Investigation on the effect of low-pressure plasma treatment on the adhesion properties of different carbon-fiber-reinforced-polymer materials for structural adhesive bonding

This three-part study, developed with the collaboration of the Istituto Italiano di Tecnologia (IIT), reports a systematic and quantitative evaluation of the effects induced by various low-pressure plasma (LPP) treatments on the adhesive properties of Carbon Fiber Reinforced Polymer (CFRP) substrates. In particular, Part A of this work was focused on the surface activation of CFRP substrates, made via traditional vacuum-bag technique, which was performed using several combinations of LPP parameters. From the comparison with conventional pre-bonding preparations, it was possible to quantify the effectiveness of LPP in increasing the performance of adhesively-bonded CFRP joints. Further measurements of roughness and wettability were performed, and analyses via x-ray photoelectron spectroscopy (XPS) were also carried out, allowing identification of the morphological, physical and chemical phenomena involved in the treatments. Then, a quantitative evaluation of the aging behavior of the adhesively-bonded joints was the topic of the subsequent Part B. Four significant sets of LPP-treatment conditions were selected, and then subjected to accelerated temperature-humidity aging. To assess the durability of the CFRP-adhesive system under severe aging conditions, tensile shear strength (TSS) testing and wedge cleavage test (WT) were performed in parallel. The experimental findings showed that LPP treatment of the CFRP substrates results in increased short-term quality of the adhesive joint as well as in enhancement of its durability even under severe aging conditions. The last part of the work (Part C) was inspired by the recent developments in additive technologies for the manufacturing of structural thermoplastic-composite parts. In this context, the mechanical and failure behavior were investigated of continuous carbon-fiber (CCF) composite materials built via Fused Filament Fabrication (FFF) technology when used as substrates for bonded joints. Notably, the experiments were focused on verifying how the additively-manufactured substrates respond to adhesive bonding when the interface interactions are increased by preparing the surface with LPP treatment. This approach allowed detection of those criticalities that might limit the application of adhesive bonding to 3D-printed composite parts, with respect to that observed using traditional CFRP materials

Capillaroscopy in 2016 : new perspectives in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disorder of unknown etiology characterized by early impairment of the microvascular system. Nailfold microangiopathy and decreased peripheral blood perfusion are typical clinical aspects of SSc. The best method to evaluate vascular injury is nailfold videocapillaroscopy, which detects peripheral capillary morphology, and classifies and scores the abnormalities into different patterns of microangiopathy. Microangiopathy appears to be the best evaluable predictor of the disease development and has been observed to precede the other symptoms by many years. Peripheral blood perfusion is also impaired in SSc, and there are different methods to assess it: laser Doppler and laser speckle techniques, thermography and other emerging techniques

Laser surface texturing of polypropylene to increase adhesive bonding

In this paper, the main parameters of laser surface texturing of polymeric substrates have been studied. The final aim of the texturing is to increase the performance of bonded joints of grey-pigmented polypropylene substrates. The experimental investigation was carried out starting from the identification of the most effective treatment parameters, in order to achieve a good texture without compromising the characteristics of the bulk material. For each of these parameters, three values were individuated and 27 sets of samples were realised. The surface treatment was analysed and related to the mechanical characteristics of the bonded joints performing lap-shear tests. A statistical analysis in order to find the most influential parameter completed the work

Le manovre e gli esercizi

Gli esercizi e le manovre per la disfagia vengono presentate insieme alle pi\uf9 recenti evidenze nell'ambito

Hybrid FSWeld-bonded joint fatigue behaviour

Aluminium alloys, widely used in aeronautics, are increasingly involved in the automotive industry due to the good relationship between mechanical strength and specific weight. The lightening of the structures is the first objective, which allows the decreasing in the weight in motion. The use of aluminium alloys has also seen the introduction of the Friction Stir Welding (FSW) technique for the production of structural overlapping joints. FSW allows us to weld overlap joints free from defects, but with the presence of a structural notch further aggravated by the presence of a "hook" defect near the edge of the weld. Furthermore, FSW presents a weld penetration area connected to the tool geometry and penetration. The experimental activity will be focused on the combination of two different joining techniques, which can synergistically improve the final joint resistance. In particular, the welding and bonding process most commonly known as weld-bonding is defined as a hybrid process, as it combines two different junction processes. In this paper we analyse FSWelded AA6082 aluminium alloy overlapped joint with the aim of quantitatively evaluating the improvement provided by the presence of an epoxy adhesive between the plates. After optimising the weld-bonding process, the mechanical behaviour of welded joints will be analysed by static and dynamic tests. The presence of the adhesive should limit the negative effect of the structural notch inevitable in a FSW overlapped joint

Valutazione clinica e strumentale

La presentazione ricopre il tema della valutazione clinica e strumentale della disfagia

Capillaroscopy as an Outcome Measure for Clinical Trials on the Peripheral Vasculopathy in SSc—Is It Useful?

Peripheral microvascular impairment in systemic sclerosis (SSc) may be easily detected and scored in a safe noninvasive way by nailfold videocapillaroscopy (NVC). The paper highlights clinical conditions related to SSc in which NVC may represent an outcome measure of therapeutical interventions, by elaborating on their already assessed relationship with the NVC patterns and eventually scores. The 3 important biological/clinical conditions are: the positivity for SSc-specific serum autoantibodies, the presence of SSc skin digital ulcers (DUs) and of pulmonary arterial hypertension (PAH) SSc associated. In conclusion, to the question if capillaroscopy (NVC) may represent in SSc an outcome measure for clinical trials on the peripheral vasculopathy, based on the growing evidence and our detailed studies, the answer is positive. Recent therapeutic trials in SSc are confirming this role, and the experience is growing rapidly