Thermal and spectroscopic (TG/DSC-FTIR) characterization of mixed plastics for materials and energy recovery under pyrolytic conditions

Seven waste thermoplastic polymers (polypropylene, polyethylene film, polyethylene terephthalate, polystyrene, acrylonitrile–butadiene–styrene, high-impact polystyrene and polybutadiene terephthalate, denoted as PP, PE (film), PET, PS, ABS, HIPS and PBT, respectively) and four synthetic mixtures thereof with different compositions representing commingled postconsumer plastic waste and waste of electrical and electronic equipment were studied by means of simultaneous thermogravimetry/differential scanning calorimetry coupled with Fourier transform infrared spectroscopy (TG/DSC–FTIR) under pyrolytic conditions (inert atmosphere). By summing all the heat change contributions due to physical and/or chemical processes occurring (i.e., melting, decomposition), an overall energy, defined as the degradation heat, was determined for both single component and their mixtures. It was found to be about 4–5 % of the exploitable energy of the input material. Vapors evolved during the pyrolysis of single-component polymers and their mixtures, analyzed using the FTIR apparatus, allowed identifying the main reaction products as monomers or fragments of the polymeric chain. Results from TG/DSC runs and FTIR analysis show that there is no interaction among the plastic components of the mixtures during the occurrence of pyrolysis

Identification and characterization of plastics from small appliances and kinetic analysis of their thermally activated pyrolysis

The ␣rst step consisted in a ␣eld investigation carried out in Waste Electric and Electronic Equipment (WEEE) treatment plants coupled with a bibliographic product analysis and FT-IR spectroscopy polymers identi␣cation. Three main polymers of the thermoplastic fraction of small appliances were identi␣ed: in the external cases it was possible to ␣nd acrylonitrile-butadiene-styrene (ABS) and high impact poly- styrene (HIPS), while polybutadiene terephthalate (PBT) was contained in the printed circuit boards (PCBs). Taking into account this identi␣cation, a ternary polymer mixture of ABS-HIPS-PBT was prepared as a representative sample of the thermoplastic fraction contained in WEEE (real WEEE sample). From the thermal characterization (proximate and ultimate analysis, high heating value (HHV) direct mea- surement and Energy-Dispersive-X-Ray-Fluorescence analysis (ED-XRF)) the only polymer whose properties sensibly differ from the analogous virgin polymer is the one contained in PCBs. A kinetic analysis of pyrolysis occurring on the three components and on their ternary mixture was performed using a thermogravimetry (TG) apparatus in argon atmosphere under non isothermal con- ditions. Triplicates of TG experiments at four heating rates of 2, 5, 10 and 15 K min��1 were carried out and two different model-free approaches were adopted, namely the Kissinger and Ozawa-Flynn-Wall methods in order to determine the activation energy E (as a single mean value or as a function of the degree of conversion a). The conversion dependencies of both activation energy and pre-exponential factors were determined as well as the reaction model, representing the reaction mechanism. The suitability of the models selected was tested using the Akaike's Information Criteria (AIC) score, being the geometric model R3 the best found for pyrolysis of ABS, HIPS and real WEEE samples, while PBT sample showed an uncertainty between the R3 and the diffusion D2 model. The reaction time values to achieve the maximum pyrolysis rate in the three main components and in the real WEEE sample were also calculated

Thermal Behavior and Dehydration Kinetic Study of SiO2/PEG Hybrid Gel Glasses

Six different silica-polyethylene glycol (SiO2/PEG) organic-inorganic hybrid nanocomposites with different amounts of PEG 400 (6, 12, 24, 50, 60 and 70 wt.%) were synthesized by the sol-gel technique. Their thermal behavior was studied by thermogravimetry (TG) and differential thermal analysis (DTA) under a flowing argon atmosphere in a wide temperature range and their behavior was compared with those of the related materials with 60 and 70 wt.% of PEG, whose results were reported in a previously study. To identify all physical and chemical processes occurring in these promising materials, the gases evolved during TG experiments were analyzed at characteristic constant temperatures by FTIR. These measurements revealed that all the materials undergo a two-step dehydration (loosing water physically bound at temperature lower than 1008C) with overlapping of both TG and DTA curves, thus suggesting an identical behavior up to 2008C regardless the different content of PEG. A different behavior is observed at higher temperature, where three different exothermic effects were observed in the range 200–4508C accompanied by mass losses ranging from 6 to 37% for the SiO2/PEG hybrid materials

Assessment of Disintegration of Compostable Bioplastic Bags by Management of Electromechanical and Static Home Composters

Interest in small scale composting systems is currently growing, and this in turn raises the question of whether the compostable bags are as suitable as in industrial composting facilities. In this work the physical degradation percentage of compostable lightweight bioplastic bags in two types of composter was examined. The main goal was to understand whether the mild biodegrading conditions that occur in electromechanical or static home composters are sufficient to cause effective bag degradation in times consistent with the householders’ or operators’ expectations. Bags, which complied with standard EN 13432, were composted in a number of 600 L static home composters, which were run in different ways (e.g., fed only with vegetables and yard waste, optimizing the humid/bulking agent fraction, poorly managed) and a 1 m3 electromechanical composter. Six months of residence time in static home composters resulted in 90–96 wt% degradation depending on the management approach adopted, and two months in the electromechanical composter achieved 90 wt%. In the latter case, three additional months of curing treatment of the turned heaps ensured complete physical degradation. In conclusion, in terms of the level and times of physical degradation, the use of compostable bioplastic bags appeared promising and consistent with home composting practices

