– R2 = 1/T2. (1)
• R2sp is obtained through normalization with respect to a
reference sample (R°2)
– R2sp = (R2/R°2) – 1 (...
of 1

Polymer Adsorption - A Marks - Poster

Published on: Mar 4, 2016
Source: www.slideshare.net


Transcripts - Polymer Adsorption - A Marks - Poster

  • 1. – R2 = 1/T2. (1) • R2sp is obtained through normalization with respect to a reference sample (R°2) – R2sp = (R2/R°2) – 1 (2) • Plotting the measured R2sp value against (mass of particles) / ( mass of particles + solvent + dispersant) particle as % weight will yield a straight line • It has been shown that the adsorption of polymer onto the particle interface can bring associated solvent molecules to the surface or bind the water at the surface more tightly, enhancing the relaxation rate constant and thus producing a larger R2sp value and an enhancement in the gradient • Non-adsorbed loops and tails, as well as non-adsorbed polymer, have no effect on the relaxation rate Aim: To develop and validate a novel analytical approach to quantify the adsorption of polymeric dispersants onto particle surfaces, by gaining a better understanding of both the capabilities and limitations of the 13.5 MHz XiGo Nanotools Acorn NMR machine. Team members: Student– Adam Marks Supervisor– Dr. Beth Green The contents of this poster are confidential and are for internal use only. No part of this poster should be copied in anyway. • AkzoNobel is a Dutch multinational company which specialises in: – Decorative paints – Industrial coatings – Specialty chemicals • The company operates in more than 80 countries, and employs approximately 50,000 • Owner of multiple household name brands such as; Dulux, Sikkens, Eka & Hammerite • 13.5 MHz XiGo Nanotools Acorn Area bench-top nuclear magnetic resonance (NMR) machine • Low Field NMR Technique: - Relaxation rate of the solvent is studied - Unlike other NMR techniques which normally look at the surfactant / dispersant particles specifically - Measurements must be taken with and without dispersant - Surface adsorption is inferred from the change in the rate of relaxation upon addition of dispersant - Proton spin spin relaxation (T2) values recorded - An increase in available surface area leads to an increase in relaxation rate - A deuterated solvent is not needed- the protons in the solvent are studied Polymer adsorption investigation: • At pH 9 close to the IEP the non-ionic dispersant adsorbs more strongly than the anionic dispersant, this is reversed at pH 5 where the particle is less negative and this repulsion is reduced AkzoNobel Background Instrumental Technique Theory • Technique has been confirmed to show the presence/absence of polymer adsorption for multiple particle surfaces • Adsorption is dependant upon the isoelectric point, patchiness of the inorganic coating and morphology of the surface Results • Colloid Science concerns the design, creation and processing of complex fluids and ‘soft’ solids derived from an understanding of the dispersion, rheology and molecular associations of the systems involved • At AkzoNobel, the focus is on: – the formation, stabilization and characterization of emulsions, dispersions and foams, – controlling the flow behavior (rheology) of products Particle (B) y = 0.59x Particle (A) y = 0.66x Particle (C) y = 0.65x Paritlce (D) y = 0.73x Particle (C) + Disp.(A) y = 0.84x Particle (A) + Disp.(A) y = 0.76x 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 8 9 R2sp Particle / %w/w • Initial results confirm the validity of the solvent relaxation NMR technique for future use in colloidal science • Data is both reproducible and consistent with the relevant theory Particle Without Dispersant y = 4.59x Particle With Dispersant y = 7.33x 0 10 20 30 40 50 60 70 0 2 4 6 8 R2sp Particle/ %w/w Particle (A) y = 0.66x Anionic Dispersant y = 0.82x Non-Ionic Dispersant y = 0.77x 0 1 2 3 4 5 6 7 8 0 2 4 6 8 10 R2sp Particle / %w/w Particle (A) y = 0.69x Anionic Dispersant y = 0.76x Non-Ionic Dispersant y = 0.80x 0 1 2 3 4 5 6 7 8 0 2 4 6 8 10 R2sp Particle / %w/w R2sp vs %w/w at pH 5 R2sp vs %w/w at pH 9

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