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Crystallization and Mechanical Properties of the Polylactide Melt Blown Nonwovens
Lin Meng,Fangdong Zou,Mingjing Chen,Yifei Li,Yingying Wang,Xiaoxia Sun,Xinhou Wang 한국섬유공학회 2023 Fibers and polymers Vol.24 No.9
Polylactide (PLA), a promising biodegradable semi-crystalline polymer, has not been widely used in melt blown nonwoven field due to its poor mechanical property, which is related to the crystallization behavior of the polymer. This article aims to investigate the relationship between the crystallization and the mechanical property of the PLA melt blown nonwovens. PLA melt blown nonwovens were prepared under different airflow conditions. The microstructure, crystallization, and mechanical property were studied using SEM, DSC, XRD, tensile testing, and numerical simulation method. The results show that an increase of interfiber junctions or crystallinity is conducive to the improvement of the mechanical property of the PLA melt blown nonwovens. Optimizing the airflow conditions has a positive effect on the crystallization and mechanical property; however, the PLA melt blown nonwovens are still in an amorphous state with small grain size. Annealing treatment favors the formation of the ordered α crystals and less disordered αʹ crystals. Moreover, the lager grain size and crystallinity after annealing at 90 ℃ for 30 min can further increase the mechanical strength (up to 1.5 times) of PLA melt blown nonwovens.
Machine Learning Aided Tracking Analysis of Haze Pollution and Regional Heterogeneity
( Fangfang Gu ),( Keshen Jiang ),( Fangdong Cao ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.6
Not only can air pollution reduce the overall competitiveness of tourist destinations, but also changes tourists' travel decisions, thereby affecting the tourism flows. The study presents a machine learning method to analyze how the haze pollution puts spatial effect on tourism flows in China from 2001 to 2018, and reveals the regional differences in heterogeneity among eastern, central, and western China. Our investigation reveals three interesting observations. First, the Environmental Kuznets Curve of the impact of haze pollution on tourism flows is not significant. In the eastern and western regions, the interaction between haze pollution and domestic tourism flows as well as inbound tourism flows shows an inverted U-shaped curve respectively. Second, there is an significantly positive spillover effect of tourism flows in all of the eastern, central, and western regions. As to the intensity of spillover, domestic tourism flows is higher than that of the inbound tourism flows. Both of the above figures are greatest in the eastern. Third, the Chinese haze pollution mainly reduces the inbound tourism flows, and only imposes significantly negative direct effects on the domestic tourism flows in the central region. In the central and eastern regions, significantly negative direct effects and spillover effects are exerted on inbound tourism.