The production of flexible polyurethane foams (FPF) with good acoustical performance to control sound and noise and incorporating bio/recycled raw materials is an interesting alternative to ...conventional acoustic absorbent materials. In this sense, biobased polyols like glycerol (GLY) or hydroxylated methyl esters derived from tung oil (HMETO) as multifunctional polyols, and waste tire particles (WTP) as fillers of low thermal conductivity and good capability for acoustical absorption, are prospective feedstocks for FPF preparation. In this work, FPF were prepared by adding different amounts of these components to a formulation based on a commercial polyether polyol. Results of scanning electron microscopy (SEM) analysis, compression tests and normal-incidence sound absorption coefficient (αN) measurements are presented and discussed. The addition of WTP or GLY to the commercial formulation enhanced both the modulus and yield stress of the obtained FPF in all cases. Moreover, a high recovery of the applied strain (>90%) was attained 24 h after the compression tests. On the other hand, the normal-incidence sound absorption coefficient, αN, reached high values mostly at the highest evaluated frequencies (αN ∼0.62–0.89 at 2000 Hz and αN ∼0.70–0.91 at 5000 Hz). SEM micrographs revealed that the foams obtained present a combination of open and closed cell structure and both the modifiers and particles tend to decrease the cell size.
The environmental accumulation of microplastics poses a formidable global challenge, with tyre wear particles (TWPs) emerging as major and potentially harmful contributors to this particulate ...pollution. A critical pathway for TWPs to aquatic environments is via road drainage. While drainage assets are employed worldwide, their effectiveness in retaining microplastics of highly variable densities (TWP ~ 1–2.5 g cm
3
) remains unknown. This study examines their ability to impede the transfer of TWPs from the UK Strategic Road Network (SRN) to aquatic ecosystems. Samples were collected from the influent, effluent and sediments of three retention ponds and three wetlands. The rate of TWP generation is known to vary in response to vehicle speed and direction. To ascertain the significance of this variability, we further compared the mass of TWPs in drainage from curved and straight sections of the SRN across eight drainage outfalls. Pyrolysis gas chromatography-mass spectrometry (Py-GC–MS) was used to quantify tyre wear using benzothiazole as a molecular marker for TWPs (with an internal standard benzothiazole-D4). Tyre wear was present in drainage from the SRN at concentrations of 2.86 ± 6 mg/L and was found within every sample analysed. Drainage from curved sections of the SRN contained on average a 40% greater TWP mass than straight sections but this was not significant. The presence of wetlands and retention ponds generally led to a reduction in TWP mass (74.9% ± 8.2). This effect was significant for retention ponds but not for wetlands; most probably due to variability among sites and sampling occasions. Similar drainage assets are used on a global scale; hence our results are of broad relevance to the management of TWP pollution.
The pyrolysis of waste tires has been considered a potential sustainable solution in light of escalating carbon dioxide emissions. Nevertheless, current research indicates a lack of comprehensive ...understanding regarding the movement of waste tire particles in a single horizontal-axis stirred pyrolysis reactor. This study employed EDEM 2021.2 software to perform comprehensive numerical simulations of a single horizontal-axis stirred pyrolysis reactor, examining the impact of three main production factors—particle size, feed rate, and central axis speed—on particle motion. By acquiring contact data between particles and reactor walls, we illustrated the persistent motion of particles during the operation of the equipment. The research findings suggest that with the rise in rotational speed, there is a corresponding increase in particle accumulation. In high-speed conditions, the interaction between particles and the reactor wall is intensified. The contact level increased by 15.54% (at 3 r/min) and 25.66% (at 5 r/min) with the rise in rotational speed. Furthermore, at an identical rotational speed, the interaction between the larger particle group and the wall surpassed that of the smaller particle group. Doubling the feed rate led to a reduction of over 10% in the contact level between particles and the reaction wall at varying speeds. Through a thorough analysis of various factors influencing particle motion, our objective is to elucidate the motion traits of particles in the reactor, offering crucial theoretical direction and technical assistance to enhance production efficiency and ensure the secure and steady operation of pyrolysis reactors.
Detection and quantification of tread wear particles in the environment have been a challenge owing to lack of a robust method. This study investigated the applicability of a combination of ...Simultaneous Thermal Analysis (STA), Fourier Transform Infra-Red (FTIR), and Parallel Factor Analysis (PARAFAC) in the detection and quantification of tire particles from formulated sediments. FTIR spectral data were obtained by heating 20 samples in STA. Among the 20 samples, 12 were tire granules in formulated sediments (TGIS) containing 1%, 2%, 5%, and 10% by mass of tire granules, while the remaining eight contained 0.5, 1, 2.5, and 5 mg of tire granules only (TGO). The PARAFAC models decomposed the trilinear data into three components. Tire rubber materials in tire granules (RM) and a combination of water and carbon dioxide were the components identified in all samples. The linear regression analysis of score values from the PARAFAC models showed that the RM quantity predicted were comparable to measured values in both TGIS and TGO. Decomposing the overlying components in the spectral data into different components, and predicting unknown quantity in both sample types, the method proves robust in identifying and quantifying tire particles from sediments.
