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Accurate Determination of the Equilibrium Surface Tension Values with Area Perturbation Tests
Published on: August 30, 2019
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Methods for evaluating leaf surface free energy and polarity having accounted for surface roughness
Justin J Nairn1, W Alison Forster1
1Plant Protection Chemistry NZ Ltd, Rotorua, New Zealand.
Pest Management Science
|February 15, 2017
Summary
Characterizing leaf surface polarity and roughness is crucial for agrochemical efficacy. The wetting tension-dielectric (WTD) method effectively separates these properties, improving spray formulation technology.
Area of Science:
- Agricultural Science
- Surface Science
- Physical Chemistry
Background:
- Leaf surface wettability can be similar despite differing roughness and polarity.
- Accurate characterization of leaf surface polarity and roughness is needed for agrochemical bioefficacy.
- Existing surface evaluation techniques have limitations when applied to diverse leaf surfaces.
Purpose of the Study:
- To review established surface evaluation techniques for leaf surfaces.
- To compare and contrast methods for characterizing leaf surface polarity independently of roughness.
- To assess the suitability of various techniques using a comprehensive dataset of contact angle measurements.
Main Methods:
- Review of established surface evaluation techniques.
- Comprehensive dataset of static contact angles using 12 chemical solutions on 15 plant species.
- Comparison of techniques for isolating leaf surface polarity from roughness.
Main Results:
- Many techniques were limited in characterizing leaf surfaces.
- Surface free energy (SFE) is affected by both physical and chemical properties.
- SFE values are dependent on the probe solution, not just leaf surface chemistry.
Conclusions:
- The wetting tension-dielectric (WTD) method effectively isolates and quantifies leaf surface roughness and polarity.
- A novel WTD roughness correction factor is proposed to enhance SFE determination.
- The WTD method is valuable for evaluating leaf surface-droplet interactions and advancing agrochemical spray formulations.
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