... 

Hose extrusion includes forcing of the polymer melt through the annular slit of the extrusion head, pneumatic blowing of the hose, folding and removal in vertical or horizontal direction. This method produces biaxial films with perfect physical-mechanical characteristics, it is rather simple and economical, and is suitable for the production of laminated film materials by co-extrusion. 

Slot extrusion is used to form flat inhibited films and laminated films. To this end, flat co-extrusion, extrusion pasting and lamination methods are used [7,14,18,28,34,40,82]. Commonly, preliminary granulated mixtures of film-forming pol3miers and Cl participate in extrusion. To avert foaming of the melt by VCI vapors, adsorbents like silica gel [7] are introduced into the polymer composition. 

Recent efforts by Arora et al. have led to the development of DE based liber actuators [262]. These actuators are essentially miniaturized tube actuators. In their work, prestrain was applied by both uniaxial elongation as well as inflation. These actuators may be of interest for artificial muscle applications since they mimic the fibular nature of natural muscle however, unUke natural muscle, their method of actuation is through elongation and the maximum strains reported were limited to 7% in the axial direction. Cameron et al. have performed similar work on co-extruded tube DE actuators [263]. Their co-extrusion process presents a fast, easy, scalable method to produce small diameter tubes, or hoUow fibers, for use as DE actuators that would make these actuators very amenable to mass manufacturing. Strains, thus far, are limited to approximately 2%. 

Co-extrusion processing using thermoplastic binder systems for ceramic bodies has been described by Van Hoy [Hoy 98]. The major binder component used in this study was ethylene vinyl acetate, and methoxypoly-ethylene glycol was used as a plasticizer. Feedstocks of alumina, a piezoelectric ceramic powder and carbon black were repeatedly co-extruded to form an array of fine M -shaped structures. With this method the size of the alumina M shapes could be reduced by a factor of 915. In this example the use of solvent-based binders would have been problematical because of drying of the feedstocks and extrudates during the co-extrusion process and during handling. 

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