Mechanical recycling of waste plastics is an environmental solution to the problem of waste plastic disposal, and has already become a common practice in industry. However, limited information can be ...found on either the industralised plastic recycling or the recycled materials, despite the use of recycled plastics has already extended to automobile production. This study investigates the life cycle environmental impacts of mechanical plastic recycling practice of a plastic recycling company in China. Waste plastics from various sources, such as agricultural wastes, plastic product manufacturers, collected solid plastic wastes and parts dismantled from waste electric and electronic equipments, are processed in three routes with products end up in different markets. The results of life cycle assessments show that the extrusion process has the largest environmental impacts, followed by the use of fillers and additives. Compared to production of virgin plastics and composites, the mechanical recycling is proved to be a superior alternative in most environmental aspects. Substituting virgin plastic composites with recycled plastic composites has achieved the highest environmental benefits, as virgin composite production has an impact almost 4 times higher that of the recycled composite production in each ReCiPe endpoint damage factor. Sensitivity analysis shows that the coverage of collecting network contribute affect little to overall environmental impact, and centralisation plays an important role in reducing overall environmental impacts. Among the fillers and additives, impact modifiers account for the most significant contributions to the environmental impacts of recycled composites. This study provides necessary information about the existing industrialised plastic recycling practice, and recommendations are given. Research implications are presented with the purpose to achieve higher substitution rate and lower environmental impact.
Display omitted
•Extrusion and additives make most significant contributions to environmental impacts.•Centralised recycling is a more environmental mechanical plastic recycling practice.•Highest savings are achieved by substituting virgin composites by recycled ones.
To promote low-carbon economy and sustainable energy consumption, new energy vehicles (NEVs), a typical eco-innovation, are drawing intensive attention from manufacturers, administrators and ...academics. Despite extensive literature investigates factors that affect research and development (R&D) of NEVs, yet little is known about the role of technological capability as well as the interaction between internal technological capability and external resources (e.g., ownership, government subsidy and external cooperation). This might lead to the overlook of technological capabilities and the misallocation of external resources. In present study, we investigate how firm-level technological capability (measured by R&D expenditure) affects its eco-innovation performance (measured by eco-innovation patents), as well as the moderating impacts of ownership and governmental support (i.e., subsidy). Further, we explore the correlation between firm’s technological capability and its R&D strategy (i.e., internal R&D or cooperative R&D). Our investigation is based on a unique set of panel data from 127 listed companies in the Chinese automotive industry, spanning from 2009 to 2018. The empirical findings demonstrate that firm-level technological capability is positively related to eco-innovation performance, and state ownership intensifies this positive relationship. Surprisingly, increasing government subsidy tends to weaken this correlation. The results also show that firms with higher technological capabilities prefer cooperative R&D, while those with lower technological capabilities tend to choose internal R&D. These findings promote the understanding on the cost-effectiveness of R&D investment in the NEV industry, and also shed light on the interactions of internal and external resources. The study offers managerial implications to promote the prosperity of the NEV industry.
Display omitted
•Firm-level technological capability significantly contributes to NEV-related innovations.•State ownership strengthens this positive R&D input-output relation.•Government support weakens this positive R&D input-output relation.•Technological-leading firms are more likely to adopt cooperative strategy in the R&D of NEVs.
Introduction of electric vehicles (EVs) is regarded as an effective measure to mitigate air pollution. Although intensive efforts have been invested on examining the factors affect the adoption of ...EVs, the potential impact of air pollution on EV sales is severely underexamined. In this study, we pioneer to examine the relation of air pollution (measured in terms of the concentrations of PM2.5) to the sales of EVs. Our empirical analysis is based on a unique panel data comprises of the monthly sales volumes of EVs and the monthly average PM2.5 concentration levels from 20 major cities in China. The data spans from 1st May 2014 to 30th April 2018. Additionally, we employ the urban population, industrial output and disposable income per capita as controls. The results show that the PM2.5 concentrations are significantly positively correlated to the sales volumes of EVs as well as those of battery electric vehicles (BEVs), while no significant relationship between the PM2.5 concentrations and the hybrid electric vehicles (HEVs) sales is observed. The significant and positive effect of the PM2.5 concentrations on the EVs sales persists, in EVs with different brand popularities and in cities of different average income levels. Amongst the selected controls, only disposable income is significantly and positively related to the sales volumes of EVs, while the others only impart insignificant effects on the EV sales. Further, we confirm the robustness of the results by using the different sectors of the panel data. Our findings contribute to the growing body of EV adoption literature, and policy implications are provided.
