Spin films

Extmsion technology is used to produce spunbond, meltblown, and porous-film nonwovens. Fabrics produced by these systems are referred to individually as spunbonded, meltblown, and textured- or apertured-film nonwovens, or genericaHy as polymer-laid nonwovens. These fabrics are produced with machinery associated with such polymer extmsion methods as melt-spinning, film casting, and extmsion coating. In polymer-laid systems, fiber stmctures are simultaneously formed and manipulated. 

Some of the innovative materials contain PAC in a highly dispersed heterogeneous distribution. Others are homogeneous and soluble. All of them can be processed by conventional techniques such as melt and blow extrusion, fiber spinning, film casting or spin coating. And some of them even provide the necessary matrix stabilization for turning polyacetylene into a useful material. 

Post-die processing includes a niunber of operations carried out at the exit of the extruder die in a free-siuface way. Examples of such processes are fiber spinning, film blowing, and sheet forming. The shape and dimensions of the extrudate material are determined by the rheological properties of the melt, the die dimensions, the cooling conditions, and the take-up speed (relative to the extrusion rate). 

Processing of Polyesters and Properties of the Derived Materials.— Processing methods in current use for polyesters include melt spinning, film extrusion-casting, and injection moulding. Interest in this area mainly involves 2GT. 

Typical processing methods extrusion blow molding, fiber spinning, film extrusion, injection blow molding, injection molding, maohining, profile extrusion, thermoforming, wire and cable extrusion ... 

In this report, EB refers to emeraldine base which is partly (< 2%) doped with HCl Where known, the level of doping (protonation) is specifically stated in each case. In examples employing 100% doped EB, d,l -camphorsulfonic acid was used as the dopant acid for convenience in spinning films. 

Rheological studies on concentrated solutions provide information on intermolecular interactions in addition to data that can help to design processing conditions for fabrication techniques involving concentrated solutions, e.g., fiber spinning, film casting, film extrusion, etc. 

Modeling Compared with fiber spinning, film blowing has been the object of few models including crystallization phenomena [111-115]. Most of them are based on Nakamura s model (Eq. 15.10). As for fiber spinning, the variations of K with both temperature and flow are taken into account. The two-phase model of Doufas et al. has been also applied to film blowing [112, 114]. 

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