Scaling equation for viscosity of polydimethylsiloxane in ethyl acetate: From dilute to concentrated solutions

Airit Agasty,Agnieszka Wisniewska,Tomasz Kalwarczyk,Kaloian Koynov,Robert Holyst

doi:10.1016/j.polymer.2020.122779

Airit Agasty, Agnieszka Wisniewska + Show 3 more

Open Access

https://doi.org/10.1016/j.polymer.2020.122779

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Abstract

Rheology of polymer solutions suffers from lack of universal model of viscosity applicable across wide range of concentrations. Here we build such a model on the basis of measured viscosity of polydimethylosiloxane (PDMS) in ethyl acetate in a wide range of polymer concentrations: from dilute up to highly concentrated solutions. The relationship between viscosity and different polymer parameters in solution such as coil size, correlation length ξ, monomer–solvent and monomer–monomer interaction parameter were established experimentally as a function of concentrations [from 0.001g∕cm3 to 8.000g∕cm3], temperature [in a range 283–303K] and molecular masses [9–139kg∕mol]. Entanglement onset at the crossover from dilute to semi-dilute solution as well as the solvent–monomer contact reduction at the crossover from semi-dilute to concentrated regime are captured by the model. This model is in accordance with the Eyring rate theory for activated processes.

Highlights

Processing of polymer materials in polymer/food industry requires precise control over flow of polymer solutions/ melts
For all molecular weights and concentrations of PDMS-ethyl acetate systems, extensive viscosity measurements were performed at different temperatures in the range 283–303 K, at every 5 K rise in temperature
We have shown that the viscosity scaling form previously established for aqueous polyethylene glycol (PEG) solutions can be applied to solutions of PDMS in ethyl acetate

Summary

Introduction

Processing of polymer materials in polymer/food industry requires precise control over flow of polymer solutions/ melts. Flow of polymer solutions is highly influenced by their intrinsic microstructure, which in turn is heavily dependent on the polymer molecular weight and its concentration [1,2]. Control of the process of polymer flow requires good understanding of viscosity of polymer solutions. The correlation length strongly depends on concentration of polymer in solution. Polymer solutions are usually classified into three characteristic categories depending on polymer concentration: dilute, semi-dilute and concentrated [2,5,6]. In a series of recent papers [3,7,8,9] we analysed the viscosity of polyethylene glycol (PEG) solutions in water in dilute and semi-dilute concentration regimes. We found a characteristic form of the viscosity for PEG–water solution [3,7,8]: η

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