Composite material with EMI shielding properties and process to produce it
摘要
說明書
From the results, it can be seen that the best compromise between the EMI shielding and the density is achieved by the composite material containing silver glass fibres in the presence of stearic acid. With carbon nanotubes composites, even if composites densities remain decent, a shielding of 40 dB at 1 mm thickness was never surpassed without important drawbacks in processing and composite mechanical properties. The improvement of shielding properties in the presence of stearic acid for silver glass fiber composites was unexpected since, for carbon nanotubes, the addition of stearic acid brought no improvement of composite electromagnetic shielding properties (see S5 and S6). Comparing S1 and S2 it can be seen that at a similar filler volume concentration, the silver glass fibre composites display shielding values superior to 40 dB in the presence of stearic acid at 1 mm thickness, and the composites densities remain interesting. Tin composites display interesting shielding at 2 mm thickness but the density of the resulting composite is too high and involves an increase of the weight for the products made from the composite, which goes against the concern of lightening the weight of the vehicles to limit the production of greenhouse gases when they are driven.
Several composite materials being polypropylene-based composite material containing silver glass fibres were produced with different content of metal-coated particles (component B) and/or with different content of dispersant (i.e. component C).
The samples are polypropylene-based composite material prepared in the absence of acid stearic or the presence of acid stearic using the process of example 1. The mixing was done at 50 rpm.
