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Study on the Oxyfluorfen Thixotropic SC

Author: LianYingHui
Tutor: LiLiFang
School: Shandong Agricultural University
Course: Pesticides
Keywords: Oxyfluorfen Suspensions concentration Rheology Thixotropy Highpolymer
CLC: S482.4
Type: Master's thesis
Year: 2013
Downloads: 12
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Abstract


This thesis chose oxyfluorfen as the research object. We did more research about thephysical stability of pesticide suspension concentrate from thixotropy and influencing factorspoint of views. The following aspects were studied in this thesis:1. Zeta potential method was used to select wetting dispersant in preparing25wt%oxyfluorfen suspension concentrate in this study, the average particle diameter (Dav) of testsystem was determined using laser particle distribution instrument. The results showed thatT-2700, T-4894and Soprophor SC could make the suspension particle to reach the absolutevalue of Zeta potential (│ζ│) in excess of40mV, and the suspension concentrate werecomparatively stable. However602P and T-4894particle sizes were smaller changes beforeand after heating. Thus the dispersing effect of wetting dispersant in suspension concentratecould be well represented by the zeta potential value and the average particle diameter.2. In this paper, we have studied the rheology and thixotropy of MT and HTlc. With theincrease of w, pure MT suspension and pure HTLc suspension system changed fromNewtonian-like fluid to plastic one. The thixotropic type of the pure MT suspension changedfrom non-thixotropy, positive thixotropy to complex one. The pure HTLc suspension systemshowed positive thixotropy in addition to1%of the system, and the thixotropic extentshowed a tendency to increase. Description of the rheological behavior of the suspensionsystem is closely related to the shape of the solid particles and the interaction force betweenthe particles.3. We investigated polymers (gum arabic, CMC, and PVA)/the MT or HTLc mass ratioR, the electrolyte (NaCl, MgCl2and AlCl3), pH value and temperature on the rheological andthixotropic compound suspension system. The results show that gum arabic/HTLc ofsuspension system are positive thixotropy with the R value increased. The degree ofthixotropy first increases and then weakened as R increased. The n value decreased, and the K,τ0value gradually increased. Gum arabic/HTLc of composite suspension system showed thepositive thixotropy-complex thixotropy with increasing NaCl concentration. The K, τ0valueincreased with the electrolyte concentration changes.A positive thixotropic plastic fluid characteristic of CMC/MT system does not change, with the increase of mass ratio (R) of CMC to MT (fixing wMT=2.0%in all the systems), theyield value (τ0) and consistency coefficient (K) increased. The hysteresis loop area (S)increased initially and then decrease, along with the zeta potential absolute value ζ synchronous variation. When increasing the concentration of electrolyte (such as NaCl,MgCl2and AlCl3), both the yield value τ0and consistency coefficient K increased. With theexperimental temperature increased, τ0, K and S all decreased.,The thixotropic type of theCMC/MT suspension was transformed from negative into positive, depending on the pHvalue (lower than6.60or higher than7.27), and the zeta potential decreased to a lowernegative value with the increase of pH. The hysteresis loop area and viscocity reached theirmaximum value at pH=8.46.Gum arabic/MT suspension system had undergone a complex thixotropy-positivethixotropy-the complex thixotropy as R changed. The n and τ0initially decrease and thenincreased; the S and K increased initially and then decrease. Thixotropic change in the type ofgum arabic/MT system was more obvious. NaCl changed the system positive thixotropy tocomplex thixotropy, MgCl2change system was negative thixotropic, the AlCl3did not changepositive thixotropic type of system.Positive thixotropy of the PVA/MT suspension system had not changed with the R value.As the salt concentration increases, the positive thixotropic fluid characteristics of PVA/MTsuspension system did not change. With the changes in pH, the PVA/MT suspension systemremained positive thixotropy.4. gum arabic/HTLc, gum arabic/MT, CMC/MT and PVA/MT were added to the25wt%oxyfluorfen suspension concentrate respectively. We found that these systems showed thepositive thixotropy. The degree of thixotropy of the system thixotropic stromal and polymerwas changed with the original system. The thixotropic of suspending joined the CMC andMT increased the most obvious, and PVA/MT suspension system became weakened with theoriginal system, and the factor is not conducive to the stability of the suspensions ofoxyfluorfen.

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CLC: > Agricultural Sciences > Plant Protection > Pesticide ( chemical control ) > Various pesticides > Herbicides ( herbicide )
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