The EU Emission Trading System (ETS) is the oldest and currently the largest carbon market in the world, but its purpose of stimulating carbon emissions via trading profits remains unexamined. Based ...on the complete firm-level transaction records of the EU ETS Phases I and II, here we show that the participating firms' trading profits and their emission abatements are positively correlated, and the correlation becomes stronger in Phase II than Phase I. Specifically, we observe that non-linearity exists in the correlation; higher firm-level emission abatements can realize larger trading profits. This pattern affects the market fairness, though it may be helpful to incentivise emission abatements. The correlation is more regulated in Phase II than it is in Phase I, thereby indicating that the Phase II is more mature. We also observe that the state-level abatements are largely driven by industrial giants.
Due to the vast consumption and shortened lifespan of mobile phones, waste mobile phones (WMPs) have become one of the fastest-growing global waste electrical and electronic equipment (WEEE) streams. ...Although the recycling potential of WMPs is well-recognized, the current recycling rate remains low, jeopardizing the sustainability of both the environment and mobile phone industries. With the objective of identifying limitations in the current method developments that hinder WMP recycling, we review the material recovering technologies for WMP recycling, published in academic journals and/or conferences between Jan 2005 and Apirl 2019. Most WMP recycling processes have been developed to recover precious metals (such as gold and silver) from mobile phone printed circuit boards (PCBs), via acid leaching processes. However, pre-treatment and separation steps required to concentrate the waste stream for efficient extraction are often overlooked. In addition, to separate the individual components of the WMP, most recycling methods use manual disassembly as their first step, a practice which is not suitable for scale-up. Generally, particle size ranges used in laboratory trials are smaller than those used in current industrial practice, as it is not economically feasible to acquire such small particle sizes industrially. There is a current trend to replace the inorganic acids used for metal leaching with more environmentally-friendlier lixiviants, however, industrialization of these approaches is not economically viable. This review serves as a guidance for future research and development in this area, providing information to facilitate WMP management.
•Current material recovery methods for waste mobile phones are reviewed.•Reviewed articles are discussed based on targeted components and materials.•Shortcomings of the reported material recovery processes are identified.•Recommendations for future research and development are offered.
Monolayer transition metal dichalcogenides (TMDs) have emerged as widely accepted 2D gain materials in the field of light sources owing to their direct bandgap and high photoluminescence quantum ...yield. However, the monolayer medium suffers from weak emission because only a single layer of molecules can absorb the pump energy. Moreover, the material degradation when transferring these fragile materials hinders their cooperation with the optical cavity further. In this study, for the first time, a high‐quality monolithic structure is developed by directly growing single‐domain tungsten diselenide (WSe2) bilayers on single silica microsphere (MS) cavities. Such a completely wrapped structure guides the indirect‐to‐direct bandgap transition of WSe2 bilayers, leading to a significantly improved photoluminescence intensity by about 60‐fold. Moreover, the high‐quality monolithic structure enhances the confinement factor of the cavity by more than 20‐fold. Based on the above advantages, a bilayer WSe2/MS microlaser is realized with an ultralow threshold of 0.72 W cm−2, nearly an order of magnitude lower than the existing records. The results demonstrate the possibility of using multilayer TMD materials as 2D gain media and provide insights into a new ultracompact monolithic platform of TMD material/cavity for lasing devices.
A transition metal dichalcogenide (TMD)/cavity monolithic cavity is achieved by directly growing single‐domain tungsten diselenide (WSe2) bilayers on single silica microsphere (MS) surfaces. The thermal strain induces bilayer bandgap from indirect to direct, and the cavity confinement factor is also improved, which directly realizes room‐temperature whispering‐gallery‐mode lasing, with a threshold nearly an order of magnitude lower than the existing records.
•A novel plastic separation process based on magnetic separation is proposed.•The magnetic separation process is not affected by particle sizes.•Multiple plastic mixture can be completely separated ...with purities of 100%.•Correlation between magnetic field, density and levitated position is presented.•The process is promising in both performance and environment aspects.
Separation becomes a bottleneck of dealing with the enormous stream of waste plastics, as most of the extant methods can only handle binary mixtures. In this paper, a novel method that based on magnetic levitation was proposed for separating multiple mixed plastics. Six types of plastics, i.e., polypropylene (PP), acrylonitrile butadiene styrene (ABS), polyamide 6 (PA6), polycarbonate (PC), polyethylene terephthalate (PET), and polytetrafluoroethylene (PTFE), were used to simulate the mixed waste plastics. The samples were mixed and immersed into paramagnetic medium that placed into a magnetic levitation configuration with two identical NdFeB magnets with like-poles facing each other, and Fourier transform infrared (FTIR) spectroscopy was employed to verify the separation outputs. Unlike any conventional separation methods such as froth flotation and hydrocyclone, this method is not limited by particle sizes, as mixtures of different size fractions reached their respective equilibrium positions in the initial tests. The two-stage separation tests demonstrated that the plastics can be completely separated with purities reached 100%. The method has the potential to be industrialised into an economically-viable and environmentally-friendly mass production procedure, since quantitative correlations are determined, and the paramagnetic medium can be reused indefinitely.
