Influence of wax inhibitor molecular weight: Fractionation and effect on crystallization of polydisperse waxes

Ruwoldt, Jost; Kurniawan, Muh; Sørland, Geir Humborstad; Simon, Sébastien; Sjöblom, Johan

doi:10.1080/01932691.2019.1614946

Cited by 13 publications

(20 citation statements)

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“…Conversely, PPD τ and PPD Ω are manufactured for general purposes, and HPLC chromatograms indicate that both PPDs have narrow molecular weight distributions. 25 Fractionation procedures are implemented to obtain PPD samples with common chemistries but with segregated molecular weight distributions. The prescribed stepwise precipitation procedure successfully separates the broadly polydisperse PPD α and PPD β into samples containing high and low molecular weight polymer fractions.…”

Section: Resultsmentioning

confidence: 99%

“…It is noted that the calculated MW averages are to a certain extent merely estimates, as a portion of the integration signal resides outside the instrument calibration region. 25 The PPD precipitation temperature is an essential property for interpretation of the interaction mechanism between PPD and wax at a given temperature. In the current work, PPDs are applied to model waxy oil samples at a polymer concentration of 500 ppm for subsequent rheological assessment after a cooling rate of 1 C min −1 .…”

Section: Resultsmentioning

confidence: 99%

“…Detailed protocols for the precipitation fractionation and ultrasonic disintegration are presented elsewhere. 25 Molecular weight distributions and molecular weight averages for the original PPDs, derived precipitation fractions, and derived scission products were characterized by HPLC-SEC (high performance liquid chromatography−size exclusion chromatography). NMR-DOSY (nuclear magnetic resonance−diffusion ordered spectroscopy) was used to determine the hydrodynamic radius of the PPD polymers in solution.…”

Section: Methodsmentioning

confidence: 99%

“…NMR-DOSY (nuclear magnetic resonance−diffusion ordered spectroscopy) was used to determine the hydrodynamic radius of the PPD polymers in solution. Detailed protocols of the HPLC-SEC and NMR-DOSY techniques are presented elsewhere, 25 and obtained number-average molecular weights and hydrodynamic radii are summarized in Table 1. Precipitation temperatures of the PPD solutions were estimated by using differential scanning calorimetry.…”

Section: Methodsmentioning

confidence: 99%

“…24 The current report investigates the influence of PPD molecular weight on the treatment efficacy of various PPD chemistries for monodisperse n-paraffin solutions. Selected PPDs, derived PPD fractions, and PPD scission products 25 are doped into an homologous series of monodisperse model fluids containing n-C 24 , n-C 28 , n-C 32 , or n-C 36 in dodecane. The utilized series of paraffin carbon chain lengths facilitates elucidation of component-specific efficacies and interactions.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Wax Inhibitor Molecular Weight on Solution Crystallization and Rheology of Monodisperse Waxes

et al. 2021

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Molecular weight fractionation via stepwise precipitation or chain scission is performed on four pour point depressant polymers to study the pour point reduction mechanism. An homologous series of model oils is prepared by dissolving 5 wt % of a single-component paraffin wax (n-C24, n-C28, n-C32, or n-C36) in n-C12. The polymers are dosed at 500 ppm in the model oils and moderately reduce crystallization temperatures by elevating the nucleation barrier. Polymers containing carboxylate or acrylate moieties also modestly enhance equilibrium wax solubility. Reduction in crystallization temperature is largely independent of polymer molecular weight, except for carboxylate polymers where low molecular weight fractions are largely ineffective. In general, model fluids containing shorter wax chains show a larger reduction in crystallization temperature than model fluids containing longer wax chains. However, yield stress reduction often shows a distinct dependence on polymer molar mass. Low molecular weight fractions of carboxylate and acrylate polymers provide smaller reductions in yield stress than the overall parent fraction. Cross-polarized microscopy reveals that polymers reduce the crystal size, alter the crystal morphology from platelet to needle-like, and induce branching. Crystal branching and formation of dendrite-like structures result from strong polymer binding at the wax crystal interfaces. Hence, single-component wax crystal branching occurs phenomenologically along with yield stress reduction.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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