Qualitative and quantitative contaminants assessment in recycled pellets from post-consumer plastic waste by means of spectroscopic and thermal characterization

The complexity of any plastic recycling initiative lies in the heterogeneous nature of the post-consumer commingled plastic waste stream: recycling treatments are challenging without prior reliable sorting. A suitable identification system should be able to recognize different plastics and blends. Nowadays, the main technique used as quality control in plastic waste sorting centers is differential scanning calorimetry, whose result can be purely qualitative or semi-quantitative, since only the crystalline fraction is evaluated. Moreover, the time required for data acquisition is relatively long. Infrared spectroscopy is an alternative, faster technique extensively used in applied research, but not widely utilized in industry. In this work, the cross-use of infrared spectroscopy and calorimetry is tested in a real, practical case: the quality control of recycled pellets (namely composed of polyolefins only), which represent the output of a commingled plastic recycling plant and are used as secondary raw materials for different applications. Appropriate infrared spectroscopy calibration curves were built to allow the quantitative analysis with respect to the most common polymers found in the commingled plastic waste stream; the composition and contaminants in the recycled pellets were thereby determined and tracked through different production batches through the cross-use of the two techniques outlined above

Impact sound of timber floors in sustainable buildings

Timber buildings represent a robust alternative to traditional heavyweight constructions. They allow CO2 storage, high structure and performance reproducibility, fast assembly and final certification of every panel. Nowadays, acoustic insulation is one of the most requested performances on the part of inhabitants, but not always fulfilled. Since these kind of edifices are relatively new in the market, there are very few studies on acoustic properties, regarding on impact sound performances. In this paper, an in-depth analysis of impact noise on bare timber floors is presented, focusing on how impact sound reduction cannot be as efficient as in heavyweight constructions. Two new equations are proposed, modelling the impact sound pressure level of common bare timber structures and the influence of traditional floating floor systems is analysed

Innovative thermal and acoustic insulation foam from recycled waste glass powder

An innovative powder-foaming process able to produce thermal and acoustic insulating foams obtained by sol-gel and a subsequent freeze-drying process was developed. Gel containing glass powder was formed using alginate, a polysaccharide composed of 1-4linked \u3b1-L-guluronic acid and \u3b2-D-mannuronic acid, capable to form stable gels in presence of calcium cations. In order to obtain a porous foam, gels were frozen and then freeze-dried. Foam properties strongly depend on production parameters, particle dimension and different binder concentrations, their influence was investigated. The resulting glass foams were characterized in order to evaluate structure, density, mechanical and acoustic properties. The results pointed out an improved acoustic insulating performance respect to rock wool. Foams were also subjected to a thermal process to better fix powders into the final glass structure

The effect of artificial weathering on PP coextruded tape and laminate

The aim of this work was to analyse the influence of artificial weathering on polypropylene (PP) selfreinforced composite both as fabric constituent (tape) and as laminate. Particular attention has been focused on the interaction between radiation and material microstructural characteristics, especially for the selective action that the former causes in PP amorphous regions. The evaluation of carbonyl index performed by Fourier Transform Infrared (FT-IR) spectroscopy has highlighted that tapes are more prone to degradation since their drawn structure induces internal stress. Differential scanning calorimetry (DSC) measurements have denoted a shift towards lower temperature of PP melting peak. While crystallinity determination performed by DSC and FT-IR spectroscopy has underlined an increasing trend for laminate over exposure time due to the higher amount of amorphous phase, Raman spectroscopy has revealed that photo-degradation induces a rise of the isomeric defect fraction, limiting chemicrystallisation both for tapes and laminates

Failure investigation of a protective epoxy coating by means of crosscheck between infrared spectroscopy and thermal analysis

