207 research outputs found
Port noise impact and citizens' complaints evaluation in rumble and mon acumen interreg projects
No full textAfter the publications of the European Environmental Noise Directive in 2002, many noise maps and action plans, as well as a consistent number of scientific papers, emerged for roads, railways, airports and industrial noise. Unfortunately, noise produced by ports in their surrounding areas seems to be forgotten at present, even though there could be many areas affected by it. Relevant attention from authorities and scientific community seems to be devoted to noise produced underwater for its interference with wildlife, rather than noise produced in the urban portion, that is causing disturbance and consequent complaints by some citizens. The INTERREG Maritime projects MON ACUMEN and RUMBLE aim to study noise originating from port activity in order to assess the currently unexplored situation and then identify solutions for a long-term environmental sustainability. More specifically, RUMBLE aims to effectively and efficiently implement small mitigation interventions, while MON ACUMEN will gather the preliminary knowledge on the issue of noise generated by ports. In this context, questionnaires submitted to north Tyrrhenian port authorities concerning the description of the port area, the present monitoring systems, the measurement campaigns and acoustics maps performed are discussed. Furthermore, by analyzing the citizen's complaints where present, the critical aspects of the analyzed ports will be studied © Proceedings of the 26th International Congress on Sound and Vibration, ICSV 2019. All rights reserved
Physical aging in side-chain liquid crystal polymers: A DSC investigation of the enthalpy relaxation
No full textThe enthalpy relaxation of the glasses of two side-chain liquid crystal polymethacrylates was studied with physical aging experiments detected with differential scanning calorimetry. The experimental traces were fairly well reproduced in the framework of a recent configurational entropic model. The temperature dependence of the equilibrium structural relaxation times was obtained with a simultaneous fit of several different thermograms and compared with-the behavior found for the poly(methyl methacrylate) (PMMA). The comparison evidenced the stronger character of the two liquid crystal polymers, in the frame of the strong/fragile classification of glass-forming systems. At variance with the prediction of the energy landscape model, the heat capacity increment at the glass transition was greater than in PMMA, confirming some recent results on polymeric glass formers
Optical bit stability and relaxation processes in a liquid crystal polymer with a photosensitive azo dye molecule as side group
No full textOptical bit stability and relaxation processes in a liquid crystal polymer with a photosensitive azo dye molecule as side group
No full textWe present a study of optically-induced molecular relaxation and optical writing processes in a photosensitive liquid crystalline polymer, containing the azobenzene moiety in the side chain. Linear and non linear ESR spectroscopies, thermal analysis and rheology investigations carried on azo polymethacrylate (PMA) samples subjected to different thermal treatments have allowed to single out a suitable procedure to get stable, homogeneous substrates. Optical studies on micrometer length scale, adopting the selected procedure, have confirmed the stability conditions in both unaligned and aligned samples. The temperature dependence of the bit stability has been determined. The writing threshold power and writing rate have been measured. The results are discussed within the perspective of extension to the nanometer length scale
Enthalpy relaxation in polymers: A comparison among different multiparameter approaches extending the TNM/AGV model
No full textThe enthalpy recovery mechanism of polymers is usually described in terms of the Tool-Narayanaswamy-Moynihan model (TNM). Even if it is able to qualitatively reproduce all the peculiar features of the aging process, clear discrepancies have been found in quantitative analysis. In this work, differential scanning calorimetry experiments are performed in two different polymers, and data are used in order to compare the predictions of a recently developed configurational approach with possible extensions of the TNM model. All the approaches add a free parameter with respect to the original TNM model. In this study we have found that appreciable improvements between experimental and calculated DSC traces can be observed if the configurational entropy approach is adopted. Furthermore, the long-term annealing experiments performed in one of the polymers clearly support the basic hypothesis of the entropic approach concerning the limit state of the structural relaxation
A calorimetric study of structural relaxation in the glassy state of a liquid-crystal polymer
No full textThe physical ageing of a side-chain liquid-crystal polymer is investigated by means of differential scanning calorimetry, which allows one to follow the enthalpy relaxation of the glass. Measurements are performed for different thermal treatments and compared with the predictions of two phenomenological models where the nonlinearity of the ageing process is accounted for by multiparameter expressions. The experimental results can be described with the model based on the Narayanaswamy expression for nonlinearity. although it seems that the model based on the Hodge expression fits experimental data more satisfactorily. In particular, a single set of parameters is determined which describes different experiments. However, the value of the enthalpy loss as a function of the ageing time is greatly overestimated by both models
Crossover region and entanglement in nearly monodisperse polyethylacrylates studied with ESR spectroscopy.
No full textHeterogeneity in the dynamics of a molecular tracer in liquid crystalline homo- and co-polymers
No full textThe effects of molar mass and molar mass distribution on the optical recording on a LC azobenzene polymer
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