Copper polyethylene interface

Microscopic Mechanisms of Oxidative Degradation and Its Inhibition at a Copper-Polyethylene Interface... 

Example 2.2 Consider an impact between a polyethylene particle (dp = 1 cm) and a copper wall. The incident velocity is 2 m/s, and the incident angle is 30°. The friction coefficient of the interface is 0.2. The densities of polyethylene and copper are 950 and 8,900 kg/m3, respectively. What is the contact time duration for the collision Estimate the rebound velocity of the particle. Repeat the problem for a copper particle colliding with a polyethylene wall. 

The interfaces formed by evaporating copper, nickel and chromium layers on polystyrene, polyvinyl alcohol, polyethylene oxide, polyvinyl methyl ether, polyvinyl acetate and polymethyl methacrylate have been studied with X-ray photoemission spectroscopy (XPS). At submonolayer coverages of the metals, the peak positions and widths of the metallic electron core levels vary significantly from one polymer substrate to another. Most of... 

Shin, M., Umebayashi, Y., Kanzaki, R., andlshiguro, S. I. (2000). Formation of copper(II) thiocyanato and cadmium(II) iodo complexes in micelles of nonionic surfactants with varying polyethylene chain length. J. Colloid Interface Sci. 225(1), 112-118. 

TV/Tetal surfaces often have adverse catalytic effects on the rates of oxidative degradation (by molecular oxygen) of polymers, particularly polyolefins. Previous papers in this series have shown for the specific case of the 02/polyethylene/copper system between 40 °C and 90 °C that copper carboxylate salts, initially formed at the interface, are re-... 

Mechanisms of Inhibition. A number of diffusion experiments were run in which various concentrations of N,N -diphenyloxamide (< 0.1 wt % or 3 X 10 3 mol/kg) were loaded in the polyethylene films. The great majority of runs showed essentially no effect of the additive on the diffusion rate, nor were any unusual surface phases reproducibly noted (see Tables I and III for typical results). Previous work (2,5) has indicated that the inhibition effect of a deactivator may be caused by both surface and homogeneous scavenging effects. On the basis of the present results we conclude that the major effect of the deactivator involves surface-interface reactions rather than bulk scavenging mechanisms. The former may consist of poisoning of active surface sites on the Cu20/Cu film (13) and/or conversion of an interfacial copper carboxylate layer to a relatively inert phase of insoluble copper complex (5). Work is in progress to separate these mechanisms further. 

INTERFACIAL CATALYSIS plays a very important part in surface (interfacial) degradation. Oxidation can be catalyzed by various metals. Catalysis can start at metal/polymer interfaces and metal ions can diffuse into the polymer. The catalytic action by copper or its oxides, for instance, during oxidative degradation of polyethylene and isotactic polypropylene, respectively, has been studied in detail. Some relevant results will be briefly discussed here. 

---