ABSTRACT
Three multifunctional smart composites for next-generation applications have been studied differently through versatile nanoindentation investigation techniques. They are used in order to determine peculiarities and specific properties for the different composites and to study the charge/matrix, charge/surface, or smart functions interactions. At first, a mapping indentation test was used to check the distribution of hardness and modulus across a large region to examine any non-uniformity due to structural anomalies or changes in properties for a carbon nanotubes (CNTs)-reinforced polypropylene (PP V-2) nanocomposite. This smart composite is suitable to be used in axial impeller fans and the results can be used to improve the process of the composite produced by injection moulding. Secondly, the interfacial properties of the carbon fibre (CF) and the resin were evaluated by a push-out method utilizing the smaller indentation tip to target the individual CF and apply load to measure its displacement under loads. This is useful to evaluate the effectiveness of the surface modification on the CFs, such as sizing. Finally, nanoindentation at different temperatures was used for the probing of the in situ response of smart shape memory polymer composite (SMPC) usable in grabbing devices for aerospace applications. Furthermore, the triggering temperature of the shape memory polymer response can be determined by observing the change of indentations after the heating and cooling cycles.
ABSTRACT
In the last decades, there is more awareness on the impact on human health of pollutants emitted during cooking processes, both from commercial and from domestic activities. In this study, a new method exploiting solid-phase microextraction and gas chromatography coupled to mass spectrometry (SPME-GC-MS) was developed to analyse the volatile organic compounds (VOCs) emitted during cooking. The air above the cooking plate was sampled using a polyethylene terephthalate olfactometric bag that allows to transport the sample to the instrument location and to perform the SPME extraction of the sampled air. The efficiency of different extraction systems and different extraction times (1, 8, 16, and 24 h) was evaluated in order to obtain sufficient sensitivity. Thus, the proposed system, combining the use of olfactometric bags and SPME-GC-MS, was applied for the first time to study VOCs emitted during cooking allowing to perform the analysis, even on samples produced in sites far from the instrument location, in an easy way and with instrumentations available in most of laboratories. Then, the method was applied to assess the efficiency of odour filters used in common kitchen hoods, using deep frying of potatoes in sunflower oil as cooking model system. VOCs were analysed in the air before and after passage through the filter, calculating then percentages of dejection for the different classes of VOCs that resulted to be in the range 31-77%.
