Exposure to graphene in a pilot production plant

Workers exposure to graphene was measured in a pilot production plant. Reduced graphene oxide was produced through graphite oxidation and posterior thermal reduction. The monitoring was performed using two handheld on-line devices covering the particle size range from 10 nm to 10 μm (CPC3007 and OPS3330). Simultaneously, personal and area filter samples were collected for off line analysis, including gravimetric, elemental carbon analysis and SEM/EDX. Significant releases of particles were identified in two tasks, during the graphene oxide washing, and during its milling. However, the analysis of the particles size distribution and of their morphology suggested that the released particles were not the target nanomaterial but engine generated nanoparticles. The mass of elemental carbon in the collected filters was below the quantification limit and the calculated graphene mass concentrations were quite below the selected reference exposure limit. Overall, this work showed that worker exposure to graphene was low in this pilot plant, contributing to guarantee a safe process, prior to its industrialization.This research was carried out as part of the project FAST- Functionally Graded Additive Manufacturing Scaffolds by Hybrid Manufacturing. The project FAST has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 685825

Environmental Particle Emissions due to Automated Drilling of Polypropylene Composites and Nanocomposites Reinforced with Talc, Montmorillonite and Wollastonite

In this study, the effect on nanoparticle emissions due to drilling on Polypropylene (PP) reinforced with 20% talc, 5% montmorillonite (MMT) and 5% Wollastonite (WO) is investigated. The study is the first to explore the nanoparticle release from WO and talc reinforced composites and compares the results to previously researched MMT. With 5% WO, equivalent tensile properties with a 10 % weight reduction were obtained relative to the reference 20% talc sample. The materials were fabricated through injection moulding. The nanorelease studies were undertaken using the controlled drilling methodology for nanoparticle exposure assessment developed within the European Commission funded SIRENA Life 11 ENV/ES/506 project. Measurements were taken using CPC and DMS50 equipment for real-time characterization and measurements. The particle number concentration (of particles <1000nm) and particle size distribution (4.87nm - 562.34nm) of the particles emitted during drilling were evaluated to investigate the effect of the silicate fillers on the particles released. The nano-filled samples exhibited a 33% decrease (MMT sample) or a 30% increase (WO sample) on the average particle number concentration released in comparison to the neat polypropylene sample. The size distribution data displayed a substantial percentage of the particles released from the PP, PP/WO and PP/MMT samples to be between 5-20nm, whereas the PP/talc sample emitted larger particle diameters.The work is funded by and part of the European Commission Life project named Simulation of the release of nanomaterials from consumer products for environmental exposure assessment (SIRENA, Pr. No. LIFE 11 ENV/ES/596). The access and use of the facilities at the Flemish Institute for Technological Research (VITO) was funded by QualityNano Project through Transnational Access (TA Application VITO-TAF-382 and VITO-TAF-500) under the European Commission, Grant Agreement No: INFRA-2010-262163. Kristof is also thankful for partial funding by the School of Engineering at Robert Gordon University for his studentship

Desarrollo y caracterización de un material compuesto de matriz de aluminio 6061 y partículas de TiB₂

The incorporation of ceramic particles has been one of the ways developed to improve the mechanical properties of aluminium alloys during the last years. The main objective of this work has been to develop the manufacturing process of the reinforced aluminium alloy and analyse its mechanical properties and microstructure. Details about an innovative MMC manufacturing process and the results obtained in the development of a new family of TiB 2reinforced aluminium alloys for forging and extrusion applications are presented. It has been observed that the considered manufacturing process, consisting in the fabrication of particles by SHS and their incorporation into the selected alloy, is a feasible process to manufacture reinforced alloys that can be subsequently extruded or forged. The final result is the development of a material suitable for extrusion and forging applications and that presents an improvement of fatigue and tensile properties of the matrix alloy.Peer reviewe

Estudio de la intercara de una preforma híbrida infiltrada sin presión

This work presents an interfacial characterization of the matrix/reinforcement interface of an aluminium matrix composite reinforced with Saffil fibres and alumina particles was manufactured using the Primex ™ pressureless infiltration process. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to carry out the microstructural and chemical characterization of the composite material. In addition, a mechanical characterization was conducted by the nanoindentation technique. This research concludes that the composite presents a good bonding between the matrix and the reinforcements.Peer reviewe

Particle emission measurements in three scenarios of mechanical degradation of polypropylene-nanoclay nanocomposites

