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31.
Study on the relationship between the particle size distribution and the effectiveness of the K‐powder fire extinguishing agent 下载免费PDF全文
The relationship between the particle size distribution and the extinguishing effectiveness of the new K‐powder fire extinguishing agent has been studied experimentally, to explore the reason of the great extinguishing efficiency exhibited by the new K‐powder fire extinguishing agent on Class B fire (liquid fuel fire). The results of the experiment showed that the extinguishing effectiveness increased along with the decrease of the particle size distribution. In addition, a sharp discontinuity appeared around the limiting size, about 40 μm. The powder with the particle size below 40 μm exhibited highly effective extinguishing with the minimum effective extinguishing concentration Cxr = 23 g·m?3, while the powder with the particle size above 40 μm exhibited little fire extinguishing efficiency. Compared with other fire extinguishing agents produced by different substances, the new K‐powder fire extinguishing has the bigger limiting size. That means, in the same particle size distribution, the new K‐powder fire extinguishing agent contains more highly effective powder than others contain, and is more effective. 相似文献
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Isothermal crystallization kinetics and subsequent melting behavior of β‐nucleated isotactic polypropylene/graphene oxide composites with different ordered structure 下载免费PDF全文
Yansong Yu Fangxinyu Zeng Jinyao Chen Jian Kang Feng Yang Ya Cao Ming Xiang 《Polymer International》2018,67(9):1212-1220
The effects of ordered structure on isothermal crystallization kinetics and subsequent melting behavior of β‐nucleated isotactic polypropylene/graphene oxide (iPP/GO) composites were studied using differential scanning calorimetry. The ordered structure status was controlled by tuning the fusion temperature (Tf). The results showed that depending on the variation of crystallization rate, the whole Tf range could be divided into three regions: Region I (Tf > 179 °C), Region II (170 °C ≤ Tf ≤ 179 °C) and Region III (Tf < 170 °C). As Tf decreased from Region I to Region III, the crystallization rate would increase substantially at two transition points, due to the variation of the ordered structure status. Calculation of Avrami exponent n indicated that the ordered structure induced the formation of two‐dimensional growing crystallites rather than three‐dimensional growing crystallites. Moreover, in the case of isothermal crystallization, the ordered structure effect (OSE) can also greatly increase the relative content of β‐phase (βc). In Region II, OSE took place, resulting in evident increase of βc, achieving 92.4% at maximum. The variation of the isothermal crystallization temperature (Tiso) had little influence on the Tf range (Region II) of the OSE. The higher Tf in Region II was more favorable for the formation of higher βc. The ordered structure was favorable for the improvement of the nucleating efficiency of β‐nucleating agent (β‐NE), and was more effective for the improvement of lower β‐NE. © 2018 Society of Chemical Industry 相似文献
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Owing to lack of proper recycling methods, plastic flexible film wastes are usually directly discarded or incinerated, which brings about severe environmental pollution. Therefore, converting plastic wastes into value‐added products has received more and more attention in recent years. In this work, paper‐like composites derived from plastic flexible film wastes were prepared via the thermally induced phase separation method by adding polyethylene‐graft‐maleic anhydride (PE‐g‐MAH) as a compatibilizer and fumed silica as an additive. The resulting paper‐like composites were characterized by SEM and infrared spectroscopy. Other properties such as mechanical properties, thermal properties, whiteness, printability and adsorption performance were also tested in detail. It was found that remarkable enhancements in mechanical, thermal and printable properties of the paper‐like composites were obtained when nano‐SiO2 loading was 2.5–3 wt%. Uniformly distributed holes that can endow good printability by providing space for ink or other functional molecules were observed by using SEM. Furthermore, the CIE whiteness value of the resulting composites can reach 91.6%–96.7% on adding nano‐SiO2. Additionally, the paper‐like composites integrating nano‐SiO2 and PE‐g‐MAH exhibited good solid ink affinity and high water or oil adsorption capacity. Thus, according to this research, high‐performance printable paper‐like composites used as major components of multifunctional papers can be prepared based on plastic flexible film wastes. © 2019 Society of Chemical Industry 相似文献
36.
