Poly appearance after exposure

The interaction volume of 20 kV electrons in poly(methyl methacrylate) (PMMA) has been shown directly by using its radiation sensitivity [39]. After exposure to a beam of electrons, the material was cross sectioned, polished, and etched. Pear-shaped holes up to 10/rm deep appear (Fig. 2.5) showing where the beam interacted with the PMMA (and reduced its molecular weight) [39]. Calculation of the interaction... 

Approximate frequencies in Hz where the three peaks appear when high density polyethylenes are oxidised and dielectric loss is measured at fixed temperatures. VJhen peaks are observed with low density polyethylenes, the frequences are 2 to 3 times higher. Columns II refer to the normal peaks and columns D to the shifted peaks, which were observed after exposing the samples to labile deuterium, usually in alcohol C2H5OD. The shifts were reversed by subsequent exposure to C2H5OH or other labile protons. An asterisk denotes that the observations were made with oxidised poly(C2D ). 

At room temperature, polymers appear to be inert toward nitrogen trifluoride. Samples of polyethylene, polypropylene, polystyrene, or poly-a-methylstyrene exposed for 6 d to 5 atm of NF3 at 135°C showed a mild surface reaction. After six weeks of exposure to 10 atm at 150°C,... 

Surface scattering. A ripple structure appears on amorphous poly(ether sulphone) (Fig. 9.8) and polyimide films after a single exposure with a... 

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