Researchers and legislators have both claimed the necessity to standardize the exposure assessment of polymer nanocomposites throughout their life cycle. In the present study we have developed and compared three different and independent operational protocols to investigate changes in particle emission behavior of mechanically degraded polypropylene (PP) samples containing different fillers, including talc and two types of nanoclays (wollastonite-WO- and montmorillonite-MMT-) relative to not reinforced PP. Our results have shown that the mechanical degradation of PP, PP-Talc, PP-WO and PP-MMT samples causes the release of nano-sized particles. However, the three protocols investigated, simulating industrial milling and drilling and household drilling, have produced different figures for particles generated. Results suggest that it is not possible to describe the effects of adding nano-sized modifiers to PP by a single trend that applies consistently across all different protocols. Differences observed might be attributed to a variety of causes, including the specific operational parameters selected for sample degradation and the instrumentation used for airborne particle release characterization. In particular, a streamlined approach for future assessments providing a measure for released particles as a function of the quantity of removed material would seem useful, which can provide a reference benchmark for the variations in the number of particles emitted across a wider range of different mechanical processes

Analysis of the solidification and properties of plaster cast al based composites

The present work deals with aspects related to the solidification and properties of an Al-Si10Mg/SiC 20p alloy cast in plaster moulds. Several strategies were followed to shorten its solidification time such as embedding copper tubes into the mould to make circulate cooling fluids immediately after the casting step. The analysis of cooling curves provided valuable information on the effect of the particles on solidification events. The precipitation of different phases of the MMC takes place at higher temperatures and earlier than in the case of the non reinforced alloy. Particles affect the solidification pattern of the alloy and play a noticeable role in the precipitation of the phases. This fact should be taken into account to design the filling and feeding systems correctly and for modelling and processing parameters as well as in thermal treatments. Eventually samples were obtained under the highest solidification rate conditions to analyse the microstructure and tensile properties of the MMC material.Part of the results of this work were obtained in the frame of the research project IMINCAST (Contract number G1ST-CT-2002-50268) partially funded by the European Commission. The Danish company Temponik A/S collaborated in the design of the moulds and interpretation of the results.Peer reviewe

On the experimental approaches for the assessment of the release of engineered nanomaterials from nanocomposites by physical degradation processes

The LIFE+ Project SIRENA, Simulation of the release of nanomaterials from consumer products for environmental exposure assessment, (LIFE11 ENV/ES/596) has set up a Technological Surveillance System (TSS) to trace technical references at worldwide level related to nanocomposites and the release from nanocomposites. So far a total of seventy three items of different nature (from peer reviewed articles to presentations and contributions to congresses) have been selected and classified as "nanomaterials release simulation technologies". In present document, different approaches for the simulation of different life cycle stages through the physical degradation of polymer nanocomposites at laboratory scale are assessed. In absence of a reference methodology, the comparison of the different protocols used still remains a challenge.Peer reviewe

Analiza krzepnięcia i właściwości odlewanych kompozytów na bazie aluminium

The present work deals with aspects related to the solidification and properties of an Al-Si10Mg/SiC20p alloy cast in plaster moulds. Several strategies were followed to shorten its solidification time such as embedding copper tubes into the mould to make circulate cooling fluids immediately after the casting step. The analysis of cooling curves provided valuable information on the effect of the particles on solidification events. The precipitation of different phases of the MMC takes place at higher temperatures and earlier than in the case of the non reinforced alloy. Particles affect the solidification pattern of the alloy and play a noticeable role in the precipitation of the phases. This fact should be taken into account to design the filling and feeding systems correctly and for modelling and processing parameters as well as in thermal treatments. Eventually samples were obtained under the highest solidification rate conditions to analyse the microstructure and tensile properties of the MMC material.Praca przedstawia aspekty związane z krzepnięciem i właściwościami stopów Al-Si10Mg/SiC20p odlewanych w formach gipsowych. Aby skrócić czas krzepnięcia stopu testowano kilka strategii, takich jak osadzanie rur miedzianych w formie aby umożliwić obieg cieczy chłodzących natychmiast po odlaniu stopu. Analiza krzywych chłodzenia dostarczyłacennych informacji na temat wpływu cząstek na proces krzepnięcia. Wydzielanie różnych faz w kompozytach metalowo-ceramicznych odbywa się w wyższych temperaturach i wcześniej, niż w przypadku nieumacnianego stopu. Cząstki wpływają na schemat krzepnięcia stopu i odgrywają zauważalną rolę w wydzielaniu faz. Fakt ten powinien być brany pod uwagę przy projektowaniu prawidłowego systemu zalewania formy, modelowaniu parametrów procesu, jak również obróbki cieplnej. Na koniec pobrano próbki otrzymane przy najwyższej szybkości krzepnięcia do analizy mikrostruktury i właściwości wytrzymałościowych kompozytu metalowo-ceramicznego