《Food Control》2015
The effects of antimicrobial agents (nisin, chitosan, potassium sorbate (PS) or silver substituted zeolite (AgZeo)) incorporated into low density polyethylene (LDPE) on the physicochemical and microbial quality of chicken drumsticks stored at 5 °C for 6 days were investigated. Active multilayer bags (LDPE/polyamide/LDPE-containing 2% antimicrobial agent) were used to pack chicken drumsticks under vacuum. Their efficiency in inhibiting total aerobic mesophilic bacteria (APC), total coliforms and total molds and yeasts were evaluated by comparison with control bag (LDPE-polyamide-LDPE). APC counts of samples packed in bags containing chitosan, nisin, AgZeo and PS were 1.03, 0.98, 0.51, and 0.17 log respectively were lower than those of samples packed in control bags. Samples packaged in active bags had lower microbial counts and thiobarbituric acid reactive substance (TBARS) values than those of samples packed in control bags. The pH, color and hardness of the samples were not affected significantly by use of different packaging films (p > 0.05). Therefore, the bag including chitosan or nisin can be suggested as a suitable packaging material for chicken drumstick to increase safety and quality. 相似文献
37.
Xiaopeng Yue Yongjian Xu Nina Gou Hongkui Li 《Polymer-Plastics Technology and Engineering》2015,54(6):639-646
A long fatty side chain was introduced into the macromolecule of hydroxyethyl cellulose (HEC) via esterification reaction. The hydrophobicity of hydroxyethyl cellulose lauric acid ester (HECLAE) was enhanced in comparison with HEC. The obtained HECLAE was used as macromolecular coupling agent in poly (butylene succinate)/wood flour composites and exhibited a positive influence on improving the mechanical performance of composites. Besides, HECLAE plays a role as a hydrophobic agent in composites. A significant increase in storage modulus (E’) was observed upon the incorporation of treated wood flour. SEM images showed that the dispersion of treated wood flour in PBS matrix was improved. 相似文献
38.
配位剂是影响电镀废水稳定达标的主要因素之一。指出电镀废水应考虑其中所含配位剂的性质,从源头分类收集,采用氧化、水解、化学沉淀、生物等方法预处理。电镀废水治理的重点是重金属离子,难点是配位剂,关键是分类收集。 相似文献
39.
The effects of physical embodiment and physical presence were explored through a survey of 33 experimental works comparing how people interacted with physical robots and virtual agents. A qualitative assessment of the direction of quantitative effects demonstrated that robots were more persuasive and perceived more positively when physically present in a user׳s environment than when digitally-displayed on a screen either as a video feed of the same robot or as a virtual character analog; robots also led to better user performance when they were collocated as opposed to shown via video on a screen. However, participants did not respond differently to physical robots and virtual agents when both were displayed digitally on a screen – suggesting that physical presence, rather than physical embodiment, characterizes people׳s responses to social robots. Implications for understanding psychological response to physical and virtual agents and for methodological design are discussed. 相似文献
40.
《Advanced Engineering Informatics》2015,29(3):355-365
The performance of physical assets has become a major determinant success factor for urban flood control. However, managing these assets is always challenging as there are a huge number of diverse assets involved, which are distributed throughout the city, and owned by different agencies. Aiming at improving the management efficiency of these assets, and ensuring their performance, this paper proposes the concept of cloud asset based on cloud computing, mobile agent, and various smart devices. Through hardware integration and software encapsulation, cloud asset could sense its real-time status, adapt to varied working scenarios, be controlled remotely, and shared among agencies. It enables accurate real-time control of every asset, and thus improves the management efficiency and effectiveness. This paper first presents the concept of cloud asset with its technical architecture, and then analyses the software agent model for cloud asset, which is the key enabler to realize UPnP (Universal Plug and Play) management of assets, and provides mobility and intelligence for them. After that, the framework of cloud asset-enabled workflow management is built, in which cloud asset could be easily found and dynamically invoked by different workflows. Finally, a demonstrative case is provided to verify the effectiveness of cloud asset. 相似文献