In this study, tri‐layered composites were prepared by reinforcing poly‐lactic acid (PLA) nano‐hydroxyapatite (n‐HA) (1 and 5 wt%) and 20 mol% continuous phosphate glass fibers (PGF). Initially, the ...effect of addition of 1 and 5% n‐HA on the structural, thermal, mechanical, and thermo‐mechanical properties of 100% PLA was investigated. With 5 wt% n‐HA addition the tensile modulus (TM), flexural modulus (FM), tensile strength (TS), and flexural strength (FS) of 100% PLA was improve by 14.9, 47.4, 6, and 32.9%, respectively. Whereas, the un‐notched impact strength of the nanocomposites suffer 2% deterioration. However, T
g decreased by 0.3°C and T
c increased by 10°C as 5 wt% n‐HA was added to 100% PLA. Afterwards, the 5% n‐HA/PLA composite were reinforced with 20 mol% continuous PGF and the TM, FM, TS, and FS of the tri‐layered composites were 162.6, 412.5, 28.4, and 157.4% higher as compared to 100%PLA. Furthermore, the storage modulus of the 1% n‐HA‐filled composites was 500 MPa lower than 100%PLA, while 5 wt% n‐HA‐filled composites showed similar storage modulus as 100% PLA. 5 wt% n‐HA‐filled composite showed the highest peak of loss modulus which may be attribute to the chain segment of PLA matrix after the incorporation of HA. Thus, n‐HA and PGF reinforcement resulted in improved mechanical properties of the composites and have great potential as biodegradable bone fixation device with enhanced load‐bearing ability.
The deformation-induced transformation characteristics and texture evolution of α′-martensite during cold rolling together with the tensile properties of two specially prepared initial ...microstructures (bimodal elongated γ grains and fine equiaxed γ grains) were investigated in high manganese TRIP steels. The results showed that the thermally induced martensite was restrained effectively by refining grains or introducing crystal defects like dislocations, which provided a nearly full austenite phase for the subsequent TRIP process. Compared with the solution-treated sample containing coarse equiaxed γ grains, the fine-grained sample revealed a better plasticity and a higher strength due to grain refinement and progressive TRIP process. The bimodal elongated-grained sample exhibited the highest strength and sufficient plasticity because the dislocation strengthening exceeded the fine-grain strengthening and martensitic transformation was delayed. The transformation textures of two kinds of samples differed in that the fine-grained sample demonstrated typical {113} α from the Copper-type γ texture and {332} α from the Brass-type γ texture, whereas {001} α texture occurred in the bimodal elongated-grained sample in addition to the above two components. In the early stage of TRIP, there was an obvious orientation dependence, and the {100}- and Copper-oriented γ grains preferentially transformed to martensite rather than γ grains with Brass orientation.
Investment of clean energy industry aims at developing clean alternative energy sources to substitute fossil fuels, the consumption of which leads to climate change and air pollution. However, how ...the supply and demand of steam coal affect the investment remains an extremely understudied issue, as the extant research focuses on crude oil, while steam coal satisfies most of the energy demand in emerging economies like China. This study empirically investigates the time-varying co-movements between steam coal prices and clean energy stock indices in China at the sectoral level; the former denotes the supply and demand, and the latter represents the investment. Five clean energy sectors are considered, including geothermal power, hydrogen power, nuclear power, solar power and wind power. The studied period is from Jan 2, 2008 to Feb 28, 2019. The analysis is carried out using a VAR-DCC-GARCH framework. The empirical findings indicate the presence of significant bi-directional volatility spillover between the steam coal market and the clean energy stocks. We further portray and explain the dynamic conditional correlation among steam coal prices, clean energy sectoral indices and an environmental under the fluctuating China's stock markets. Based on the empirical evidence, we provide policy implications to facilitate the development of the clean energy industry.
•Co-movements between steam coal and clean energy investment are investigated.•Sectoral clean energy stock indices are employed.•Significant bi-directional volatility transmission is observed.•Strong stock market tends to weaken risk and volatility spillovers.
PDF
