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Poly stretch-oriented

These results support current interpretations of the bathochromic shifts observed in dialkyl-substituted poly silane. Experimental results for poly(di-n-hexylsilane) indicate that as the temperature is cooled below a transition temperature of roughly -35 °C, the major absorption peak shifts from a broad peak at about 310-320 nm (3.9-4.0 eV) to a narrower peak at about 350-370 nm (3.3-3.5 eV), with the red shift being attributed to a transition from a disordered system with a large population of gauche bond twists in the silicon backbone and in the alkyl substituent to a planar dll-trans backbone conformation (5-8, 15). Results from polarized absorption spectra of stretch-oriented samples for the cooled samples exhibit absorbance only for polarizations parallel to the stretch (and presumably the chain axis) direction (22). [Pg.549]

Stretch-oriented poly(vinyl alcohol) films which contain iodine are essential light polarizing components in today s liquid crystal displays (LCDs). They do, however, suffer from the inherent diffusion and sublimation problems of iodine and its chemical aggressiveness. The latter also prevents realization of new LCD... [Pg.22]

The physical properties of polypropylene, poly(ethylene terephthalate), and polyimide are greatly influenced by orientation of the polymer. Polypropylene and poly(ethylene terephthalate) become highly crystallized upon stretching. Oriented, crystalline poly(ethylene terephthalate), for example, has significantly higher modulus, tensile strength, and continuous use temperature than its extruded, unoriented analog (see Table II). [Pg.528]

Electropolymerization of polythiophenes on the transparent electrode material Indium-Tin-Oxide (ITO) is known to be difhcult unless considerable overpotential is used. Satoh et a. [58] and later Mardalen et al. [40] studied the x-ray diffraction from such materials. The films may be stretch-oriented with an elongation up to a factor 1.6. Mdrdalen el al. also studied poly(alkylthiophene)s obtained this way. [Pg.100]

Mardalen, J., E.J. Samuelsen, O.R. Gautun, and P.H. Carlsen. 1991. Molecular structure of stretch oriented poly(3-hexylthiophene) studied by an extended x-ray difiraction mapping. Solid State Commun 80 (9) 687-689. [Pg.393]

Gustafsson, G., O. Inganas, S. Stafstrom, H. Osterholm, and J. Laakso. 1991. Stretch-oriented poly(3-alkylthiophenes). Synth Met 41 593. [Pg.743]

Similar results also has been obtained by Swiatkiewicz and co-workers [205] in stretch-oriented films of poly-(2,5-dimethoxy-p-phenylenevinylene) thin films. Also, oriented films of PPV have been fabricated with the LB technique [201]. The value (at A = 1.064/i,m)ofanLBfilmofpoly-... [Pg.810]

J. Swiatkiewicz, P. N. Prasad, F. E. Karasz, M. A. Druy, P. Glatkowski, Anisotropy of the linear and 3rd order nonlinear optical properties of a stretch oriented polymer film of poly-2,5-dimethoxy paraphenylenevinylene, Applied Physics Letters 1990, 56, 892. [Pg.311]

Fig. 25.15 Typical 6-26 P3AT X-ray diffraction spectra for unoriented (powder) samples of (a) poly(3-hexylthio-phene), (b) poly(3-octylthiophene) and (d) poly(3-dodecyl-thiophene). The two additional scans are spectra from a stretch-oriented (6 1 draw ratio) P3DDT sample (c) in the (hkO) equatorial plane (perpendicular to the chain axis) and (e) along the 001) meridional direction (parallel to the polymer chain axis). Fig. 25.15 Typical 6-26 P3AT X-ray diffraction spectra for unoriented (powder) samples of (a) poly(3-hexylthio-phene), (b) poly(3-octylthiophene) and (d) poly(3-dodecyl-thiophene). The two additional scans are spectra from a stretch-oriented (6 1 draw ratio) P3DDT sample (c) in the (hkO) equatorial plane (perpendicular to the chain axis) and (e) along the 001) meridional direction (parallel to the polymer chain axis).
SWIATKIEWICZ J., PRASAD P.N., KARASZ F.E., DRUY M.A. and GLATKOWSKI P., (1990), Anisotropy of the Linear and Third-Order Nonlinear Optical Properties of a Stretch Oriented Polymer Film of Poly-[2 5-dimethoxyparaphenylenevinylene Appl. Phys. Lett., 56, 892-89. ... [Pg.554]

