Polymeric films elongation

A direct semi-quantitative determination of polymer-filler bonding by electron microscopy has been accomplished by Hess, Lyon and Burgess (32). A modification of the method of Kruse (33), in which a microtome section of the filled rubber is supported on a clear polymeric film, makes it possible to observe de-wetting of the filler as a function of elongation. Another technique designed to estimate rubber-filler ad-... 

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). 

Effect of polymerization conditions Hagiwara et al. on elongation of films [115]... 

Other workers have coated nylon by imbibing pyrrole into the film followed by exposure to oxidant.43 Polymerization only occurred in the surface layer (5 pm), resulting in the formation of a heterogeneous structure. Nylon 6,6 (N66) with incorporated PPy had a much higher initial modulus of 2.6 GPa, compared to 1.7 GPa for N66 alone. However, the elongation to break was also markedly reduced, from 350% for N66 to 60% for N66/Ppy. 

Table 4. Polymeric HALS as Antioxidants in LDPE Film Days at 100 C to 507, Retention of Elongation...

The preparation of composite materials in general is a very important appHca-tion of the mechanical properties of nanodiamond. With many polymers like caoutchouc, polysiloxanes, fluoroelastomers polymethacrylates, epoxy resins, etc., composites with markedly improved mechanical characteristics have already been obtained from the noncovalent incorporation of nanodiamond by simple admixing during polymerization. The modulus of elasticity, the tensile strength, and the maximal elongation of the material all increase upon this modification. Depending on the basic polymer, just 0.1-0.5% (w/w) of nanodiamond are required to achieve this effect (Table 5.3). Polymer films can also be reinforced by the addition of nanodiamond. For a teflon film with ca. 2% of nanodiamond added, for example, friction is reduced at least 20%, and scratches inflicted by mechanical means are only half as deep as in neat teflon. 

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