Rheological design of thickened alcohol-based hand rubs

Abstract

The handleability and sensory perception of hand sanitisers by consumers affect the hygiene outcome. Spillage may result in under-dosing and poor sensory properties can lead to under-utilisation. We first propose four principles (low runoff, spreadability, smoothness and non-stickiness) for designing the rheology of thickened alcohol-based hand rubs with acceptable handleability and hand feel. We then evaluate a commercial hand gel and a variety of simplified formulations thickened with microgels (Carbopol 974P, Carbopol Ultrez 20 and Sepimax Zen), or linear polymers (Jaguar HP 120 COS), and evaluate them against these design criteria. All four additives provide acceptable spreadability by shear thinning to $$\eta \approx {10^{-1}\,\mathrm{\text {Pa}\text { s}}}$$ η ≈ 10 - 1 Pa s at $$\dot{\gamma }\sim {10^3\,\mathrm{\text {s}^{-1}}}$$ γ ˙ ∼ 10 3 s - 1 . Either the finite yield stress conferred by the microgels ($$\sigma _y \gtrsim {10\,\mathrm{\text {Pa}}}$$ σ y ≳ 10 Pa ) or the increase in low-shear viscosity provided by the linear polymer ($$\eta \gtrsim {1\,\mathrm{\text {Pa}\text { s}}}$$ η ≳ 1 Pa s at $$\dot{\gamma }\lesssim {0.1\,\mathrm{\text {s}^{-1}}}$$ γ ˙ ≲ 0.1 s - 1 ) give rise to acceptably low runoff. However, the formulation using the linear polymer shows a filament breakage time of $$\tau _\mathrm{b} \approx {1\,\mathrm{\text {s}}}$$ τ b ≈ 1 s in capillary rheology, which may result in stickiness and therefore a less than optimal hand feel.

Antimicrobial Efficacy Assessment and Rheological Investigation of Two Different Hand Sanitizers Compared with the Standard Reference WHO Formulation 1

“…In recent years, several studies have been published on the efficacy on the rheological characterization of alcohol-based hand sanitizers, with the final aim of optimizing the formulas by providing greater handleability and hand feel [18,19]. Similarly, this type of formula has been the subject of various efficacy studies to prove the antimicrobial action against the most common pathogenic microflora.…”

Evaluation of Anti-nociceptive and Anti-Inflammatory Effects of Markhamia tomentosa Cream Co-Formulated with Eucalyptus Oil

“…The formulation with the least spreadability was A3, as it had the highest Carbopol concentration, while the formulation with the highest spreadability was A4, having a lower concentration of the thickener Carbopol. A4 also had the lowest viscosity, which explains why it was quickly spreadable [43]. Carbopol is a hydrophilic polymer composed of acrylic acid monomers.…”

Development and Characterization of a Hand Rub Gel Produced with Artisan Alcohol (Puntas), Silver Nanoparticles, and Saponins from Quinoa

“…In the sensory aspect, the gel will be distributed on the skin for 20 to 30 s and dry entirely afterward [52]. For this reason, hydrogels can be considered more desirable than liquid forms due to the effortless application, alcoholic evaporation rate, and increased lethality in microorganisms [53].…”