In order to preliminary investigate the opportunity to whole substitute natural aggregates of conventional concrete with steel slag and scrap tire particles. Volume deformation, compressive and ...flexural strength of concrete containing EAF slag and (or) scrap tire particles as aggregate were experimentally investigated by strength test according to the specification of GB/T 50081-2002 and unrestrained specimens volume deformation test. The results indicate that the mechanical strength of steel slag concrete is acceptable, though slightly lower flexural strength than that of conventional concrete. The expansion induced form steel slag using as both coarse and fine aggregates in concrete may lower the shrinkage and expansion to a certain extent. By partial substitution of fine steel slag aggregate with scrap tire particles, both the mechanical strength and the volume stability of scrap tire particle modified steel slag concrete are satisfactory, with similar strength properties to conventional concrete and obvious lower volume deformation change.
Quantifying microplastics and other microparticles is a matter of interest in the field of environmental science. Stereomicroscopy is one of the most common methods to identify and enumerate ...micro-size particles. However, the process of enumerating an entire environmental sample can be tedious and time-consuming, especially when target particles are abundant. Here we present a method to develop a subsampling strategy and spreadsheet-based tool to speed up the process of microparticle enumeration while maintaining particle count accuracy. We first identified the pattern in which tire road wear particles (TRWPs) from environmental samples were distributed on a filter when vacuum-plated, then used particle abundance within relatively homogeneous subsection arrangements to establish stratified random subsampling schemes. We describe a repeated sampling experiment using count data to test the stratified design and illustrate the relationship between the fraction of the filter counted (sample size) with accuracy and variance in the extrapolated total sample count and the corresponding analyst time savings when applied to analyzing TRWPs isolated from sediments. Based on the results, a particle enumeration tool was created in Microsoft Excel Visual BasicⓇ configured using a 47 mm gridded filter, and the source is available for free modification under the same open license.•Vacuum-plated microparticles are often highly abundant and not homogenously distributed across a filter.•A random sampling selection data tool was created using knowledge of particle distribution.•Method describes how to structure and use partial filter counts to extrapolate for total particle enumeration.
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Tire particles (TPs) are one of the main emission sources of micro- and nano-plastics into the environment. Although most TPs are deposited in the soil or in the sediments of freshwater and although ...they have been demonstrated to accumulate in organisms, most research has focused on the toxicity of leachate, neglecting the potential effects of particles and their ecotoxicological impact on the environment. In addition, studies have focused on the impact on aquatic systems and there are many gaps in the biological and ecotoxicological information on the possible harmful effects of the particles on edaphic fauna, despite the soil ecosystem becoming a large plastic sink. The aim of the present study is to review the environmental contamination of TPs, paying particular attention to the composition and degradation of tires (I), transport and deposition in different environments, especially in soil (II), the toxicological effects on edaphic fauna (III), potential markers and detection in environmental samples for monitoring (IV), preliminary risk characterization, using Forlanini Urban Park, Milan (Italy), as an example of an urban park (V), and risk mitigation measures as possible future proposals for sustainability (VI).
Considering the large amount of tires that reach the end of life every year, the aim of this study was the evaluation of both acute and chronic effects of end-of-life-tire (ELT)-derived rubber ...granules (ELT-dg) and powder (ELT-dp) on a freshwater trophic chain represented by the green alga Pseudokirchneriella subcapitata, the crustacean Daphnia magna and the teleost Danio rerio (zebrafish). Adverse effects were evaluated at the organism and population levels through the classical ecotoxicological tests. Acute tests on D. magna and D. rerio revealed a 50% effect concentration (EC50) > 100.0 mg/L for both ELT-dg and ELT-dp. Chronic exposures had a lowest observed effect concentration (LOEC) of 100.0 mg/L for both ELT-dg and ELT-dp on P. subcapitata grow rate and yield. LOEC decreased in the other model organisms, with a value of 9.8 mg/L for D. magna, referring to the number of living offspring, exposed to ELT-dg suspension. Similarly, in D. rerio, the main results highlighted a LOEC of 10.0 mg/L regarding the survival and juvenile weight parameters for ELT-dg and a LOEC of 10.0 mg/L concerning the survival and abnormal behavior in specimens exposed to ELT-dp. Tested materials exhibited a threshold of toxicity of 9.8 mg/L, probably a non-environmental concentration, although further investigations are needed to clarify the potential ecological impact of these emerging contaminants.
Waste tires/sand-based autoclaved aerated concrete (SAAC) composites were prepared by mixing waste tires, which have different particle sizes and content. The physical performance, mechanical ...properties, freeze–thaw resistance, impermeability performance, phase composition, and microstructure of waste tires/sand-based autoclaved aerated concrete composite materials were examined. The results demonstrated that the 750-μm-sized waste tire particles on the surface of the SAAC composite did not agglomerate. Moreover, these particles did not damage the pore structure of the composites. The SAAC composites, with a relatively high compressive strength and low mass-loss rate, were obtained when the contents of waste tire particles ranged from 1.0 to 2.5 wt.%. For composites prepared with 2.0 wt.% of 750-μm-sized waste tire particles, the optimal compressive and flexural strength values were 3.20 and 0.95 MPa, respectively. The increase in the rate of water absorption on SAAC composites was lowest (i.e., 16.3%) when the soaking time was from 24 to 120 h.
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