Spatially resolved spectroscopy of an atmospheric pressure microwave plasma jet used for surface treatment

In this study, the variations of properties of a microwave plasma jet (surfatron) along the discharge axis have been investigated using optical emission spectroscopy. As the argon jet is not enclosed, the spatial distribution of individual species in effluent plasma is the result of rather complicated interplay between energy loss and gradual mixing with the air. Spatial 2D relative intensity profiles of atomic lines and molecular bands at 310 nm, 336 nm, 391 nm and 656 nm are presented in the form of colour maps revealing different positions of maximum emission intensity for 310 nm and 336 nm (in the effluent plasma) and for 391 nm and 656 nm (inside the discharge tube). The plasma jet was used for surface treatment of heat resistant samples (stainless steel, aluminium, silicon wafer) and the effectiveness of the plasma treatment was evaluated by measuring the sessile drop contact angle, with water and glycerol as testing liquids. The optimal position for plasma treatment (close to the tube nozzle) combined with longer treatment time (10 s) lead to hydrophilic properties of samples with contact angles as low as 10°

Improvement of mechanical properties of polylactic acid adhesion joints with bio-based adhesives by using air atmospheric plasma treatment

The packaging industry generates a high volume of wastes; so that, there is a high demand of biodegradable materials, which do not damage the environment. Nowadays, there is an interesting consumption of polylactic acid (PLA) due to its biodegradable features. This work focuses on the improvement of mechanical properties of PLA adhesion joints for uses in the packaging industry. In order to achieve that purpose, atmospheric plasma treatment is used to selectively modify PLA surface properties. The obtained experimental results show that the atmospheric plasma treatment is suitable to increase the mechanical performance of PLA-PLA adhesive joints. Optimum conditions for the atmospheric plasma treatment were obtained with a nozzle-substrate distance of 10 mm and an advance rate in the 100-300 mm s(-1) range; for these particular conditions, the effectiveness of the surface modification is the highest. The main plasma-acting mechanisms are microetching together with the insertion of polar groups which lead to an interesting synergy that causes a remarkable increase in mechanical properties of adhesion joints. In particular, the shear strength of untreated PLA-PLA adhesion joints is close to 50 N cm(-2) and this value is increased up to values of about 168.7 N cm(-2) with optimum plasma treatment conditions. This indicates that atmospheric plasma treatment is both a technical and an environmental friendly technique to improve mechanical performance of PLA adhesive joints. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42391.Jordá Vilaplana, A.; Sánchez Nacher, L.; Fombuena Borrás, V.; García García, D.; Carbonell Verdú, A. (2015). Improvement of mechanical properties of polylactic acid adhesion joints with bio-based adhesives by using air atmospheric plasma treatment. Journal of Applied Polymer Science. 132(32):42391-1-42391-9. doi:10.1002/app.42391S42391-142391-91323

Modeling of Semisolid Flow

Numerical simulation of semisolid processing can be carried out using one- or two-phase modeling. Various models based from either fluid or solid mechanics formalisms were developed. The most sophisticated one-phase models account for shear thinning, thixotropy, and solidification/melting phenomena. They are of great interest to investigate the flow front and optimize die geometry, temperature of die, and billet. Liquid-solid segregation prediction requires two-phase modeling. Basic equations and constitutive models currently used for numerical simulation of semisolid processing are presented and discussed

Surface and Adhesion Characteristics of Current and Next Generation Steel Packaging Materials

Steel packaging remains an important mean by which foodstuffs and other products can be stored safely for a prolonged period of time. The industry is being challenged by the dual legislative pressures which require the elimination of Chrome (VI) from the manufacturing process and the elimination of bisphenol A as a component from the lacquer system. Initial indications suggest lower adhesive performance, and it has been postulated that thermal treatment may be a mean of improv- ing adhesion. Three substrates (two current and one future) were physically and chemically characterized prior and post treatment and the resultant impact of adhesion was quantified. The net impact of the thermal treatment is that it increases the adhesion of the lacquer on the surface. As there is minimal change in the physical characteristics of the surface, the authors propose that this is a result of changes in the chemical surface species, particularly the increase in the oxidic nature of each of the substrates which provides additional bonding sites for the organic species in the lacquer. These trends are observed for current substrate materials as well as next generation Chrome VI free substrate. Next generation replacement substrate materials perform better than current materials for dry adhesion while next generation bisphenol A non-intent lacquer mate- rials perform poorer than the current epoxy phenolic materials

