Oriented tape

The sensitivity of the NMR anisotropy to the conformation of the glycol residue, which was a complication in polyethylene terephthalate, can be turned to advantage in 4GT, as shown by some recent research 36). The anisotropy of the second moment was determined for three cases, starting with a highly oriented tape ... 

Another important area is oriented tapes and webs which are used in the fabrication of porous fiber, fabric, tube, and sheet. These porous articles find applications for protective clothing, waterproof and weatherproof fabrics, gaskets, filter bags, and many other items. 

Oriented Film Film that has been oriented either monoaxially (in one direction), the direction of tear, or biaxially (in two directions), to achieve strength and stiffness. Monoaxially oriented tape exhibits stronger MD (machine direction) tensile properties than biaxially oriented tape. Materials that have been oriented bear an O before the acronym (e.g., OPS, oriented polystyrene). 

Fig. 4. CorO for the unique axes of fluorescent VPBO molecules dispersed in uniaxially oriented tapes of polyethylene terephthalate plotted against the birefringence — of the tapes. O, samples drawn at S(PC to draw ratios between 1 and 6 . samples drawn to draw ratio 2 7 at temperatures between 65° and 90°C. (Reproduced by permission from Ref. 18. Copyright I PC Business Press Ltd.)...

Fig. 7. Co O and co O plotted against draw ratio, /.. for chain a.xes in uniaxially oriented tapes of polyethylene terephthalate.. cos O and O. cos determined from Raman intensity measurements on the 1616 (vn line. Curves (a) pseudo-affine cyg regate deformation model, atrves (b) affine rubber elasticity model.

In a previous work, the same authors also observed that the composite peel strength was significantly increased by introducing interleaved films of the same polymer between the layers of woven oriented tapes [30]. They continued working on PP self-reinforced composites enhanced with the addition of CNT, trying to improve properties by the use of interleaved films [28]. Samples of single-polymer polypropylene composites were produced with and without interleaved films, and with and without carbon nanofibers, located either in the oriented polypropylene tapes, in the interleaved film or in both. Maximum peel strength was observed... 

BNL tape candidates are required to meet an empirical elongation to contraction ratio of 2 1 As a general rule, it was found that the elongation to fracture usually increased as a result of orientation, and the thermal contraction decreased following this treatment. The 293 to 4.2 K contraction of the laminated biaxially oriented tapes was found to be 0.641, and E/C ratios for this material are greater than 12 1. (Details of the BCL thermal expansion technique are described in Appendix I.)... 

Defects in orientation, tape width, length, ply thickness, angle of cut, or smoothness are foimd mainly by visual inspection. An extremely high accuracy and control are required of the tape supply magazine and its programming. 

Most polypropylene used in various textile products is produced from isotactic polymers. Isotacticity of polypropylene has significant influence on tape or fiber property. Only iso- and syndiotactic polymer have sufficient molecular order to create polycrystalline structure and hence acceptable physical and tensile properties for oriented tapes. Isotactic polymer chain is characterized by the arrangement of the functional group on one side of the plane. 

Direct compaction of a pile of woven mats consisting of oriented fibers or tapes where only the outer skins of the resulting mesh are made to melt. Here, the oriented tapes or fibers are initially woven into a mat. Several mats are then compacted (or thermoformed) under pressure and heat. 

Figure 9.1 DSC curves of a single PP tape with a melting temperature of approx. 160°C and oriented tapes in the woven part with a melting temperature that is approx. 20°C higher (shaped part) [7]...

TABLE 8 Comparison of some basic properties of different PO polymers used to produce staple fibers, continuous filaments and oriented tapes for possible use in textiles... 

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