Markus Grob

Percolation network in polyolefins containing antistatic additives Imaging by low voltage scanning electron microscopy

Abstract Polyolefin samples containing a new, percolating, antistatic stabiliser based on a polyamide copolymer were studied by low voltage scanning electron microscopy (LVSEM). This technique is generally used on insulators either to increase the spatial resolution or to decrease any electron beam damage. On conductive samples, a contrast due to the conduction is added to the topographical image giving information on the conduction itself. By adjusting the acceleration voltage (0.5–5 kV), the electron range (depth of penetration of the primary beam) can be varied from 25 nm to 1.0 μm (calculated for a “carbon” sample with a 0.9 density), and the conductive pathway can be revealed in the volume beneath the sample surface. Results show that LVSEM is an effective tool for studying such antistatic systems. It allows estimation of the thickness of the polymeric skin which covers the first conductive layer. Also, it offers the possibility of accurately imaging the percolating network thus allowing checking of the influence of processing on the efficiency of the antistatic system.

Permanent antistatic additives: new developments

Abstract The current demand for permanent antistatic additives can be satisfied by the use of special hydrophilic copolymers, alongside the established existing range of anti-stats. Irgastat® P22 is a new development particularly, but not exclusively, suited for polyolefins. The recommended processing temperatures is 230–260°C. Through the development of AS4312 with a melting point around 180°C the processing window can be enlarged to include lower temperatures, which is suitable for LDPE film blowing. Both these products fulfil the requirements for permanent antistatic additives: they are colourless, do not migrate, show no deterioration of the polymer surface and are also effective at very low relative humidity (