Aluminum oxide barrier coatings on polymer films for food packaging applications

In the field of packaging, barrier layers are functional films, which can be applied to polymeric substrates with the objective of enhancing their end-use properties. For food packaging applications, the packaging material is required to preserve packaged food stuffs and protect them from a variety of environmental influences, particularly moisture and oxygen ingress and UV radiation. Aluminum metallized films are widely used for this purpose. More recently, transparent barrier coatings based on aluminum oxide or silicon oxide have been introduced in order to fulfill requirements such as product visibility, microwaveability or retortability. With the demand for transparent barrier films for low-cost packaging applications growing, the use of high-speed vacuum deposition techniques, such as roll-to-roll metallizers, has become a favorable and powerful tool. In this study, aluminum oxide barrier coatings have been deposited onto biaxially oriented polypropylene and polyethylene terephthalate film substrates via reactive evaporation using an industrial 'boat-type' roll-to-roll metallizer. The coated films have been investigated and compared to uncoated films in terms of barrier properties, surface topography, roughness and surface energy using scanning electron microscopy, atomic force microscopy and contact angle measurement. Coating to substrate adhesion and coating thickness have been examined via peel tests and transmission electron microscopy, respectively. © 2013 Elsevier B.V

Experimental characterisation on the behaviour of PLLA for stretch blowing moulding of bioresorbable vascular scaffolds

Processing tubes from poly (l-lactic acid) (PLLA) by stretch blow moulding (SBM) is used in the manufacture of bioresorbable vascular scaffolds (BVS) to improve their mechanical performance. To better understand this processing technique, a novel experimental setup by free stretch blow inside a water bath was developed to visualise the tube forming process and analyse the deformation behaviour. PLLA tubes were heated, stretched and blown with no mould present inside a temperature-controlled water bath whilst recording the processing parameters (axial force, inflation pressure). The onset of pressure activation relative to the axial stretch was controlled deliberately to produce a simultaneous (SIM) or sequential (SEQ) mode of deformation. Real-time images of the tube during forming were captured using high speed cameras and the surface strain of the patterned tube was extracted using digital image correlation (DIC). The deformation characteristics of PLLA tubes in SBM was quantified by analysis of shape evolution, strain history and stress-strain relationship

Characterization and modelling the mechanical behaviour of poly (l-lactic acid) for the manufacture of bioresorbable vascular scaffolds by stretch blow moulding

Bioresorbable Vascular Scaffolds (BVS) manufactured from poly (l-lactic acid) (PLLA) offer an alternative to metal scaffolds for the treatment of coronary heart disease. One of the key steps in the manufacture of these scaffolds is the stretch blow moulding process where the PLLA is biaxially stretched above glass transition temperature (Tg), inducing biaxial orientation and thus increasing ductility, strength and stiffness. To optimise the manufacture and performance of these scaffolds it is important to understand the influence of temperature and strain rate on the constitutive behaviour of PLLA in the blow moulding process. Experiments have been performed on samples of PLLA on a custom built biaxial stretch testing machine to replicate conditions typically experienced during blow moulding i.e. in a temperature range from 70 °C to 100 °C and at strain rates of 1 s−1, 4 s−1 and 16 s−1 respectively. The data is subsequently used to calibrate a nonlinear viscoelastic material model to represent the deformation behaviour of PLLA in the blow moulding process. The results highlight the significance of temperature and strain rate on the yielding and strain hardening behaviour of PLLA and the ability of the selected model to capture it

Problem odpowiedzialnosci korporacji wielonarodowych w Prawie Miedzynarodowym za naruszenia Praw Czlowieka

The article presents the problem of responsibility of multinational corporations under International Law. Firstly, it is presented the question of proper terminology regarding multinational corporations. The author also discusses the history of multinational corporations, since the second half of the XIXth century. Secondly, the author presents the vital problem of responsibility of multinational corporations, its origin and examples of human rights violations committed by multinational corporations. Such responsibility under International Law is discussed under the notion of state responsibility. The author presents various treaty norms as well as jurisprudence regarding the subject of state responsibility for actions of non-state actors. It is also discussed the question of boundaries of such responsibility. In the last part of the article, the author introduces the possibility for direct responsibility of multinational corporations under International Law. At the very end of the article, the author evaluates direct as well as indirect responsibility of non-state actors under International Law.Multinational, transnational, corporation, history, responsibility, human rights