Stretching method

Preparation of highly oriented thin films of polymers film stretching method [2, 3,16,17]... 

Polypropylene and polyethylene microporous films obtained by this method are available from Cel-gard48.5o,54,55 Ube. The dry process is technologically convenient because no solvents are required. However, only a uniaxial stretching method has been successful to date, and as a result, the pores are slitlike in shape and the mechanical properties of films are anisotropic. The tensile strength in the lateral direction is relatively low. 

J.J. Kim, T.S. lang, Y.D. Kwon, U.Y. Kim and S.S. Kim, Structural Study of Micro-porous Polypropylene Hollow Fiber Membranes Made by the Melt-Spinning and Cold-Stretching Method, J. Membr. Sci. 93, 209 (1994). 

The DNA was stretched on the mica with a spin stretching method and suck up method Preparation of FISH San )le... 

Some separators are made of crimped perforated sheets and sheets modified by the break-and-stretch method. These separators are easy to make, good at whirling the fluid, but significantly mask the membrane. 

Fig. 10.3 Scheme of the preparation of nanopmous polymer template by stretch method and LCP composite film with mesogens highly aligning along with the stretch direetion (a). SEM images of the initial porous polymer film (b) and the polymer eomposite film after filling with LC mixture and polymerization (C). Reproduced with permission from [38]. Copyright 2013... 

In stretch blow molding, a heated pre-formed melt is positioned in the blow mold (Figure 1.5). A center rod extends which stretches the preform with axial orientation. Blown air then expands the preform in the mold, fcwming a bottle with radial orientation. The stretch process takes advantage of the crystallization behavior of the resin and requires the pre-form to be temperature conditioned and then rapidly stretched and cooled. PET soft drink bottles are formed using the stretch method. PET bottles are also formed using extrusion blow molding. 

Figure 3.7 Schematic diagram showing the principal features of the filament stretching method for extensional viscosity measurements (a) vertical filament stretching (b) horizontal filament stretching.

To eonfirm the theoretical predictions that the 7-stress affects the directional stability of cracks, DCB specimens with adhesive C and adherend thicknesses of 4.8 mm were prepared. The surface preparation for the adherends was simply an acetone wipe, and various levels of residual stress were achieved among the specimens using the stretching method. Specimens were then tested quasi-statically according to the procedure discussed earlier. The resulting fracture surfaces of the specimens were carefully examined and three representative specimens were selected as shown in Fig. 9, from which, the effect of the 7-stress on the directional stability of cracks can be inferred. The initial residual stress... 

Li et al. (2003) proposed the use of polyethylene (PE) and polypropylene (PP) hollow-fiber membranes for desalination by DCMD and VMD. The hollow-fiber membranes were prepared by the melt-extruded/cold-stretching method. Compared to PP hollow-fiber membranes, higher water fluxes have been obtained for the PE membranes in both DCMD and VMD. This was attributed to the larger pore size of the PE membranes. The highest permeate flux reported was 0.8 L/m h in DCMD and about 4 L/m h in VMD. 

In the stretching method, fibres are suspended over grooves in a striated and transparent substrate. The AFM, situated above the sample, is used to laterally stretch the fibres. To measure the applied force, the fluorescence microscope/optical microscope, situated below the sample, is usually employed to visualise the stretching process (Fig. 4.22a) [233-235],... 

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