Film properties tensile strength

Mechanical film properties (tensile strength (o) and elongation ( )) were estimated by the tensile testing machine ZWIC Z 005 at 50-mm/min tensile speed. 

The tensile properties (tensile strength, Young s modulus, and elongation) of unoriented, noncrystalline films were investigated for those polymers that formed clear films by solvent casting. The results collected in Table I allowed several general conclusions. 

Composites of polypyrrole and poly(vinyl chloride) have been prepared by several groups (64-67). Polythiophene-poly(vinyl chloride) composites have also been prepared (68). The electropolymerization of pyrrole on poly(vinyl chloride)-coated electrodes yielded composites with mechanical properties (tensile strength, percent elongation at break, percent elongation at yield) similar to poly(vinyl chloride) (65) but with a conductivity of 5-50 S/cm, which is only slightly inferior to polypyrrole (30-60 S/cm) prepared under similar conditions. In addition, the environmental stability was enhanced. Morphological studies (69) showed that the polypyrrole was not uniformly distributed in the film and had polypyrrole-rich layers next to the electrode. Similarly, poly(vinyl alcohol) (70) poly[(vinylidine chloride)-co-(trifluoroethylene)] (69) and brominated poly(vinyl carbazole) (71) have been used as the matrix polymers. The chemical polymerization of pyrrole in a poly(vinyl alcohol) matrix by ferric chloride and potassium ferricyanide also yielded conducting composites with conductivities of 10 S/cm (72-74). 

Polychlorotrifluoroethylene Thermoplastic polymer of chlorotrifluoroethylene. Has good transparency, barrier properties, tensile strength, and creep resistance, modest dielectric properties and solvent resistance, and poor processibibty. Processed by extrusion, injection and compression molding, and coating. Used in chemical apparatus, low-temperature seals, films, and internal lubricants. Also called PCTFE. 

The most commonly measured mechanical properties for films are tensile strength, tear strength, and impact resistance. The first two are generally measured in both the machine and transverse directions (MD and TD). The last one is a biaxial test, examining MD and TD simultaneously. 

The filler content of the base film is usually between 40-70 wt.%. Afterwards, this base film is stretched successively in the machine direction (MD) and the transverse direction (TD) in order to develop microporous structure. The main advantages of this process are (1) easy control of pore size and porosity, which significantly affect the gas permeability (2) tailoring of the mechanical properties (tensile strength at yield and elongation to break) in both MD and TD, which is of great practical importance (3) uniform stretchability of the base film, which is one of the most important issues in manufacturing of microporous PP films. 

Molecular Weight and Molecular Weight Distribution. Molecular weight and molecular weight distribution affect extrusion and orientation processes and the physical properties of the film, eg, tensile strength, elongation, impact resistance, (qv) and optics (see Molecular Weight Determination). 

The choice of an appropriate electrolyte for the doping of polypyrrole during electrochemical polymerization can improve the mechanical properties of the films obtained. Thus, polypyrrole films electrogenerated in the presence of large electrolytes, as /7-toluensulpho-nate, tosylate, benzene sulfonate, etc., yield flexible films with tensile strengths similar to polystyrene [113]. We can extrapolate this behaviour by combining the... 

Table 7.6 Mechanical properties (tensile strength (a) elongation at break (e) and modulus (E)) and crystallinity (C) of drawn PHBH films and dependence on the content of hydroxyhexanoate (H) and draw ratio (DR)...

Physical properties Tensile strength, hardness, extensibility, glass transition temperature These data (derived from manufacturer s literature or practical experience) indicate the limits of use PVAL coatings form strong films but have little adhesion to picture varnish... 

TABLE 1 Water vapor permeability (WVP), oxygen permeability (OP), and mechanical properties (tensile strength, TS elastic modulus, EM and % elongation, %E) of various edible films from wet process (solution casting)... 

Figure 13.11 Mechanical properties of composite films (a) tensile strength and (b) elongation...

A compression-molded film (250"C) had the following properties Tensile strength = 6000 psi Tensile modulus = 160,000 psi Elongation = 6% Modulus of elasticity = 396,000 psi Flexural... 

A film of this polymer had the following properties Tensile strength = 10,400 psi Tensile modulus = 240,000 psi room temp.) and 110,000 psi (200X) Elongation = 18%. Dielectric strength Short time =167 volts/mil step by step= 226 volts/mil. 

Stable (shelf life 5 18 months) dispersions are obtained, with particle size of 30-35 nm. From these dispersions, stable elastic films with high mechanical properties (tensile strength, a, of 8.9 40.0 MPa and elongation at break, e, in the range of 400-1500%) can be formed. 

BiaxiaHy oriented films have excellent tensile strength properties and good tear and impact properties. They are especially well regarded for their brilliance and clarity. Essentially all poly(ethylene terephthalate) film is biaxiaHy oriented, and more than 80% of polypropylene film is biaxiaHy oriented. Polystyrene film is oriented, and a lesser amount of polyethylene, polyamide, poly(vinyl chloride), and other polymers are so processed. Some of the specialty films, like polyimides (qv), are also oriented. 

---