Thermal behavior and structural study of ZrO2/poly(ε-caprolactone) hybrids synthesized via sol-gel route

The thermal behavior of pure ZrO2 and four ZrO2-based organic-inorganic hybrids (OIHs) containing increasing amount (6, 12, 24 and 50 wt%) of poly(ε-caprolactone) (PCL) (named Z, ZP6, ZP12, ZP24 and ZP50 respectively) has been studied by simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC). The FTIR analysis of the gas mixture evolved at defined temperatures from the samples submitted to the TG experiments identified the mechanism of each thermally activated process. The obtained results suggest that the inorganic matrix of the OIHs prepared by this method exerts a stabilizing effect on the polymer, in particular for poor-PCL hybrid materials. In fact, the different thermal behavior of the ZP50 sample suggests that the polymer is not entirely bonded to the -OH groups of the zirconia matrix due to their saturation. For this reason a part of PCL is not affected by the stabilizing effect of the matrix and is subjected to thermal degradation. Finally, by observing their thermal behavior it was possible to select the most suitable temperatures for thermal pretreatment: 400, 600 and 1000 °C. The structural analysis by X-ray diffraction (XRD) revealed that at 400 °C the materials are amorphous, while at 600 °C they are mostly tetragonal, and the content of the tetragonal phase decreases with increasing the amount of PCL in the OIHs. All the materials treated at 1000 °C are monoclinic, but their crystallinity decreases with increasing the PCL content

Characterization of Some Real Mixed Plastics from WEEE: A Focus on Chlorine and Bromine Determination by Different Analytical Methods

Bromine and chlorine are almost ubiquitous in waste of electrical and electronic equipment (WEEE) and the knowledge of their content in the plastic fraction is an essential step for proper end of life management. The aim of this study is to compare the following analytical methods: energy dispersive X-ray fluorescence spectroscopy (ED-XRF), ion chromatography (IC), ion-selective electrodes (ISEs), and elemental analysis for the quantitative determination of chlorine and bromine in four real samples taken from different WEEE treatment plants, identifying the best analytical technique for waste management workers. Home-made plastic standard materials with known concentrations of chlorine or bromine have been used for calibration of ED-XRF and to test the techniques before the sample analysis. Results showed that IC and ISEs, based upon dissolution of the products of the sample combustion, have not always achieved a quantitative absorption of the analytes in the basic solutions and that bromine could be underestimated since several oxidation states occur after combustion. Elemental analysis designed for chlorine determination is subjected to strong interference from bromine and required frequent regeneration and recalibration of the measurement cell. The most reliable method seemed to be the non-destructive ED-XRF. Calibration with home-made standards, having a similar plastic matrix of the samples, enabled us to carry out quantitative determinations, which have been revealed to be satisfactorily accurate and precise. In all the analyzed samples a total concentration of chlorine and/or bromine between 0.6 and 4 w/w% was detected, compromising the feasibility of a mechanical recycling and suggesting the exploration of an alternative route for managing these plastic wastes

Hospital of Objects. Recycling plastic from the small electronic devices to redesign old objects by the 3d printers

"Hospital of Objects" is a service that provides for the recovery of forgotten, obsolete and accidentally broken objects, it fall within typical chain of personal manufacturing. Through the design input of the designer / maker, the obsolete object reacquires an aesthetic and functional dignity, according to the contemporary hybrid design and hacking design logic. The aim is to give new life to small everyday objects , recomposing, aggregating or replacing some parts with new parts 3d printed, using filament obtained from the recycling plastic of WEEE waste. The service through the exchange of expertise (including Laboratory for the recycling of WEEE and Rapid Manufacturing Laboratory), cooperation (between user and designer / maker), attention to environmental impact, leading to the creation of a particular product: hybrid of languages and technologies, that allows experiments in the field of recycling, technology and creativity, exploiting the 3D Printing aimed at small- scale production or unique pieces

Thermal and catalytic pyrolysis of a mixture of plastics from small waste electrical and electronic equipment (WEEE)

Pyrolysis seems a promising route for recycling of heterogeneous, contaminated and additives containing plastics from waste electrical and electronic equipment (WEEE). This study deals with the thermal and catalytic pyrolysis of a synthetic mixture containing real waste plastics, representative of polymers contained in small WEEE. Two zeolite-based catalysts were used at 400 °C: HUSY and HZSM-5 with a high silica content, while three different temperatures were adopted for the thermal cracking: 400, 600 and 800 °C. The mass balance showed that the oil produced by pyrolysis is always the main product regardless the process conditions selected, with yields ranging from 83% to 93%. A higher yield was obtained when pyrolysis was carried out with HZSM-5 at 400 °C and without catalysts, but at 600 and 800 °C. Formation of a significant amount of solid residue (about 13%) is observed using HUSY. The oily liquid product of pyrolysis, analysed by GC–MS and GC-FID, as well as by elemental analysis and for energy content, appeared lighter, less viscous and with a higher concentration of monoaromatics under catalytic condition, if compared to the liquid product derived from thermal degradation at the same temperature. HZSM-5 led to the production of a high yield of styrene (17.5%), while HUSY favoured the formation of ethylbenzene (15%). Energy released by combustion of the oil was around 39 MJ/kg, thus suggesting the possibility to exploit it as a fuel, if the recovery of chemical compounds could not be realised. Elemental and proximate analysis of char and GC-TCD analysis of the gas were also performed. Finally, it was estimated to what extent these two products, showing a relevant ability to release energy, could fulfil the energy demand requested in pyrolysis