Diffusion through rubber

Laboratory workers handling NDMA could potentially be exposed to the nitrosamine as a result of diffusion through rubber gloves. Walker et al. (1978) showed that rubber gloves worn in research laboratories do not provide complete protection from dermal exposure to NDMA, because 11.8% of the NDMA contained in a dichloromethane solution was found to diffuse through latex surgical gloves into saline solution, over a period of 20 minutes. Dichloromethane is a common solvent for NDMA. 

The properties of He deserve special note it can diffuse through rubber and most glasses. Below 2.18K, ordinary liquid He (but not He) is transformed into liquid He(II) which has the remarkable properties of a thermal conductivity 600 times that of copper, and a viscosity approaching zero it forms films only a few hundred atoms thick which flow up and over the side of the containing vessel. 

The properties of He deserve special note it can diffuse through rubber and most glasses. Below 2.18K, ordinary... 

In the steady state of diffusion the velocity of diffusion is inversely proportional to the thickness of the membrane. This is shown by the results of Edwards and Pickering (6) who allowed hydrogen to diffuse through rubber membranes of varying thickness, and plotted the reciprocal of the per-... 

Finally, a property of practical importance which may be noted is the ability of noble gases, especially He, to diffuse through many materials commonly used in laboratories. Rubber and PVC... 

The core is put into a Hassler sleeve inside a core holder where overburden pressure is applied outside of the sleeve by using water. Gas is not used, since it has the potential to diffuse through the rubber sleeve. The overburdened core holder is connected to the Isco pump, from which 1% acidified brine is pumped into the core. The needle valve that restricts flow from the output end of the core is opened slightly to allow the escape of air and air-saturated brine. The needle valve which restricts flow from the input end of the core is opened fully. Complete saturation is attained after several pore volumes of brine have been pumped through the core under pressure, and this fully saturated core is used throughout the experiment. 

J. Quillet The thing that is not realized is that diffusion of benzene through rubber is about the same as benzene through benzene. The kinds of motion found in a liquid are in fact very similar to those found in a rubber. It s just that the translational motion of the large molecules is restricted. It is not too surprising that rubbers would show up in some cases as 1iquids. 

Diffusion through Cases A principal mechanism for this steady-state release is direct diffusion of the explosive molecules through the munition case. Clearly, the rate of this diffusion is dependent on the case material, through a property called the diffusivity. Metal cases offer essentially zero diffusion, but cases made of some polymers or natural rubber have high enough diffusivities to enable substantial diffusion rates. 

Several different membrane materials have been used, namely Teflon, polyethylene, and silicon rubber among others. It is possible to obtain some degree of selectivity by choosing the material of this membrane according to the conditions of the application. The diffusion through such a structure is more complicated. For radial geometry, the steady-state current is given as... 

The ability to infiltrate the surface of a host material decreases with molecular size. Molecules ofM > 5 x 103 can hardly diffuse through a porous-free membrane. Self-diffusion is when a molecule moves, say in the melt, during crystallization. Also, when bonding rubber, the so-called tack is explained by the self-diffusion of the molecules. The diffusion coefficient for self-diffusion is of the order of... 

The literature contains a very large amount of both experimental and theoretical information on the diffusion of small molecules, especially gases, in polymers. Since the pioneering works (1,2) on the diffusion of gases through rubber septa interest in diffusion phenomena in polymers has continously increased and diversified. The considerable interest and the concentrated academic and industrial research efforts in the study of diffusion in polymers arises from the fact that important practical applications for these materials depend to a great extent on diffusion phenomena. In the last five decades a series of classic books and reviews have been devoted to the presentation of the main topics, experimental results, theories and applications for the diffusion of small penetrants in and through polymers (3-19). An interested reader will most certainly find in one of these references information which apply to her/his special area of interest. 

The water permeability of rubber closures used in injection vials is considered an important parameter in assessing the closures, but quantitative prediction of water permeability through rubber closures is difficult because the diffusion coefficient of water is dependent on relative humidity [14],... 

---