In conventional tenter orientation, the sequence of steps is as described above (MD—TD). In some cases it is advantageous to reverse the draw order (TD—MD) or to use multiple draw steps, eg, MD—TD—MD. These other techniques are used to produce "tensilized" films, where the MD tensile properties are enhanced by further stretching. The films are generally unbalanced in properties and in extreme cases may be fibrillated to give fiber-like elements for special textile appHcations. Tensilized poly(ethylene terephthalate) is a common substrate for audio and video magnetic tape and thermal transfer tape. [Pg.381]

Soft-drink bottles made from poly(ethylene terephthalate) (PET) are usuady made by stretch-blow mol ding in a two-step process. Eirst, a test-tube-shaped preform is molded, which is then reheated to just above its glass-transition temperature, stretched, and blown. Stretching the PET produces biaxial orientation, which improves transparency, strength, and toughness of the botde (54,56). A one-step process is used for many custom containers that are injection stretch-blow molded. [Pg.143]

Biaxial orientation effects are of importance in the manufacture of films and sheet. Biaxially stretched poly(ethylene terephthalate) (e.g. Melinex),... [Pg.52]

There has been considerable interest in the structure and properties of poly(tetra-methylene terephthalate) 4GT, stemming from the observation that when the oriented polymer is stretched, the crystalline regions are transformed from one structure to a new one30,3l). It appears from the X-ray diffraction data that in the structure... [Pg.110]

Similarly, oriented crystallisation can be induced by stretching sheets or films of polymers in two directions simultaneously. The resulting materials have biaxially oriented polymer crystals. Typical examples of such materials are biaxially stretched poly(ethylene terephthalate), poly(vinylidene chloride), and poly (propylene). Since the oriented crystals do not interfere with light waves, such films combine good strength with high clarity, which makes them attractive in a number of applications. [Pg.44]

When X = Y, as in polyethylene, poly-(tetrafluoroethylene), polyisobutylene, and poly -(vinylidene chloride), the polymers are highly crystalline products with sharply definable melting points (except for polyisobutylene, which crystallizes readily on stretching but with difficulty on cooling). Oriented specimens of high strength may be obtained, exactly as in the crystalline condensation polymers. [Pg.56]

We now report that in the region of the absorption band the flow linear dichroism of a solution of 1 is positive (Fig. 3). Assuming that the nature of the flow orientation is of the usual kind, i.e., that the polymer chains in a random coil conformation which dominates in solution (34) tend to align with the flow direction, this observation provides additional support for the absolute assignment of the transition moment direction along the chain direction, even in solution. Similar conclusions based on polarization studies on a stretched film of poly(di-n-hexyl silane) have recently been reported (36). [Pg.66]

Stretching a polymer in two perpendicular directions, either successively or by blowing a bubble of molten material, leads to its biaxial orientation, which strongly improves mechanical properties in the stretching directions and/or gas permeability (e.g., biaxial orientation of polypropylene leads to BOPP (for biaxially oriented polypropylene) or biaxial orientation of poly(ethylene terephthalate) gives CC>2-impermeable bottles for carbonated beverages.) (Characterisation methods for determining molecular orientation are considered in Chapter 8.)... [Pg.32]

This stretching, similar to the drawing of fibres, which promotes orientation and crystallite formation, is called biaxial orientation. It gives the film added strength and gas-barrier properties. In some processes, monoaxial (uniaxial) drawing is employed, e.g., polypropylene, which is then slit into thin strips and fabricated into heavy duty sacks, carpet backing, etc. The stenter process is used to make biaxial oriented poly(vinylidene dichloride) ("ding" film), polyester, polyamide and polypropylene films. [Pg.80]

Compression molded (150°C for 3 minutes press chilled with cold water immediately thereafter) samples of poly(trans-l,4-hexadiene) (14) and poly(5-methyl-l,4-hexadiene) were examined with a General Electric (XRD-3) X-ray unit. Transmission Laue X-ray photographs were taken using nickel filtered copper X-radiation. Samples were stretched to four times of their original lengths to obtain oriented fibers. The fiber patterns were obtained in a flat plate film holder with the specimen to film distance standardized at 5 centimeters. X-ray diffraction patterns were similarly obtained for the hydrogenated sample of poly(5-methyl-l,4-hexadiene). [Pg.174]

The AES results indicate that the aniline coverage is more than two times greater than the maximum coverage based on van der Waals radii. The TPR results show this species is too stable to be a condensed multilayer. Hence, we conclude that aniline polymerized forming a very stable polymer layer. In addition, the absence of infrared bands corresponding to C=C stretches or ring vibrations indicated that the poly(aniline) film was formed with the phenyl rings parallel to surface. The infrared results also indicated that the poly(aniline) film had N-H bonds which were oriented perpendicular relative to the surface. [Pg.89]


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