Solvent Effects in Degradation Kinetics of Emamectin Benzoate

2009 ◽  
pp. 129-129-9
Author(s):  
RF Peterson ◽  
MD Alvarez ◽  
PK Mookerjee
2021 ◽  
Author(s):  
Roel Kleijwegt ◽  
Wyatt Winkenwerder ◽  
Wim Baan ◽  
John van der Schaaf

<div>Surfactants such as quaternary ammonium salts (QAS) have been in increasing demand, for emerging new applications. Recent attempts at process intensification of</div><div>their production, have disclosed the need for a better understanding of QAS thermal stability. This work aims to determine degradation kinetics of various QASs, and the</div><div>associated solvent effects. Degradation kinetics of four methyl carbonate QASs were determined in various</div><div>polar solvents in stainless steel batch autoclaves. <sup>1</sup>H NMR spectrometry was employed for online analysis of the reaction mixtures. The kinetic parameters were then used</div><div>to compare the thermal stability of the four compounds in the polar solvents. Water showed not degradation, and methanol (MeOH) was the solvent that provided the</div><div>second-best stability. Water-MeOH mixtures may provide an overall optimum. More, and longer long-chain substituents increased the degradation rate. Thermogravimetric Analysis was used to obtain the thermal stability in a solid-</div><div>state, i.e. solventless environment. Isoconversional analysis showed that no reliable kinetic parameters could be determined. Nevertheless, the data did allow for a compar-</div><div>ison of the thermal stability of 14 different QASs. Furthermore, the relative instability of the compounds in solid-state demonstrated the challenges of solventless QAS production.</div>


2021 ◽  
Author(s):  
Roel Kleijwegt ◽  
Wyatt Winkenwerder ◽  
Wim Baan ◽  
John van der Schaaf

<div>Surfactants such as quaternary ammonium salts (QAS) have been in increasing demand, for emerging new applications. Recent attempts at process intensification of</div><div>their production, have disclosed the need for a better understanding of QAS thermal stability. This work aims to determine degradation kinetics of various QASs, and the</div><div>associated solvent effects. Degradation kinetics of four methyl carbonate QASs were determined in various</div><div>polar solvents in stainless steel batch autoclaves. <sup>1</sup>H NMR spectrometry was employed for online analysis of the reaction mixtures. The kinetic parameters were then used</div><div>to compare the thermal stability of the four compounds in the polar solvents. Water showed not degradation, and methanol (MeOH) was the solvent that provided the</div><div>second-best stability. Water-MeOH mixtures may provide an overall optimum. More, and longer long-chain substituents increased the degradation rate. Thermogravimetric Analysis was used to obtain the thermal stability in a solid-</div><div>state, i.e. solventless environment. Isoconversional analysis showed that no reliable kinetic parameters could be determined. Nevertheless, the data did allow for a compar-</div><div>ison of the thermal stability of 14 different QASs. Furthermore, the relative instability of the compounds in solid-state demonstrated the challenges of solventless QAS production.</div>


Author(s):  
Zafirah Mahyun ◽  
Noor Fazliani Shoparwe ◽  
Ahmad Zuhairi Abdullah ◽  
Abdul Latif Ahmad ◽  
Mardawani Mohamad ◽  
...  

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1597
Author(s):  
Iman Jafari ◽  
Mohamadreza Shakiba ◽  
Fatemeh Khosravi ◽  
Seeram Ramakrishna ◽  
Ehsan Abasi ◽  
...  

The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (Ea) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.


2021 ◽  
pp. 100757
Author(s):  
Akshay Sonawane ◽  
O.P. Chauhan ◽  
Shubhankar D. Semwal ◽  
A.D. Semwal

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2872
Author(s):  
Seyed Mohamad Reza Paran ◽  
Ghasem Naderi ◽  
Elnaz Movahedifar ◽  
Maryam Jouyandeh ◽  
Krzysztof Formela ◽  
...  

The effect of several concentrations of carboxylated nitrile butadiene rubber (XNBR) functionalized halloysite nanotubes (XHNTs) on the vulcanization and degradation kinetics of XNBR/epoxy compounds were evaluated using experimental and theoretical methods. The isothermal vulcanization kinetics were studied at various temperatures by rheometry and differential scanning calorimetry (DSC). The results obtained indicated that the nth order model could not accurately predict the curing performance. However, the autocatalytic approach can be used to estimate the vulcanization reaction mechanism of XNBR/epoxy/XHNTs nanocomposites. The kinetic parameters related to the degradation of XNBR/epoxy/XHNTs nanocomposites were also assessed using thermogravimetric analysis (TGA). TGA measurements suggested that the grafted nanotubes strongly enhanced the thermal stability of the nanocomposite.


Materials ◽  
2017 ◽  
Vol 10 (11) ◽  
pp. 1246 ◽  
Author(s):  
Samson M. Mohomane ◽  
Tshwafo E. Motaung ◽  
Neerish Revaprasadu

2016 ◽  
Vol 34 (10) ◽  
pp. 1175-1184 ◽  
Author(s):  
Giovana Bonat Celli ◽  
Rojin Dibazar ◽  
Amyl Ghanem ◽  
Marianne Su-Ling Brooks

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