No abstract

Expensive polymer food packaging consisting of multilayer systems of different polymers will be increasingly replaced by cheap homopolymeric materials. Low‐pressure plasma deposition of SiOx layers provides a promising alternative to achieve barrier properties on homopolymeric materials directly comparable to those of multilayer polymer packaging. Oxygen and HMDSO were applied for depositing SiOx layers on poly(propylene) (PP) and polyethyleneterephthalate (PET) foil samples by using two different low‐pressure microwave plasma sources. Significant improvements of the barrier properties were achieved in the first experiments, e.g. the oxygen permeability could be reduced by a factor of 65.

Deposition of SiOx layers by low‐pressure microwave plasmas is an excellent means to add missing barrier functionalities to cheap and material‐saving homo‐polymeric materials that will increasingly replace expensive multi‐layer polymer food packaging. SiOx coatings were deposited in an ECR plasma process on polyethyleneterephthalate (PET) foils using two different precursors, HMDSO and HMDSN. O2 transition rates of less than 1 cm3 (m−2·24 h−1·bar−1) were obtained for the best performing SiOx coatings deposited from O2/HMDSN gas mixtures. First ECR plasma deposition tests on polypropylene (PP) trays show the high barrier potential of SiOx coatings even on three‐dimensional polymer food packaging.

Scaling up metal nanoparticle production is a desired goal of much research, the need of the industry due to the growing market of applications increases significantly. However, a scale up of production rate often leads to an increase in particle size and a broadening of size distribution. Particle characterization in terms of size is mostly done after synthesis. In this work, a transferred arc process is optimized to increase the production rate of pure copper nanoparticles economically. The maximum production rate for different particle sizes is determined by TEOM measurements. While the influence of different carrier gases has been investigated before, different mixtures of nitrogen and argon as carrier gas are used to manipulate the primary particle size. Primary particle size determination is performed by a novel analysis method based on parallel online ELPI and SMPS measurement. An equation is found to calculate the mass mobility exponent directly on the basis of the effective density of an agglomerate. Hence, the method is suitable for determining the primary particle sizes directly online.

The performance of particle‐based products depends on a multiple set of particle properties. To monitor them during particle manufacturing, three novel aerosol measurement techniques were developed: wide‐angle light scattering (WALS), three‐dimensional laser scattering (3D‐LSS), and differential aerodynamic particle sizing (DAPS). They measure particle shape, aggregate structure, and particle size, i.e., radius of gyration and aerodynamic diameter. The techniques were tested for rod‐like organic pigments and partially sintered SiO2 aggregates, which were produced by two new aerosol generators.