This paper reports the failure of an epoxy coating that was applied for corrosion prevention on the inner walls of a heat exchanger. The coating became brittle and detached from the walls of the exchanger after one year of service. An investigation was performed in order to evaluate the failure cause by means of thermal analysis, optical microscopy and infrared spectroscopy. Thermal analysis excluded an incomplete curing of the detached paint. Optical microscopy highlighted sediments, pores and cracks over the detached coating surface; infrared spectroscopy revealed vibrational bands associated with thermo-oxidative phenomena. A thermo-oxidative simulation was performed on fresh coating samples, pointing out that epoxy coating starts degrading around 100-120 \ub0C. Taking into account the temporary malfunction of the cooling system reported by the user, the failure cause was identified in an overheating that induced a thermo-oxidative degradation of the coating and its subsequent embrittlement and detachment

Life cycle analysis of a novel thermal insulator obtained from recycled glass waste

This paper focused on the application of the Life Cycle Analysis methodology to a novel thermal insulator by means of comparison with traditional materials widely used in the building sector. This innovative insulating foam was produced from recycled glass powder and green-chemistry reagents via a freeze-drying process. The materials inventory for this insulator was built from primary laboratory data, while energy flows were estimated according to available secondary sources. Materials inventory, energy flow and emission data for traditional insulators were obtained and averaged from literature and relevant environmental product declarations. Global warming, acidification, eutrophication and abiotic resource depletion potentials were evaluated as environmental impact factors to assess the environmental performances of the innovative insulator respect to the available materials. The benefits of the novel material in terms of these indexes were then highlighted taking into account also different local energetic sources

Acoustic of lightweight timber buildings: A review

This paper presents a literature overview of the acoustic studies dedicated to lightweight wooden constructions. The reviewed articles contain prediction models, laboratory and field measurements, finite element or computational investigations as well as subjective survey describing the vibro-acoustic behaviour of a large range of wooden structures. The review analyses different type of timber constructions and investigates the acoustic research methodologies highlighting the following aspects: airborne sound insulation, impact noise reduction, flanking transmissions, human perceptions and pros and cons of the presented methods. Furthermore, an in-depth analysis of impact noise of bare floors focuses on how impact sound reduction could not be as efficient as in heavyweight constructions; the comparison between the different approaches on prediction of airborne sound insulation of multilayer timber partitions compared to traditional heavy building materials is shown. Finally a subjective method survey is provided, underlining the weakest point of timber buildings: low frequency sound insulation

Impulse response method for defect detection in polymers: Description of the method and preliminary results

The major problem encountered in the application of polymer industrial products is the difficulty of effectively modelling and predicting material performance and service life according to applied loads and operating environmental conditions. Furthermore, the presence of defects such as voids or inclusions created during manufacturing may affect the final performance. The aim of this study is to present and investigate the development of an innovative acoustic non-destructive technique (patent pending), able to verify defects into composite laminates. The analysis was carried out in two steps: the first aims to verify if distinct phases can be recognized within a material, while the second has the purpose of testing the proposed method on defective materials ad hoc prepared

Low frequency noise and disturbance assessment methods: A brief literature overview and a new proposal

Several studies have presented the effects of environmental noise on communities, focusing attention on sleep time events. The noise introduced into a dwelling is mostly evaluated using the A-weighted sound pressure level (LAeq) as the only parameter to determine the perceived disturbance. Nevertheless, if noise is produced by activities or sources characterised by a low frequency contribution, the measurement of LAeq underestimates the real disturbance, in particular during sleep time. The aim of this contribution is to analyse the low frequency disturbance phenomenon into technical and scientific literature and to investigate if any possible objective method is available in order to assess noise disturbance inside dwellings

Time-depending performance of resilient layers under floating floors

In the floating floor system the performance of resilient layers, in terms of impact sound pressure level reduction, is of paramount importance. In the present study in order to evaluate the time-depending performances, a comprehensive characterization of twenty different layers was carried out, evaluating dynamic stiffness, compressibility and compressive creep. The aim of this work was to find out a possible correlation among these parameters and the effect of service time on mechanical and acoustical properties. Results indicated that a general rule couldn\u2019t be defined. Furthermore, the presence of a coating, as well as different density and/or contact shape, has proved to influence the final acoustical performances