Deltamethrin emulsifiable concentrates droplets superposition and coagulation behavior on water spinach leaf surface
Received:March 11, 2019    Download the full
DOI：10.16801/j.issn.1008-7303.2019.0069
Key Words:deltamethrin  emulsifiable concentrates  water spinach leaf surface  droplets superposition and coagulation  dynamic contact angle  spreading diameters
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Author NameAffiliationE-mail
LU Jun College of Jiyang, Zhejiang A & F University, Zhuji 311800, Zhejiang Province, China
Local and National Joint Engineering Laboratory of Biopesticide High-Efficient Preparation Technology, Zhejiang A & F University, Hangzhou 311300, China 		 
JIN Tianshu Local and National Joint Engineering Laboratory of Biopesticide High-Efficient Preparation Technology, Zhejiang A & F University, Hangzhou 311300, China  
ZHANG Hongtao Institute of Electric Power, North China University of Water Resources and Electric Power, Zhengzhou 450011, China zht1977@ncwu.edu.cn 
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Abstract:
      In order to investigate the superposition behavior of 25 mg/L emulsion deltamethrin emulsifiable concentrates droplets on the surface of water spinach (Ipomoea aquatica Forsk) leaves and the change of dynamic contact angle, fiber fineness analyzer and optical contact angle measuring instrument ware used to observe the leaf surface morphology of water spinach and measure the surface tension of deltamethrin emulsifiable concentrates droplets, dynamic contact angle, spreading diameter and other wetting parameters. According to the power law, the causes of droplets superposition spreading driving force were analyzed. The result showed that the surface tension of deltamethrin emulsifiable concentrates was 29.02 mN/m. There were two kinds of different behavior happen in the overlying process of the same volume (5 μL) droplets on water spinach leaves surface. The former behavior was to roll into the bottom and the latter behavior was to inhale directly at the top. The time for the superposition to condense and form a new droplet were 0.035 2 s and 0.025 1 s, respectively. The former condensed into a new droplet and the contact angle decreased by 12.9%. As for the latter, the contact angles all increased and the maximum increase rate was 27.4%. The spreading diameters of the new droplets formed by the two superposition methods showed linear relationship with time and in accordance with the power function relationship (power α < 0.1). Those results demonstrated that the former was a super spreading behavior caused by the surface tension gradient, and the latter was the spreading behavior driven by the dynamic surface tension. And the former was superior to the latter in terms of spreading effect.
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