Over the past half-century, plastic consumption has grown rapidly due to its versatility, low cost, and unrivaled functional properties. Among the diff erent implemented strategies for recycling waste plastics, pyroly...Over the past half-century, plastic consumption has grown rapidly due to its versatility, low cost, and unrivaled functional properties. Among the diff erent implemented strategies for recycling waste plastics, pyrolysis is deemed the most economical option. Currently, the wax obtained from the pyrolysis of waste plastics is mainly used as a feedstock to manufacture chemicals and fuels or added to asphalt for pavement construction, with no other applications of wax being reported. Herein, the thermal pyrolysis of three common waste polyolefin plastics: high-density polyethylene(HDPE), low-density polyethylene(LDPE), and polypropylene(PP), was conducted at 450 ℃. The waste plastics-derived waxes were characterized and studied for a potential new application: phase change materials(PCMs) for thermal energy storage(TES). Gas chromatography–mass spectrometry analysis showed that paraffin makes up most of the composition of HDPE and LDPE waxes, whereas PP wax contains a mixture of naphthene, isoparaffin, olefin, and paraffin. Diff erential scanning calorimetry(DSC) analysis indicated that HDPE and LDPE waxes have a peak melting temperature of 33.8 ℃ and 40.3 ℃, with a relatively high latent heat of 103.2 J/g and 88.3 J/g, respectively, whereas the PP wax was found to have almost negligible latent heat. Fourier transform infrared spectroscopy and DSC results revealed good chemical and thermal stability of HDPE and LDPE waxes after 100 cycles of thermal cycling. Performance evaluation of the waxes was also conducted using a thermal storage pad to understand their thermoregulation characteristics for TES applications.展开更多
The increasing prevalence of infectious diseases in recent decades has posed a serious threat to public health.Routes of transmission differ,but the respiratory droplet or airborne route has the greatest potential to ...The increasing prevalence of infectious diseases in recent decades has posed a serious threat to public health.Routes of transmission differ,but the respiratory droplet or airborne route has the greatest potential to disrupt social intercourse,while being amenable to prevention by the humble facemask.Different types of masks give different levels of protection to the user.The ongoing COVID-19 pandemic has even resulted in a global shortage of face masks and the raw materials that go into them,driving individuals to self-produce masks from household items.At the same time,research has been accelerated towards improving the quality and performance of face masks,e.g.,by introducing properties such as antimicrobial activity and superhydrophobicity.This review will cover mask-wearing from the public health perspective,the technical details of commercial and home-made masks,and recent advances in mask engineering,disinfection,and materials and discuss the sustainability of mask-wearing and mask production into the future.展开更多
基金financial support from Individual Research Grant (Grant reference No.: A20E7c0109) of the Agency for Science,Technology and Research of Singapore (A*STAR)。
文摘Over the past half-century, plastic consumption has grown rapidly due to its versatility, low cost, and unrivaled functional properties. Among the diff erent implemented strategies for recycling waste plastics, pyrolysis is deemed the most economical option. Currently, the wax obtained from the pyrolysis of waste plastics is mainly used as a feedstock to manufacture chemicals and fuels or added to asphalt for pavement construction, with no other applications of wax being reported. Herein, the thermal pyrolysis of three common waste polyolefin plastics: high-density polyethylene(HDPE), low-density polyethylene(LDPE), and polypropylene(PP), was conducted at 450 ℃. The waste plastics-derived waxes were characterized and studied for a potential new application: phase change materials(PCMs) for thermal energy storage(TES). Gas chromatography–mass spectrometry analysis showed that paraffin makes up most of the composition of HDPE and LDPE waxes, whereas PP wax contains a mixture of naphthene, isoparaffin, olefin, and paraffin. Diff erential scanning calorimetry(DSC) analysis indicated that HDPE and LDPE waxes have a peak melting temperature of 33.8 ℃ and 40.3 ℃, with a relatively high latent heat of 103.2 J/g and 88.3 J/g, respectively, whereas the PP wax was found to have almost negligible latent heat. Fourier transform infrared spectroscopy and DSC results revealed good chemical and thermal stability of HDPE and LDPE waxes after 100 cycles of thermal cycling. Performance evaluation of the waxes was also conducted using a thermal storage pad to understand their thermoregulation characteristics for TES applications.
文摘The increasing prevalence of infectious diseases in recent decades has posed a serious threat to public health.Routes of transmission differ,but the respiratory droplet or airborne route has the greatest potential to disrupt social intercourse,while being amenable to prevention by the humble facemask.Different types of masks give different levels of protection to the user.The ongoing COVID-19 pandemic has even resulted in a global shortage of face masks and the raw materials that go into them,driving individuals to self-produce masks from household items.At the same time,research has been accelerated towards improving the quality and performance of face masks,e.g.,by introducing properties such as antimicrobial activity and superhydrophobicity.This review will cover mask-wearing from the public health perspective,the technical details of commercial and home-made masks,and recent advances in mask engineering,disinfection,and materials and discuss the sustainability of mask-wearing and mask production into the future.
